BU 100: Try as I might, I failed to split this double. I even cheated and looked up the Rho and Theta for the companion and still failed. I could, however, see a dim star about 6" arc south of BU 100. I have not looked up that star's magnitude just yet, but I am curious about it. I did spend a lot of time with this first double of the evening, because at mag 11 I really needed to be fully dark adapted to have a chance. Still, no success. At 3.2" sep, it sits very near my 4th diffraction ring (~3.6" arc.)
STT 145: Split. Companion easily seen near PA 340 just outside the first ring at 263x (UO 12mm HD Ortho, 1.6x Barlow.)
A2450: Split. Faint companion easily seen at ~3" arc sep near PA 120 to 130 (south east, anyway.) However, it's PA is listed at 053. I suspect this is incorrect, but I just don't know. If it's correct, then I failed to split it and simply observed another star near PA 130. But, my gut tells me the listing is incorrect. That pair just looked and felt like a double. Stellarium, ironically, shows the companion more south of PA 90, too.
STT 171. Split - maybe. ...
Wilfried and others, the above is quoted from Norme's observations reported 30 January 2013. As I've now caught up with a few of these I thought I'd provide my observing notes, done without benefit of checking what Norme wrote.
The folowing are with my 140mm refractor, seeing started at fairly good, becoming good-plus (7/10) for the more difficult ones. Unfortunately I didn't get to STT 171. These are in Gemini. Night of a 6 day moon recently. Nelm in the observed area was perhaps 4.5, despite moonlight.
For purposes of comparison, I started with STT 140, listed for a mere 117mm aperture - the mag 10.1 companion was seen at 160x, not very difficult; delta-m here is 3.2 mags. I compared it with A2450, same separation, delta-m 3.0, but fainter - mags 8.05 and 11.06. A2450 also showed as a double at 160x - however on the Gemini list it's got 140mm aperture indicated. It was nearly as easy as STT 140 - only the fainter magnitude of the companion made it less obvious.
BU 100 - mags 7.3 and 11.1 at 3.2" (listed for 144mm) was easier - the companion star showed at 100x. It was noticeably easier than A2450, and at 160x the companion was obvious.
STT 145 - mags 7.3 and 9.9 at 1.5" - listed for 147mm aperture. More difficult, but the companion was a just visible speck close to the primary at 160x, and more clear at 230x.
My feeling is that the model used for the Gemini doubles (since revised) was not entirely consistent in predictive capacity; and that exceeding it was not of high difficulty for at least some doubles.
I still have some other pairs, already observed, to provide notes for. And if the weather here ever stops being cloudy I can move on to Eridanus.