The Frozen Dome

Normally, if I heard or read the words 'Dome C' I would think they referred to the third dome in a cluster of structures at some observatory. Recently, I've come to learn that Dome C is also the name for one of the coldest places on earth, one of several summits on the Antarctic Ice Shelf.

Ironically, there is still an astronomical link. Dome C is considered to be one of the best potential sites for a new observatory on the face of our planet. For one thing, the Sun never gets higher than 38 degrees above the horizon, so there is a lot of night time for observing from the south polar region. Even better, there is almost no infrared sky glow, the air is extremely dry, there is almost no aerosol or dust, and no light pollution. The Antarctic Plateau is the largest desert on Earth, so there is very little precipitation and a very high percentage of cloud-free time. Surprisingly, the wind is also quite mild at Dome C, averaging a mere 6 mph in winter. That is a good thing, considering the average annual temperature is -55C, with lows of -80C and balmy highs in the -25C range. Who needs wind chill when it's that cold?

Most importantly, the seeing is typically 2.5 times better at Dome C than at the best existing observatories. Star images taken through a telescope at Dome C would be 2.5 times sharper and 6 times brighter.

The image on the left is a simulation of a star field as observed from the best existing observatory sites; the image in the middle is the same star field as observed from Dome C. To see as many stars from a mid-latitude observatory, you would need to build a telescope 2.5 times bigger, which would cost ten times as much, and would give the image on the right, which makes the stars look brighter but doesn't improve the sharpness of the image.

Image and text from 'Exceptional astronomical seeing conditions above Dome C in Antarctica', by
by Jon S. Lawrence, Michael C. B. Ashley, Andrei Tokovinin, and Tony Travouillon, published in Nature, 16 September 2004.

Three interesting papers have been released to the pre-print server arXiv.org describing the PILOT program (the Pathfinder for an International Large Optical Telescope), a proposed observatory on Dome C in Antarctica. The first paper presents an overview of the instrumentation suite and its expected performance, a summary of the key science goals and a discussion of the future of Antarctic astronomy.

Paper 2 describes a series of projects dealing with the distant Universe. One potential project that caught my eye is the search for pair-instability supernovae (PISNe) and gamma-ray burst afterglows. These could be our best glimpses into stars formed in the very early days of the Universe. PISNe are predicted to be the product of super massive stars formed in the early history of the Universe. These stars were formed before there were any heavier elements, so their unique chemical composition and masses resulted in a different kind of final disruption of the supernovae progenitors in this era. The light curves of these PISNe are predicted to be have slower rise times and to stay bright for much longer than SN closer to home. This is pretty cutting edge astrophysics, seeing as how no PISN has ever been found.

PILOT could also examine some of the first evolved galaxies and galaxy clusters to inform us of the processes in the evolution of structure in the Universe. They also propose a large-area weak-lensing survey and a program to obtain supernovae infrared light-curves to examine the nature and evolution of dark energy and dark matter.

The ability to do infra-red astronomy from the planet's surface makes PILOT a good match and essentially the only competition for the James Webb Space Telescope in the coming decade.

Paper 3 presents a series of projects dealing with the nearby Universe. Several projects are proposed that examine stellar populations in nearby galaxies and stellar clusters, to gain insight into the formation and evolution of younger galaxies and stars.

Other projects will investigate the formation processes of stellar and planetary systems. Three projects in the field of exoplanet science are proposed. These include a search for free-floating low-mass planets and dwarfs, a program of follow-up observations of gravitational microlensing events, and a study of infrared light-curves for previously discovered exoplanets.

Free-floating low-mass planets; now there is a category of interesting objects. The plan is to examine nearby star clusters to search for planets not associated with stars down to several Jupiter masses. Why would astronomers be so interested in free floating planets? Because typically, exoplanets light is difficult or impossible to disentangle from the light of their accompanying star. If we can find exoplanets free of the overpowering glare of their host stars we can study the chemical composition and atmospheric properties of these planets.

And finally a study of coronal mass ejections from the Sun, and a monitoring program searching for small-scale Low Earth Orbit satellite debris items are also proposed.

The opportunities to do exciting, results-oriented science exploration and discovery from Antarctica is is almost as mind-numbing as the night time temperatures resident astronomers and technicians will have to bear to perform the work.

Constructing, operating and maintaining a telescope at the bottom of the world under these conditions will be another great story. Now that I know about Dome C and PILOT, I'll keep an ear to the ground and let you know when there are new developments.

Dr. Andrew Drake Interview

Andrew Drake is a Research Scientist with Caltech's CACR (Center for Advanced Computer Research) in California. His astronomical interests are varied, and include exoplanet discovery, microlensing of Machos and other baryonic dark matter, Supernovae/Hypernovae and mining large data sets. He is the principle investigator for the Catalina Real-time Transient Survey.

Because one of the byproducts of the CRTS is the discovery of numerous cataclysmic variables I thought it would be interesting to have him to tell us about the methods and goals of the CRTS team, and what they are doing with all the new science coming out of their survey.

Mike: Hi Andrew. Thanks for granting this interview. Let's start off with a description of the Catalina Real-time Transient Survey, the methodology, it's science goals, and then discuss what your group is doing and what you're learning. So first, what telescopes and instruments are used for CRTS?

Andrew: It is my pleasure. The Catalina Real-time Transient Survey (CRTS) currently uses data from the Catalina Sky Survey's (CSS) 0.7m Schmidt telescope. The CSS team hunts for Near Earth Objects (NEOs) while we hunt for other kinds of stationary optical transients.

Mike: What is the observing cadence and how much of the sky do you cover?

Andrew: The Schmidt has an eight square degree fov and covers the visible sky between -30 and +70 degrees.
However, we avoid the Galactic plane by 10 degrees because of crowding. About 1200 square degrees is observed four times on each of the 21 darkest nights per lunation, to V~20.

Mike: Your interest and the science you are going after seems to relate mostly to supernovae in general and then supernovae in faint galaxies, correct? What are you hoping to learn from the survey?

Andrew: Our interest is in optical transients of all kinds. However, we are particular interested in the rare kinds of transient phenomena that can only be found through synoptic surveys covering a very large area. Two particular types of transients that have become of interest since we started the survey, supernovae in faint galaxies, and hypernovae.

Mike: In order to study these supernovae you need a way to filter out all the other stuff you're not looking for, which includes asteroids, cataclysmic variables, other types of variables, image artifacts, etc. You have to be able to classify objects quickly and accurately. I imagine that is one of the bigger challenges in your work. How do you go about doing that?

Andrew: Filtering artifacts and asteroids is perhaps the most difficult part of the survey. Fortunately most asteroids are known to the depth of our observations and can be removed using the ephemeris files that the Minor Planet Center (MPC) distributes. Additional asteroids and artifacts can be removed checking for motion, or offsets, between images. Even so, there is a balance between missing some real transients with strict filtering or allowing some junk through with looser filtering. We have never tried to filter CVs because we know many people are interested in them, particularly when they are in outburst. To improve classification we follow-up almost everything we discover with the Palomar 60" and also make this data public. Our hope is to obtain fully automated classification network to replace the final classification which still must be done by a person (gathering all data sources, cross-checking and making a decision). We hope our future automated classification will enable rapid robotic follow-up of short timescale transients.

