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Oct - Nov 97
DISCOVERY!
By Jerry Armstrong
"Starlight, Starbright" By Jon Ramer
On the 1st of April, 1994, Tim Puckett and I were observing comets with a 16-inch newtonian reflector and a CCD camera. Earlier in the day I had prepared finder charts for the fourteen or so comets that we expected to image that night. As I was preparing the charts, I noticed that we would have about a one hour gap between two of the comets that were on the list. We decided that we could take advantage of this gap and shoot some "fun" objects. I show slides of fun objects in local schools because children like to see them. We finished up an exposure of periodic comet Tempel 1, then the next object was the ill fated periodic comet Shoemaker-Levy 9. SL9 was over an hour away from becoming high enough in the sky to image, so we went ahead with the fun objects. Little did I realize how my night was about to change. We chose as our fun object perhaps the most often "looked at" galaxy in the entire sky, known as The Whirlpool Galaxy or M 51. Almost immediately Tim and I both noticed a bright star very near the center of the galaxy. I have observed M 51 numerous times in the past and could not recall seeing the star before. Once a possible discovery is made, there are procedures that must be done before notifying the appropriate authorities. If one does not follow these procedures and the announcement turns out to be false, you are forever held in poor judgment by the International Astronomical Union. So verification is most important. There are several effects that can mimic a supernova on a CCD camera. One are the ever present cosmic rays, which can produce false stellar images. These can usually be suspected immediately by the very hard squarish appearance. The method to eliminate a cosmic ray strike is to take another image. During the acquisition phase of imaging, an exposure is made approximately every ten seconds. All we had to do is watch the screen, ten seconds later - the image of the suspected supernova was still there. Once a cosmic ray strike was eliminated, the possibility of an interloping asteroid had to be dealt with. By extending the exposure to five minutes we could detect motion if it was an asteroid. No motion was detected and this possibility was also eliminated. Next, was this a variable star unknown to us but listed in the catalogs? We had an extensive computer catalog of all known variable stars. The closest variable star was in the outermost reaches of M 51 and is in fact a foreground star belonging to our own system. Lastly was the possibility that the star has been there all along and we had just failed to notice it. The power of a CCD camera is enormous, a normally faint insignificant star is at times brought to prominence, especially if the location is unusual. As anyone who has used a CCD camera has found out, they have an extended infra-red sensitivity. However remote, there was still the chance that we were picking up an infra-red star. These are notorious for being invisible visually, but very bright when seen through a CCD. We began searching for another picture of M 51 to compare our view against After ten very hectic minutes I remembered the cover of the new magazine called CCD Astronomy had an excellent CCD image of M 51. The core was resolved with all sorts of details like knots and swirls, with dark nebulae interspersed. And most important - NO STAR in the position of the suspected supernova! We made a hurried phone call to the Central Bureau for Astronomical Telegrams, followed by an e-mail. At ten the next morning I called CBAT. Brian Marsden, the person who decides who gets credit for any discovery, answered the phone himself. After identifying myself, Brian stated that yes, Tim and I were indeed the first to recognize it as a supernova and that congratulations were in order. He also informed me that the Berkley Supernova Search Team was just 40 minutes behind us. I was elated to say the least. At home e-mail began to pile up as congratulations started pouring in. I learned the very first professional telescope to be turned toward the star was none other than my favorite, the 200 inch Hale Reflector at Mt. Palomar. During the next twenty four hours no less than one hundred e-mails and telegrams were received by the IAU announcing independent discoveries of the supernova. Later I learned that every major observatory on Earth began observing the supernova in various wavelengths. Hubble was called to work on it, as was the Very Large Array in New Mexico. Astronomers programs were delayed in order to take advantage of this transit phenomena. The supernova itself actually exploded thirty five million years ago. We had discovered it approximately ten days before maximum light, it was a relatively rare type of supernova. In closing, we finally did go back to the telescope that night after we sent the e-mail off. I still had one target left and that was the periodic comet Shoemaker-Levy 9 which would in just four short months crash into Jupiter. When the image of Shoemaker-Levy 9 came upon the screen, there was the tell tale trail of an UNKNOWN ASTEROID, but that is another story!
International Association of Astronomical Artists