Can Dew Observing

by Randy Muller

The cloudy weather finally an quite miraculously opened up on Saturday, so I headed to my favorite winter/spring observing hangout near Fiddletown.

I met Jane Smith, a Fiddletown newbie, at the Pokerville Market in Plymouth, and we continued on to the observing site. Steve Gottlieb, Dennis Beckley and Ray Cash were there setting up when we arrived, so we proceeded to find spots and set up our scopes. This was Jane's first light in the dark with her new 12.5" Starmaster. Allan Keller arrived later with his 18" Astrosystems Telekit, bringing the total number of observers to 6.

There was a healthy mixture of low, dark, moisture-laden and high cirrus clouds, and Ray was hesitating on setting up his imaging scope, an 8" Celestron SCT. He made up for this by setting up 3 refractors in the 4" range. The other scopes were all newtonians of various sizes, mostly in the 18" range.

After setting up, I helped Jane collimate. During this process, it cleared up completely. I conjecture that collimation is as effective as a telescope sacrifice in propitating the weather gods, although Ray never did set up his SCT, so that may have been the actual reason it cleared up.

After that, I noticed an ominous sign: Dew was forming on my table and it was still early twilight!

While waiting for it to get dark, the International Space Station passed almost directly over us. Flying with the docked space shuttle, it was really bright. At first I thought it was an Iridium flare, but the flare never went out. I guess that it was about mag -4 or -5 when I first saw it, quickly dimming to mag -2 as it headed east.

Presently it was dark enough to start looking at some brighter objects, so I gawked at M109, a galaxy in the Big Dipper for a while. Then I looked at M101 and some of its many neighbors as twilight deepened.

Finally, it became dark enough for an enjoyable walkabout up and down Markarian's Chain. I enjoyed just wandering around as galaxy after galaxy entered and exited the field of view. Wandering around, I ran into the interesting pair NGC 4568 and 4567, also known as the Siamese Twins. After looking at lots of Hickson Compact Galaxy groups, which are typically small and dim, this area continues to be a real visual delight. I've seen these objects before, but never with such clarity. It was a good, transparent night, even with all the moisture.

It was finally dark enough to continue my program of observing Hickson groups, so I started with Hickson 45 in Ursa Major. This group has 4 components, but I was only able to see the brightest one, UGC 5564 (Hickson 45A), at photographic magnitude 15.9.

At 300x, UGC 5564 was barely visible only about 10% of the time, located between a pair of mag 12 and 13 stars, slightly closer to the western (dimmer) one. It was very diffuse and utterly shapeless.

After spending quite a bit of time here, I decided to check out M51, the Whirlpool galaxy, which was very near the zenith. Climbing to the second step of my two step ladder, I was rewarded with the view of a lifetime.

It was so big and bright compared to the Hickson I had just viewed, and I could easily see lots, and I do mean lots of spiral structure. I could clearly see the classic S structure as the two spiral arms almost wound completely once around. It was, by far, the most detailed and gorgeous view of M51 I had ever seen in any scope, including this same scope last year.

I suggested to Jane that she take a look at it, so she began hunting for it, having finished with M97, the Owl Nebula and the nearby tortured galaxy, M108.

In the mean time I began a search for Hickson 47, but it set behind the observatory before I could use high power to dismantle the faint glow I spotted in the correct place. The reason I had some trouble with it soon became clear.

A group of us went to look at the gigantic globular cluster Omega Centauri transiting the meridian with Dennis' large binoculars. While there, we also checked out the "Hamburger Galaxy" (aka NGC 5128 and "Centaurus A", although I'm always uncomfortable when people refer to it as "Centaurus A", since that designation refers to a radio source. It would be like refering to M87 as "Virgo A".)

Jane was becoming frustrated searching for M51, and I didn't want to spoil it by telling her what to expect, so I just kept telling her that she would know it when she found it. After a while, I began searching for it with Jane's scope, and to my surprise, I couldn't find it.

After viewing a star with a halo around it, it appeared the eyepiece was dewed up, so I asked for another. This one had the same problem, so I got one of my own which I knew to be dew free. After I popped it into the focuser, stars were still nebulous. That's a bad sign. I removed the eyepiece and checked the secondary mirror, and, sure enough, there was a heavy coating of dew on it.

Allan Keller came to the rescue with a portable hair dryer for just such circumstances. Soon Jane was dew free and Allan helped her find M51. Her 12.5" gave a really nice view of it, showing quite a bit of spiral structure -- alot more than I ever saw in my 10".

I used Allan's dryer to remove the dew from my own secondary, which was also heavily dewed. Pretty soon I could hear another hair dryer sound coming from Dennis Beckley's compound.

While dew free, I hunted down Hickson 82 in Hercules. Of the four components, I could see three:

NGC 6162 (Hickson 82A); fairly bright, stellar center, diffuse halo.
NGC 6163 (Hickson 82B); dimmer than A, otherwise very similar appearance.
NGC 6161 (Hickson 82C); Very dim, completely diffuse, shapeless.

The severe dew was also causing issues with my laptop glare screen, and it kept falling off as the adhesive on the back of the velcro pads failed. My log book was soaked and it was becoming difficult to write on it.

While I was at Steve Gottlieb's scope looking at a couple of IC galaxies in the Centaurus galaxy cluster, a bright Lyrid (apparently) meteor flashed overhead, leaving a persistent trail and ending its track with a bright flash that lit up the whole landscape. I happened to be looking near the right direction when I saw it out of the corner of my eye. We all started talking about it, and the trail just continued to sit there for a few moments before it dissipated.

After drying my secondary 2 more times, I gave up and started packing up at about 1:30.

Except for the dew, it was a wonderful night, and it was enjoyable to see such nice views in Jane's new 12.5" scope.

Reports | About Reports | TAC | About TAC | Join TAC