8 april 2023

We seem to have come through the rainy season at last.  It was clear last night with some haze, 3/5 transparency, but good seeing.  Better than good, actually.  I used the 20-inch and was able to chase after some close pairs.  The power on the Servocat kept cutting out, which was frustrating.  It is likely due to it sitting for so long and the metal contacts getting corroded.  

During the long interval between observing I have been going through the 6th Orbital Catalog is more detail.  Previously I had assembled my observing list only from checking a minimum separation value, 0.2".  But doing so will leave off pairs which are at an undetectably close periastron which, over the years, may separate enough to be seen.  I sorted the Catalog by period and, with orbital grade of 3 or better, looked up the orbit on Stelle Doppie for anything with a less than 200-years period.  I wanted to sort out pairs which would not make any significant movement in the next 20 years, and keep anything which might be resolvable at some point with a 20-inch scope.  I ended up with more than 500 pairs, 445 of which are visible from my latitude.  I've loaded this list on SkyTools and will use it nearly every time I observe with the 20-inch as seeing allows.  Many of the pairs deserve annual observations give the pace of their movement.  Besides, I need to track stars at periastron to have a more complete record of their movement.  And, it is not often that seeing will permit viewing of such pairs.

Which brings me to my dilemma.  Good seeing is rare for my observing site.  There are many pairs on the list where apastron is <0.25".  How am I to resolve those?  Unless I can observe with aperture from a mountaintop site with good seeing -- to get above the Bay Area haze.  Such a place is Fremont Peak, but it would mean I need to transport my 20-inch.  Or, I need to have another scope.  The 30-inch at the Peak would be preferable, but I have been so frustrated each time I used it -- difficult to move and point, poor eyepiece placement, crummy focusers, inability to view to the north.  I wish it was not the case, since it drives me to make an expensive choice.  I happen to have two 20-inch mirrors (I haven't sold Swayze yet) -- though at 2" Pyrex it is not the best choice for cooldown, the 1" Zambuto quartz beats it by a mile.  I'm thinking as I type this I could always just move the Zambuto between two different telescope structures, one for home and one for travel...an interesting idea.  It all has me shopping for different solutions.  I have some time to think about it since the road to Fremont Peak was washed out in the storms and it's not clear when it can reopen.

In any case, it was really nice to be back out observing.  Seeing is good again today so some solar observing will be coming up later this morning.

FIN 325 AB: 508; 400x: Using 400x and higher magnifications, the pair appears consistently as a rod with PA just east of north.  There is a nearby field star to mark the place.  Some atmospheric dispersion at highest powers but not influencing the observation.  SOC grade 2 orbit 31.43-years, it is NE now and will be closing to the E through the rest of the 2020s, widening through the 2030s to the S, apastron 2042.

07h 52m 47.87s -05° 25' 41.5" P.A. 356.60 sep 0.1 mag 7.32,6.19 Sp F5IV dist. 39.71 pc (129.53 l.y.)

STF1196 AB: 508; 280x: Zeta Cnc. Lovely near equal pair, light yellow-white color, with a third of similar color and magnitude off to the side.  SOC grade 1 orbit, 59.42-years, it's at N apastron now and will close slightly a quarter turn W by 2040. 

08h 12m 12.79s +17° 38' 51.2" P.A. 0.90 sep 1.1 mag 5.30,6.25 Sp F8V dist. 25.08 pc (81.81 l.y.)

A 2554 AB: 508; 850x: It seemed obviously enlongated WSW with a weaker end to the W.  No notching.  SOC grade 3 orbit, it is at W apastron now, will widen S by 2029 and SE periastron 2040. 

08h 53m 51.95s +01° 49' 28.0" P.A. 316.80 sep 0.1 mag 7.44,9.64 Sp F0 dist. 67.61 pc (220.54 l.y.)

AC 5 AB: 508; 560x: Just enough magnification to split the pair.  There is a significant magnitude difference, PA northward, with a field star to mark the position.  SOC grade 2 orbit, 77.82-years.  It is closing from NNE to apastron in the early 2030s, splitable again in the late 2040s to the SE.

09h 52m 30.47s -08° 06' 17.7" P.A. 34.30 sep 0.5 mag 5.43,6.41 Sp A1V dist. 85.11 pc (277.63 l.y.)

 

STF1523 AB: 508; 140x: Alula australis.  Quite easy, PA to SE and 1 Dm.  SOC grade 1 orbit, it is at SE now and will slowly widen to the E into the early 2040s.  

11h 18m 10.90s +31° 31' 45.0" P.A. 148.80 sep 2.2 mag 4.33,4.80 Sp F9V+G9V dist. 10.42 pc (33.99 l.y.)

HU 1134 AB: 508; 1000x: Viewed at all high powers, it is obviously not round but I could not pin down the PA exactly, it seemed on a NW to SE line but very tough.  SOC grade 3 orbit 81.47-year period, it is edge on and will be at periastron in 2028 before diving to apastron and be essentially undetectable for the rest of its orbit. 

11h 32m 12.54s +36° 14' 50.4" P.A. 300.00 sep 0.2 mag 7.24,7.85 Sp G8III dist. 177.3 pc (578.35 l.y.)

KUI  44 AB: 508; 1000x: 20 Leo.  Using all all high powers, seen as an elongation with a weak end consistently to SW.  SOC grade 3 orbit 113.1-year period, it will widen in the same direction to apastron in 2050.

09h 49m 50.12s +21° 10' 46.0" P.A. 225.50 sep 0.2 mag 6.62,7.31 Sp A7IVn dist. 191.57 pc (624.9 l.y.)

KUI  48 AB: 508; 1000x: At all high powers, appears as a very subtle egg shape, PA seems NW.  SOC grade 2 orbit 17.83-year period.  It will hang NW the next couple of years until reappearing SE 2031 apastron.

10h 08m 15.94s +31° 36' 15.4" P.A. 181.80 sep 0.1 mag 6.90,7.20 Sp F4V dist. 61.24 pc (199.76 l.y.)

KUI  37 AB: 254; 280x: 10 UMa. Using a 10-inch mask to deaden the primary's diffraction, B seen as a difficult point at the first diffraction ring PA NW.  Difficult needed to try all my tricks.  SOC grade 1 orbit, 21.8-year period, it is NNE PA now and will slightly widen to the N in late 2024, before tightening W and S during the 2030s--given the magnitude difference it will be difficult to see.

09h 00m 38.42s +41° 46' 57.6" P.A. 53.30 sep 0.6 mag 4.18,6.48 Sp F3V+K0V dist. 16.07 pc (52.42 l.y.)