Used acronyms: NEML=Naked Eye Magnitude Limit, SQM=Sky Quality Meter, TML=Telescope Magnitude Limit, CO=Central Obstruction, delta_m=difference in magnitudes between double star components, RoT=Rule of Thumb, pD_mm=proposed D_mm for resolving a binary (ident with earlier used pA=proposed Aperture), D_mm=Diameter (of scope) in mm, UCAC4=USNO CCD Astrograph Catalog 4th edition
Quote:Perhaps someone could suggest another to take it's place in the table?
Quote:It seems that COU1900 is dubious but the data for BU1074 is as far as I can see very solid - so the double negative report from Mark makes me cautious. A positive on BU1074 and a negative on COU1900 would have been more convincing.
Quote:There are a couple of positive sightings of BU 1074 as a double in this thread, in addition to the old observations by Burnham and Aitken, so I don't think there's any good reason to doubt its existence as a double. The difficulty of seeing the companion, sometimes even with a 15-inch telescope, might be informative about the vagaries of seeing very uneven and quite close pairs. In particular, local seeing conditions, telescope thermals, and sometimes other factors can make such companions obscure or invisible.
Quote:SEE 291 in Scorpius - not observed yet; I'll put it on my list to do soon.
Quote:I'm of the opinion the secondary is really there, but it would be great if someone could come up with a photo of it in order to confirm it.
Quote:An additional oddity; slight de-focusing revealed two "knots" in the diffraction ring 180° apart. One at PA 310, the other at PA 170. Typically, with a single point source, de-focusing simply shrinks the diameter of the Airy disk and throws more light into the diffraction ring equally, in all directions. Knots usually suggest the presence of multiple objects. At no time did I observe elongation in the primary itself.
Quote:... Often wondered why we're chasing this object in the first place. For the fun of it, I suppose...
Quote:... Any ideas as to what's involved in getting a photometric value of the secondary's magnitude that is equivalent to the visual value? ...
Quote:BTW - for COU1900 I would get a delta-m of ~7 if we take Mark's observation with 381mm aperture as limit observation.Wilfried
Quote:It would be instructive if someone with an 11 or 12 inch instrument could take a crack at it and report their results here.
Quote:...I estimate the roof blocked about a third of the aperture when I made this observation.Did I inadvertently "mask" my aperture to an instrument of this size last night?