Saturday, September 29, 2001

More doubles under the full moon.

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.

Friday, September 28, 2001

Doubles under a full moon

Friday night at Houge Park was an amazing experience for anyone there with a telescope set up. Even before dark, crowds were beginning to gather, and I could tell something was up. By dark hundreds of interested school kids, mostly 3rd and 6th graders, and their families were amassed.

Once I looked up and saw lines 30 people deep at my telescope and Kevin Schuerman's. Ours were the "big guns" that night, mine a 14.5" f/5.6 Dob, Kevin's a 13.1" f/4.5 Dob. Kevin had thought he'd have the biggest scope there, with so much moon out. Sorry Kevin ;-) Lines at the scopes lasted a few hours, then things settled down.

I began by showing Albiero, but soon realized that my ladder was not tall enough to allow the younger children to reach the eyepiece. For a while I would watch parents strain to lift their children skyward, up on a ladder. I soon concluded there had to be another good double to show that would not entail such risk.

I pointed the scope at Eta Cass. This was much better. As each person looked at the double I would ask them quietly to describe the colors. Since we had a discussion on this mailing list about color perception I was interested in a wide sample of opinions. Amazing what a divergent reply one can get. I do believe that experience tends to be an equalizer, since the replies I heard ranged from yellow and tan to white and orange, white and white (amazing!), red and gray, even white and silver!

Later I began pointing the scope at M22, M13, M31 and other bright deep sky objects. The results were quite good. I attribute it to aperture. I also attempted to show a few people NGC404, which was clearly visible just off Beta Andromeda if you knew where to look. Transparency must have been very good.

I had come to Houge Park Friday night with a list of double stars to observe. Little did I expect an invasion. My list waited until the next night.

Saturday about sunset I rushed out to unpack the 14.5" from the back of my truck and set it up in the back yard. It was nearly a full moon, close enough anyway. But I figured it should still be possible to split some doubles. Someone had mentioned on TAC's mailing list the "astronomy forecast" was favorable, and soon after dark I was collimating. After an hour's cool down, I found the star images were still pretty fuzzy, and this was not going to be a great night for pinpoint stars.

However, the list I had was not tight doubles, but the Saguaro Astronomy Club's Best Multiple Stars. So long as there was sufficient separation, I still could observe.

I began with Beta Cepheus. This is Alphirk, the northeastern star in the "box" that defines the main body of the constellation. The primary is very bright white at mag 3.8 with a yellow or rose colored companion west of and close to the primary, significantly dimmer at mag 7.8.

I moved next to Struve 2816, which had been a topic of conversation on TAC during recent discussions on star colors. This is easy to locate along the southern boundary of Cepheus' constellation lines. Find Alderamin, Alpha Cep sitting between the bottom stars of Cepheus' box. Move south and outside the box past Mu Cephei to this triple star. The primary component is visible naked eye in dark skies, at mag 5.7, is bright yellow/white. Two companions shine at mag 8, one 7" NE, the other 2" WSW. This is a nice triple.

I mentioned Mu Cephei. While it is not a double, the sheer richness of color in this star is amazing. If you want to see pure gold in a star, this is a great example.

Just west of the center of the box that makes up the southern part of the constellation Cepheus is the star Xi Cephei. I saw this as a bright white primary with a dimmer yellowish-red companion almost 2" W. The seeing was not good enough to split the third component apart from the secondary, just 1" to its E. I'll try splitting this one again tonight.

Next on my list of colored doubles was Delta Cephei, which I immediately felt was an Albiero clone. The double sits in an area rich in open clusters, I recall visiting many times over the years. The star sits at the northwestern apex of a triangle of bright naked eye stars, at the southwestern corner of the box of Cepheus. Even with the large moon they were visible, at mags 3, 4 and 5. Delta's primary shines at mag 4 and is a nice gold/white color, not quite as rich gold as Albiero. The companion is very blue and sits a wide 42" south.

