Tuesday, October 18, 2016

observing last night

It had been such a long time observing I went out last night despite the poor seeing and worse transparency.  I also wanted to make sure mice had not intruded into the shed.  It is dark by 7pm so I was able to get 2 hours in, 7-8pm in Delphinus and then 9-10pm in western Pegasus, mostly checking out doubles, using the 12.5-inch.  Doubles mostly at 277x unless otherwise noted:

Beta Delphinus (BU 151, Rotanev): Bright white A and much fainter, widely separated B.  Rich field.  [Obviously an erroneous observation as the AB pair is currently 0.3" separation.  There are also C, D, and E components orbiting around the AB pair, so I may have seen one of these.   S.W. Burnham discovered the AB pair in 1873, while he was still a backyard ameteur, using his 6-inch refractor!  Pretty amazing, and inspiring.  101 light years away, 26.66 year period.]

Gamma Delphinus (STF 2727): Rich gold-yellow A, blue-white B, ~6" separation estimated by eye.  Very pretty pair.  [4.36, 5.03; 8.9", 2305 year period.  There is also an AD pair (but no C?) 109.4" separation discovered in 1998.]

STF 2725: Can be seen just stretching to edge of FOV with Gamma Delphinus; but not a comfortable view.  Near equal yellow-white stars, wide separation.  Seeing is not very good, a lot of diffraction.  [AB is 7.54, 8.20; 6.1", 2925 years.  There is also an Aa and Ab system, 0.1" separation, discovered in 2008].

STF 2738: ~1 magnitude difference, widely separated white pair.  [Sigh.  This is an optical triple system.  I saw AB, 7.51, 8.57; 14.9" -- proper motion indicates is an optical pair.  There is an AC pair which is also optical, and a BC pair which is also optical.]

STT 213: Bright yellow A, ~2 magnitudes fainter B, very wide separation.  Kind of a stab in the dark as I don't notice any other possible close pairing.  [Seems I was correct: 6.66, 9.22; 70.5"]

This last star is near NGC 7006, a globular cluster, which was fairly small, faint, loose concentration, not much brightening to the middle.  Appeared open-cluster like and needed to move the scope around to confirm, it was so faint.

Theta Delphinus: I paused in my star hop to have a look around.  Delphinus is in the Milky Way stream, after all, and even though I can't see the MW from my yard I often find lovely rich fields through the eyepiece.  Theta Delphinus turns out to be a bright orange star, likely a carbon but I can't find much information about it.  Pretty, though.

STF 2723: Seeing not supporting higher magnifications, though I should have tried anyway.  Either a very close near equal magnitude peanut shape, or a very bright A and a very faint B widely separated.  Shot in the dark.  [This time I might've been right!  AB is 7.01, 8.30; 1.2".  AC is 13.00, 36.1".  There is also a Aa, Ab system with 0.1" separation.]

STF 2690: Widely separated near equal white stars.  [This is a quintuple system.  The A, BC pairing was discovered in 1777!  By whom, since Struve was not born yet?]

ΒU 63 (1 Del): Not resolved if this is a close pair; night be one of the fainter stars about.  [The description is about right, meaning I didn't see the close pair: 6.20, 8.02; 0.9".  Burnham found the AB pair in 1872, and also found the AC pair in 1885, the C being 14.4 magnitude and 16.9 separation -- very remarkable since I think he was still using his 6-inch at that time.]

STF 2665: Nice!  Brighter A, white; very close B ~2", orange-red and much fainter.  Resolved when the scope stops shaking and the seeing stills.  [Quadruple system with three visible.  A,BC is what I saw, 6.88, 9.55; 3.3" separation.  Aitken found the BC pair in 1907, C being 10.80 and 0.1" separation.]

