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.)

 

fun with 80mm pt 2

I added a 50mm finder scope to the 80mm and I was much more productive last night. I really appreciate how clean the airy disks are even with what would be poor seeing with the 20- or even 7-inch. I'll definitely continue to use this scope for night viewing even when I have the 6-inch set-up.

STF1596 AB; 80; 94x: 2 Com. I think last night I noted the incorrect star. This one is really nice, 2 delta mag, orange and blue, close but nicely split.
12h 04m 16.60s +21° 27' 33.0" P.A. 236.00 sep 3.7 mag 6.18,7.48 Sp F0IV-V dist. 101.01 pc (329.49 l.y.)

STF1657 AB: 80; 94x: 24 Com. Lovely bright orange A and blue B, wide.  Very deserving of its showcase reputation.

12h 35m 07.76s +18° 22' 37.4" P.A. 272.00 sep 20.2 mag 5.11,6.33 Sp K2III dist. 138.12 pc (450.55 l.y.)

STF 1633: 80; 94x: Close, equal white stars. 
12h 20m 41.37s +27° 03' 16.4" P.A. 245.00 sep 9.0 mag 7.04,7.13 Sp F3V+F3V dist. 91.83 pc (299.55 l.y.)

M53: Appears as a round haze, no stars resolved, really looks like a comet's halo, like Messier probably saw it.

STF 1854 AB: 80; 94x: B is widely separated but with averted vision

14h 29m 49.66s +31° 47' 28.2" P.A. 256.00 sep 26.1 mag 6.05,10.62 Sp A0Vs dist. 110.13 pc (359.24 l.y.)

STFA 27 AB: 80; 94x: Delta Boo.  Wide, large delta mag B, a 76,000-period pair!  

15h 15m 30.16s +33° 18' 53.4" P.A. 78.00 sep 105.0 mag 3.56,7.89 Sp G8IIICN-1 dist. 37.34 pc (121.8 l.y.)

STFA 28 AB: 80; 94x: Alkalurops  Bright yellow-white A and bluish B, which is itself a slightly unequal close double, finely split (STF 1938 Ba,Bb) -- 256.5-year period, now coming off apastron.

15h 24m 29.54s +37° 22' 37.1" P.A. 172.00 sep 109.0 mag 4.33,7.09 Sp F2IVa+G0V dist. 34.69 pc (113.16 l.y.)
15h 24m 30.89s +37° 20' 52.5" P.A. 2.10 sep 2.2 mag 7.09,7.63 Sp G0V dist. 36.06 pc (117.63 l.y.)

STF 1825: AB; 80; 94x: Very fine split, >2 delta mag, white A and blue B, nice.

14h 16m 32.84s +20° 07' 18.7" P.A. 152.90 sep 4.4 mag 6.47,8.42 Sp F6V dist. 32.63 pc (106.44 l.y.)

STF 1864 AB: 80; 94x: White stars, 1 delta mag, nicely split.

14h 40m 43.56s +16° 25' 05.9" P.A. 113.00 sep 5.4 mag 4.88,5.79 Sp B9pMnHg dist. 93.72 pc (305.71 l.y.)

STF 1888 AB: 80; 94: Yellow A and orange B, 2 delta mag, nice.  Only 22 light years distant, it is physical with a 298-year period, and will tighten the next 30 years.

14h 51m 23.38s +19° 06' 01.7" P.A. 297.00 sep 5.3 mag 4.76,6.95 Sp G8V+K5V dist. 6.71 pc (21.89 l.y.)

STF 1919 AB: 80; 94x: Near equal, white, wide

15h 12m 43.48s +19° 17' 09.8" P.A. 11.00 sep 23.4 mag 6.71,7.38 Sp G1V+G5V dist. 27.24 pc (88.86 l.y.)

STF 1884 AB: 80; 94x: More difficult than nearby Izar.  Extremely fine, 1 delta mag, notched, to overlapping disks at best moments.  Physical with a 1398.2859-year period, it has a nearly edge-on orbit and is currently at the shorter of the two furthest reaches of its orbit.

14h 48m 23.37s +24° 22' 01.0" P.A. 54.40 sep 2.1 mag 6.58,7.48 Sp F8IV-V dist. 84.67 pc (276.19 l.y.)

fun with 80mm

I misjudged the weather last night. During the late afternoon a cool wind started, and that usually means the marine layer is on its way. So, I didn't open up. It turns out the sky did have a thin haze, but was not covered over, and the seeing was about average. So I brought out my 80mm f/15, which I've mainly used for solar observing, and set-up in the back yard. It has really good optics, and when matched with a 2" prism diagonal, produces very nice images. I only had a Telrad to find stars, but I think I'll add a finder scope to help navigate to fainter stars, since it would save having to swap eyepieces. As it was I found all the bright stars just with the Telrad. I'd even consider using an equatorial mount rather than the alt-az, maybe at least at a dark site. As always, it's always better to go out and observe...