Struve 2486 is comprised of a pair of twin yellow/white stars off the eastern wing of Cygnus. When looking at MegaStar, this star appears a triple, although again I only saw a double in the soft seeing last night. I had to work a bit to locate this double, matching star patterns on my Tirion Sky Atlas 2000. The approximate location is reached by starting at Gamma Cygni and drawing a line to Delta Cygni. Continue not quite the same distance past Delta. One odd finding was to see the Saguaro list showing a 2 magnitude difference, mag 6.6 and 8.6, but I found the components to be of nearly equal magnitude.

I moved next to Beta Cygni... Albiero. No kidding, this is easily the most magnificent double in the northern sky for color. Albiero is simply stunning. It is even more impressive after sampling other notable doubles. The richness of color is awesome.

I finished the night working hard to locate h1470, approximately between Gamma and Eta Cygni. I star hopped using Tirion's Sky Atlas 2000. A good landmark to start from was a notable chain of stars running NNW/SSE for about one degree just east of the constellation line. It was easily worth the effort. Other than Albiero, which even in all its beauty is rather pedestrian since it is so popular, h1470 is the winner of last night's observing session. It is like Albiero, but the yellow component is a ruddy yellow/red... so rich it was outstanding by itself. Add to that a secondary component so blue that it borders on purple, and you have absolute jewels of stellar evolution. It is a wide pair, almost 30" between the components. The dimmer star lies N of the primary. This is one to add to an observing list!

I'm hoping the steadiness will be better tonight. The scope is still set up, the moon is bigger, and there are many more doubles on the list.

Doubles under a full moon can be fun.

Thursday, September 6, 2001

Backyard observing 9/6/01

Backyard - Los Gatos. Dim Milky Way visible. 8" f/6.9 Dob with 20mm Nagler, 12mm Nagler and 7mm Meade Research Grade Ortho.

This night's targets were varied.

Sigma CrB - easy split at 70x, the brighter component is EENE of the companion. Colors are equal.

17 Dra - mag 5.6 visible naked eye. Nice white pair with 16 Draconis just 7' N. Pair is tight at about 1.5" with brighter star to the W.

Mu Dra - Gold pair that is very tight with a clean split at 100x. The components are equal brightness and lay N/S.

NGC 6913 - M29 - Open cluster in Cygnus. I find this the most difficult of the Messier open clusters, in the heart of the Milky Way, only about 6 bright stars. Components are in two equal length chains of three stars each, arced away from each other. Hints of other faint stars involved. Chains are N/S in the field.

NGC 6939 - Open cluster in Cepheus. At 70x this cluster is small and faint - rather dull. There appear to be no bright stars, just a faint glow. At 100x many faint stars appear. the cluster is maybe 10' in diameter. I looked for NGC 6946 in the field both at 70x and 100x but did not find it.

NGC 7027 - PN in Cygnus. Easy target close to two bright stars E of Deneb. Fuzzy at 70x. At 195x the planetary begins to show elongation of bi-lobed feature. AT 350x it is clearly bi-lobed and a gray-green. The west end is a bit larger and notably brighter. A star may be embedded in the extreme western end.

NGC 7092 - M39 - Open cluster in Cygnus. 70x is a great magnification for this bright but sparse large open cluster. About 20 bright stars comprise the group. I like this better than M41 in Canis Major, and think of it as something of a poor-man's M45. Measured 35' diameter.

NGC 7209 - Open cluster in Lacerta. AT 70x this is a nice large cluster with many components. It is not exceptionally bright, but is easy to identify among the surrounding fields. 8' to 10' in size, it looks like two arcs of stars to the N and S with a large opening to the W and a much smaller one at the E end. Easy to locate star hopping from Xi to Rho Cygni then again the same distance in the same direction.

NGC 7243 - Open cluster in Lacerta. At 70x I had a very nice view. Large, amorphous - approximately 25 bright stars with many dim but resolvable other components. In three groups ... one of 3 stars, another with 15 and the third with about 9. Empty lanes running NNE/SSW ran between the three sections.

