First Doubles

[Shabadoo]

Have a look at this topic:
viewtopic.php?f=6&t=5513&p=50132&hilit= ... s+B#p50132
It contains tons of observing suggestions. You will need them all.

Holy cannoli!
I kept going into the Belgians report and drawing.

[mikemarotta]

Gamma Andromedae
(I don't remember where I read the hint. I already have four different lists of "favorite binaries" from different sources.)

I also found eta Piscium again last night, more purposefully and planfully competent this time.

[Bigzmey]

Nice notes Michael!

[Shabadoo]

Michael- your enthusiasm is inspiring.

[mikemarotta]

We had a local contact at the astronomy club from a someone who inherited an 80mm f/12 telescope.So, just to see what you can see, I took my 70mm f/10 out to look for binaries that I know. These were all observed with the 17mm ocular and 2x Barlow.
Abireo (1851 hours) was easy.
iota Orionis (2258 hours) was harder, if only because of the very crowded star field.
eta Cassiopeiae (2308 hours) was easy because I knew what I was looking for, and therefore looking at.

[mikemarotta]

Last night, I failed again to split epsilon Lyrae A-B and C-D using the 70mm f/10 National Geographic. That afternoon, I took the mount apart and reassembled it. Being tighter helped a lot, but could do nothing for the optics. I checked some numbers. I found the Dawes Limit and Rayleigh Limit.
Theoretical Dawes Limit = 116/D in arc seconds. = 1.65 arc seconds
More Practical Rayleigh Limit = 113/D in arc seconds. = 1.61 arc seconds
According to Wikipedia:
AB = 2.3 arc seconds
CD = 2.4 arc seconds

I can do the big ones, and I can do all four with my 102mm. But even down to 6mm with a 2x Barlow, all I got in the 70mm was the two main stars, no companions. I do have Bortle 7 skies. So, there is that. It is not as though my night was ruined. I was out with my telescope looking at stars. Good times.

[Bigzmey]

Yes, getting tight splits are more challenging with smaller scopes, but that makes it more fun. The good news is that light pollution has little effect on doubles, so your Bortle 7 sky is not an issue. Good seeing is the most important factor. Unfortunately, I don't have 70mm scope in my stable, but from the numbers it should be doable.

Since you are now a double star enthusiast, maybe it is time to invest into a set of Orthos? They are sharpest EPs and have excellent light scatter control.

I would also recommend a good quality prism diagonal for splitting doubles. Prisms have less light scatter than mirrors.

Both, specialized EPs and diagonal have improved performance of my scopes on doubles (and also Moon and planets) considerably.

[mikemarotta]

Since you are now a double star enthusiast, maybe it is time to invest into a set of Orthos? They are sharpest EPs and have excellent light scatter control. I would also recommend a good quality prism diagonal for splitting doubles. Prisms have less light scatter than mirrors. Both, specialized EPs and diagonal have improved performance of my scopes on doubles (and also Moon and planets) considerably.

Beg your pardon, but I am not an enthusiast, just curious. However, I appreciate your suggestions because based on my current reading they seem the most cogent choices. Unfortunately, my 102 is achromatic. So, I would start with an APOchromatic telescope and add the oculars, etc., to that. I am about to post about two bad choices I am living with. Education can be expensive, but ignorance is worse.

The binaries are interesting, to be sure. Perhaps the most interesting fact about them is how common they are. Solitary suns may be the unusual ones. The nice thing about knowing these doubles is that when we open up again for star parties, I will have targets for the visitors.

Best Regards,
Mike M.

[mikemarotta]

Lion and Bears

It was clear overnight the 24th and 25th. Not having to work the next day, I set out my Explore Scientific First Light 102mm refractor. After midnight Mass (virtual from the Vatican), I went out to observe.

I drew Leo for myself because a couple of weeks ago, I went out and was confused about Regulas and gamma Leonis. I thought that Regulus was a red giant but just looks white because of the atmosphere or something. I spent some time then re-aligning my finder with Sirius and assuring myself that that is what was on-center. It is hard to miss. Then, I went back to Regulus and then to gamma Leo but was still unhappy with being uncertain. Reading Burnham's and a standard text (Chaisson & McMillan), I see that Regulus is a B7 V, a main sequence blue star more like Vega and Rigel. So, what was the source of my misunderstanding? I blame my mother. She was a Leo and she had red hair.

Burnham has some discussion of the perceived colors of gamma Leonis. I went with yellow-orange for the primary and yellow-white for the secondary.

It is always nice to go out and look. What is more interesting is that Polaris is a yellow supergiant over 5 solar masses.

I do these measurements with a technique I described here earlier, keeping both eyes open and using a ruler (6 inches with a millimeter scale). Because I enjoy this aspect of observing, I am going to shop for a reticle.

[Shabadoo]

Gee. I never thought of using a Barlow on my highest power lense to split Polaris.

Next time out- I’ll give it a go!

