by Mark Wagner
I was observing in my backyard again last night. It was beautiful outside... I was in shorts and a t-shirt until I came in at 11 p.m.
Using a 14.5" f/5.6 Dob and a combination of 20mm and 12mm Naglers, I observed double stars and several deep sky objects. Seeing was much steadier than the night before, about 7/10.
I began with Alpha Herculis, aka Rasalgethi. I was surprised to learn that Alpha Herc is located so close to Ophiuchus. I always think of Hercules as the Keystone, but it is a large constellation by area. The double has a gold primary with a green companion several magnitudes dimmer and closeby only 53" to the SSE. The primary shines at mag 3.5, which was naked eye low to the south. The companion shines at mag 5.4.
More difficult to find was 95 Herculis. This star required use of my 11x70 finder to locate the proper field. 105 Herc was just visible naked eye at mag 4.3, which aided in getting to the correct area. This star was gorgeous! Two mag 5 stars sitting just 6.8" apart, one gold, the other a brilliant blue-white. I called my wife and daughter out back to see these jewels.
Once my daughter was outside by the telescope, I had to yield to her request to find something. I suggested Gamma Aries, the next star on my list. I pointed out Alpha and Beta Aries and described where to find Gamma. Mimi was on it instantly, thrilled to find a tight pair of equally bright white stars in the eyepiece!
She then pointed the Dob at M13, M92, M57, M15, M31 and the Double Cluster. She was most interested in knowing what happens to collapsing globular clusters, like M15. She noted the compressed core and I explained that in an S&T article within the past year or two that M15 was described as collapsing. Mimi wanted to know if the stars would fall together and become a black hole.
At 10 p.m Mimi went to bed, since it was a school night. But how nice for her to be able to walk out into her backyard and spend an half an hour doing astronomy!
I continued on with more doubles.
1 Aries was next on my list. I find it to be a very tight double of gold and white, with a large difference in magnitude between the pair. I would think this double would be a great field to observe in a dark sky, as there are many galaxies in the immediate area.
I moved to Eta Persei which was another Albiero. I am convinced that the most plentiful combinations of colors in doubles must be blue and gold. Eta is an easy target, although sky brightness made it a challenge in the glare of the moon and San Jose. Imagine, it was hard to pick out a mag 3.7 star! But its location is easy, being the most northerly bright star in the constellation. The stars sat east/west of each other, the blue component more of a steel blue than Albiero's.
Pisces was very close to the most moon-washed part of the sky, but I decided to try my hand at what can only be described as star-hopping by Braille.
I went next to 55 Piscis, another small Albiero. The blue component was much dimmer than the medium bright gold primary, and sat close to its north. The star is close to the Pegasus border and required using Zeta Andromeda and Gamma Pegasi to locate.
I finished the night on Zeta Pisces. This was work. The star was not visible naked eye... it is one of the chain of stars leading north from the Circlet under Pegasus... all dim stars even in dark skies. I used my finder to star hop off my Sky Atlas 2000 chart. When I hit the double it was obvious. The double is comprised of two white stars that area close together, but not what I'd call "tight". The brighter component was to the west, and the companion was a bit more gold than the primary.
It was another nice night outside. The moon does not pose too many problems for double stars. With enough aperture, it is even reasonable to hunt deep sky objects too, as Mimi had proven.