11 may 2021, short periods

Last night's forecast was for "excellent" seeing and transparency, at least until 2am.  Seeing was not all that great, likely do to heat being released from the neighborhood roofs and pavement.  And transparency was more normal with a light marine haze, which subtly thickened through the night.  I tried to rest before going out, since I knew it would be a late night.  I observed from 10pm until 1:30am, when I felt kind of "done" and seeing hadn't improved from what it had been, and the haze seemed noticeably more dense.  I focused on the short period and sweet spot lists.

STF3121 AB: 508; 533x: IP Cnc.  I had observed this last year but failed to make a sketch, and wanted to re-observe it before it got too low, because it's a rapid mover.  Light yellow-orange stars, 1 delta mag, clean well split.  34.17-year period, it's coming off apastron and will make a quarter turn by 2030.  PA to the NE.  
09h 17m 53.45s +28° 33' 37.7" P.A. 34.40 sep 0.433" mag 7.90,8.00 Sp K0 dist. 17.27 pc (56.33 l.y.)

A 222 AB: 508; 667x: Suspect it at all powers up to 667x, where I get a persistent clean split through the seeing.  Light orange stars, 1 delta, PA just east of north.  155.08-year period, it will only cross the north line to head west by 2030.

09h 26m 02.33s +28° 39' 01.5" P.A. 2.60 sep 0.4 mag 9.13,9.41 Sp F8 dist. 111.61 pc (364.07 l.y.)

A 2373 AB: 508; 889x: Just split hairline at best moments, touching disks otherwise, 1 delta mag, very tough. In my notes I put the PA to the NNE, but this is a reversal of what is listed as SE.  100.26-year period, 0.218" now, it will make a barely perceptible arc to the south in the next couple of decades.

10h 52m 02.94s +16° 05' 44.0" P.A. 213.90 sep 0.2 mag 8.80,8.80 Sp F5 dist. 387.6 pc (1264.35 l.y.)

HU 874 AB: 508; 1067x:  34 Leo. A notched elongation is the best I could see, not resolved well.  Slight mag difference but really too hard to tell A from B.  My PA estimate is off 90-degrees.  This is rapidly closing and will be at periastron by the middle of 2022, opening again and should be better detectable again by 2029 when it will be 0.208".  17.962-year period.

10h 11m 38.19s +13° 21' 18.7" P.A. 288.40 sep 0.112" mag 6.90,7.87 Sp F6V dist. 64.6 pc (210.73 l.y.)

BU 614 AB: 178; 533x: "Very difficult, B is a very dim point just separated with seeing."  Turns out I did not see this.  I thought I confirmed by comparing its PA with the widely separated FOX 179 AB-C, but my SkyTools data is incorrect or out of date.  The PA now is due east, I had it the the NNW.  830.72-year period, it won't make a perceptible change in my lifetime -- but I should go back to try it again.  Burnham writes: "This very difficult pair was discovered with the 18.5-inch.  The principal star is identical with that of STT 271, which was marked 'oblonga?' in the Poulkowa Catalogue of 1843, but rejected as single in the revised edition of 1850.  It is not certain that the very minute star now measured [11.7m] has any connection with the suspected elongation previously noticed.  At the time of making the measures given above, the principal star was perfectly round, with the 18.5-inch and 36-inch refractors.  It is the southern star of three in the field."  AB is physical but WDS gives the magnitude as 9.95 -- delta mags often appear to be larger than reality for very close pairs.  0.6" at discovery, AB is physical with a 104.4 year period and currently to the east.  Burnham says it is "southerly" but spinning back the orbit should place it in the west around the time of discovery.  As for STT 271 and the close duplicity of the primary star, neither Aladin Simbad or Gaia DR2 give a second star next to A which would elongate it.  

13h 53m 56.79s +10° 08' 19.9" P.A. 97.40 sep 0.4 mag 8.02,9.95 Sp F0 dist. 141.84 pc (462.68 l.y.)

A 1609 AB:  508; 889x: Notched elongation with the fainter end PA just south of east, very difficult, with seeing only.  44.24-year period, it is nearing periastron and won't appreciably widen, at the opposite PA, until the mid 2030s.  

13h 25m 48.12s +44° 29' 38.3" P.A. 84.70 sep 0.228" mag 9.49,8.79 Sp K0 dist. 52.66 pc (171.78 l.y.)

STT 251 AB: 508; 667x: Best seen at 667x, but could also see at 533x and 445x.  Split, much fainter B about 1.5 delta mag, light orange A and blue B.  540.56-year period, it will reach apastron in 100 years but makes a very close periastron in 400 years.

12h 29m 07.72s +31° 23' 25.4" P.A. 62.20 sep 0.7 mag 8.35,9.27 Sp G0 dist. 173.61 pc (566.32 l.y.)

COU1579 AB: 508; 889x: Very tough notched elongation and instants of splits, I had difficulty sketching it and estimated PA west of north or along that line. Very small scale.  Actual PA is SSE, so I had the alignment correct.  It will be at periastron next year, and get to easy split by 2029 at around 0.231", at the opposite quadrant. 

12h 53m 17.33s +42° 46' 16.8" P.A. 158.30 sep 0.161 mag 9.40,9.70 Sp G9V

A 1095 AB: 508; 889x: Hairline split, >1 delta mag.  187-year period, it will make a slight movement to the north in my lifetime but will be closer to periastron. 

13h 33m 33.77s +29° 44' 16.9" P.A. 294.20 sep 0.3 mag 8.98,9.32 Sp G0 dist. 132.98 pc (433.78 l.y.)