Kathleen S. Moore
Summer 2001 S.T.A.R.S. Program
AstroPhysics Project
Comet 2001A2
A comet is an orbiting iceberg. When the solar system formed, large chunks of rock and ice combined to form the planets. Some of this ice did not attach to form a planet and was left in its own orbit. This is the comet. Most comets have extremely long orbiting periods. Comet2001A2 is projected to have an orbiting period of approximately 34,000 years.
Comet 2001A2 was discovered on January 15, 2001 by the Lincoln Near Earth Asteroid Research (LINEAR) project. In March, the comet's nucleus split into two parts. In May, the comet again split. C/2001 A2 made its closest approach to the sun on May 25th at a distance of approximately 116 million kilometers and to the earth on June 30th. In mid-July, the earth passed through the comet's orbit creating a meteor shower as dust fell into the earth's atmosphere. When the comet was observed on July 14, 2001, it had a magnitude of approximately 5.0 and was barely visible with the naked eye. The comet had an unexpected outburst on July 13 resulting in an increased magnitude. Prior to the outburst, the magnitude was 5.8. The comet has continued on its orbit away from the earth and is gradually becoming less bright. Last observations are expected to be in late fall.
On July 14,2001, at approximately 4:00 A.M. Ohio time, I observed the comet using the 10" Great Ohio Telescope and a SBIG ST-8 CCD camera. The goal was to try to observe the multiple nucleus of the comet. 1/10 second explosures in an "R" filter were utilized for this process. For general observation of the comet 10 second exposures were obtained using the "R", "V", "I", "H alpha", and "H continium" filters. Two five minute exposures in "R" and "V" were also obtained.
All images are corrected using standard software available under IRAF (The Image Reduction and Analysis Facility).
The darks with the same exposure time were combined. The flats were combined into a single data file. The zeros were combined. These were all then subtracted from the data frames. This resulted in frames with equipment flaws removed. In the picture above a slight trailing to the right of the stars is evident. This is a charge problem with the CCD and standard software will not remove it.
Once the frames were cleaned, the comet was then registered in each frame and the exposures in each filter were added. After the individual filters of each time length were added, they were combined to create the picture above. The 2 good 10 second exposures in each filter were added to create this composite. The registering of the comet instead of the stars results in the different colors of the stars and the movement of them in a straight line.
We discovered that the 1/10 second exposures were not useful in obtaining data about the comet. The 10 second exposures yielded much more information and resulted in a refinement of 2 arcsec. This pushed the capacity of the equipment. It was hoped that the data would expose the multiple nucleus of the comet; however, the resolution was not such that this was achievable. The picture above was created using 2 10 second exposures in R, I, and V filters. Professor Statler had said not to expect results better than 5 arcsec; so we discovered new limits for the equipment when we resolved exposures with 2 and 3 arcsec resolution. The white center of the picture above is 3.5 arcsec in diameter.
The exposures in Halpha and Hcontinium did not result in any data collection. The most effective filters for the comet were I,R, and V.
Reduction of the five minute exposures resulted in the following composite.
I would like to thank Dr. Tom Statler for giving me the opportunity to learn about astronomy and astrophysics this summer. I have learned knowledge that I will be able to utilize in my middle and high school classrooms.
I also want to thank my fellow comrade, Jessica Lancaster , a Senior from Lancaster Schools.
A special thanks goes to the following undergraduate and graduate students: Anca Constantine , Robert Salow , Tim Lester, and Russell Ryan who helped me learn UNIX and IRAF. Without their help, none of this work would have been possible.
Internet sites utilized for this project were:
Orbit ofComet C/LINEAR (2001 A2-B)
Comet LINEAR (includes many links to other pages)
BAA Comet Section (has observations from different comets)
A good site for learning comet terminolgy is: The Skyhound's Guide to Comets
A good site for information on observing comets is: The Skyhound's Guide to Finding Comets
A good site for obtaining information on ccd tachnology is: The Curtis Schmidt Users' Manual
