Afternoon Gerhard and other readers No problem in giving identifications but sometimes there may be a slight delay - depends how close my nose is to the grindstone. First Ive heard about asteroids being classified -- dont believe it as there is absolutely no reason to do such unless of course someone is worried we might pick up a NEO on collision course with earth :-))). I tried solving your image with APEX but it was too noisy - one of your previous images I did solve okay but I think the main problem is that the field of view is too large in this case and the star trails too short -- ie the image scale makes it difficult for APEX to find stars. What APEX does is choose the 30 or 45 brightest stars from the star catalog used for the field of view and try and find a match with 20 stars in the image. The problem is "which are the brightest stars in the image" when they are all very much alike so APEX just cant match enough stars to give a valid solution. Also the magnitude scale in your image is not necessarily the same as the magnitude system used in the star catalog for a variety of reasons, so when you have something like say 6000 stars from the catalog in the field of view its easy to get the "30 or 45 brightest stars " wrong. In my early days with APEX I used a catalog that gave something like 90000 stars in the field of view from the catalog - the computer churned away for a LONG time as it tried to match stars - in one or two cases it got it right but more often than not it failed - one has to "sort of match" the field of view to the star density in the catalog - too big a field of view makes this generally difficult. Cheers Greg ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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