Mike: What results have you found so far in your supernovae studies?

Andrew: One surprise to us was that a large fraction of the supernova we find are in intrinsically very faint galaxies. This is not expected because there is much more stellar mass in large galaxies and nobody has seen this before. We believe the reason this has been missed in the past is that most searches for nearby supernovae follow only a few hundred very bright galaxies. The increased SN rate in faint galaxies appears to be mainly due to an extremely high star formation rate in some low mass dwarf galaxies. One particularly interesting SN we discovered was 2008fz.

Mike: What was so special about SN2008fz? Was this a hypernova? What is the difference between a supernova and a hypernova?

Andrew: SN2008fz was a type IIn supernova discovered by CRTS and appears to be the most energetic supernova ever discovered. Such bright supernovae are often called hypernovae and are proposed to be the result of either the collapse of a massive star like Eta Carinae or an extremely massive population III star. The exact origin of hypernovae is not yet clear as few have been discovered. They up to a few magnitudes brighter thanregular type Ia and type II SN and have also been linked to exceptionally bright gamma ray bursts.

Mike: Now you've developed some tools and resources for amateurs and others to use to follow up on newly discovered CVs from CRTS. Tell us about that.

Andrew: When we classify our detections place them on a number of web pages where we hope people will find and follow them. New bright CVs are among our most common discoveries, although we include known CV outbursts also. As with all our discoveries these are made public as quickly as possible. Our hope was that people would work with us on the discoveries or at least inform us that they are following CVs, as they do with supernovae. Unfortunately, we find that they are taken from the webpages and circulated to email lists where they are quickly renamed and followed and even published under that name. Nevertheless, we are continuing to openly publish the new CV discoveries.

Mike: You're also logging data collected serendipitously on known CVs. Is there a plan to share these observations with AAVSO or other researchers? Is there maybe a project here for the CV section, or perhaps the data mining section, to convert your data into a format that can be periodically entered into the AAVSO International Database?

Andrew: Yes, as we cover a large fraction of the sky every lunation we realized that the data would regularly cover thousands of CVs and other interesting variables. We thought it may be useful for us to provide up to date measurements for known interesting objects so that CV astronomers might follow-up those that that they deem interesting. We certainly hope that the AAVSO will ingest this data.

Mike: So what are the plans for the future? Are you going to expand the project? How long do you think you will continue?

Andrew: Soon we hope to start processing the data from two additional dedicated CSS telescopes that use the same camera setup. There are also plans to expand the fields of the existing telescopes by a large factor. Depending on funding we plan to continue for three more years. Part of our goal is to make all the past CSS data public so that everyone may perform their own searches for variables, etc., among the tens of terabytes of existing images and photometry.

Mike: Well, I wish you the best of luck. Let's do this again some time. You can bring us up to date on what has developed for you and your team, and it will give us an opportunity to thank you for all the interesting CVs you're going to discover for us in the meantime!

Andrew: You are most welcome.

Tom Boles- Supernova Supersleuth

In August 2009, British amateur astronomer, Tom Boles broke Professor Fritz Zwicky�s 36-year-old record for the number of supernovae discovered by an individual when he bagged his 124th supernova. The fact Tom has been so prolific, observing from the cloudy, rainy United Kingdom makes this record even more remarkable.

Tom has graciously agreed to give us a look inside the process, the tools and the reasons behind his stunning success.

Mike: What brought you to astronomy in the first place, and how did that evolve into a passion for discovering supernovae?

Tom: Hi Mike it�s good to talk to you.
Like so many amateur astronomers it happened at school. A boy in my class brought in a small telescope and let me look through it at Saturn and the Pleiades. (I lived in Scotland then and it is dark at 5 pm in winter) I was hooked immediately.

Searching for supernovae seemed a logical progression. I have always been interested in cosmology so there is a strong tie as supernovae are essential tools for studying the large scale Universe.

As you rightly say, the skies in the UK are less than ideal. It is difficult to find many good nights suitable for photometry but there is rarely a clear night when I don�t attempt to look for SNe. Even on very poor nights the brighter galaxies can be imaged. They are often not pretty pictures that I record but suitable for purpose, only the limiting magnitude drops.

Mike: Tell us about the observatory. Where is it located, how was it financed and built and what instruments do you currently employ in your search program.

Tom: The observatory is based on the periphery of a little quiet town called Coddenham in the heart of rural Suffolk in the UK. I moved here from central England because the light pollution there had deteriorated. Suffolk also offered me the chance to get a few extra clear nights each year. As a rule, the weather system in the UK improves slightly as you move farther east and south.

There are only two street lights in the village and they are in a dwell which keeps their glow hidden on all but the mistiest nights.

The observatory was privately financed by me. It was part of my �master plan� when I took early retirement to get more involved with astronomy and supernovae in particular. I use three C14 SCTs on Paramounts. Two of my Paramounts are the original design and were the early form of the new ME. The third is the slightly later black version the 1100 which was the immediate precursor to the ME. I use three Apogee AP7, thinned and back illuminated CCD cameras which help me to get use from every photon the C14s provide. I think this is near the ideal set up for supernova hunting other than moving to much larger telescopes.

I did have a scare a couple of years ago when the observatory was struck by lightning. I lost three PCs, my network and one of the Paramount�s electronics. I was down for several months. Thankfully I had excellent support from Software Bisque who patiently talked me through replacing several controller boards that they supplied. I was glad on the excellent support that I received.

I built the observatory myself, not that I wanted to but when I described what I wanted to professional shed builders they just laughed and shook their heads. On reflection, I am glad that I did. Many challenges arose during the construction. I could work them out in bed at night. Had I had a tradesman it would have overrun and cost me a fortune.

Mike: How much of the process is automated? Do the telescopes work unattended, controlled by software, or do you control them to some degree from a control room nearby?

Tom: The telescopes are controlled over a local area network. The control room is in my house only about 100 feet from the observatory. I produce scripts, which consist of lists of target galaxies for the cameras to image. They point, settle for a few seconds, image, name and store each image automatically. A typical script is 200 galaxies long and will run unattended for up to 4 hours. I rarely leave them unsupervised in case the weather changes. On good nights I use 30 second integrations and on poorer nights 60 seconds. This can mean I collect up to 135 images an hour between the 3 systems. The image collection is the easy bit. Checking the images is where the hard work is. In mid winter, darkness can last 13 or 14 hours; that�s a lot of images. I use one PC to control each telescope and another indoors to monitor the images coming down and to ensure all is well. An additional one with an extra large screen is used to check the images against my master/library images.

Mike: You currently monitor around 12,000 galaxies. How has your search program evolved over time? Do you monitor a specific type of galaxy to maximize your efforts?

Tom: I started off very modestly just checking a few galaxies. That meant nice open face on spirals that maximized the chances of seeing the supernovae free from obscuring dust in the galaxy. I then added edge on spirals and moved on to others like SO galaxies and even irregulars and ellipticals. I use a galaxy�s size and recession velocity to give me an indication whether the SN will be too faint to see or not. To get to 12,000 galaxies I had to drop some of my criteria and add many other morphological types. Eventually the recession velocity (galaxy distance) where it was known, was the only criterion. I patrol 12,000 frames, that is, master fields. In practice there is often more than one galaxy in the same field so the full image needs to be checked.

