Posted 13 January 2013 - 10:52 PM
Wilfried has posted a note in the "Some doubles in Tau and a bonus" thread, that gives access to a list he's made of Orion doubles, for testing telescope resolution, pairs bright and faint, even and uneven.
I thought I'd post here my observations of some of these as a way to give easier access (Orion in an Orion thread).
STT 133 in Orion: 0608.0, +2118: mags 7.35, 11.17 (delta-m of ~3.8) separation 3.3" - observed with 140mm refractor, no moon, fairly good seeing, it was surprisingly easy - I could see a hint of the companion at 80x, and it was a clear tiny speck just offset from the primary at 114x. [listed for 150mm aperture]
Also on the list is an old friend, much discussed - part of STF 748, which refers to various of the stars of the Trapezium in the Orion Nebula. The particular pair listed by Wilfried is the AE pairing, mags 6.55 and 11.1, at 4.6" - I've seen this one readily with the 140mm refractor on good nights, not too difficult. [listed for 138mm]
Harder, as often remarked, is the CF pairing, mags 5.06 and 11.5 at virtually the same separation these days, 4.5" (it's been widening) - I've also seen this one, though harder, with the 140mm when seeing cooperates. I don't think CF is in this list.
The 6-inch f/8 Newtonian that I had years ago also showed both C and F.
Next clear night (this week, I'm hoping) I'll try some more from the list along with more of the Taurus doubles.