15 august 2022: close pairs

There's a heat dome over the Bay Area, and while it locks in haze (Antares looked particularly red), it also provides pretty good seeing.  After trying out a couple test pairs with 20-inch aperture, I found I could push resolution and magnification, so I switched over to my short period list.  I only made a few observations, but they were all good.  I started to run out of targets in this right ascension!

STF2247 AB: 508; 145x: Bright wide pair, near equal.  WDS says parallax indicates it's physical, and there is 62% overlap of the parallax ranges, 1,890 AU weighted separation, 1.5+1.3 Msol, and the radial velocity delta 0.7 is less than the escape velocity 1.6 -- it is most likely binary, and someone should run an orbit!  COU1003Aa,Ab was discovered at 0.2" but is now at periastron 0.047" with a 159-year period, not detected

17h 59m 24.52s +29° 29' 29.6" P.A. 188.00 sep 11.6 mag 9.17,9.88 Sp F5

HU319 AB: 508; 1016x: Notched snowman, PA to south, momentary hairline split with seeing.  WDS uncertain, and unfortunately no Gaia parallax data for the primary and no data at all for the secondary.  Last measures in 2012.

18h 16m 27.03s +22° 49' 03.9" P.A. 120.00 sep 0.2 mag 9.10,9.50 Sp A5

BU631 AB: 508; 1270x: Touching disks to hairline at >500x, but better viewed with steady close split at 1270x (brighter stars have larger apparent disks, needed more magnification to separate them), near equal orbs, pretty bright, PA ENE.  0.332" now.  147.5-year period, surprisingly there is no Gaia parallax data for the primary.

17h 39m 57.70s -00° 38' 21.2" P.A. 75.80 sep 0.3 mag 7.23,7.40 Sp B9IV dist. 245.7 pc (801.47 l.y.)

STF2272 AB: 508; 145x: 70 Oph.  Beautiful, cream white A and 2 Dm light orange B, well separated, PA to SE.  The easiest short period binary one can find--and a better double star than Albierio to show at an outreach event because 70 Oph actually is binary and individuals, especially the younger, can be inspired to follow the orbit throughout their lifetimes, and they can do so with small telescopes.  88.3983-year period, it is coming off a long apastron and will be due east by the late 2040s.  

18h 05m 27.37s +02° 29' 59.3" P.A. 120.90 sep 6.7 mag 4.22,6.17 Sp K0V+K4V dist. 5.08 pc (16.57 l.y.)

HO87 AB: 508; 850x: Clean split at 570x, better view at 850x, PA to ESE, well split, >1 Dm, light yellow-orange stars, B a deeper orange. 119.39-year period, it will widen slightly and be to the SE by the mid-2040s.  Lacks parallax data in Gaia DR3.

18h 38m 36.74s +16° 32' 27.7" P.A. 97.50 sep 0.4 mag 8.34,8.98 Sp G5 dist. 128.7 pc (419.82 l.y.)