As I added more and more galaxies I started to look for ways of making the search more effective. I soon split my galaxies into 3 categories depending on their brightness and distance. I do the easier ones on the poorer nights and vice versa. I also run a patrol worksheet which schedules how often I try to observe any given galaxy. This is to make sure that every part of every script gets sufficient attention. I also changed the order that I patrol galaxies so that the telescope has the minimum of movement between images. This speeds things up and maximizes the number of images I can capture. More images of course mean more supernovae.

I also never leave anything to memory. In the small hours your brain is not at maximum efficiency. I use a check list that I mechanically go through to eliminate anything that might not be a real supernova.

Mike: How many images have you taken to discover 127 supernovae, as of November 2009? Do you examine each one by eye, or do you have some part of the �blinking� process automated as well?

Tom: I often get asked this question and fortunately it is easy to answer. I keep a very detailed log book of all my patrols. I also store every image that I have ever taken. These are used to eliminate unknown variables that appear in the fields. I check every image of a galaxy before I report a suspect. This sounds tedious but it isn�t. The log book and filing system make it easy.

I have recently celebrated breaking through the 500,000 count for images. It doesn�t take too much arithmetic to estimate the average discovery rate by patrol number and the number of hours spent patrolling.

I use two blinking methods. This is a recent development and has helped my productivity immensely. I use a small program called �GrepNova.� This is a free program developed for me by Dr Dominic Ford from Cambridge University.  A search on Google will show this up. The other program I use is Visual PinPoint. Each of these is best suited for different types of field, that is, whether the field has many reference stars or not.

Mike: Do you do follow up observations, and build light curves of your discoveries, or do you just keep the telescopes churning, looking for new ones?

Tom: The only time I do follow ups is when requested by a professional team who is also working on the supernova. I have no filters mounted on any of my systems so that I can get the maximum limiting magnitude on any given night. I usually achieve a limiting magnitude of around 20.5. I usually only admit to 19.5 to keep my reporting easier. That does mean that most of my discoveries are in the range 17.5 to 18.5. My skies are very challenging to do photometry on SNe this faint.

Mike: Can you explain the difference between the two types of supernovae, and why they are astrophysically interesting or important?

Tom: This used to be easier to answer than it is today. Once upon a time it used to be type Ia SNe and all the others. Type Ia are the sexy ones at the moment. Lots of progress has been made recently with these. They are not standard candles as once thought but they are �standardizable� candles. This means that they can be used to measure cosmological distances and so discover the size and age of the Universe. They were used to discover the acceleration of the Universe at the end of the last century. All the others are core collapse supernovae. These occur when massive stars reach the end of their lives. These include all the type II SNe and the Ib and Ic types. The latter are often associated with Gamma Ray Bursters (GRBs) and are particularly interesting. Core collapse SNe shed their inner elements into space. By measuring the elements present and their quantities, it is possible to model what is happening in stars� hidden interiors.

Mike: Have any of your discoveries been unusual or special, resulting in a research paper or further investigation with larger telescopes or satellites?

Tom: These change constantly. I was very proud of 2003L. This was the second most powerful supernova in history. That record didn�t last too long as new specimens keep getting discovered. Only last week a new paper was published describing one discovered behind the Magellanic Cloud that pushes it into somewhere like 5th or 6th place.

Strangely, I was also a co-author in a paper published in Nature on 2006jc. This was a SN that �appeared� twice, once in a pre-explosion years earlier and then finally in 2006. It was a very useful tool for astrophysicists. I didn�t even discover that one. All I did was use my 12 years of archived data to prove that it hadn�t flared at any other times. There�s a good lesson here about keeping conscientious notes and logs.

My latest is still current and is the optical transient UGC2773-OT that I discovered in August 2009. Five teams are currently working on this very sub-luminous candidate. It is probably not a SN at all but an unusual outburst by a Luminous Blue Variable (LBV) star. It is only visible because the galaxy is so close. The precursor has been imaged by the HST.

All the major telescopes in the world, and in space, have followed up one or more of my supernovae. The VLA in New Mexico follows up all the radio noisy ones like 2003L. Very often a barrage of telescopes gets involved with the interesting ones, including the HST and space telescopes such as Chandra. My biggest thrill was when the 200 inch Hale was used. This was the biggest telescope in the world for so long when I was a boy and I remember marveling at its pictures at school. It is a thrill to know that these telescopes are looking at something because of something that I did. Patrolling is a lot of hard work and seeing large telescopes following up on your work keeps the motivation alive.

Mike: Is it still as fun and exciting after 127 discoveries as it was when you first started some 13 years ago?

Tom: I think it is more fun. When I made my first discovery I was terrified. I didn�t know what to do or whom to tell and I was afraid that I could make a false report. I was stressed for several days until it was confirmed spectrographically. With more experience that fear goes away (not entirely, which is good, so the buzz is still there) as a result I can enjoy my discoveries more as they happen.

Mike: Do you ever do any other kind of observing, like enjoying the night sky with a pair of binoculars or a small telescope while the C-14s are busy patrolling the universe?

Tom: I have a whole range of telescopes and binoculars. It will be a sad day when I stop using eyepieces. I have a ten inch that I use for visual use. I also take it to local schools and groups for Outreach sessions. In a few weeks I am accompanying a group of tourists over the Atlas Mountain in North Africa as their �teaching� astronomer. They want to learn something about the skies and discuss cosmology over several bottles of wine by the camp fire in the evening. Astronomy is fun no matter how you do it. If it ever stops being fun I will stop doing it.

Mike: Do you have any advice for anyone considering supernova searching?

Tom: First of all expect some hard work before making your first discovery.  AND IMPORTANTLY, you DON�T need expensive telescopes to do it. The Messier galaxies are being neglected by most patrollers. They are just too big for our tiny CCD chips. It would take me all night to check M31 properly. Visually it can be done in seconds. So the advice is, check the messier galaxies and the Caldwell and the brighter NGC galaxies. Do it as part of your normal observing run. The key is not just to look but to check. Some discoveries have been photographed by other people first but they didn�t check their images. Looking is not the same as checking. A SN discovered in one of these bright galaxies is often more valuable scientifically than a dozen fainter ones.

Finally, speak to someone already doing it and get encouragement and advice. They will save you a lot of effort.  Most patrollers are happy to help. I am happy to help anyone wanting to give it a try.

Mike: Is there anything else on your supernovae wish list, like finding one in our own galaxy?

Tom: I need to be realistic. The first person to discover a SN in our galaxy won�t be me with my narrow fields of view. It will be someone walking along a lane and looking up, enjoying the sky, and spotting a constellation that no longer looks familiar. It will happen. Our next galactic supernova is well overdue. I bet when it comes it will be like busses, two or three will come together.

From a personal point of view I would like to discover another type Ic SN similar to 2003L probably associated with a GRB.  SN2003L didn�t fit any of the theories for how central engines power SNe. Alicia Soderberg at the VLA in New Mexico proposed that it might be a new type of SNe. It was a very powerful SN with a very weak central engine. I won�t hold my breath. Even if it is, less than 1% of SNe are bright enough to qualify, so it could take longer than the next SN in our galaxy to prove it.

