The accidental discovery of Apollo asteroid 2002BJ2 and periodic comet P/2002 BV (Yeung) The sky is full of interesting discoveries. While some are relatively easy to find, some know how to masquerade themselves. On Jan. 21, 2002, while trying to recover the PHA 1998FW4, with the expert help of NEO Technical Specialist Tim Spahr of the MPC, a km size Apollo NEA 2002BJ2 was spotted right the way (full story at http://groups.yahoo.com/group/mpml/message/6256), along with a couple more seemingly normal discoveries. As I had said many times in the past, the NEA surveys are both a competitor and helper to amateurs. With their large sky coverage and MPC's more and more powerful orbit linking codes, once an amateur discover a new asteroid with two night observation, he/she usually didn't have to do too much follow up. For example, as of Mar. 28, 2002, out of the 1,498 discoveries at 333, only 150 or so have no orbit or orbit shorter than 30 days! Having said that, once in a while, I would still scan my past discoveries to see any interesting objects that had not been followed up by the surveys. Then it is time for me to do the dirty job :-). Around early April, I noticed 2002BV. It was discovered in the second half of Jan. at low solar elongation, mag. 20 with a two day arc. By now it should have brighten by at least one mag. and must have been picked up by the surveys! But they haven't picked it up! Before trying to recover it, I emailed Tim again to see whether he could do some magic work and extend the arc with some latest survey data or ons data. He did. Suddenly it became a multi. Opp. object (3 nights in 1998, one night in 2000 and 3 nights in 2001). The orbit has a=3.51 and e=0.36. All these data didn't mean much to me. Later one day out of the blue I got an email from Tim. Basically he said that the orbit was such that it must be a comet and he said that he would use a bigger scope on Mt. Hopkins to check it. Being no orbital calculation expert I kept my finger crossed. I did do my own checking and I emailed Tim the following note below on May 3: Tim, I saw 2002BV last night, it was very low, 30 degree above horizon. But the field is not too crowded. One image seems to show a small tail but it was in the wrong direction (NE). [Note 1] Bill For some reasons, other than saying that the images he obtained were weak and hard to detect a tail, Tim didn't seemed too eager to disclose any more information confirming the cometary nature of 2002BV to me. I didn't push him. Thinking it may be a repeat of 2000VU2, another discovery of mine which had a cometary orbit (a=7 e=0.55) but also no coma or tail could be detected. Thanks to Dr. Alan Harris breaking the news on May 9th on the MPML list, IAU Circular No. 7896 did announced on May 9, 2002 that asteroid 2002BV was indeed a comet, designated P/2002 BV (Yeung). May be Tim just want to give me a pleaseant surprise. He did. My main interest has always been main belt asteroids. For some reasons I have never been too crazy about comet, but I have to admit that after this one things change a bit. I would also like to take this chance to thank Tim Spahr once again for his excellent work in linking the orbit and confirming the cometary nature of this comet. I still feel that it is a shame that the comet naming rules are so rigid that the comet hasn't be named as Comet Spahr-Yeung. I would have thought that the story should have end here. But it didn't. Today out of the blue I received an email from Mr. Edwin Aguirre, an Associate Editor of Sky & Telescope handling the magazine's Amateur Astronomer Department. He might be interested to write a story about my discovery of 2002BJ2 and 2002BV. Thanks to him, at the end of his email he asked a seemingly odd question:" Were the comet and asteroid found on the same night? Kindly let me know." I would love to provide an answer below. Suddenly I realized that BV and BJ2 were indeed very close. I was a lousy record keeper and I gave myself the excuse that handling four telescopes kept me busy enough. 2002BJ2 is easy as it was discovered on Jan. 21. It is the comet that is the trouble maker. First I input P/2002 BV into MPC ephemeris web page, it didn't want to provide me the residual file that show the discovery date (also no mag. was provided!)To make a long story short, Tim came to my rescue again by emailing me all actual astrometry on the comet. Discovery astrometry of 2002BJ2 First triplet (2002BJ2) Y00C62 * C2002 01 21.49201 15 04 33.42 -13 46 05.7 21.2 Y00C62 C2002 01 21.51399 15 04 34.53 -13 46 24.3 20.9 Y00C62 C2002 01 21.53601 15 04 35.67 -13 46 43.9 21.7 Second triplet (2002BJ2) Y00C62 C2002 01 21.49546 15 04 33.41 -13 46 08.0 22.0 Y00C62 C2002 01 21.51748 15 04 34.68 -13 46 27.2 21.4 Y00C62 C2002 01 21.53949 15 04 35.95 -13 46 47.2 20.5 Discovery astrometry of P/2002 BV PK02B00V C2002 01 21.49201 15 03 44.64 -13 47 01.1 20.4 PK02B00V C2002 01 21.51399 15 03 46.73 -13 47 14.5 21.5 PK02B00V C2002 01 21.53601 15 03 48.78 -13 47 27.0 20.3 Amazing! Not only were both objects discovered on the same day, they were less than 13' apart and were recorded on the same image (note the exact time)! The more I think about it the more I have to call myself lucky. At first when I know that my first Apollo discovery was ONLY 1 km in size I was kind of disappointed. Only later did I learn that the total inventory of km plus NEA is only estimated at about 1,300 or so and it is lucky to have contributed one. I don't know how many short period comets have been discovered but a short search on the net yield a number of at most a hundred or so. So what is the chance of discovering a NEA and short period comet in the same set of images? Well, I think if one work hard enough, one get to get lucky eventually. I am going to buy a lottery ticket tomorrow :-). Bill Yeung 333 [Note 1]: NE is indeed the right direction! Actual PA=315 degree] All Rights Reserved