by Robert Leyland
At Lake Sonoma we had over a dozen telescopes, which is more than usual. The combination of new moon, and closing of one of Palmieri for Deer Hunting Season (SCAS regular deep sky site) brought out a few more visitor than usual.
Also Dave Silva had his new 14.5" Starmaster (with GOTO!), and Steve Gottlieb made a surprise visit on his way back from Lassen. So we had three 17.5" Dobs, a 14.5", a C14, a C11, and two or three C8s, and a mix of smaller scopes.
A sunset breeze gave way to a fairly still night, of relatively soft seeing. Perhaps some of the fires in Northern Califonia have generated enough dust and ash in the air to reduce our seeing. It was, however still relatively clear, and M13 was an easy naked eye object, and the Healdsburg light dome was minimal in the dry air.
| Observer | Robert Leyland |
|---|---|
| Date | 18 Aug 2001 |
| Time | 2130-0130 PDT (UT -7, or 0430-0730 19 Aug 2001 UT) |
| Location | Lake Sonoma CA, 38°43'N 123°02'W Elev ~1400 (Lone Rock Flat) |
| Weather | 17°C Temp 35-55% Humidity, westerly breeze |
| Seeing | LM 6+, transparency 7/10 |
| Equipment | 17.5" F5 Truss Dob, +Telrad, Pentax XL EPs |
I'm still learning my new telescope (a Discovery 17.5" Truss Dobsonian), and it's a lot of fun. Recent observing has been a bit scattered as I try out different things, and look at objects that were well out of reach of my 8".
Initial collimation tests demonstrated that the Laser as supplied by Discovery is out of true. Steve Gottlieb's 2" Laser clearly improved the collimation. I'll need to put the collimator onto a V block, and check its adjustments.
The conditions weren't good enough for a full star test, but I could see that the collimation could still be improved. There is a subtle difference between the inside and outside focus images.
After looking at a few brighter objects, and sharing views (especially M8), I tried to go with my observing program, and returned to look at a few objects in Bootes.
NGC 5633 is a nice elliptical galaxy with a dense core and nice halo, easy to find off sigma and rho Bootes, half way up the ice cream cone.
NGC 5641 another nice elliptical in Bootes, which shows up well in the big iron. Easy to see once I found it, but clearly my rate will improve with practice, and with a finder scope :-)
A slight distraction took me to Draco (thanks Colin) for NGC 5866, which we came across while looking for 5907. 5866 is an easy "winged" galaxy, one side is notably darker with incursions of dust. An easy pair of stars bracket the galaxy.
NGC 5907 itself is a really nice edge on, sharp with a hint of dust in it. Steve Gottlieb got us on track for that. It's nice to have some more experienced observers around :-)
Steve then suggested going for some of the interesting items he was tracking down. Tonight it was galaxies in the halo of M92. He had charts for four (or so), and I was able to find two of them. This also gave us a chance to compare telescopes directly.
The galaxies themselves are not related to M92, which is a globular cluster in orbit around the Milky Way, they just happen to be in the same direction when viewed from Earth. The galaxy closest to M92 is a very dim blob, and a bit of a challenge.
His 17 showed it a little more clearly, and I think it is baffled better. Steve had just added a light shield, and a black velvet patch across from the focusser. I wasn't using a shroud tonight, and periodically would catch a glimpse of red-light from one of our fellow observers. With better baffling this will be easier.
The second galaxy is significantly brighter, about 1.5° away from M92, it was a fairly easy find by following one of the three-star chains out from M92, and traversing a line a right angle to the chain. I sketched a diagram so that I can track this one down again.
A little later Dick Flasck suggested going for G1, a globular cluster that orbits M31. That's quite a challenge. He had an excellent chart from an article in Sky & Telescope. We followed the star hops from the Andromeda galaxy (once again sketched in my notebook). At 110x it shows up as a slightly fuzzy star, at the point of a V formed by a double star (which points at the cluster, and a field star. At 320x the cluster can be seen distinctly separate from two very nearby stars, and the true shape of the cluster can be seen.
This was a lot of fun to find, and Matt Marcus tracked it down in his C8, which is a great accomplishment.
Finally I had a good look at NGC 891, which has always been a challenge in the 8". It is a really nice edge on galaxy. It has a fairly low surface brightness, but is quite large, and very detailed with a great dust lane. An easy find at 100x, where it had been hard to see in the smaller scope.
All in all, lots of fun, and I'm still learning how much I don't know.