Cassiopeia Observatory

Dwarf Planet Makemake, Comet C/2012 S1 ISON

Posted: 2 March 2013

The observatory was opened Friday, 1 March 2013, at 1816 MST, 70°F, to clear skies, for what was a frustrating but ultimately successful night. While waiting for twilight to end I began preparing the D7000 DSLR for prime focus + off-axis guider imaging. At 1831 MST, viewed Jupiter, 77X. Three moons were visible. The Great Red Spot was near the limb and rotating out of view.

At 1845 MST, I mounted the camera on the 8" LX200-ACF. My first planned imaging target would be Comet C/2012 S1 ISON.

As I continued waiting for the sky to darken, I observed a low elevation pass of the International Space Station (ISS). I tried to see the SpaceX Dragon spacecraft but the still bright twilight sky prevented seeing the small and faint Dragon.

At 1927 MST, did a focus test with the Bahtinov Mask on the star Pollux. I connected the iPhone 4 to the telescope using the SkyWire serial cable. Using SkySafari Pro on the iPhone, I did a GOTO to Comet ISON. I then began looking for a guide star to use during the 10 minute exposure. Unfortunately, no good guide stars were located before the telescope was pointing near the POD "zenith blind spot". I would now have to wait until Comet ISON was west of the zenith.

At 1948 MST, the Zodiacal Light was looking very nice. I enjoyed just looking at the night sky while waiting for Comet ISON to move westward.

At 2034 MST, I decided that as the waning gibbous would be rising about 2230 MST, I should image my planned second target for the night, the dwarf planet Makemake, Magnitude +16.9, rising in the east, while waiting on the comet to be better positioned. Slewed to Regulus at 2050 MST and did another focus test image. Using SkySafari, did a GOTO Makemake. It was currently too low for imaging, but I did a search for a suitable guide star. I found a faint one. By the time I did the actual imaging of Makemake at 2130 MST, I had located a better guide star. During the 10 minute exposure, I kept losing sight of the guide star, which yielded bad guiding during the exposure. In addition, when I checked the image on the camera screen, I discovered that the focus had shifted slightly (yes, I had locked the telescope mirror). So, it was back to Regulus for another focus test. At 2149 MST, I took this 10 minute, ISO 6400, guided exposure, showing the dwarf planet Makemake:

The suspected position of Makemake was determined by comparing the image to the position of Makemake as shown in SkySafari Pro for Mac OS X. I plan to take a second image on the next session to show the change in Makemake's position, which will confirm that I captured Makemake.

At 2200 MST, using SkySafari Pro on the iPhone to control the telescope, did a GOTO to Comet ISON, which was now west of the zenith. I located a faint guide star and did a 10 minute exposure. During the exposure, I kept losing the guide star in the illuminated reticle eyepiece, which resulted in horrible guided. Beginning at 2228 MST, I did a second 10 minute, ISO 6400, guided exposure, using a better guide star. This is the resultant image showing Comet C/2012 S1 ISON. The inset shows a magnified view.

I ended imaging at 2240 MST. The eastern sky was beginning to brighten from the rising waning gibbous moon.

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