2020-Nov-19 PM: Globular Exploration; Multiple Multiple Stars.

First night of decent seeing for a while, so I took my dob out to look at planets. Last night I went out to observe Mars late, but the darn scope wouldn't cool down and the image was horrible. Tonight was pretty good. In addition to doing some planet viewing, I got some exploration done, and it's always a nice night when you get to see something new.

When I first set up, I had to collimate the scope, and having done so I think it has very well paid off--through gaps in the seeing I was getting some real sharp images. I started the night getting my family to observe Jupiter & Saturn as well as a waxing crescent The Moon. I was out about sunset, and found Jupiter just after the Moon. Seeing Jupiter before it gets real dark is always very pleasant, the colors seem richer.

After dinner (during which I left the scope out to cool) I brought my family out to see the Moon & bright planets. After a while my scope cooled enough that I could see a dark spot had resolved into a pinprick shadow transit. Only two of Jupiter's moons were visible; I assume one was in front and one was behind. Saturn was moderately sharp with moments of true clarity, and the Cassini division and cloud banding were quite obvious. I was eventually able to observe as much as five moons, though I did not write their positions down in my log. According to Stellarium's moon positions at the time I was out, it looks like I saw Titan, Iapetus, Dione, Rhea, and Tethys.

The Moon was excellent. Unfortunately I haven't really been making any good documentations of lunar observations since my Half-Month of Lunar Observing in late June. My favorite lunar crater, Messier, was well placed for observing both is cometary albedo feature (subtle) and its actual shape, and it looked great.

I saw two satellites in the eastern sky of 2nd magnitude. Almost certainly Starlink. About 5 minutes later I saw another bright satellite come within half a diameter of Saturn while observing at 200x. The damned thing nearly transited. I suspect it too was a Starlink. I abhor these things.

I also received a cheap Svbony 2x Barlow in the mail while observing. The 2x Barlow works very well for the price! Unfortunately Svbony sells two cheap 2x Barlows, one which is a single-element unit which is trash--I got rid of the one I bought a few months ago. The two-element one works very well considered it cost $17. I'll be giving it away as part of a gift which I will report more on after Christmas.

Alright. Warm up over. Time to find Messier 15. I observed M15 first during the 2017 Observational Astronomy class, where I noted it has a very sharp light/radius curve. I have certainly observed it more times since, but none since the pandemic and all by myself, until a few days ago, when I used a 4" f/5 refractor (another piece of the Christmas gift puzzle) to observe it. It wasn't structured, but I definitely noticed the sharpness. I resolved to go back and observe it with the Dobsonian.

Through the Apertura DT6 (6" f/8) it was very easy to find in the 32mm Plossl eyepiece. At the sidereal time I was observing, it turns out to be an azimuth-only slew from Enif. At other times when it's diagonal away from Enif, it will require ever so slightly more thoughtful star-hopping. To find Enif, follow the limb of Pegasus that is opposite on the Great Square from the limb which reaches out towards M31 & Cassiopeia.

At all powers with a 6" scope in my observing conditions (which were slightly worse than the last few nights due to moonlight and slightly worse transparency--though the transparency was still above average) M15's details were elusive or invisible. After several minutes of observing at 200x I could begin to pick out hints of granularity and suspect a few individual stars especially in the outskirts of the cluster. The more I looked, the more the granularity became noticeable.

Sketch of Messier 15. 6" f/8. 200x.

With my main goal done, I considered packing up then and there, but I decided to keep going even though it was pretty chilly. Nearby to the south is another globular, Messier 2. It's easy to find, as it's roughly a third of the way from Sadalsuud to Enif. Just before you get to Enif, the path seems to fork from Biham in Pegasus to either Enif to the North or Sadalmelik to the South. Continuing to the southwest from Sadalmelik gets you to Sadalsuud.

M2 and M15 are the same magnitude (6.5 vs 6.4) and similar sizes, though I think M2 was perhaps slightly larger. My notes show that I have observed M2 in 2017, though it didn't make as much of an impression as M15.

M2 still lacked detail at low and medium powers, but at 200x, its granularity was subtle but definite. Staring at it more, the granularity became somewhat more certain, and stars towards the outskirts were very visible. M2 was much "rounder" than M15, in terms of the light/radius curve, though it seemed to me that there was a little bit more structure to it, with a subtle lump to the left. 

Sketch of Messier 2. 6" f/8. 200x.

