18 october 2023 short period pairs

Another pretty good night, drier with better transparency, but seeing was not quite as good as the night before.  I went after pairs in lower parts of the sky since I had already covered most of the higher elevations.  I observed to 11:30pm, being very tired from the night before and having fairly well tapped out the list.

BU  270 AB: 508; 635x: Hairline split with seeing, very tough, B very small and faint.  SOC grade 3 orbit, 106.78-year period, it is rapidly closing to periastron and will likely not be detectible after a couple more years through 2050.  It will be for a future generation to visually observe it again.

21h 13m 27.24s +07° 13' 04.9" P.A. 342.00 sep 0.366 mag 7.42,9.40 Sp A7V dist. 95.6 pc (311.85 l.y.)

STF2737 AB: 508; 1690x: Appears single through all powers.  SOC grade 2 orbit 104-year period, it will be at apastron in 2030 and not be visually observable again until the 2040s. 

20h 59m 04.54s +04° 17' 37.8" P.A. 125.00 sep 0.108" mag 5.96,6.31 Sp F6IV dist. 54.08 pc (176.41 l.y.)

A  617 AB: 508; 1690x: Very weak out of round olive through all powers, appears weakest in the SW.  SOC grade 2 orbit, a mere 6.03-year period, it will have apastron in 2025 at 0.174" (I might be able to see notching!) then close very rapidly.  I observed a weakness in the shape which might indicate the stars are not of equal magnitude (?).

21h 21m 21.56s +10° 19' 56.6" P.A. 45.00 sep 0.118: mag 7.50,7.50 Sp F7V dist. 47.89 pc (156.22 l.y.)

HU  767 AB: 508; 1690x: Can only see as single through all powers.  SOC grade 2 orbit, 34.33-year period, it will reach ~0.2" apastron by the mid-2030s. 

21h 13m 28.77s +15° 58' 56.8" P.A. 183.00 sep 0.11" mag 7.05,7.13 Sp A5V dist. 87.64 pc (285.88 l.y.)

COU 542 Aa-Ab: 508; 1690x: Component of POU5764, Seen as single all powers.  SOC grade 2 orbit, 30.95-year period, it will widen to ~0.2" apastron in 2032, and I hope to resolve the bugger then.

22h 57m 02.47s +24° 40' 55.9" P.A. 121.00 sep 0.18" mag 9.29,9.93 Sp K0 dist. 88.97 pc (290.22 l.y.)

HO  296 AB: 508; 1690x: Can only see as single all powers.  SOC grade 1 orbit, it is closing to 2025 periastron and will reach a resolvable ~0.3" apastron by 2035. 

22h 40m 52.71s +14° 32' 57.5" P.A. 26.00 sep 0.196" mag 6.14,7.22 Sp G4V dist. 33.8 pc (110.26 l.y.)

STF2912 AB: 508; 1690x:  37 Peg.  Can only see as single at all powers -- likely because of the >1 delta magnitude.  SOC grade 2 nearly edge on orbit, 123.53-year period, it will widen slightly to 0.38" by 2032 then close rapidly, resolvable again in the mid 2030s.  

22h 29m 57.93s +04° 25' 54.1" P.A. 298.00 sep 0.279 mag 5.75,7.26 Sp F2V+F2V dist. 51.87 pc (169.2 l.y.)

STT 536 AB: 508; 1270x: Snowman, slightly unequal light orange stars, PA to NNW.  SOC grade 2 orbit, nearly edge-on, 26-year period, it will widen to 0.279" in 2026 then close rapidly, resolvable again through the 2030s.  

22h 58m 35.08s +09° 21' 24.6" P.A. 347.00 sep 0.203" mag 7.00,7.30 Sp G2V+G4V dist. 32.56 pc (106.21 l.y.)