Summer Projects

We have been busy this month at Little Piney Observatory. Summer brings a lot of things, some good, and some bad. Part of the good is the beautiful large nebula in the night sky. It was time to put the RC away and get out the Star71 for some widefield imaging. Since the RC telescope was going to be out of service a while, I decided it was time to give the primary mirror a long overdue bath.

The bad that comes with summer is the awful heat and humidity. Last summer was a constant battle to keep the observatory under 100 degrees. We often lost that battle, and it was such a hassle and a constant worry, that we decided to do something about it this year. Little Piney Observatory received a new roof this month, along with some one inch insulating foam with a reflective backing. The super thin sheetmetal on the roof was removed and replaced with some quality metal and a substantial overhang was added to keep things dry inside.

Lets start with cleaning the mirror. There are several of these GSO RC scopes being used, and I thought someone might like to see just how easy it is to remove these primary mirrors. The GSO scopes come with various names including Astro Tech, TPO, Levenhuk, Teleskop Service, and others. I have owned this scope almost two years. It has seen a lot of use in that time, and with the pollen, dust, and the spiders that found their way into the optical tube assembly (OTA), it was time for a cleaning.

The first thing to do is take the top and bottom dovetail screws out. Then there are two other screws on the side of the OTA that need to be removed. After this the entire rear cell with primary mirror can be removed.

Secondary mirror with primary mirror removed

Carbon fiber tube

Rear cell with primary mirror and baffle tube. Seen here after cleaning.

I chose to remove the mirror from the cell before cleaning. To remove the mirror the baffle tube needs to come off. The entire baffle came off for me in one piece. Others have said the small piece at the bottom of the tube remained attached and they needed some small allen wrenches to remove the rest of the baffle tube assembly. Once this is removed the mirror can be lifted right out of the rear cell. For more info on the baffle tube, please see this thread on cloudy nights that goes into more detail on removing this piece.

After removing the mirror, I ran some warm water in the kitchen sink along with just a drop or two of dish soap. I placed the mirror on a towel and let it soak for about half an hour.

I put about half a dozen cotton balls on the mirror and moved them from center of the mirror out to the edge without putting any pressure on the mirror. Discard these cotton balls and repeat. I used my fingers to get off any stubborn pieces and rinsed the mirror with distilled water. After rinsing I used a micro fiber cloth to remove puddles of water and dried it quickly with a blow drier.

Install the mirror back into the cell and reverse procedure to put the scope back together. I am sure the collimation will need a couple of tweaks to get the mirrors lined up again, but I have not checked it yet. It is sitting on the shelf now awaiting that next galaxy or globular. I plan to check and align the optics soon.

RC ready to be collimated

The new roof that I mentioned required a little bit of money and a lot more work. It also significantly increased the weight of the roof and made it a little harder to open and close by hand. However, with the drop in temps inside the observatory during the daytime, it was very much worth the time and effort that went into it. I plan to eventually add a gate opener to the roof, but it's nothing that needs to be done right away.

Removed old sheetmetal from the roof and removed aluminum flashing from the sides

Added new gable ends and solid boards in place of old flashing

Added new 2X4 laths for attaching new sheetmetal

Installed new foam insulation

Installed new sheetmetal and ridge cap

New roof with added overhang = Much improved!!

I still have to find something (lightweight) to cap off the ends of the newly added overhang, but I am very happy with the new roof. Temps inside now get to only 1-2 degrees above outside air temps, and the inside remained dry after a substantial rainfall dropped by a passing thunderstorm.

I'd like to end this month's post by showing off a few of the wonderful summer nebulae that require a short focal length scope to capture (without having to do mosaics). For these I used the William Optics Star71 telescope, a very small f/4.9 apo with a focal length of just 348mm.

My first Image of the Day on Astrobin!!!

For full size views of these and other images, please see my gallery on Astrobin. I just started a couple more projects, including a widefield Sh2-101, the Tulip Nebula in Cygnus. Cygnus is a treasure trove of fascinating targets that will keep me busy for many summer's to come.

Have a safe and happy summer everyone! :)