[Bigzmey]

Nice splits Michael! I like the sketches to. Mizar and Alcor are annotated as A and C. Looks like you have captured two other components for Zeta UMa: B - mag 3.9, separation from A - 14.4"; and D - mag 7.6, separation from A - 493.2".

[mikemarotta]

Zuben el Genubi
We had clear skies for three days and nights. So, I took out the 10-inch Meade "advanced" Richey-Cretien on loan from the local club. I checked the overnight dew points and it remained dry. I covered the scope with a couple of mover's blankets, but the deck table etc. all were dry in the mornings.
I get up early normally and I stepped out to check the sky and saw Scorpio easily. (Live in the city: Bortle 6-7 on a good night.) And the two Claws (now in Libra) Zuben al Shamali and Zuben el Genubi. I looked them up and Wikipedia said that the Southern Claw is a system with an easy binary.

Burnham's Celestial Handbook was not helpful on this. I did find other information online.

Rather like Mizar and Alcor, it is a naked eye double, flanked four minutes of arc (0.06 degree) to the northwest by a fifth magnitude (5.15) companion. The two are probably a physical pair, as they move through space together, both of them 77 light years away from us. The fainter (called Alpha-1 because it is the westerly of the two) is a class F (F4) star that at about 6700 Kelvin is 1000 Kelvin hotter than the Sun, while the brighter (Alpha-2) is a much warmer white class A (A3) subgiant with a temperature of 8500 Kelvin. (http://stars.astro.illinois.edu/sow/zubenel.html )

0.06 degree or 4 minutes is closer than I estimated. I used both eyes open and pegged them across the fields of view with my index finger.

[pakarinen]

Good targets for moonlight / LP is bad. I haven't intentionally looked for many, but I have stumbled across quite a few, according to Sky Safari, and they're always a pleasant surprise.

[mikemarotta]

I split Castor tonight. I used my Explore Scientific 102 mm refractor. (FL=660mm f/6.47).

It was almost visible with the 32mm ocular and a 2X Barlow. With a 17mm and 2X it was plain. With the 8mm and 2X I had nice sharp images and good Airy disks around both. I also tried the 6mm and 2X and, of course, at 220X, they were that much bigger.

I got two white stars, B being about two-thirds the size of A and separated by about the diameter of B.

I have a Baader reticle that has been something of a challenge. We have clouds the next few days, but when it clears up, I will try my 70mm refractor and the Baader and attempt a measurement. (See posts in the Baader Eyepiece thread.)

[mikemarotta]

This arrived today. The cover and title notwithstanding, many of the "visual double stars" here are gravitational binaries.

[mikemarotta]

Castor Over Two Nights and Three Instruments

I had a 10-inch Meade "Advanced" (i.e. fake) Ritchey–Chrétien on loan from the local club. When I first used it on Mars, I felt that It needed collimation. I used twice again to make sure, and I then accepted that it would help with a first-approximation viewing, at least, for stars, as the surface details are not a consideration. My primary instrument is an Explore Scientific First Light 102-mm refractor. But I also took out my National Geographic 70mm just to see how it would measure up against the others for this. (It has some good features, but the Altitude-Azimuth mount is wobbly despite my attempts to firm it up with rubber bands and other bearings and fittings.) This weekend I returned the Meade 10-inch to the equipment chairman who was somewhat impressed with my success. "When I used it, I saw two Jupiters," he said. I did not ask him why he thought that it was appropriate to lend it out if he knew that.

In this month's [April 2021] Astronomy magazine, James O'Meara tells of viewing "canals" (transient features) on Mars with a 3-inch refactor at 200X to 300X. He does not go into details on the instrument (APO, ED, or whatever). I mention it because my 70mm teaches me often what is possible - or not - with a small telescope. I mean, look, Mount Palomar at 200 inches is only the 18th largest in the world now. And it is stuck here on Earth when others are in orbit--and you are not. So, while instruments do matter, at some level, they do not: you make the most of the tools you have.

[mikemarotta]

Two nights ago, I split Delta Corvi. I grew up at 40 degrees North, so the southern sky is still unfamiliar to me. I was looking for Virgo. Leo and Scorpio were easy. I later revisted Zuben el Genubi, which is also Alpha Librae. But I could not make out any more of Virgo than seeing Spica, which is hard to miss. Anyway, I decided to check out the trapezium in the south. I found Corvus. It goes back to the Babylonians nearly unchanged in name as a recognized constellation.

When I came in, I looked it up and printed out the Wikipedia entry for my notebook. It's pretty interesting.

An enigmatic star around 2.7 times as massive as the Sun, it is more luminous (65–70 times that of the Sun) than its should be for its surface temperature of 10,400 K, and hence is either a 3.2 million year-old very young pre-main sequence star that has not settled down to a stable main sequence life stage, or a 260-million-year-old star that has begun to exhaust its core hydrogen and expand, cool and shine more brightly as it moves away from the main sequence.

We have clear skies again tonight. So, I am going out again.