Ho 131: Suspected a very faint (averted vision necessary) B ~3" from an orange A, when seeing stills.  Used 553x.  [G.W. Hough, 19th c. American astronomer from New York.  Very possible I saw the AB pair, 6.97, 10.60; 3.5".  There are also AC and AD components, fainter and much further separated.  I hope he likes that someone looked at his star; last measurement was made 15 years ago.]

S 752: Widely separated white, near equal brightness.  [Complex quintuple system.  What I saw was the AC pair, 6.80, 7.30; 106.5".  The rest are closer in and 11 - 15th magnitude.  

As a change of pace, I moved the scope down to Mars, which has been making a bee-line through Sagittarius this last month and provided many opportunities for pretty pairings with various deep sky objects.  Last night Mars was NE of the teapot's handle (too bad it was cloudy a couple days ago, Mars passed close to M22).  Mars was visible all summer, and because it's relative motion is eastward in the sky is still in good position now, if further away from us.  I was still at 277x when I viewed Mars at first, which was slightly gibbous and with Syrtis Major jutting down; but the view was soft.  I switched to 71x and 1.1° FOV to see if any other objects could be seen.  No DSOs noticed but Mars was in between two reddish stars, spread fairly wide on either side, and in a pretty star field with many triangle asterisms.  Some of the fainter stars seemed to be reddish too.  I bet if the sky were darker and less moist the view would be spectacular and colorful.

S 798, Enif: Very bright, nothing close by.  Some stars wider.  [I thought this was a bad observation but I find AB is 2.53, 12.80; 83.2", and AC is 8.74, 145.4".  So some of the stars I saw were the pair, even though I didn't know.]

I tried for an anonymously plotted double star to the south of Enif, but it was not resolved.

STFA 56: The main pair was a fairly bright A, ~1 magnitude fainter B, widely separated.  However there were two other pairings in the view, making it look like a triple double: pointed at by the AB pair, a very close, faint red-orange pair of stars, and then further on a very fainy, tremulous pair a little more widely separated.  There are more stars in the view but they don't seem to be associated.  [AB is 6.18, 7.50; 38.9" and certainly seen.  The other two I can't identify.  I did a Declination sort in the Carro double star catalog, but don't find any obvious pair -- except for STT 443, 9.47, 9.67, 8.2", which might be the second pair mentioned.  A pretty view, and a mystery to be solved.]

M2 was close by, and since I hadn't seen it this season stopped for a look.  It was visible in the 50mm finder as a hazy star.  It is a compact globular cluster, dense core like fine sand in a pile.  Many faint stars resolved; averted vision reveals brighter stars across its face.  Seeing was becoming more poor.

STF 2809: Bright A, widely separated, ~2 magnitudes fainter B.  [Triple system.  AB seen, 6.22, 9.36; 31.1".  AC discovered in 1998 13.84 and 37.8" separation.]

STF 2909: Very bright white, equal magnitude, fairly close ~2".  Seeing is poor, stars are bloated and flaring.  [4.34, 4.49' 2.3"]

h 5529: Too-bright A -- if it's a close pair cannot resolve it; otherwise it's a faint nearby star.  [Option 2.  5.16, 12.20; 87.1".  There's an AC pairing discovered in 1980 which is an absurdly wide 999.9" -- does it mean the separation is not yet determined?  In any case, the AB at least is an optical double.]

HN 140: Pretty orange star, but where's the pair?  [Not surprising I didn't see them; B is 10.92 magnitude and given the conditions, with a thicker haze in the air, it would have been difficult to see it even with 61.9" separation.  There's also a C pair, and an Aa and Ab.]

STF 2944: Pretty close equal white pair, ~2.0", split.  faint blue C widely separated?  [AB is seen, 7.30, 7.68; 1.8", 1160 years.  There are three other pairings in the system, most should be visible.]

The seeing became worse.  The thick haze in the air scattered light from the rising moon.  So, having already filled several notebook pages, I decided to call it a night.  Seeing and transparency are to be average again tonight, but the rest of the week looks really good so I plan to get out more.

No comments:

Post a Comment