Since I was using the CDSA 2nd edition, all of these are physical unless noted:

STF 1351: 80; 92x: 23 UMa.  Light yellow and much fainter wide B. 
09h 31m 31.57s +63° 03' 42.5" P.A. 267.00 sep 22.7 mag 3.65,9.19 Sp F0IV dist. 23.82 pc (77.7 l.y.)

STF 1315: 80; 92x: White, wide, near equal.

09h 12m 45.94s +61° 40' 32.7" P.A. 28.00 sep 25.1 mag 7.33,7.65 Sp A3IV dist. 100.2 pc (326.85 l.y.)

STF 1306: 80; 150x: Suspected very close unequal white stars.  920-year period, slowly widening

09h 10m 23.53s +67° 08' 03.3" P.A. 346.30 sep 4.5 mag 4.87,8.85 Sp F7V dist. 20.38 pc (66.48 l.y.)

STF1692 AB: 80; 92x: Cor Caroli, showpiece, almost three detla mag and nicely split.  Nice round star images.

12h 56m 01.67s +38° 19' 06.2" P.A. 230.00 sep 19.5 mag 2.85,5.52 Sp A0pSiEuHg dist. 35.2 pc (114.82 l.y.)

STF1877 AB: 80; 150x: Izar: Dull yellow-orange A and dull orange B, nice round images so split easily.  No parallax for the B star, so it's uncertain if physical

14h 44m 59.14s +27° 04' 29.9" P.A. 347.00 sep 2.8 mag 2.58,4.81 Sp K0II-III dist. 62.11 pc (202.6 l.y.)

STF1670 AB: 80; 92x: Porrima.  Nice and easy, yellow-white equal stars.  169-year period.

12h 41m 39.60s -01° 26' 57.9" P.A. 357.50 sep 2.9 mag 3.48,3.53 Sp F0V+F0V dist. 11.68 pc (38.1 l.y.)

STF 1724: 80; 92x: Extremely faint B, just visible, brighter white
13h 09m 57.01s -05° 32' 20.1" P.A. 342.00 sep 6.8 mag 4.40,9.39 Sp A0IV dist. 96.81 pc (315.79 l.y.)

STF 1764 80; 92x: Extremely faint B flashes with averted vision only.  Lower to horizon and in haze, so it was more difficult to see the faint star.

13h 37m 44.01s +02° 22' 56.5" P.A. 31.00 sep 16.1 mag 6.79,8.56 Sp K2III dist. 625 pc (2038.75 l.y.)

STF 1523 AB: 80; 150x: Alula australis.  Slight magnitude difference, hairline split, light yellow A and darker yellow B.

11h 18m 10.90s +31° 31' 45.0" P.A. 152.60 sep 2.2 mag 4.33,4.80 Sp F9V+G9V dist. 10.42 pc (33.99 l.y.)

BU 603 AB: 80; 150x: Elongated but not split.  129-year period.

11h 48m 38.71s +14° 17' 03.2" P.A. 327.70 sep 1.0 mag 5.97,8.53 Sp A8III dist. 59.74 pc (194.87 l.y.)

STFB 7 AB: 80; 92x: 93 Leo.  Pretty orange and blue, wide, 2 delta mag.

11h 47m 59.23s +20° 13' 08.2" P.A. 355.00 sep 74.9 mag 4.59,9.03 Sp A7V dist. 71.33 pc (232.68 l.y.)

waiting for the seeing

For months now I have not had good enough seeing conditions to push the limits of my double star observing.  So I've mostly just masked down to 7-inches to try to make the most of it, but I've tapped out most of the other >1" 5-8th magnitude pairs in the spring sky.  When seeing might be good, marine haze would roll in and rob me of the views. Yesterday's forecast was for both good transparency and "excellent" seeing -- but only after 1am. So I waited for it. I let the scope cool starting at 5pm after the hot day, and since I've been having some pointing problems, ran a 30 star TPAS cycle with my Argo as soon as it got dark. Then, at 9:30pm, instead of continuing to observe I disengaged the drives and went inside. I napped a little, and got up at midnight to go back outside.

Now the spring constellations were nearly set and summer's were getting pretty high. Seeing was not quite great when I started, but per forecast by 1am it was good enough to start pushing limits. I have two lists for such occasions: a Short Period list of physical doubles with <80-year periods which I am trying to track over the next many years to try to detect change, and a "Sweet Spot" list, which are doubles of 8th-9th mag with very close separations which are well suited for splits with the 20-inch scope -- the stars are not too bright to cause too much diffraction but bright enough for airy disks to show. Most of the latter are physical but the periods are >80-years, so I may or may not notice change, but they are good for challenge pairs.

This morning I have the feeling of having come back from some great adventure, seeing things few have seen, a kind of glow from the experience about me. That could just be feeling overtired, but it's a good feeling to have.

