by Randy Muller
Having been clouded out of our regular Saturday evening 3rd quarter moon deep-sky observing session, a small group of observing desperadoes met Sunday night, May 13, at the Sacramento Valley Astronomical Society's dark sky observing site 5284 ft. high in the Sierra Nevada mountains.
The weather, which had suddenly turned bad on Saturday, even more suddenly changed for the better on Sunday. The weather gods, clearly thinking their work was done on Saturday, let their engines of bad weather idle on Sunday.
Gregg Blandin (homebuilt f/4.5 25" truss tube dob), Alvin Huey (homebuilt f/4.5 16" truss tube dob which started its life as a Meade sonotube), I and a rogue observer named Steven (f/5.6 10" Discovery dob very similar to my own 10" Orion) observed under wonderfully perfect conditions.
It was ultra dry, the sky was ultra clear (except for a few small bands of cirrus which never interfered with observing), it was cool but not really cold. Transparency, clarity and contrast were all outstanding, as is common during the spring. Seeing was "pretty good".
While waiting for it to get dark enough to start my *real* observing program, I looked at Jupiter and Mercury, which were close together in the west, having just emerged from the underside of some threatening cirrus clouds as they set.
Steven had pointed out what he thought was Mercury before it went behind the cloud bank. I doubted it, since I thought he was referring to Jupiter, which had been easily visible. But sure enough, the bright dot to the right of Jupiter was indeed Mercury.
The seeing was terrible so low in the sky, and Mercury showed no detail except a gibbous phase and lots of atmospheric chromatic abberration. It was surprisingly bright.
I glanced at Jupiter, but knew I would be disappointed by the bad seeing, so I didn't spend much time on it.
After it got a bit darker, I took a look at M109, which was nearly at the zenith. I was surprised to see that it was on the verge of showing some spiral detail, and with a little more darkness, it would be a fabulous sight. Unfortunately, I never returned to it, but it was a good indicator of the transparency to come.
Twilight continued to deepen, and in honor and remembrance of our observing comrade Shneor Sherman, who is currently in New Zealand for 2 weeks, I took a peek at the gigantic globular cluster Omega Centauri, to give my scope a little horizontal time. He can't hog *all* the southerly photonic phun!
At declination, -47° 29' this is close to the southernmost object I've ever seen through a telescope.
I happened to notice comet McNaught-Hartley flying through Draco on my laptop chart, so I decided to hunt it down. On my way there, I ran across a nice galaxy, NGC 6643, and a pretty double star, HD 176795, also known as STF 2452, first catalogued by Wilhelm Struve in 1832.
Comet C/1999 T1 McNaught-Hartley gave a nice, if faint view as it drifted through Draco. The nucleus was easily visible in Gregg's 25", but it was challenging in my small 18".
It is currently departing the torrid inner solar system for the comet-friendlier climes of the Oort Cloud.
The Zodiacal light was very obvious in the west, long after the sun set. The Milky Way showed lots of structure. It was really nice to have a good night after so many marginal ones.
Before it was fully dark, I chose to look at some big bright spiral galaxies in anticipation of seeing lots of faint ones later on.
I took a peek at M51, the Whirlpool Galaxy, as it went near the zenith. What a spectacular view! This big, bright, boffo galaxy never disappoints!! Lots of detail was visible in the spiral arms which wind forever around the center.
Not nearly as bright, and therefore less detailed was M101. This galaxy is mammoth. Spiral detail was not quite visible, but there was lots of mottling and varigated texture in this large clump of light.
I spent some time looking through Gregg's 25" scope. For every open cluster I viewed through Gregg's leviathan, I suggested that it was comparable to or better than NGC 7789 in Cassiopeia, which is Gregg's favorite.
Gregg got me back though. He casually mentioned that there was a cat in his vehicle at one point. That made my adrenalin flow as I rushed to protect my mirror from cat paws. Ha ha.
Eventually it was dark enough and time to embark on my program of observing the 100 Hickson Compact Galaxy Groups. Observing these groups requires the finest conditions to see as many of these generally faint galaxies as possible.
I personally spend a lot more time on these darn faint Hicksons than I do on the brighter Messiers or Herschels, just trying to see stuff I can't possibly see, and trying to verify stuff I think I see that is at the ragged edge of observability. But I consider it time well spent and have a lot of fun doing it.
I saw 3 out of 4 components of this one at 226x (10mm plossl):
MCG+3-27-7 (HCG 46b): Small, stellar center. Very small halo. Nice
pair with 46c.
MCG+3-27-8 (HCG 46c): Small, stellar center.
MCG+3-27-9 (HCG 46d): Very faint. Only visible intermittently.
I was a bit surprised and disappointed that I could not see HCG 46a, supposedly the brightest component.
