From early 1997 through 1998, I was part of a group of astronomers searching distant galaxies for supernovae. The group was composed of myself, Dr. Mark Adams, Dr. Craig Wheeler, Andy Howell, Mike Ward and Bill Wren. Six nights a month, we used the 30 inch telescope at McDonald Observatory to image distant clusters of galaxies (Abell clusters) in hopes of finding a supernova, an exploding star. The information gained from observing supernovae can be used to determine the distance to the galaxy which can then be used to refine the value of the Hubble Constant which determines the size and age of the Universe.
At 3:45 a.m. the morning of Sunday, November 30th 1997, I imaged the cluster Abell 595, a group of galaxies almost 900,000,000 light years distant. I reduced the data about 2 1/2 hours later, just as the sky was beginning to brighten. Much to my surprise, there was a supernova visible in one of the galaxies which make up the cluster.
This is the discovery image, which appeared on my screen Sunday morning (without the labels). There are actually 4 images in this photo, one at each corner. The image at the lower left is the galaxy as imaged over a year ago. This is our "template" image. The galaxy has looked liked this for billions of years. Notice the galaxy is perfectly circular. For you amateur astronomer types, it is an E0 elliptical galaxy. The image at the upper right (the new image) is the same galaxy as it looked Sunday morning, November 30, 1997. A "knot" or "bump" is clearly visible on the right side of the galaxy. That "bump" is the supernova. The image at the lower right is the discovery image adjusted to the same "seeing" as the template image. The image at the upper left is the template image subtracted from the discovery image. The stellar image of the supernova is clearly visible. The other "star" in the upper left image is the nucleus of the galaxy - they tend to not subtract perfectly.
We observed the same galaxy again 3 nights later to insure that the supernova had not moved. This technique of subtracting old images from new images to discover supernovae also discovers dozens of asteroids. A supernova does not move whereas an asteroid does. Fortunately, the image of the galaxy still clearly showed the supernova on the right side, so we published an IAU (International Astronomical Union) circular to inform every astronomical facility in the world of the discovery.
This image (negative reversed, white is black) shows the suspect elliptical galaxy at the center. The supernova is clearly visible as a bright "star" at the right side of the galaxy. We have added cross hairs to point to it. Well to the right is another faint galaxy. The supernova was approximately 19th magnitude when discovered, well beyond the visual range of amateur telescopes. The faintest stars in the above image are approximately 21st magnitude.
The supernova was observed spectroscopically at Kitt Peak National Observatory in Arizona the night of December 4th. Kitt Peak confirmed that it was a type 1A supernova, approximately 2 weeks past maximum. The IAU assigned the supernova the designation 1997EA.
The above image shows the spiral galaxy NGC 3877. Clearly visible just above the nucleus of the galaxy is supernova 1998S. The night I took this image (3/20/98) the supernova was 11th magnitude and still getting brighter.
This is a color image I took using the 30 inch telescope. The supernova (arrow) is clearly visible.
I did not discover this supernova. This galaxy is too close to be of cosmological interest.
Supernova Research
Discovery Image
Bright Supernova in NGC 3877