Cassiopeia Observatory

iPhone Crater Clavius, D7000 M92 and Comet Garradd

Posted: 3 February 2012

I opened the observatory, Thursday, 2 February, at 1808 MST, 56°F. The sky was mostly clear, with some clouds low along the northern horizon. During the day, there had been strong winds blowing; there was still a breeze blowing after sunset. At 1814 MST, viewed Venus at 77X and 206X. I set up for iPhone 4 afocal imaging of Venus. With the iPhone mounted on the 8" LX200-ACF using the MX-1 Afocal Adapter, I used the iOS Camera app to record a video of Venus at 231X through a combination of a Moon Filter and a #21 Orange Filter to reduce the brightness of Venus. This is one frame of the video, edited to remove saturation, and cropped from the full-frame image:

At 1825 MST, viewed Jupiter at 133X. The four Galilean Moons were visible. I then tried the same iPhone technique on Jupiter but surprisingly, the Camera app would overexpose Jupiter, masking any details.

At 1838 MST, viewed the moon at 77X and tried 364X, but that was too much magnification for the poor seeing. Switched to 206X, which provided better viewing, and did a tour of the lunar terminator. Selected the crater Clavius for high magnification imaging, which at times showed some nice details on the crater wall and floor. Used the #21 Orange Filter to enhance the view; it reduced some of the effects of the poor seeing. (This was a tip I saw on Will Gater's blog: http://willgater.com.) I then set up for iPhone afocal imaging of the moon. This is 77X:

I also did a video recording (5 seconds) and stacked 185 frames to make this cropped image of Clavius:

At 1910 MST, returned to lunar observing. Used 364X + #21 Orange Filter. The views were OK at times, but mostly the seeing was just not good enough. Removed the filter; views of Clavius were fascinating, even with the poor seeing.

At 1948 MST, returned to Jupiter and viewed it at 133X. The temperature was down to 42°F now. Although I had originally planned to spend most of the night in the observatory, I decided to close up for awhile and take a short nap. Closed the observatory at 2015 MST.

The observatory was re-opened at 0035 MST, temperature = 38°F. At 0038 MST, viewed Mars at 77X, 133X, 206X, and 364X. Seeing was not good enough for 364X but at 206X the North Polar Ice Cap, Utopia Planitia, and Syrtis Major were seen. I then viewed the moon again; Clavius was still looking nice at 206X. I then returned to Mars and tried iPhone imaging. Unfortunately, even with a moon filter, the iOS Camera app overexposed the planet, masking any details. I ended imaging at 0116 MST.

At 0121 MST, slewed the telescope to M92 globular cluster, which was just above the northeastern horizon. Using 77X, I searched for and found Comet C/2009 P1 (Garradd), faintly visible about 1/2° away from M92. Began setting up for D7000 DSLR prime focus imaging. Add the focal reducer. Then began waiting for M92 and Comet Garradd to get higher in the sky. At 0147 MST, viewed M51, the Whirlpool Galaxy. Nice view even with the moonlit sky. Then returned to M92. At 0155 MST, I put the telesope to sleep, closed the dome, and went to the house to process the images from earlier in the night. Re-opened the dome and woke the telescope at 0305 MST. At 0308 MST, I was viewing M92 and the comet again.

I attached the D7000 DSLR at prime focus + focal reducer + Off-Axis Guider (OAG), and did a focus test on the star Vega using the Bahtinov Mask. Locked the focus. Then went back to M92 and did an unguided framing test image, 1 minute, ISO 6400, slightly cropped:

I then slewed to get Comet Garradd in the viewfinder along with M92. Had to rotate the OAG to properly frame both objects in the FOV. I did another framing test exposure but discovered that the focus had changed. Went back to Vega for another focus test. That done, went back to M92 and the comet and took this 1 minute, ISO 6400, unguided (full-frame) image:

I then did a guided 5 minute, ISO 6400, exposure. With some editing, I was able to bring out the ion tail (left) and dust tail (right):

I ended comet astrophotography at 0410 MST. I then did some more viewing of the comet and M92 at 77X, both in the same FOV. The comet's nucleus and coma were clearly seen. Both tails were faintly visible, one easy and the other more difficult.

I then viewed Saturn at 77X, 133X, 206X, and 364X. It was lovely at all magnifications. The Rings had opened up nicely since Saturn was last observed on 23 September 2011.