Mike: Thank you, Tom. It�s been great learning all about you and your discovery process.

Tom: Thanks Mike. It�s been a pleasure and privilege to take part.



You can see Tom's observatory and the full list of his supernovae discoveries at his observatory website.

Caroline Moore and Supernovae on Slacker Astronomy

The latest Slacker Astronomy podcast is all about various types of supernovae and features an interview with the youngest person to ever discover a supernova, Caroline Moore.

Caroline Moore (middle) displays the award give to her by the AAVSO in November 2009.

Paula Szkody, AAVSO President (left) Arne Henden, AAVSO Director (right)

So click here or go to http://www.slackerastronomy.org/wordpress/ to hear the latest podcast.

T Pyxidis: The Story That Just Won't Die

Normally I wouldn't do this, but this story has propagated itself so widely through the internet and blogosphere I feel I have to chime in, if for no other reason than to help set the record straight. So what you are about to read is a story about a Tweet about a blog, about a blog, about the other blog, about several news articles, about a press release, about a research paper about...a variable star.

Artists image of the recurrent nova RS Oph

Credit: David Hardy/PPARC

It all started last week when Edward Sion and his team from Villanova announced results of research they had done on the recurrent nova, T Pyxidis. Among other things, they claimed this recurrent nova may be at or near the tipping point in its evolution, and that it will someday (soon) become a supernova. They also re-estimated the distance to T Pyx as being much closer than thought before, approximately 3300 light years distant. Then the misinformation bomb was dropped, as the last bit of their press release states:

"...gamma radiation emitted by the supernova would fry the Earth, dumping as much gamma radiation (~100,000 erg/square centimeter) into our planet, which is equivalent to the gamma ray input of 1000 solar flares simultaneously."

Even though these claims were disputed at the press conference by other supernovae experts in attendance, namely Alex Filippenko, the genie was out of the bottle and before you could say, "Wait, you don't understand!", the popular press was claiming the end of the world was near.

The Daily Telegraph ran with the headline Earth 'to be wiped out' by supernova explosion, The Sun ran The death star, and bloggers began trying to undo the damage. Unfortunately, they managed to splurt out some erroneous or misleading information of their own.

First, let me begin by saying, astronomers do not really know for sure what the progenitors of supernovae explosions are. We have some very convincing arguments and theories, but there are still entire astronomical conferences held on this subject each year, presenting differing points of view based on new observations and models.

The main reason they are so interesting to astronomers is because type 1A supernovae are used as standard candles to determine the distances to galaxies too far away to estimate their distance any other way. All of our theories on the history and future of the Universe are based largely on measurements of galaxies at high redshifts. The whole theory of the acceleration of the expansion of space is based on galaxies not behaving as predicted, based on measurements of distance based on...you guessed it, type 1A supernovae measurements.

The connection between supernovae and recurrent novae is not firmly established. Yes, they MAY be part of the population of progenitor systems that eventually become supernovae, but we don't know this for sure. If they are, well that makes them a much more interesting type of variable star, which also makes it easier to obtain observing time on a space telescope, or a grant to do research on them. So for those studying recurrent novae this is a convenient connection to try to make. After all, refining the cosmological distance scale and the expansion of the Universe, and how that relates to dark matter and dark energy are some of the hot, sexy topics in astronomical research these days.

Claiming a supernova could release as much gamma radiation as Scion and colleagues claimed is factually incorrect. Phil Plait does an excellent job of explaining the relative damages a supernova or a gamma-ray burst in our galaxy could do to the Earth in his book 'Death From the Skies', and a supernova explosion at that distance has no chance of damaging our planet.

Unfortunately, Phil did manage to get some of the facts about recurrent novae wrong in his blog rebuffing Scion's claims when he wrote, "Lots of recurrent novae are known, and are fairly well understood."

Not exactly. The currently known recurrent novae are T Pyx, IM Nor, CI Aql, V2487 Oph, U Sco, V394 CrA, T CrB, RS Oph, V745 Sco, and V3890 Sgr. That is only ten stars. Out of the billions of stars in our galaxy, thousands of known cataclysmic variables and hundreds of known galactic novae, ten are known to be recurrent novae. Recurrent novae, like R CrB type stars are actually quite a rare phenomena, as far as we know.

If they were fairly well understood, the definitive paper to date on the subject of their history and behavior, Comprehensive Photometric Histories of All Known Galactic Recurrent Novae by Bradley E. Schaefer, would not still be asking at its heart: What is the death rate of RNe in our galaxy, are the white dwarfs gaining or losing mass over each eruption cycle, and whether or not RNe can be the progenitors of Type Ia supernovae.

Given a little time to reconsider what he wrote, I'm sure Phil would change that sentence. On the other hand, I have to give him credit for coining one of 2010's leading candidates for 'best skeptical science phrase' when he came up with "disaster-porn".

"There was no need to disaster-porn this release up the way it was done. Recurrent novae and Type Ia supernovae are fascinating, well worth our attention for any number of reasons including of course their potential danger."

My friend, Ian O'Neill, has commented on this situation also, on the Discovery Space News and AstroEngine.

The last bit of misinformation that really needs to be adrressed before leaving this subject, is the notion that any of this will happen any time soon. The title of the press release, "The long overdue recurrent nova T Pyxidis: soon to be a Type 1A supernova", was as misleading as the facts presented.

Soon on human, everyday-guy-on-the-street terms, means this week or this year. When astronomers use the word 'soon' or the phrase 'in a short time' they can and do usually mean tens of thousands or millions of years. Not much at all happens soon with recurrent novae, that is one of the reasons we know so little about them. Recurrent nova eruptions happen on human time scales of decades or possibly once per 100 years. To astronomers these are relatively short time scales, as compared to the thousands or millions of years between classical nova eruptions or the billions of years it takes for most stars to evolve and show any change at all. But that means that since we've been paying attention and monitoring the sky with cameras and telescopes keeping records, we've only seen these recurrent novae go into outburst a few times in history.

In fact, if you now the story of T Pyx, you know that one of the things that makes it interesting is the fact that it is overdue for a recurrent novae outburst. If it had kept to its usual pattern it would have already erupted some time ago. But if you read the Schaefer paper, he explains that T Pyx is actually evolving into a new type system and may not erupt again for hundreds of years, and "soon" won't be a recurrent nova at all.

"We now realize that what has happened is that the T Pyx accretion rate dropped substantially soon after the time of the last eruption, so it will be a long time until the next eruption (Schaefer 2005). Indeed, a more detailed accounting that includes the recent declines since 2005 plus the associated larger trigger mass implies that T Pyx won�t erupt for many centuries (Schaefer et al. 2009). Also, with the likely continuing decline in accretion, T Pyx will soon be going into hibernation, and thus will not suffer any further RN events for almost a million years (Schaefer et al. 2009). That is, T Pyx has stopped being a recurrent nova."

Recurrent novae are rare and beautiful beasts in the cataclysmic variable zoo. Their eruptions and behavior are interesting enough to garner our attention. There really is no need to "disaster-porn" their stories to make them interesting to the astronomical community or the public.

Brad Schaefer is a very enthusiastic and engaging speaker. If you haven't heard this before, check out my interview with him on Slacker Astronomy where we talk about recurrent novae, and T Pyx.

