Japanese version Home Page Updated on August 18, 1999
August 15, 1999
Asteroids in our images
MISAO Project Announce Mail (August 15, 1999)
Hello. I am Seiichi Yoshida working on the MISAO project.
The number of CCD images taken by the Ageo Survey Team (KenIchi Kadota, Seiichi Yoshida) is 4188 so far, from 1998 March 7 to 1999 July 30.
All the images are examined by the PIXY system, then checked for new objects or new variable stars, and the magnitude data of known variable stars are recorded. As the announce mail on Aug. 8 reported, 134 new variable stars have been discovered. However, no comets, asteroids, novae nor supernovae have been discovered.
In fact, the situation on asteroids has been very strange. No new asteroids were discovered from the 4188 CCD images. On the contrary, known asteroids could not be detected at all, except for two cases.
The automatic new objects survey by the PIXY system must output asteroids as candidates of new objects if they happened to be in the images, and there are some past images of the same area. However, only two asteroids have been detected hitherto, (4) Vesta as reported in the announce mail on Feb. 26, and (349) Dembowska detected from CCD images of M66 taken in January.
I investigated if it means asteroids so rarely happen to be in the images by chance, or it means the PIXY system cannot detect new objects completely because of some bug. Because the PIXY system cannot detect 16 mag at best from the Ageo Survey Team images, I investigated if asteroids until number 1000 have been in the field of the images in the past. As a result, I found that 42 asteroids were in the field of Ageo Survey Team images and brighter than the limiting magnitude.
Here are the list of asteroids in the Ageo Survey Team images taken by 530-mm or more focal length telescope, the main instruments recently.
Most of asteroids in the field of the images have been output as candidates of new objects. However, because there were no past images for reference, the system could not determine they are really new objects or just normal stars not recorded in star catalog. So they were ignored. Most of faint asteroids near the limiting magnitude were not detected.
There is one special case, that is (230) Athamantis. It must have been output as a candidate of new object because there were past images. But I guess the focal length of the past images were so different (180mm against 530mm), I ignored the output. Because no report is remained now, I cannot say any more.
After all, I can see the following conclusions.
-- Seiichi Yoshida firstname.lastname@example.org http://www.info.waseda.ac.jp/muraoka/members/seiichi/index.html