Exploratory Trip to Henry Coe State Park – Hunting Hollow Lot

This is my report of an exploratory trip to Henry Coe – Hunting Hollow Lot. I have been interested in exploring this parking lot as a potential site that club members could visit for dark sky viewing and imaging. I came across this lot when I was out scouting for new sites to view and image from back in January and wanted to bring some members back with me to an Exploratory Trip. On Fri. May 21st. Lee Hoglan, Gary Chock and I met at this site to explore it and do some observing. First view of the lot, it is big. It is 265 feet by 171 feet. For comparison, RCDO is 146 feet by 70 feet.

We setup our gear as the sun was going down. Lee brought the “son of the beast” scope, a 16 inch Dob, Gary had his Astro72 refractor and 20×80 Celestron Binoculars and I had my Oberwerk 28×110 Binoculars. As sun went down, we started to look at the objects in the west, The Pleiades, The Orion Nebula, Double Cluster. There was a light dome in the west, the Orion Nebula in the 16” dob was very bright and impressive but, so was the sky glow behind it. I wanted to see how it would in my binoculars. I put in my DGM Optics NPB filter in the binoculars and the view was quite good, not quite as bright as the dob but, very nice. The difference was that with the filters in the binoculars, the skyglow was cut down quite a bit and the contrast and detail on the nebula really popped out.

Then we went on a galaxy hunt. In both the Dob and the 28×110 binos we had pretty good views of the Leo Triplet, M95, M96, M105, the Markarian Chain, M51, M101, M106, M108, M109, Owl Nebula, M81, M82, M64. Gary was having some nice views of the bigger star clusters like the Hyades, Beehive and Mel 111. We ended up wrapping up about 10:30pm. We all agreed it was one of the best nights of observing we have had in a long time.

As far as the site:
The Good – This site is big, all of the regular SJAA members who come out to view on a regular basis could fit in that lot with room to spare. There is no lock or gate at the entrance so it’s 7/24 hour access. You pay for use via dropping $6 into a slot in a metal pole. Easy drive within 1 hour from HP. 10 mins from Mendoza Ranch. The road ends shortly after the lot so there is not too many cars going on that road. The site is pretty dark, SQM meter reading of 21.1 around 9:30pm. Overnight camping if you want to stay overnight.

The Bad – The is no lock or gate at the entrance so it’s 7/24 hour access so, we have no control other cars driving in while we are viewing. Horizons not that low. From center of the lot, the south is about 30 degrees, east, west about 20 degrees, north is about 15 degrees. Elevation is about 600 feet so there could be fog on some nights.

The Ugly – Possible that night hikers could pull into the lot, happened to us. They had some lights on for about 15mins as they were gathering their stuff to hike into the park. This site I would say is more suited to viewing then imaging for this reason.

Overall impression of the site:
I think this is a good site for viewing. It is the darkest of the sites that club members currently go to (RCDO, Mendoza Ranch) It’s good to know that this site is available for use on a 7/24 basis. While it’s not perfect, neither are the other sites that we have access to. I think overall the good does outweigh the bad on this site.

The GPS location of the site is: 37°04’33.6″N 121°27’59.4″W

-Ed Wong