My "discovery" of cluster Alessi 10

by Bob Jardine

At Montebello OSP last night, I was tracking down an Asteroid -- 39 Laetitia. I noted that it was in a fairly rich little star field, possibly a cluster. It showed as a fuzzy spot in binocs and comprised about 1 dozen stars of magnitude 8 to 9 and perhaps another dozen dimmer ones. It was a fairly large and well resolved cluster, and it seemed pretty well separated from the surrounding field stars. The mag 9 asteroid seemed to be just another cluster member.

But it wasn't charted in SA 2000. Since I could see it pretty easily in binocs, I wondered why not. It looked like a pretty obvious cluster to me! Tonight, I checked in Uranometria -- I could see about 4 of the brightest stars, but no cluster marked. However, looking in Archinal and Hynes' definitive cluster book, I found it -- Alessi 10 (a.k.a. LeDrew 3).

Dang. I thought I was going to get to name a newly discovered cluster myself!

The cluster is in Aql, not far from Alpha Cap. Coordinates are: 20 04.6 -10 31 (J2000).

Joe Bob says: check it out (especially you closet OC lovers)!

(my observations were with a 12.5" f/5 Portaball with 35 Panoptic & 9 Nagler)

Posted on sf-bay-tac Jul 28, 2005 22:27:57 PT
Converted by report.pm 1.2 Mar 06, 2006 21:18:18 PT