Rho Her - 70\x gorgeous right white pair in a nice field showing elongation. 100x split the pair cleanly. The brighter component was to the SE.


Wednesday, September 5, 2001

70 minutes in Hercules and Cygnus

These objects may be pedestrian, but hopefully others will see that backyard observing can be rewarding, even in San Jose.

I put my 8" f/6.9 scope out back after dinner then went out to run some errands. I returned home at twilight and soon was out back with the sky darkening nicely. With the Edmund Scientific Mag 6 Star Atlas, I turned to the first chart with constellations I could see overead. The sky was not dark, but dark enough for some star hopping. While hunting my first object, NGC 6229, I could barely make out 42 and 52 Herculis, both at mag 4.8. and bracketing my target.

NGC 6229 is a bright small globular cluster north of the Keystone toward the Draco border. AT 70x the globular is granular with some hint of individual stars. It is a nice view, as two equally bright stars, the brightest in the field, stand equidistant 8' west of the glob. Nice triangle. At 100x the granularity is more pronounced and the bright core diminishes evenly out to the edges. Seems to be about 1.5' diameter.

NGC 9341, M92 - globular cluster in Hercules. What a veiw after having picked off the smaller glob just minutes before. The view at 70x is fantastic. It is large and bright (by comparison) with many stars resolved over a wide area surrounding a very bright yet rather small core. 100x results in some stars popping out of the core. There are many stars at the periphery, maybe stragglers, that seem to form a rectangular frame elongated N/S. Estimated at 8' overall diameter. Brightest part of the core may be only 1.5' diameter, but there seemed a dimmer second halo of core stars also about 2' wide may envelop the brighter core. The core area appears brighter and larger on the WNW side. Spectacular object!

Looking overhead, I could now just make out the Milky Way through Cygnus. I had to agree, it was "Milky" looking.

NGC 6826 - planetary nebula in Cygnus. Easy to find off the arc of Theta, Iota and Kappa Cygni at the bend of the western wing of the constellation, this is the Blinking Planetary. Aiming the Telrad and looking in the eyepiece, I found a wonderful 70x view of 16 Cygni, the nice close double 30' W of the planetary. The double appeared almost neon-green tinted and lying NW/SE. All I had to do was let the view drift and the target appeared from the E. At 70x it was an obvious small fuzzy star. The central star seemed blue/green at low power. At 100x the central star was very obvious and I could easily perform the trick for which the object is named. Another star of equal brightness to the planetary's central star sits close to the S. AT 195x the halo is very nice... even and gray. I don't know what I was seeing, but at 350x a slight haze to the SE appeared. At that magnification the planetary was slightly elongated NW/SE and gave hints of two shells.

NGC 6866 - Open cluster in Cygnus. At 70x this cluster is obvious. It is not one of the spectacular opens like M11, or the M3x's in Auriga, but yes, obvious and interesting. I thought it was shaped like a flattened "T" ... a long top and a short leg. The long dimension was 18' long laying E/W across the field. The short leg was defined by what seemed four bright stars falling off to the S about 4' in length. All four appeared roughly equal magnitude, but one was actually a double comprised of two dimmer stars that together gave an impression of equal brightness with the other three in line. The cluster has many dim components, which showed more obviously at 100x (as did the little double in the chain of four) and was perhaps more concentrated E of the estimated visual center of the group. When viewing at 100x I had the impression of a bird in flight.

NGC 6910 - Open cluster in Cygnus. Just N of Gamma Cygni. I went to get the 20 Nagler and something bright hit my eye from the E. Moonrise. I was about done. I hunted briefly for the open cluster and at 70x found a small group of stas, just five of them, where I expected the open cluster. Two sets of stars perpendicular to each other, with a fifth bright member between them. Was this NGC 6910? I'll find out tomorrow after some investigation.

I packed up and was inside in 5 minutes. A nice hour+ in Hercules and Cygnus.

The scope is out there still, waiting for sundown tomorrow.