short period night

The forecast last night was for clear skies, above average transparency, and excellent seeing -- and for once that last forecast did not disappoint.  Except for a pleasant twenty minutes on Jupiter when it was at culmination, I spent all my time observing short period binaries, with good results.  Apodising mask used throughout, since it wasn't quite perfection, but it was pretty close.

BU 1129 AB: 508; 889x: Light orange stars, obviously not single at 445x, and the disks separated as I powered up.  Less than 1 delta mag, the best view with 889x, which showed a constant hairline split even with wavering seeing, PA NNW.  A really nice pair.  Spectral class A8III (white).  121.7-year period, currently 0.328" separated, it is approaching apastron now and will hang there until the 2050s.  Burnham discovered in 1889 on the Lick 36-inch at 0.3" and noted "If [the proper motion in Ast. Gess. Catalogue]...is substantially correct, this is a physical system."   

19h 21m 36.09s +52° 22' 34.9" P.A. 339.20 sep 0.3 mag 7.69,7.84 Sp A8III dist. 205.34 pc (669.82 l.y.)

STT 400 AB: 508; 445x: Easy, nice clean disks, nicely split, 1 delta magnitude cream white A and light orange B, three field stars forming a triangle around it as reference.  PA to NW.  Spectral class G3V (yellow).  Physical with 85.61-year period, it is 0.647" separated at apastron now and with make a quarter turn and tighten to 0.2" in the 2040s.  

20h 10m 13.32s +43° 56' 44.2" P.A. 325.40 sep 0.7 mag 7.60,9.83 Sp G3V dist. 51.33 pc (167.44 l.y.)

MCA 55 Aa-Ac: 508; 445-1778x: Alberio A.  Using all powers at both 20-inch and 7-inch, A is consistently out of round with the weaker end in the southern direction.  Alberio B remains relatively round in the diffraction dance.  Currently 0.365", it is widening to apastron by 2035 and might even be splitable by then.

19h 30m 43.29s +27° 57' 34.9" P.A. 239.40 sep 0.4 mag 3.37,5.16 Sp K3III+B0V dist. 133.16 pc (434.37 l.y.)

COU1962 AB: 508; 889x: Very tough, light orange stars, just barely split at best moments, almost 1 delta mag, PA to S.  =V2425 Cyg, for which I don't find a light curve on AAVSO -- I assume it's easier to observe the split when this is at minima.  Spectral class K0 (yellow-orange).  Currently 0.119" !  Only a 20.414-year period, it will make a quarter turn and widen slightly by 2028, and reach apastron by 2033.  

20h 31m 07.72s +33° 32' 33.6" P.A. 121.80 sep 0.1 mag 9.03,9.51 Sp K0 dist. 48.85 pc (159.35 l.y.)

STT 533 ?: 508; 889x: Split disks within diffraction, light yellow orange A, B is more orange, 2 delta mag, PA to S.  Spectral class G1IV+K2IV (yellow/yellow-orange).  WDS does not give any close pairing; they reference proper motions differences indicating--presumably--the wide pair is optical, but again no pairing listed for a ~0.5" binary.  WDS notes say "Gontcharov & Kiyaeva (2010) detect variation in Hipparcos data which they conclude is due to an unseen companion, orbiting the primary with a period of 45 +/- 5 years. The companion is >4 mag fainter than the primary; spectral type estimated as WD or RD, mass 0.4 +/- 0.3 Msun."  The Sixth Orbital Catalog provides the orbital solution for the Gontcharov pair, shown here, which nearly matches my observation however what I see is much brighter than ">4 mag fainter." and definiely "seen" not "unseen."  I think this is a case where a direct observation (speckle interferometry or more visual observations) need to be made.

KUI 102 AB: 508; 667x: Overlapping disks, strongly notched, white stars, PA to south.  Currently 0.22" it will continue to widen into the 2040s.  58.4-year period.

21h 00m 03.95s +07° 30' 58.2" P.A. 193.20 sep 0.2 mag 6.23,8.13 Sp F1Vp dist. 75.82 pc (247.32 l.y.)

SE 2 BC: 508; 667x: Component of STF2481, which are light yellow-orange near equal well split stars.  High power showed maybe one of them (which I mistook for the primary) was out of round? This is SE 2.  PA of the main pair is nearly N-S, so in my sketch I noted the out of round perpendicular to this, which is nearly correct to the current SW PA.  62.79-year period, currently 0.17" it will make a half circuit and substantially widen by 2050 so it's worth coming back to.

19h 11m 07.99s +38° 46' 52.4" P.A. 256.10 sep 0.2 mag 8.31,9.40 Sp G5V dist. 52.85 pc (172.4 l.y.)

BU  696 AB: 508; 667x: At finest moments very clean clear split, round disks, 1.5 delta, PA just west of north, with two field stars forming a triangle.  160.3-year period, it is approaching apastron and will widen by 2050, currently 0.329".  Burnham discovered in 1877 with the Dearborn 18.5-inch at 0.5" and says: "Obviously the movement of both stars is the same."

22h 04m 30.12s +15° 51' 28.6" P.A. 354.00 sep 0.3 mag 7.95,9.63 Sp G0V dist. 93.37 pc (304.57 l.y.)

HEI 88 AB: 508; 889x: Difficult observation and my notes are a very simple "Maybe?" showing a PA to the SSW.  This turns out to be correct!  35.46-year period, near apastron now, it will widen and turn slightly north to a more westerly PA by 2030.  Currently 0.256".

23h 20m 52.91s +16° 42' 39.2" P.A. 207.70 sep 0.3 mag 9.05,9.84 Sp F7V dist. 77.7 pc (253.46 l.y.)

BU 1099 AB: 508; 889x: Obvious elongation but no notching, PA seems NNE, in a lot of diffraction.  83.1-year period, currently 0.157", it will make more than a quarter turn and widen to 0.2" by 2038.  Burnham discovered in 1889 with the Lick 36-inch at 0.2" and says it's a "close and difficult" pair.  

00h 56m 46.94s +60° 21' 46.3" P.A. 44.00 sep 0.2 mag 6.10,6.57 Sp B7V+B7V dist. 165.02 pc (538.3 l.y.)

BU 1026 AB: 508; 533x: Split with seeing, 2 delta mag, fairly difficult, PA WNW.   Currently 0.345" it will tighten and have a northerly PA by 2040.  

00h 12m 08.05s +53° 37' 26.1" P.A. 326.30 sep 0.3 mag 7.25,8.46 Sp A7Vn+F2V dist. 119.9 pc (391.11 l.y.)