My hunt for Hickson 47 began at Regulus (Cor Leonis, Basilica Stella, The Little Ruler). I immediately became distracted by the idea of finding Leo I, a photographic magnitude 10.2 dwarf elliptical, about 20 arcminutes N of Regulus. I had never seen it before, but had heard others comment on it. It is challenging due to its large size and low surface brightness.
14 arcminutes wast of it lies IC 591, which I observed as a bonus. At photographic magnitude 13.1, it was very easy to see due to its compact size.
After much study of the field, I was able to barely detect it. Detecting it required getting Regulus out of the field of view, and moving the scope. The faint patch of light persisted in the same spot in the sky as the scope moved around and was bounced back and forth. Alvin confirmed its presence in the field of view, and he had a photographic finder chart of the area, in which the stars matched.
Finally, I headed for Hickson 47 itself. I had just missed this one at Fiddletown last month, because it set behind the observatory. I found the field at 87x (26mm plossl), and saw an undifferentiated flow in the right area. At 226x (10mm plossl), the glow separated into two components, but the best view was at 301x (7.5mm plossl):
UGC 5644 (HCG 47a): Fairly large, brighter in center. Nearly stellar
center.
MCG+2-27-13 (HCG 47b): Diffuse, fainter than 47a. No detail visible.
Alvin could see a third component, but I could not see it.
I decided to go for some Hicksonian eye candy, so I observed HCG 57, also known as Copeland's Septet. "Eye candy" is a relative term, and this only looks great after feasting on a steady diet of spare Hickson groups.
In spite of its faintness and smallness, it is an amazing and surprising configuration of 7 galaxies. This Hickson group actually has 8 members, including a magnitude 17 PGC galaxy which neither I, nor apparently Copeland saw.
The group was visible at 87x as I hopped to it, but, like so many of the Hicksons, it was best view at the highest power available to me, 301x. The group is arrayed as two parallel lines of 3 galaxies each, with a mag 11 star between them making a U formation. The seventh member is somewhat outside this tight group of six galaxies.
NGC 3750 (HCG 57c): Oval, diffuse, less bright than 57a, medium size.
NGC 3753 (HCG 57a): Large, bright, elongated, diffuse.
NGC 3754 (HCG 57d): Small, diffuse, fairly bright.
NGC 3746 (HCG 57b): Big, medium bright, oval.
NGC 3745 (HCG 57g): Faint, almost stellar.
NGC 3748 (HCG 57e): Round, fairly bright.
NGC 3751 (HCG 57f): Large, faint, diffuse, stellar center.
I could see two of the four members of this group. At 301x:
NGC 5306 (HCG 67a): Fairly bright, concentrated center, oval.
MCG-1-35-13 (HCG 67b): HUGE, extremely elongated, very faint.
Although it was boiling pretty much and I didn't spend much time on it, Mars offered a really nice view, the best I've seen yet of that planet. The contrast between the dark and the orange areas was amazing, and it appeared there were clouds at the limb.
I viewed it about 2am local time (May 14, 2001, 9:00 UT), but it was fairly low in the sky and suffered from some bad seeing. But it still showed a truly amazing amount of detail and riot of color that I've only ever seen before in Jupiter. I viewed it at 226x with a 10mm plossl. I believe the longitude of the Central Meridian was about 221 (see pg 106 of the May 2001 Sky and Telescope).
Hellas was a brilliant white at the south western (areographic) limb. It combined with the light colored area called Eridania to the east, and it appeared that it was filled with bright white clouds. I've never seen anything like it before when looking at Mars with my 10" dob.
Syrtis Major was an obvious dark blue color, contrasting sharply with the orange of the light areas, the browns of the dark areas and the white of Hellas/Eridania. The colors were very stark and contrasty and exciting to see.
Along the southern temperate latitudes (assuming anything on Mars can be temperate!), Syrtis Major, Syrtis Minor and other dark brown extensions from Mare Tyrrhenum formed what looked like a serrated knife edge, with the sharp areas jutting north into the orange area. Libya was clearly visible as a light orange area between Syrtis Major and Minor, and was part of the serrated look.
Around the limb of the planet, particularly on the NW and NE sides there were light areas, which seemed to be more clouds.
I did not see either polar cap, but I did not study it very long, and was quite taken by the serrated edge effect.
The names I used are those used in the Sky and Telescope article, and I believe they are not the standard IAU names.
All in all, I had a wonderful night, a night of galactic happiness in the mountains.
| Date | May 13/14, 2001 8:30pm-2:30am (May 14 3:30-9:30 UT) |
|---|---|
| Location | Henry Grieb Observatory near Sacramento, CA 36.85N 121.57W |
| Instrument | Starmaster 18" f/4.3 dob-newt |
| Oculars | 7.5, 10, 17, 26mm Sirius Plossls;
1.15x Tele Vue Paracorr |
| Seeing | 7/10 |
| Transparency | 8/10 Cirrus clouds west & north, a few came over |