16 june 2023 short period pairs

Seeing was forecast to be above average last night so I opened up the 20-inch.  Though it wasn't excellent I did go after some short period binaries on my "movement" list with decent success.  After a couple hours observing I felt I had a good enough night, and since seeing wasn't getting any better decided to pack it in.

STT 298 C; 203; 280x: Easy split, near equal light orange stars, PA SSW, with a similar magnitude star near to mark PA.  20% PRO, 25 AU WS, 0.8+0.9 Msol, certainly binary.  SOC grade 1 orbit 55.42-year period, it will close slowly to the west by 2042.

15h 36m 02.22s +39° 48' 08.9" P.A. 190.50 sep 1.2 mag 7.16,8.44 Sp K2V dist. 22.31 pc (72.78 l.y.)

HU 1168 AB: 508; 600x: Extremely fine split, light orange stars, PA WNW, with seeing.  -49% PRO, through 32 AU WS, 0.8+0.9 Msol, SOC grade 3 orbit 88.57-year period.  If it is a true binary it will close to the SW in the 2040s. 

15h 37m 00.37s +64° 26' 23.3" P.A. 285.10 sep 0.5 mag 9.48,9.73 Sp G5 dist. 55.71 pc (181.73 l.y.)

JEF1 AB: 508; 1270x: Using all my highest powers, a blue filter, and an apodising mask, I can see an out of round olive dancing in the diffraction, but could not tell consistent PA.  SOC grade 1 orbit, 10.54-year period, it is coming off periastron now and will be at apastron 0.314" in 2028, certainly one to keep an annual watch on.  No Gaia data on the secondary.

15h 27m 49.85s +29° 06' 19.8" P.A. 114.90 sep 0.1 mag 3.68,5.20 Sp A5+F2 dist. 34.28 pc (111.82 l.y.)

STF1937 AB: 508; 560x: Eta CrB. Nice clean split, light orange stars PA NNW.  SOC grade 1 orbit, 41.63-year period, it will widen to the NE by 2035 periastron.  No Gaia data for the secondary.

15h 23m 12.23s +30° 17' 17.7" P.A. 305.40 sep 0.4 mag 5.64,5.95 Sp F8V+G0V dist. 17.86 pc (58.26 l.y.)

STF2084 AB: 203; 280x: Zeta Her.  Using a blue filter to suppress bright A's diffraction, tiny B sits as a sharp, defined point just outside of A's first diffraction ring, very much fainter, east PA. No Gaia parallax data.  SOC grade 1 orbit 34.46-year period, at apastron now, it will slowly close to the NE by 2030 then have a quick periastron around 2035 at around 0.3".

16h 41m 17.16s +31° 36' 09.8" P.A. 100.00 sep 1.5 mag 2.95,5.40 Sp G1IV dist. 10.72 pc (34.97 l.y.)

STF1909 AB: 508; 580x: 44 Boo.  With 8-inch, a strongly notched elongation, PA to S.  With 20-inch and 580x and 850x it is split, light orange stars, noticeable difference in magnitudes.  SOC grade 2 orbit, 214.7-year period, it is coming off periastron now and will widen from the current 0.391" to around 2.5" in 2040 and >4" by 2080.  No Gaia parallax data for the primary.

15h 03m 47.30s +47° 39' 14.6" P.A. 141.70 sep 0.2 mag 5.20,6.10 Sp F7V+K4V dist. 12.51 pc (40.81 l.y.)