Cassiopeia Observatory

Comet PanSTARRS, Mare Humboldtianum, Jupiter

Posted: 17 March 2013

Friday, 15 March 2013, was cloudy. No comet (or anything else) observing that night. The sky cleared in the late afternoon on Saturday, 16 March, and the observatory was opened again at 1821 MST, 80°F. I initially delayed opening the dome due to strong breezes that were blowing, but at 1830 MST, I went ahead and opened the dome anyway. This was a few minutes before sunset.

At 1836 MST, viewed the moon, 77X and 364X. Mare Humboldtianum on the lunar limb looked nice again this night. I decided to image it after I completed comet imaging.

Switched to the visual back on the 8" LX200-ACF and inserted the 26mm (77X) eyepiece. Focused on the moon and locked the focus. I then connected the iPhone 4 to the telescope using the SkyWire serial cable and slewed to the position of Comet C/2011 L4 (PanSTARRS) using SkySafari Pro 3 (links are to my reviews). At 1844 MST, I began waiting for the comet to become visible. While waiting I prepared the camera for imaging. At 1848 MST, the comet became visible in the eyepiece. I mounted the D7000 DSLR at prime focus at 1854 MST, focused on the moon, and locked the focus. Since I was at the moon, captured this image, 1/320sec, ISO 800:

I then returned the comet and began imaging at 1902 MST. The comet was visible in the Antares finderscope and was approaching tree limbs. At 1915 MST, captured this view of the comet, 2 seconds, ISO 1000:

This is another image, cropped and rotated, taken at 1917 MST, 2 seconds, ISO 2000:

At 1918 MST, the comet was well into the trees and I ended imaging. I never saw the comet with the naked eye.

Slewed back to the moon and added a 3X TeleXtender at prime focus for imaging Mare Humboldtianum. Seeing was not very good now. This (cropped) image shows Mare Humboldtianum at the limb (center of image), "Hat Trick", ISO 100:

I slewed to nearby Jupiter and took some photos. This image (cropped) is a composite of two exposures, both taken using the Hat Trick method, one at ISO 500 showing the four Galilean Moons and the other at ISO 100 showing the planet:

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