Cassiopeia Observatory

Imaging: Mars in Scorpius, ISS & Dragon,
Night Sky, Comet Hergenrother
Posted: 10 October 2012

Opened the observatory, Tuesday, 9 October 2012, at 1813 MST, 83°F. The sky was mostly clear with a few clouds low in the northwest. At 1830 MST, viewed Mars, low in the southwest, 77X with the 8" LX200-ACF. No details were seen. The constellation of Scorpius currently appears out-of-whack due to the presence of Mars. At 1903 MST, I took this short exposure photograph of the southwestern sky showing Sagittarius, the Milky Way, Scorpius, and Mars (labeled):

I then began preparations for the upcoming passes of the International Space Station (ISS) and the SpaceX Dragon cargo ship that was enroute to the ISS. Dragon would cross the sky within seconds of the ISS, trailing behind the ISS. I did several night sky test exposures, knowing that I would be keeping the shutter open for possibly 2 or 3 minutes, yet needing a high ISO setting to capture the faint Dragon spaceship. As Dragon became visible to my eye, I started an exposure. The first photo below, taken at 1945 MST, f/3.5, 89 seconds, ISO 800, 18mm, shows the bright ISS moving from left to right above my observatory. Dragon is faintly visible parallel to and slightly below the ISS. The two vertical streaks are airplanes. If you look closely, another faint satellite has been captured; it begins near the bottom of the top airplane trail and moves to the right.

This next photo, cropped from a full-frame image, was taken at 1947 MST for 52 seconds. It shows a better view of Dragon trailing behind and slightly below the ISS. Both fade out as their orbits pass into darkness.

Since I was set up for sky photography, I decided to photograph another area of the night sky as seen from Cassiopeia Observatory. This photo, taken at 1956 MST, f/3.5, 30 seconds, ISO 1600, 18mm, shows Cassiopeia, the Milky Way, and the Double Cluster on the left, M31 and Andromeda in the middle, and the Great Square of Pegasus in the upper right:

I then ended night sky imaging and at 2014 MST, viewed Neptune, 77X and 206X in the 8" telescope. At 2020 MST, I began a tour of DSOs in the constellation of Pegasus, 77X. Viewed NGC7814 (spiral galaxy), M15 (globular cluster), NGC7331 (galaxy), and NGC7479 (faint galaxy). I then did a tour of DSOs in Delphinus: NGC6934 (globular cluster) and NGC7006 (globular cluster). I have added two galaxies to my DSO imaging list for a future session.

At 2100 MST, I decided to check on Comet 168P/Hergenrother in the constellation of Pegasus. I checked its position using Heavens-Above.com on my iPhone, slewed the 8" telescope to its RA/Dec, and was surprised by how easy it was to see this faint comet at 77X and even 133X. The tail was obvious. I decided to image it. I mounted the D7000 DSLR at prime focus using the Off-Axis Guider (in case I needed to guide during the exposures). Did a focus test on the star Alpha Pegasus using the Bahtinov Mask and then did a 1 minute, ISO 6400, framing test exposure of the comet. I looked for a good guide star but could find none. So I did 1, 2, and 3 minute, unguided exposures. This is a full-frame, 2 minute, ISO 6400, exposure, taken at 2125 MST:

Comments are welcome; use the Comments section below, or you can Email Me. Thanks.