Monday, September 23, 2024

22 september 2024

Seeing was predicted to be good, but I felt tired from a busy day so I only uncovered the 6-inch to observe.  I wanted to try a difficult double someone posted about on CN, so I spent most of my time on it:

AGC 13 AB: 152; 450x: Holy heck is it a tough one!  I had airy disks well above 300x, and what makes this tough is the secondary is hidden in the first diffraction ring.  The ring would sometimes pulse, if that's the word, with small bright globs coursing around the ring with seeing.  But the southern end was constant in its brightness, and with best seeing (and perfect focus) at 380x & 450x it hardened to a round steady star, separated, almost exactly south.  The view was improved by viewing the star through a peephole (a 1/32" hole I drilled in the center of the eyepiece's dust cap) which helps to steady the seeing a little--this is one of SW Burnham's observing tricks.  Through the peephole I could hold the secondary for longer stretches.  SOC grade 2 orbit, 49.52-year period, it will tighten in the next 10 years and turn due east, but not likely be visible.  No Gaia parallax data.
21h 14m 47.49s +38° 02' 43.1" P.A. 190.00 sep 1.1 mag 3.83,6.57 Sp F3V+F7V dist. 20.34 pc (66.35 l.y.)
STF2523 AB: 152; 125x: Clean white equal stars, also seen with 60mm at 40x. -4% PRO, 3,303 AU WS, 3.5+3.3 Msol, it is not likely binary.
19h 26m 48.38s +21° 09' 46.2" P.A. 148.00 sep 6.4 mag 7.95,8.05 Sp B3V+B7V dist. 1470.59 pc (4797.06 l.y.)

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