KUI 66 AB: 178; 445x: Light orange-yellow A, when it settles with seeing there is a persistent very faint point within the shifting diffraction, <1", large delta mag.  There are 36 measures in the WDS since 1936 discovery, but the nature of the pair is uncertain because there is no parallax data for the secondary star.
14h 14m 50.85s +10° 06' 02.2" P.A. 111.00 sep 0.8 mag 5.44,8.43 Sp K1III dist. 81.23 pc (264.97 l.y.)

BU 612 AB: 508; 1067x: Lightest orange, notched elongation to snowman at best moments.  Burnham discovered in 1878 with the Dearborn 18.5-inch, and in 1899 wrote: "It was very soon apparent from the measures that this was a binary system in rapid motion.  In the twenty years covered by the measures, the companion has passed over an arc of 175-degrees.  Glasenapp…has computed an orbit from which he finds a period of 30.00 years....This represents the observations as well as could be desired, but evidently the arc was too short for any very accurate determination, and even now widely differing apparent orbits will satisfy the observed positions equally.  It is probably that the measures of the next ten years will furnish sufficient data for an orbit which shall substantially correct."  In the period since, there have been many measures, and a grade 1 Definitive orbit is established. WDS lists it as physical with a 22.46-year period, currently at 0.1 but will widen to 0.3" by 2030 -- I can hope for a clean split by then. 
13h 39m 34.68s +10° 44' 46.7" P.A. 49.20 sep 0.1 mag 6.35,6.47 Sp F1V dist. 59.99 pc (195.69 l.y.)

STT 269 AB: 508; 1067x: Strong notch, good star images, not quite split.  I saw it as a rod at 205x, and the notch increased in strength with each magnification step up.  PA to SW.  Physical with grade 2 orbit and 53.2-year period (having made nearly one revolution in my lifetime so far!), it is 0.297" now and is coming off apastron, it will rapidly close to undetectability by the late 2030s.
13h 32m 51.02s +34° 54' 25.8" P.A. 227.60 sep 0.3 mag 7.27,8.08 Sp A6III dist. 147.93 pc (482.55 l.y.)

HU 644 AB: 508; 533x: Quite perfect star images, light orange stars, nearly 2 delta mag, well separated, PA northwest.  Grade 2, physical, 48.776-year period.  It has a slightly out of round orbit from our perspective, near it's periastron now and will widen to an easy 1.584" by 2030.
13h 19m 45.58s +47° 46' 41.1" P.A. 287.90 sep 0.3 mag 9.11,9.87 Sp M2V dist. 10.71 pc (34.94 l.y.)

A 1120 AB: 508; 889x: Fairly strong notch but no split, not separated, snowman PA to west of north, >1 delta mag.  Physical with 51.75-year period, grade 3 orbit (likely), 0.246" now.  It is now coming off apastron and will close by the early 2030s, detectible visually again by 2045 or so. 

15h 27m 18.03s +09° 42' 01.1" P.A. 336.90 sep 0.2 mag 8.50,9.10 Sp G0 dist. 96.9 pc (316.09 l.y.)

COU 612 AB: 508; 889x: Very slight elongation all powers, PA N-S but can't tell A from B.  Physical with 63.09-year period, it's coming off apastron and will be difficult to detect visually until the 2060s.  No sketch!
15h 39m 02.60s +25° 44' 47.0" P.A. 150.40 sep 0.24 mag 9.15,9.04 Sp G5 dist. 106.04 pc (345.9 l.y.)

COU 798 AB: 508; 889x: Barest of notches, white stars, noticeable magnitude difference.  PA to the south.  It's in the same low power (205x) field of view with Gemma, alpha CrB, so it looks like a piece of debris from the bright star explosion as seen in the eyepiece.  Grade 4 orbit, 0.256" now, will widen only slightly by 2050 apastron.  154.7-year period.

15h 34m 40.64s +26° 54' 42.8" P.A. 212.70 sep 0.2 mag 9.50,9.80 Sp G0+G2

HU 1163 AB: 508: 667x: Barest hairline split at the best moments, snowman otherwise, very noticeable magnitude difference, PA to south.  0.257" now, it will widen slightly the next 30 years, reaching apastron around 2090 at ~0.4".  Grade 3 orbit, 217-year period. 
15h 30m 44.95s +38° 09' 48.7" P.A. 189.70 sep 0.257 mag 9.23,9.73 Sp G5 dist. 243.31 pc (793.68 l.y.)

STF2028 AB: 508; 533x: Nice delicate split with 445x, well split clean with 533x, white stars, ~1 delta, PA to SE.  Grade 3 orbit, 105.34-year period, 0.519" now it's at apastron now and will sit there until 2050 when it will start close again in its nearly edge-on orbit.

16h 12m 48.11s +39° 21' 35.6" P.A. 147.00 sep 0.519 mag 9.88,9.14 Sp G0 dist. 67.2 pc (219.21 l.y.)