While writing this, I decided to take a look at my 2017 notes. Nov 13th. Messier 2: Very round, almost like a parabolic light curve. Wide round core. Not much structure. Messier 15: More granular, wider, 2x bigger, brighter, and sharper. Not as round as M2. Good Comparison. I drew a light curve for M2 on that night, but a couple weeks earlier I'd drawn a light curve for M15 as well, showing it as quite sharp. My drawings from Oct 30 showed a lot of detail--a "y" shape, several "loops," and it certainly makes me want to revisit it with larger telescopes and/or darker skies. Anyway it's interesting that I considered the pair a good comparison even then.

I considered my next target. I'd wanted to look at the Saturn Nebula and try for the dim clusters south of it, but they were in the trees--my home observing site is certainly not perfect.

Near Delphinus, a constellation so dim I usually forget it exists, is Caldwell 47, an 8.9 magnitude globular cluster. Follow the tail of the Dolphin by about its own length, and very slightly to the east, and you should see it in an adequate telescope in adequate conditions. The view with the 32mm eyepiece reminded me of M13 seen through a finderscope. It's dim, but clearly nonstellar and obvious with averted vision. 200x revealed no structure and no granularity. It's tiny, with a nearby star of similar magnitude right next to it.

Sketch of Caldwell 47. 6" f/8. 200x.

 

After having my fill of new globulars for the night, I turned to Cassiopeia to take a peek at the Double Cluster. Excellent as always. The red stars weren't really noticeable and I've seen better views of it with that scope--moonlight was certainly to blame. But it is still an excellent object.

I decided to take a look at Iota Cassiopeiae, which I first discovered from my house the very first night I observed there, before we'd even moved in. Double stars can be fun, but triple stars are excellent. Iota Cas isn't difficult. Follow the line from Ruchbah (Mag 2.7) to Epsilon Cas (Mag 3.3)--respectively the 4th and 5th stars, east to west, in the "W" asterism--go that length again and you'll find Iota Cas, a Magnitude 4.5 star with a subtle pale blue-white tint. At powers below 80x it is a tight double star. At 80x, the third star can be glimpsed, and at 200x, it's a very splendid compact triplet. The closest companion is the brighter of the two. Iota Cas is in fact a 5-star system, though two of its components are spectroscopic doubles which can't be split visually. Iota Cas A is an A3V and G6V double, Iota Cas B is an F5V star, and Iota Cas C is a K4V/M3V double.

Next was a favorite--Achird, or Eta Cassiopeia, which is roughly on the line between Shadir and Navi (respectively the 2nd and 3rd stars east to west in the "W" asterism). It's a 3.44/7.51 magnitude double, and is slightly difficult to split at 38x but very easy above that. 200x shows it as a very nice pair with subtle color--Achird A is a pale yellow-white (G0V sun-like star), while Achird B is a gray or perhaps pale brown star (K7V orange dwarf). They are 19.4 Light Years away, and the pair orbits each other every 480 years. Eta Cassiopeia A was the sun around which the fictional planetary colony Terra Nova was placed in the Star Trek: Enterprise episode "Terra Nova."

Then it was Almach, or Gamma Andromedae, a star I have neglected for too long! This isn't my first time observing it this year, but golly I should have seen it sooner. It's a beauty. Brighter but more compact than Alberio, and yet they're practically siblings. A bright gold star with a pale blue companion. It was slightly harder to split than Achird, though not by much. It looks excellent at 200x, with the airy disks quite close to each other and with the Airy rings of the primary overlapping with the companion.

Sketches of Iota Cas, Eta Cas, and Gamma And. 6" f/8, 200x.

 

At this point, Mars was much higher in the sky, and it was time to give it a second look. Although it is much smaller than it was during the weeks surrounding the opposition, it was still sharp and I could see albedo features well enough to recognize them. The planet is now noticeably gibbous. I could see the dark band around the south polar cap, the equatorial band of Mare Tyrrhenum & Mare Cimmerium.

Sketch of Mars. 6" f/8. 200x.

 

It was by then getting cold--but as the Pleiades was getting above the trees, I had to take a peek at it. Lovely as always, but I had nothing useful to say about it then and I don't now. I've sort of got in a habit of observing a few things every time I'm out and not writing anything down about them.

My astronomy log book, which I started on May 31st, is now nearly full. 140 pages of astronomy sketches and note spanning almost half a year, averaging close to one page a day.

I'd like the last, or second to last, page to be a very large illustration of the Moon, an object I've sort of neglected since July. Fitting, since the first page of notes contains a full-page drawing of the Moon. Once the log book is finished, I intend to scan it and upload it, both in default color (for lunar/planetary sketches) and inverted color versions (for the deep sky sketches)