Transient Astronomy
Published on Jan 10, 2008 at 10:23 am.
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Filed under astronomy, conference blogging.
When I first got started in astronomy, there was an old piece of paper thumbtacked to the wall next to the phone at the observatory at the university where I was getting my master’s degree. To my knowledge, no one ever called that number. It was the phone number for the IAU’s Central Bureau for Astronomical Telegrams (CBAT). That was, and still is, an organization operating under the auspices of Commission 6 of the International Astronomical Union to rapidly disseminate to the astronomical community about transient events. A transient event is something that is observed changing in the sky. That would include the discovery of a new comet or asteroid, a nova, supernova, or many other such things. Often, when such a thing is discovered, it can only be observed for a short while until it sets (or the sun rises) at the site of discovery. However, it is always nighttime somewhere. So, other observers could observe the object. But, how would they know where to look? Also, when new asteroids or comets are found, someone has to be able to confirm the discovery. How do they know where to look? That is that the CBAT was set up for. The graduate students at the little observatory I mentioned above had very optimistically put up the paper with the CBAT’s phone number, just in case. As I said, to my knowledge, it was never used. But, there was always the excitement that it might come in handy in case we were looking through a telescope and saw something new. (The observatory was a teaching observatory for our introductory astronomy classes, not really a research facility).
Since the invention of the telescope, discoveries required astronomers at the telescope. At first, they looked through eyepieces. Then, photographic plates took over. Astronomers would expose plates (and later film). Then, the photographs were developed, sometimes the same night, but frequently the next day. (Yes, we had a darkroom at the observatory!). The developed pictures were then studied. It took time to make discoveries, and time to disseminate those discoveries. But, technology has allowed for far quicker discoveries. CCD’s allow for near real time images. Even processing those images can be done much quicker than developing film used to be. Furthermore, computers can quickly call up prior images to check for changes, and databases of known objects are readily available to search to see if the new discovery is actually something already known. The CBAT can be reached by email, and electronic notification can go out to other observers. There are even other mailing lists and means of disseminating particular types of discoveries to special groups (such as supernovae, comets, gamma ray bursts, etc) who observe those types of objects.
But, in recent years, there have been a number of automated surveys set up. These surveys are collecting images far faster than astronomers can study them. And, as you can imagine, transients are being imaged. But, by the time an astronomer gets around to looking at the image, the transient is long gone from the sky. But, there is a solution! All it takes is a piece of computer software to get the computer to compare two images looking for differences. The differences can then be compared with known objects to see if anything known is in that part of the sky. If not, then the transient can be flagged for an astronomer to look at. In effect, the computer is now doing what the astronomer used to do, and just flagging suspect items for a human to check out. But, there is even more that computers can do.
The VOEventNet is just such a program. It is an entirely automated network for studying transients. As I gather, it can detect transients and start to monitor them before an astronomer is even involved. As a network, it does much of what had been going on before. At least that is how I gather that it works. I hadn’t heard about this before, but I saw a poster about it at the meeting yesterday. Unfortunately, there was no one at the poster when I stopped by to ask about it. But, it looks good, and interesting. Such a system is obviously a major tool for astronomers studying transient phenomena. The automated instruments find and collect data on transients. Astronomers, then get massive amounts of transient event data to study. This opens up the entire field for further study. It is certainly a leap forward.
-Astroprof
