6 february 2022

A few days ago Steve posted on TAC about Sirius B, and I shared some of my prior observations.  I gave it a try Saturday night with the 6-inch f/15 refractor, and was pleased to see it after Sirius had moved away from a neighbor's roof at around 9:30pm.  It was faint, but not too difficult.  It was my first time using the Leica zoom, a lovely and surprisingly large and heavy eyepiece.  Sirius is so bright that even when focused it showed several concentric rings, and Sirius B was a faint star fairly well separated from the primary but still within the outermost rings.  Seen even with lowest power 134x (actually it was best at this power).  I plan to try my NP101 some night this week to see if I can make an observation that low -- I am sure it is possible.

The bad news from that Saturday is I think the declination encoder is either broken or the belt has snapped or slipped off the gear wheels.  After observing Sirius I was going to observe more using the Argo but the declination numbers would not change.  I reseated all the connectors, but still no movement.  It stinks because to get at that encoder I have to tear the whole mount down.  That might turn out to be a good thing since I might change out the rings and do some other maintenance.  

Last night I observed with the 20-inch.  Seeing was ok, but not great.  Transparency better than the usual winter haze.  I ran through a 30 star TPAS with the Argo, hoping I did it correctly (the instructions are confusing) and that it sticks.  It seemed to help with initial observations but the pointing accuracy started to drift during the night.

I created new lists of doubles, specifically those only with known orbits.  I'm combining what was generated by SkyTools, which seems to be an out-of-date database, and a fresh list from StelleDoppie.  There are plenty of pairs and this should keep me occupied for a couple of years.  It will also help me sweep up some short period pairs, those with periods of greater than 80 years, which was the limit on my prior lists.  I ran through the pairs in CMi and some of Gemini last night, with good results.

STF1130 AB: 508; 300x; Light yellow-orange stars, noticeable magnitude difference, elongated at lower magnifications, hairline split at 300x.  Discovered at 2", it has a 1000-year period (give or take 300 years), it is coming off a very fast and close periastron and will widen very considerably in the coming decades.  WDS notes the orbit is premature, and needs speckle for future observations.  I don't find parallax for them in EDR3, so can't determine further.
07h 41m 42.35s +09° 42' 17.3" P.A. 69.30 sep 0.6 mag 8.76,9.48 Sp G0 dist. 66.45 pc (216.76 l.y.)

A2869 AB: 508; 667x: Light yellow-orange stars, hairline to strongly notched overlapping disks at 667x, as much as seeing will support.  PA is ESE, and the pair forms an equal triangle with two other stars in the field.  143-year period, it will made a modest movement of around 0.1" wider separation by 2040.  I don't find parallax in EDR3.
07h 30m 27.65s +07° 43' 09.3" P.A. 108.50 sep 0.3 mag 8.30,8.50 Sp A5 dist. 207.47 pc (676.77 l.y.)

STF1175 A pretty white and light yellow b, nicely split, two dm. twenty seventeen.  WDS notes this is a premature orbit, and it may not turn out to be physical.  With EDR3 data I find there is no parallax range overlap (-65%) so very likely this is not a binary.

08h 02m 26.06s +04° 09' 07.5" P.A. 288.70 sep 1.4 mag 7.89,9.13 Sp G5 dist. 40.55 pc (132.27 l.y.)

A2880 AB: 508; 1334x: Elongated with moments of strong notching, noticeable magnitude difference, PA to the SSE.  106-year period, it will have a SSW PA by 2040.  I don't find the EDR3 data.
07h 50m 47.36s +03° 16' 38.4" P.A. 176.20 sep 0.2 mag 7.10,7.10 Sp K1III dist. 150.15 pc (489.79 l.y.)

J420 AB: 508; 150; An equilateral triangle of similar magnitude stars, one corner of which is J420, which is a near equal pair, nicely split.  A 168-year period, it will remain in the same quadrant for the next 40 years.  WDS notes "Appears to be in rapid retrograde motion," and what I find in EDR3 is there is no parallax range overlap, -94%, so this is not binary at all.
08h 06m 15.16s +02° 00' 47.3" P.A. 192.70 sep 2.2 mag 11.06,11.46 dist. 114.03 pc (371.97 l.y.)

STT175 AB: 508; 889x: Light orange stars, elongated out of round but not notched, seems to be one delta.  213-year period, it may widen by 0.1" by 2040 so might become better resolved by then.  

07h 35m 08.79s +30° 57' 39.3" P.A. 338.80 sep 0.1 mag 6.08,6.49 Sp K0III dist. 114.16 pc (372.39 l.y.)

STT187 AB: 508; 667x: White stars, 1 Dm, hairline at 333x, nice close split at 667x.  254-year period, it will pretty much stay where it is the next couple of decades.  Lacks EDR3 data.
08h 04m 08.38s +33° 01' 50.8" P.A. 334.60 sep 0.4 mag 6.94,8.50 Sp A1.5V dist. 172.71 pc (563.38 l.y.)

STT149 AB: 508; 889x: At 2 Dm the pair is fairly tough to resolve.  PA is just south of west (actually just north of west), nicely split B in A's diffraction. 119-year period, it will tighten rapidly to the south and become close to undetectable by 2040.  Insufficient data in EDR3.
06h 36m 26.26s +27° 16' 42.2" P.A. 276.40 sep 0.7 mag 7.14,8.97 Sp dG2 dist. 33.11 pc (108 l.y.)