The resulting burst of light reached Earth on 28 March, the brightest in the northern sky in 50 years. Astronomers called it SN 1993J and took full advantage: over 100 scientific papers have been published on it, literally rewriting the (advanced) textbooks about supernovae types and theories. It surprisingly shifted from Type II to Ib and drove astrophysical modelers nuts. Even better, this SN was only the third to have its progenitor star identified.
I learned of SN 1993J a couple days later on S&T’s Skyline pre-recorded phone message. The newsgroup sci.astro was already abuzz, and chatter of the SN displaced talk of the “string of pearls” comet recently discovered. ASCII character finder charts (top) were being posted along with magnitude sequences to estimate brightness. Now and again, someone would upload an image of the supernova, and I used a program called "ftp" to download it, logging in as “anonymous” and remembering to set the mode to "binary." File transfer would stall as often as it would terminate successfully.
I was working my way through the Messier list with my “big” scope at the time, a 4” S-C. Peaking at magnitude 11, it was barely within reach of that modest aperture (sketch at right). I followed SN 1993J through its highly unusual second maximum and out several weeks. I was amazed to see something so big, so bright and so far away that changed almost nightly. It was very reassuring that my estimates tracked those posted to the newsgroups (below). The last magnitude estimate, 13.0, was the most challenging of all: having just focused on M81, the SN and a nearby 14th mag star, clouds rolled across the New Mexico sky. Since that view was through a loaner 17” Dob, I knew that it was probably my last glimpse. Regardless, it was cool to watch the death of this faraway star.
Since ‘93J, I’ve caught many more supernovae with a CCD camera, which coincidentally burst on the amateur scene about the same time. I still marvel at the CCD’s ability to pull down photons and reveal a pinpoint galactic core surrounded by arms delicately sprinkled with stellar nurseries (M81 five years later, bottom image).
Ten years ago not all the big things happened in the sky. One event in particular, occurred just about the same time SN 1993J’s light reached Earth, right here in Smyrna: the first meeting of the Delmarva Star Gazers. Unlike supernovae, the club’s star has continued to shine over the past decade. An active core membership supports the club’s dedicated leadership. This club now sponsors enough star parties and meetings to maintain a year-round buzz of astro-activity. Well done Delmarva Star Gazers, and Happy Birthday!
Moondark is written by Doug Miller, published on the web, and printed in the Delmarva Star Gazers' Star Gazer News. This document was last revised on 22 March 2003. Text copyright © 2003 Douglas C. Miller, All Rights Reserved. This material may not be reproduced in any form without prior permission.