Will the Real SN 2010O Please Come Forward

This morning's email contained an interesting story about Supernova 2010O. That is just an odd looking name isn't it? SN 2010O, weird.

The naming convention for supernovae is pretty straightforward. At the beginning of each year we roll back the names to the beginning of the alphabet and each supernova discovered is given a name that is the year followed by a capital letter. Thus, the first supernova this year was named SN 2010A, the second one SN 2010B and so on. After they use up the single letters, they begin adding double lower case letters, aa, ab, ac and so on. So SN 2010O was the 15th supernova discovered this year.

According to the Central Bureau for Astronomical Telegrams (CBET) #2143, published January 24, SN2010O was discovered 2".6 east and 1".3 north of the nucleus of the galaxy IC 356.

IC stands for Index Catalogue, which is a catalogue of galaxies, nebulae and star clusters first published in 1895. Since then it has expanded to list 5,387 objects, known as IC objects.

First thing this morning CBET 2144 reports "that a spectrum obtained last night of the purported supernova found in IC 356 (as reported by Dimai on CBET 2143) is in fact the spectrum of a foreground star, not a supernova."

OOPS! I don't recall ever seeing that before. Usually, these things are confirmed as supernovae before being given an official designation. Ah well, nobody's perfect. So what happens when a mistake like this is made?

The IAU can't have a star named with a supernova designation, and they can't skip a letter, no, no! Instead, they have decided to name the next supernova discovered SN2010O, and the lucky winner is...envelope please...(drum roll)...a new discovery from J. Newton and T. Puckett, located at R.A. 11h28m33s.86, Decl. +58o33'51".6, which is 3".7 east and 5".7 north of the center of its apparent host galaxy, NGC 3690.

Supernova 2010O
Image from J. Newton and T. Puckett
Puckett Observatory Supernova Search

U Sco: Long Anticipated Eruption Has Begun

Today, two amateur astronomers from Florida detected a rare outburst of the recurrent nova U Scorpii, which set in motion satellite observations by the Hubble Space Telescope, Swift and Spitzer. The last outburst of U Scorpii occurred in February of 1999. Observers around the planet will now be observing this remarkable system intensely for the next few months trying to unlock the mysteries of white dwarfs, interacting binaries, accretion and the progenitors of Type IA supernovae.

Artists rendition of recurrent nova RS Oph 

Image credit: David Hardy and PPARC

One of the remarkable things about this outburst is it was predicted in advance by Dr. Bradley Schaefer, Louisiana State University, so observers of the American Association of Variable Star Observers (AAVSO) have been closely monitoring the star since last February, waiting to detect the first signs of an eruption. This morning, AAVSO observers, Barbara Harris and Shawn Dvorak sent in notification of the outburst, sending astronomers scrambling to get �target of opportunity observations� from satellites and continuous coverage from ground-based observatories. Time is a critical element, since U Sco is known to reach maximum light and start to fade again in one day.

There are only ten known recurrent novae (RNe). This, coupled with the fact that eruptions may occur only once every 10-100 years, makes observations of this rare phenomenon extremely interesting to astronomers. Recurrent novae are close binary stars where matter is accreting from the secondary star onto the surface of a white dwarf primary. Eventually this material accumulates enough to ignite a thermonuclear explosion that makes the nova eruption. �Classical novae� are systems where only one such eruption has occurred in recorded history. They may indeed have recurrent eruptions, but these may occur thousands or millions of years apart. RNe have recurrence times of 10-100 years.

The difference is thought to be the mass of the white dwarf. The white dwarf must be close to the Chandrasekhar limit, 1.4 times the mass of the Sun. This higher mass makes for a higher surface gravity, which allows a relatively small amount of matter to reach the ignition point for a thermonuclear runaway. White dwarfs in RNe are thought to be roughly 1.2 times solar, or greater. The rate at which mass is accreted onto the white dwarf must be relatively high also. This is the only way to get enough material accumulated onto the white dwarf in such a short time, as compared to classical novae.

Recurrent novae are of particular interest to scientists because they may represent a stage in the evolution of close binary systems on their way to becoming Type IA supernovae. As mass builds up on the white dwarf they may eventually reach the tipping point, the Chandrasekhar limit. Once a white dwarf exceeds this mass it will collapse into a Type IA supernova.

A problem with this theory is the mass that is blown off the white dwarf in the eruption. If more mass is ejected during an eruption than has accreted during the previous interval between eruptions, the white dwarf will not be gaining mass and will not collapse into a Type IA supernovae. Therefore, scientists are eager to obtain all the data they can on these eruptions to determine what is happening with the white dwarf, the mass that is ejected and the rate of accretion.

 Observations from amateur astronomers are requested by the AAVSO. Data from backyard telescopes will be combined with data from mountaintop observatories and space telescopes to help unravel the secrets of these rare systems. AAVSO finder charts with comparison star sequences are available at: http://www.aavso.org/observing/charts/vsp/index.html?pickname=U%20Sco

Caroline Moore- Astronomer, Singer and An Amazing Kid

Getting to know young people like Caroline Moore gives me hope for the future. Caroline, as you may know, is the youngest person to discover a supernova. I first met Caroline when I interviewed her for a Slacker Astronomy episode last November in Boston. She had been invited by the AAVSO to come and accept an award for her achievement.

Today the Nova Science Now website features Caroline in their online series The Secret Life of Scientists. They did a great job of editing and presenting these pieces, but what really comes through in these bits is Caroline's personality. She has lots of that. I love the 30 seconds video. I'll be saying, "whatever", and laughing for weeks.

Congratulations, it's a Supernova!

Last night after dinner, I laid down to take a nap (I start observing
around midnight or so in summer). I heard a message come in on my
phone, so I checked to see if it was anything important. As it turns
out, it was an urgent plea for help from Bob Moore (Caroline Moore's
dad, the teenage girl who discovered a SN at age 14). He is trying to
confirm a suspected SN discovery but can't find any useful comparison
stars near the obscure galaxy he is examining, can I please help?

Mind you, I only get a few hours sleep a day when its clear, so I was
thinking, "shit, why did I have to check that message."

Well, Bob is a friend and I know how excited I would be if I thought I
had a SN discovery, so I called him, got the information and went back
down to the office to see if I could help him. After maybe 45 minutes
or so I had put together some reasonable photometry for him to measure
his SN with, emailed him the chart and wished him luck. I fell asleep
quickly after that.

Around lunch time today, I called Bob to see if there was any news
yet; had it been confirmed? "Nothing yet", he said, but Mike Peoples
and collaborators were pretty sure they had confirmation images from
California.

About an hour ago the Telegram from the IAU announcing the discovery
of SN 2010ew popped up in my mailbox. I forwarded a copy to Bob with
the title "Congratulations, It's A Boy".

I'm happy for you Bob et al, but don't call me after 6PM tonight. I'm
really tired now, and it's going to be unmercifully clear here for
days on end. I need some sleep.

