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And the Winner Is...;
Imaging: Double Cluster, Crab Nebula

Posted: 3 November 2015

In September the Friends of Oracle State Park (FOSP) held a fund raising raffle for its members. One of the prizes was a visit to Cassiopeia Observatory. Schedules and weather finally cooperated and the winner was able to come on Monday, 2 November 2015.

Open: Monday, 2 November 2015, 1744 MST
Temperature: 75°F
Session: 875
Conditions: Clear

The FOSP raffle winner arrived at 1805 MST. Here are Jim and Judy Walsh in front of Cassiopeia Observatory:


With husband Jim looking on, Judy is looking at the planet Saturn through the Meade 8" LX200-ACF telescope using a magnification of 83X:


And the happy winners inside the observatory:


Jim and Judy observed Saturn, the Great Globular Cluster in Hercules (M13), the Ring Nebula (M57), the colorful double star Albireo, the Swan Nebula (M17), the Double Cluster (open star clusters), the Great Andromeda Galaxy (M31) and its two companion galaxies (M32 and M110), and the Pleiades (M45). Just before they left they were able to view the distant planets of Neptune and Uranus using a magnification of 222X. During their visit several meteors were seen and they were able to appreciate the dark sky here. They left the observatory at 1955 MST after an enjoyable night of observing at Cassiopeia Observatory.

After my visitors left, I enjoyed about 30 minutes of just sitting on the observatory patio and viewing the nice dark sky at Cassiopeia Observatory. I then returned to the telescope and rechecked the mount "drift alignment". I had noticed some slight tracking error over the past several sessions and thought the mount might need to be adjusted. As it turned out, no polar alignment adjustments were needed. (During post-processing of this night's imaging I still saw some slight tracking error on the unguided exposures. I will refine the AutoStar alignment on the next session.)

2047 MST: began preparing to try to image the very faint Hartl-Dengel-Weinberger 2 planetary nebula in the constellation of Cassiopeia. I added the focal reducer and extension and mounted the Nikon D7200 DSLR at prime focus using the off-axis guider. Used the star Aldebaran for a focus test with the Bahtinov Mask. Then slewed to HDW 2 and began looking for a good star. While slewing I discovered that the camera was hitting the telescope mount. Removed the extension, did another focus test image on Aldebaran, slewed to the star Shedir in Cassiopeia and SYNCed the AutoStar, then slewed to HDW 2. I found a faint guide star and did several exposures. This is a cropped, guided, 10 minute, ISO 6400, exposure:


The faint nebula should appear surrounding the arc of stars at the center, but is too faint for my single exposure with the 8" telescope.

Slewed to the Double Cluster and took this image (slightly cropped), unguided, 30 seconds, ISO 3200:


2207 MST: did some night sky quality measurements using the Unihedron SQM-L and the iOS app Dark Sky Meter on my iPhone 6s Plus. The SQM reading was 21.10. The DSM app consistently had values of just over 18, which was way too low. I have notified the developer of the discrepancy with this new model iPhone.

Back at the telescope, I slewed to M1 (Crab Nebula), low in the eastern sky. I did several unguided images. This is a cropped, unguided, 30 seconds, ISO 12800 image:


2239 MST: ended imaging for the night. Removed the camera and focal reducer from the telescope. Viewed the Crab Nebula, 83X. Then SYNCed the AutoStar on the star Aldebaran. I then began closing up for the night. Overall, it was a fun night in the observatory and one that I was pleased to be able to share with some local residents.

Close: Monday, 2 November 2015, 2302 MST
Temperature: 61°F
Session Length: 5h 18m
Conditions: Clear

This coming Saturday, 7 November, I will be at the Grand Opening of the "Mt Lemmon SkyCenter Astrophotography Exhibit" at Oracle State Park. I will be introducing the Exhibit, noon-2pm. Adam Block of the University of Arizona's Mt. Lemmon SkyCenter has provided several of his outstanding astrophotos for the Exhibit. He is recognized around the world as a leading astrophotographer. The images he produces as part of public outreach programs are published in magazines, books, posters and widely on the Internet. He was the 2012 recipient of the Hubble Award among several notable highlights to his career. The Exhibit will run from 7 November to 20 December. On Sunday, December 20, Adam Block will offer a presentation and film at the park for the public, 3-4pm.

As part of my 10th anniversary celebration of my first visits to "Oracle Observatory", here is my report from 29-30 October 2005.

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