22 september 2020

Seeing last night was not very good, so I masked down to 8-inches.  Even then seeing did not support well above 333x.  Some thin clouds moved in very slowly from the west, slow enough where I could have a good session all the same.  I added a baffle to the upper back of the mirror box, which I think helped prevent light scattering from behind the scope and improve contrast.  Some dew but not bad.  The clouds finally moved over the hole in which I was viewing at around 10:30pm.

AG 241 AB; 203; 205x: Faint pair, one delta, wide.  Not physical.
19H 53M 19.36S +08° 20' 24.7" P.A. 217 SEP 8.6 MAG 10.40,10.56 SP A0

STF 2593 AB; 203; 205x: Almost a delicate pair, >1 delta mag, wide, both light orange.  I missed BC, 10.1/11.4 3.7" -- transparency not good enough for fainter stars.

19H 53M 16.93S +11° 50' 04.3" P.A. 242 SEP 12 MAG 8.76,10.30 SP A0

STF 2615 AB: 203; 205x: White A and much fainter reddish B, wide.  Not physical.
20H 02M 54.05S +08° 23' 50.7" P.A. 301 SEP 8.9 MAG 7.61,10.29 SP B9

DA 1 BC: 508; 533x: This is part of STF 2690 A-BC, which is a white, wide, near equal, pair (7.12/7.39 17.7") observed with 8-inch at 205x.  I suspected BC at 8-inch 333x, & had overlapping disks with 8-inch 533x.  With 20-inch 533x I see a hairline split, slight magnitude difference. Seeing is not supporting it well, but it's clear.  Very nice.  Dawes discovered in 1840 at 0.7" -- probably with his 8-inch Cooke refractor [correction: DA 1 was discovered when Dawes was working at "Mr Bishop's observatory" in London, from 1839 to 1844.] It had a 7-inch refractor by Dollond (1836) who had made both mounting and telescope. -- so at current 0.369" it's not surprising I only had overlapping disks at 8-inch.  It's a physical pair, with a 236.52 year period, and will widen another 0.1" in the next 15 years.
20H 31M 11.94S +11° 15' 33.7" P.A. 189.3 SEP 0.369" MAG 7.90,8.00 SP AM DIST. 59.99 PC (195.69 L.Y.)

J 1 AB: 203; 205x: Nice close pair, well split ~2", equal.  Physical, at apastron, 528.391 year period (to be exact!)
20H 32M 52.76S +11° 44' 37.2" P.A. 55.5 SEP 2.12 MAG 10.04,10.57

SCJ 27 AB: 203; 205x: An obvious pair, I wonder why Struve did not note it.  Wide, ~6", ~1 delta mag.  A is light orange and B a slightly deeper orange.  Lies in a dense arrow shaped asterism.  Hans Schjellerup was a 19th century Danish astronomer who was something of a polymath, who compiled a list of red stars, and studied Chinese and other languages in order to study old astronomic records. 
20H 39M 13.04S +10° 58' 42.0" P.A. 263 SEP 6.2 MAG 8.67,10.03 SP F8 DIST. 146.41 PC (477.59 L.Y.)

STF 2713 AB: 203; 205x: Easy equal white pair, ~5" 
20H 40M 55.07S +10° 34' 29.1" P.A. 63 SEP 5.1 MAG 9.80,9.80 SP B9

STF 2715 AB: 203; 205x: Obvious ~3 delta mag, wide, white.  Physical.
20H 41M 46.01S +12° 31' 07.1" P.A. 2 SEP 12.4 MAG 7.80,10.22 SP F8 DIST. 92.42 PC (301.47 L.Y.)

STF 2718 AB: 203; 205x: Easy wide, white, near equal  Psychical.

20H 42M 33.47S +12° 43' 41.9" P.A. 88 SEP 8.6 MAG 8.28,8.39 SP F5 DIST. 144.51 PC (471.39 L.Y.)

STF 2720 AB: 203; 205x: Fine pair, near equal, wide ~5", white
20H 43M 27.91S +16° 56' 41.9" P.A. 178 SEP 4 MAG 9.22,9.56 SP F8 DIST. 100.5 PC (327.83 L.Y.)

STF 2721 AB: 203; 205x: Well split ~3", ~2 delta mag. 
20H 43M 29.80S +19° 52' 52.2" P.A. 22 SEP 2.6 MAG 7.80,9.90 SP G5

STF 2723 AB: 203; 333x: Very nice, light blue A and light yellow B, fine split, almost 2 delta mag. Really nice pair.
20H 44M 54.58S +12° 18' 45.6" P.A. 140 SEP 1 MAG 7.01,8.30 SP A3IV DIST. 209.21 PC (682.44 L.Y.)

STF 2725 AB: 203; 205x: OR Del. Light yellow stars, half delta mag, wide.  Physical pair with a  2945.18 year period.  In same field with bright pair STF 2727.  

STF 2727 AB: 203; 205: Gam 2 Del.  In same field with STF 2725.  Bright light yellow stars, ~1 delta mag, wide.  Physical with 3249 year period.