*******************************************************

Electronic Telegram No. 2345
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director:  Daniel W. E. Green; Room 209; Dept. of Earth and Planetary
 Sciences; Harvard University; 20 Oxford St.; Cambridge, MA  02138; U.S.A.
e-mail:  cbat@iau.org; cbatiau@eps.harvard.edu
URL http://www.cfa.harvard.edu/iau/cbat.html


SUPERNOVA 2010ew
   M. Peoples, J. Newton, and T. Puckett report the discovery of an apparent
supernova (mag 16.6) on unfiltered CCD images (limiting mag 18.5) taken with
a 0.40-m reflector at Portal, AZ, U.S.A., on June 28.39 UT in the course of
the Puckett Observatory Supernova Search.  The new object, which was confirmed
at mag 16.6 on images (limiting mag 19.8) taken by P. Mortfield and S.
Cancelli on June 29.48 with a 0.40-m reflector at Sierra Remote Observatories
in California, is located at R.A. = 18h37m11s.88, Decl. = +30o37'49".6
(equinox 2000.0), which is 4".6 west and 7".1 north of the center of the
presumed host galaxy.  Nothing is visible at this position on images taken by
Puckett on June 13 (limiting mag 19.1); however, T. Orff reports a precovery
image (limiting magnitude of 18.5) taken by Puckett on June 20, which shows
2010ew at mag 17.1.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
    superseded by text appearing later in the printed IAU Circulars.

                       (C) Copyright 2010 CBAT
2010 July 1                      (CBET 2345)              Daniel W. E. Green

A Question of Identity

KAIT telescope

Question: When is a supernova not a supernova?

Answer: Now that's an interesting story...

It all started on Christmas night 2005, when astronomers using the Katzman Automatic Imaging Telescope (KAIT) in California discovered an apparent supernova not far from the center of the elliptical galaxy NGC 2274. There was nothing there on an image they had taken two weeks prior. Twelve hours later, Astronomers at the National Astronomical Observatory of China confirmed the 18th magnitude object was real. It was named SN2005md and the discovery was announced in CBET #332 on December 26.

A spectrogram taken on December 28 showed it to be most probably a "young Type-II supernova". This was announced in an IAU Circular (8650) on the 29th of December. Subsequent KAIT images showed that SN2005md faded rather quickly and it was fainter than magnitude 19.8 by January 2006.

Normally that would be the end of the story, but this time it wasn't.

First, it is generally accepted that the progenitors of core-collapse supernovae are massive young stars. These massive young stars are almost always found in spiral or irregular galaxies dominated by young stellar populations.

NGC 2274 is a strangely shaped early irregular galaxy (an E-type galaxy), so SN2005md was unusual. In fact, it was only one of 22 examples found in an extensive literature search of all early irregular galaxies containing core-collapse supernovae in history.

A paper published in 2008 by Hakobyan et al. (2008, A&A, 488, 523) examined all these cases and found that 19 of the galaxies had been mis-classified, and were actually spiral (17), irregular (1) or ring (1) galaxies. Of the 3 remaining galaxies with early type classification, one (NGC 2768) is a suspected merger remnant, another (NGC 4589) is definitely a merger, and the third (our NGC 2274) is in close interaction with another galaxy. This seemed to explain the contradiction of core-collapse stars residing in old non-star-forming irregular galaxies, since some amount of young stellar population in these interacting galaxies is expected.

Well then, all was right in the Universe once more...or was it.

In February 2008, while Hakobyan and company were putting the final touches to their paper for submission, an electronic telegram (CBET 1265) was issued announcing that either a new supernova in NGC 2274, very close to the position of SN2005md has erupted at magnitude 18.5, or that SN2005md itself had suddenly re-brightened!

The difference between the previously reported position of SN2005md and the "new" object was on 0.1 arc seconds in R.A. and 0.4 arc seconds in declination, but at the distance of NGC 2274 (estimated to be 70 mega parsecs) that could mean they were unrelated objects 120 parsecs apart. Measuring the exact positions of anything that faint close to a galaxy is tricky business and the likelihood they were the same object seemed greater than the probability they were two SN in the same galaxy that close together.

The fact that the previously reported spectrum only showed a featureless blue continuum, with no obvious broad supernova features, and that the object faded so quickly added to the suspicion that SN2005md wasn't a supernova at all.

The telegram went on to explain if the new object was indeed a re-brightening of 2005md, possible explanations were that it was the super-outbursts of a luminous blue variable (LBV), or multiple flares of the LBV as part of an extended eruption.  Other possible explanations included a Galactic variable star or a background AGN/blazar.

Needless to say, SN2005md was a mystery. Further observations were encouraged.

Flash forward to July 2010. Astronomers Telegram (ATEL) #2750 finally sorts it all out for us. A fully reduced spectrum taken with the LRISp on the Keck I 10 meter telescope on December 31, 2005 shows that the object originally classified as a young Type IIb supernova is in fact a galactic cataclysmic variable. That's right, it's in our own Milky Way galaxy. NGC 2274 just happens to lie in the background very close to its position on the sky. The CVs spectrum shows features typical of a dwarf nova in outburst. The Balmer emission lines were the clincher. They have an average redshift of about 300km/second, which is far to little to be part of a galaxy estimated to be receding from us at 5000+km/second.

This also explains the re-brightening in 2008, since CVs are prone to outburst over and over on various timescales from weeks to years. It also resolves the conundrum of having a core-collapse supernova in an E-type galaxy with few signs of active star formation.

And once again, order has been restored to the Universe.

The only mystery that remains is why it took them so long to figure this out. The spectrum that resolved this issue was obtained New Years Eve, 2005!

Do Puny White Dwarfs Make Wimpy Supernovae?

The binary star system J0923+3028 consists of two white dwarfs: a visible star 23 percent as massive as our Sun and about four times the diameter of Earth, and an unseen companion 44 percent of the Sun's mass and about one Earth-diameter in size. The stars will spiral in toward each other and merge in about 100 million years. (Credit: Clayton Ellis (CfA))

Based on results from a radial velocity survey, Warren Brown, (Smithsonian Astrophysical Observatory) and his team have placed a few more pieces into the supernova puzzle.

Supernovae come in many flavors. There are Type Ia, the �standard candles� everyone has heard of; and there are Type Ib and Ic, which also involve binary systems. We also have Type II supernovae that are believed to be the core collapse of single, super-massive stars. There are also super-luminous supernovae, which may be the explosive conversion of a neutron star into a quark star, and finally the weak-kneed cousins of the bunch, the under-performing underluminous supernovae.

Underluminous supernovae are a rare type of supernova explosion 10�100 times less luminous than a normal SN Type Ia and eject only 20% as much matter. Brown and his team have been investigating the connection between underluminous supernovae and merging pairs of white dwarfs.

In the 1980s, on the basis of our theoretical understanding of stellar and binary evolution it was predicted that many close double white dwarfs would exist. However, it was not until 1988 that the first one was actually discovered.

The way to find close double white dwarfs is to take high resolution spectra of the H-alpha absorption line of a white dwarf at several different times and look for variation that is caused by the orbital motion of the white dwarf around an unseen (dimmer) companion. The first systematic searches were not very unsuccessful. Only one system was found. Then, during the 1990s, Tom Marsh and collaborators concentrated their search on low-mass white dwarfs, which, based on current theories, could _only_ be formed in a binary system. In this way a dozen more systems were found.

Extremely low mass (ELM) white dwarfs (WDs) with less than 0.3 solar masses are the remnants of stars that never ignited helium in their cores. The Universe is not old enough to have produce ELM WDs by single star evolution. Therefore, ELM WDs must undergo significant mass loss sometime in their evolution. Producing WDs with 0.2 solar masses most likely requires compact binary systems.

"These white dwarfs have gone through a dramatic weight loss program," said Carlos Allende Prieto, an astronomer at the Instituto de Astrofisica de Canarias in Spain and a co-author of the study. "These stars are in such close orbits that tidal forces, like those swaying the oceans on Earth, led to huge mass losses."

Observational data for ELM WDs is pretty hard to come by because of their rarity. For example, of the 9316 WDs identified in the Sloan Digital Sky Survey, less than 0.2% have masses below 0.3 solar.

NASA/Dana Berry, Sky Works Digital

Half of the pairs discovered by Brown and collaborators are merging and might explode as supernovae in 100 million years or more.

"We have tripled the number of known, merging white-dwarf systems," said Smithsonian astronomer and co-author Mukremin Kilic. "Now, we can begin to understand how these systems form and what they may become in the near future." Unlike normal white dwarfs made of carbon and oxygen, these are made almost entirely of helium.

"The rate at which our white dwarfs are merging is the same as the rate of under-luminous supernovae - about one every 2,000 years," explained Brown. "While we can't know for sure whether our merging white dwarfs will explode as under-luminous supernovae, the fact that the rates are the same is highly suggestive."

At least 25% of these ELM WDs belong to the old thick disk and halo components of the Milky Way. This helps astronomers know where to look for underluminous SNe and where they are unlikely to find them, if the models are correct. If merging ELM WD systems are the progenitors of underluminous SNe, the next generation of surveys such as the Palomar Transient Factory, Pan-STARRS, Skymapper, and the Large Synoptic Survey Telescope should find them amongst the older populations of stars in both elliptical and spiral galaxies.

The papers announcing their find are available online at: http://arxiv.org/abs/1011.3047 and http://arxiv.org/abs/1011.3050.

Berto Monard-First Magnitude Amateur Astronomer

I couldn't help but notice this summer that South African amateur astronomer, Berto  Monard, had an amazing string of supernovae discoveries. The IAU Circulars seemed to be announcing another Monard supernova every week. So I contacted the one-man-southern-hemisphere-supernova-factory, and asked if he would grant an interview to tell us how he does it. Berto graciously accepted, and I think you'll like getting to know him as much as I did. He is in a word, remarkable.

Mike: Hi, Berto. Thanks for granting this interview. We�ve never met face to face but I�ve known you through the Internet for many years now. I�m anxious to learn more. Tell me a little about yourself.

Let�s start with where you live, and what do you do for a living.

Berto: Thanks, Mike, for the opportunity and indeed I am involved with astronomy for quite some time now.

I live with my wife, Brigitte on a small holding 35km ESE of Pretoria, the capital of the republic of South Africa. On top of the Bronberg mountain ridge we have an unobstructed view to the N and E horizons with little light pollution and beautiful sunrises. A hill behind the house cuts out 10 degrees from the other horizons, shielding the worst part of the immense light pollution of the Highveld agglomeration (Johannesburg-Pretoria) and the airfield OR Tambo Airport.
Together with the other owners around here we have established a conservancy area and we now live amidst game of the plant eating kind.

I am on pension since 2008, but still work part-time as a consulting metrologist at NMISA (National Measurement Institute of South Africa). Mainly involved with mentoring young scientists in the laboratory of Photometry and Radiometry, I still have full responsibilities in UV radiometry and spectroradiometry. NMISA is similar to NIST (USA), NPL (UK) and PTB (Germany).

Being trained as an electro-mechanical engineer (Energy conversions) / M Sc Eng, Louvain, Belgium 1974, the choice to enter into the field of optical radiometry at the time of my immigration to South Africa in 1981 was distinctly influenced by latent interests in astronomy.

Most of my free time is taken up by astronomy related tasks. Any spare time is used to do clearing work in our wattle forest and I also fancy a game of golf twice a month. We have three children and two grandchildren.

Mike: Where is Bronberg Observatory located? Is it on your home property, or is it at a remote site you have to travel to?

Berto: The Bronberg Observatory is situated 90m from the house amidst large rocks and indigenous plants. The coordinates are 25� 54� 32 S, 28� 26 18 E and the altitude is 1590m above sea.

Mike: How did you get started in astronomy, and what led you to the study of variable stars in particular?

Berto: From a young age I had admiration for the night sky and wondered what was going on there in the distance. I grew up in Belgium, a country with lots of light pollution and grey skies (with rain in the morning and showers in the afternoon, as the weather forecasts mostly went). Not much came from my interests even after buying a small telescope in 1976. But I did read books on astronomy and even studied pocket book atlases. I was especially impressed by Betelgeuse, and an awkward large star named epsilon Aurigae, of which not much was known....

I had taken that small scope with the flimsy equatorial mount into S. Africa but started only using it in 1990. Together with two work colleagues we intended to track satellites and I used that scope and a couple of star charts to do that. One of those colleagues had been involved with the organization of the Moonwatch team (late 1950s) in the Pretoria region. To that effect he had gotten lots of charts and also a set of converted apogee telescopes with 5" lenses. That's what I used from 1990 until 1996 to do variable star observing. It's a heavy and sturdy steel constructed refractor telescope that requires a firm alt-az mounting.

Initially it was interesting to wait for and spot the passage of those satellites through the 2.4 degree FOV of the apogee, but those satellites became rather boring as they had predictable orbits. Instead, I started observing R Centauri and other bright variables shown on those charts. That's how I got hooked.

Mike: What instruments do you employ at the observatory?

Berto: At the moment a 30cm (12") telescope Meade RCX 400, with reducer 0,62x and CCD camera ST7-XME, giving an effective f/5. An old filter wheel is squeezed in between the camera and the reducer, providing a firm fit onto the scope. This instrumentation is mounted on a pier, polar aligned and the images show on the screen with North up and East left. In addition to simple and straightforward observing software (I stick to CCDOPS) I use Scopedriver (S. Hutson, ADP) for driving the scope. Keypads run out of life-time eventually.

Mike: Do you still do any visual observing? If so, what do you observe?

Berto: After our move to the Bronberg I mounted the old apogee scope on the terrace there with the intention to observe bright stars and novae, but instead I now look at the impalas, wildebeest (gnus), zebras, springbuck, etc.; or at distant thunderstorms during summer. CCD cameras are dangerous things to ever start with...

Mike: I know you best from your activities observing cataclysmic variables for the Center for Backyard Astrophysics. How long have you been collecting data on cataclysmic variables (CVs) and sharing it with Joe Patterson and the gang at CBA?

Berto: CVs became my main visual observing targets since 1992, but it would be another 10 years before I joined CBA and started contributing CCD observed data.

I really enjoyed visual observing and I made quite a large number of CV observations mainly through a 32cm Dobsonian which I acquired in 1997. Constraints at that time would have made it difficult to go into CCD observing.

I am now an active CBA member since 2002 and CBA Pretoria has made significant contributions to the CBA cause, mainly during our wintertime with more than 90% of open skies. I know Professor Joe Patterson is quite pleased with my long runs on Milky Way bulge CVs. CBA is a great initiative.

Mike: Has your activity with CBA led to you co-authoring any scientific papers?

Berto: CBA observers get to share co-authorship on publications that they contribute data to. This is the going standard. CBA Pretoria has therefore co-authored several CBA publications since 2002. Besides CBA, I also contributed to VSNET campaigns with resulting publications. It's all about cataclysmic variables, how they behave during active phases and why.

I have co-authored publications resulting from my other observing activities: for instance on the interesting transient in NGC 300 which was 5 magnitudes short of what a SN would peak at. Some astronomers graduate with theses made on such objects.

Just to make sure I have publications, I write annual reports on the Bronberg Observatory / CBA Pretoria activities which are then included in the Monthly Notices of the Astronomical Society of S Africa. These reports include a list of the publications that I co-authored in that year. That's my way of documenting them.

Mike: You also make a point of following up on interesting transient objects like novae, and gamma-ray bursts. Tell us a little about chasing after GRB afterglows. It is a difficult quest, but a few amateurs, including you, have succeeded in imaging these elusive short-lived phenomena.

Berto: I have always loved to follow up on alerts. Most often it concerns faint and even undetectable objects like counterparts of X ray transients. I have been doing them since 2002, after CBA Pretoria became operational.

GRBs were another such challenge. I remember GRB 030329 which was quite bright and I was very excited to follow up on that one right from the beginning and provided some good light curves. Then there followed a period that I went after GRB alerts just to spot or even discover the counterparts and with success. It can be quite a demanding endeavour at times and a matter of fighting the sleep during such observing nights. But in fact it�s just hard routine.

I stopped GRB afterglow chasing in 2005 but still follow up on satellite-detected transients. There are a number of INTEGRAL detected magnetic CVs that are since added to my CV observing program.

Mike: The thing that got me to write you about doing this interview was your incredible success recently at discovering supernovae. I may have lost count, but I think you have discovered at least a dozen in 2009 alone! How do you do it, and how many have you discovered now altogether?

Berto: SN hunting is very much what I always wanted to do. It's the most time consuming of my projects because of the additional efforts in processing and the image inspection. SNe cannot be forced to appear, they have to happen in the galaxies surveyed and that was the case this year: six finds in July and three in August. In view of the increased competition in the southern hemisphere this is a good score. My total of SN discoveries now stands at 84. This is larger than my best golf score, therefore I am in need of another milestone ;-), perhaps reaching 100.

There is a lot of work and sophistication behind these discoveries. Enthusiasm is a great help to get started but there must be an adequate target selection to get maximum results from the time spent. Not every galaxy is a good candidate for SN production and it also doesn't help to image distant galaxies so that SNe will not be visible outside their peak brightness. It took regular efforts over three years to compose an efficient search list of around 2000 galaxies. Executing that list on a routine basis has to lead to discoveries.

Mike: What are your plans for the future? Are you planning to acquire a bigger telescope, or more telescopes? Or perhaps hiring an assistant to help you keep up the prodigious amount of work you are doing?!

Berto: I have a bigger scope, an RCX400 35cm, which is kept safely packed in the house and with it an ST8 CCD. They will be used again shortly, I hope. Break-ins in 2007 urged me to empty one of the observatories.

Our main plan now is to move to the Little Karoo in the Western Cape and to build an observatory there. That will probably take place end of 2010. We have our Bronberg property on the market but hope we can organize to still have access to the observatory there for winter campaigns. One of the reasons for our move is the bad weather over the Highveld in the period October-March with very few clear skies at night.

The best possible assistant I can imagine is a fully supportive spouse, which I have. And we both believe that if you want something done properly, you do it yourself.

Mike: Are there any other types of astronomical phenomena you would like to observe, like exoplanet transits or asteroids?

Berto: Observations of exoplanet transits were stopped in 2007, but I still monitor on an ad hoc basis faint CVs, mainly magnetic ones, around magnitude 18.5. Then I observe the southern symbiotic stars, once or twice per month depending on each star's 'merit'. This is such an exciting project, which will probably outlast all the others. Each month there is another star that tends to do something.

There are also many exciting observations I made the last few years and that are still sitting on my PC. Certain objects show unique light curves that are amazing to watch. They need publishing and I need time for that. Just look at the light curve below. These are time-series with an unfiltered CCD. The eclipse depth in V is expected to be even larger.


Since 2006, I have also joined uFUN (Microlens Follow Up Network), which is lead by Prof. A. Gould from Ohio State University.

They coordinate observations of members in different time zones. The intention is to detect exoplanets around distant stars in the Milky Way bulge. This is done by continuously monitoring microlenses that are expected to go high magnification in the hope of detecting signatures of planets orbiting the lens star. Some of these lenses remain very faint and the star density in the Milky Way requires good quality imaging.

In structure this organization is similar to Joe Patterson's CBA, but there are more professional observatories involved and a lot of mathematical modeling is required to decipher the observed anomalies.

Those uFUN projects can be very exciting and I am grateful to have been requested to get involved with these. A couple of publications on recent events will come out soon and there will also be an Sky and Telescope article on one of them.

Three years ago, I had plans and concepts to conduct a nova search. I believe a number of not so bright novae might be missed and I wanted to pick up most of those. This project was shelved in 2007.

And I would like to find comets too, but that's for in another life...

Mike: Everyone is motivated for different reasons. What keeps you working so hard night after night, and what gives you the most personal satisfaction?

Berto: I am just very excited with the possible outcome of a night's observing. Things happen and the universe is changing all the time. You never know what you will find. The excitement is in the anticipation of the unknown. That's the answer.

Mike: What advice can you give to amateurs who would like to contribute to science but may not know exactly what to do, or where to start?

Berto: Every amateur astronomer has his/her own specific range of interests in astronomy and related hobbies and some never get or want to observe. But they may get excitement out of studying observing data, optimizing instrumentation, popularizing astronomy, reading about history, etc... It's difficult to therefore give general advice, except that there must be a drive to do it and fun while doing it. This also has to apply to observing.

More specifically for variable star observers, I would suggest them trying to get at least a superficial understanding of all known mechanisms that lead to star light variations. In other words, get to know the different types of variable stars and then to perhaps observe those types that excite them most. AAVSO has a large list of traditional and more recent stars, some of them in need of observations. If those stars appeal, do them. But there are so many star and star like systems that are very interesting and nobody observes them.

It is not necessary to acquire large and expensive instrumentation to be a good observer. An adequate target selection is all that's needed.

I have always been prepared to help people out. It doesn't mean they will be successful. I have genuinely assisted individuals and groups with SN searching. It didn't always produce results. In a time where team efforts are praised as the all-encompassing means to success, I still believe in the potential of a focused and well equipped individual. If he knows how to utilize or explore existing voids in scientific fields, he/she will have major advantages over professionals. As amateur astronomers we have the privilege of an exciting and unlimited hobby, which will always distinguish us from 'normal' people.

Mike: Thank you, Berto. It has been great getting to know you. I hope we can meet in person one day and share even more.

Berto: Yes, sure. Why don't you come and visit us.

Mike: That sounds like an excellent idea! Thank you for the invitation.