Cassiopeia Observatory

Mercury & Mars, Cassiopeia, NGC896 Nebula,
Comet C/2012 S1 ISON, Sirius B
Posted: 5 February 2013

After the last session in the observatory, cloudy skies were the norm. The sky finally cleared on Monday, 4 February 2013, and the observatory was opened at 1807 MST, 68°F. At 1813 MST, viewed Mercury, 77X and 206X. It was too low for good viewing. Then viewed Mars, 77X. Too small and too low for good viewing. At 1820 MST, Mercury was visible in 7x50 binoculars, but was not yet visible to the naked eye. Mars was not yet visible in the binoculars or to the naked eye. At 1824 MST, Mars became visible in the binoculars and was in the same field-of-view (FOV) with Mercury. At 1825 MST, Mercury became visible to the naked eye, with Mars becoming visible a minute later. The planets are approaching an excellent close conjunction later this week. At 1833 MST, I took this photograph of the western sky with the D7000 DSLR, f/5.6, 1/10sec, ISO 400, 105mm, showing Mars above center and Mercury below it near the tree branches:

At 1843 MST, viewed Jupiter, 77X. Three moons were visible. At 1848 MST, I began preparations for doing imaging with the D7000 DSLR. I set up for piggyback imaging on the 8" LX200-ACF of the constellation of Cassiopeia. Beginning at 1914 MST, I began imaging the constellation. This is a guided, 10 minute, ISO 1600, 52mm, exposure:

The "M" configuration of the constellation's bright stars is at the center, with the Double Cluster in the upper righthand corner. Some nebula are visible in the image.

At 2001 MST, I began setting up for prime focus + focal reducer + off-axis guider (OAG) imaging of NGC896, a bright nebula in Cassiopeia. After doing a focus test image of the star Shedir using the Bahtinov Mask, and doing some framing test exposures of NGC896, I located a faint but usable guide star. This is a 5 minute, ISO 6400, guided image, full-frame:

I removed the focal reducer and remounted the camera at prime focus + OAG, did a focus test on Pollux with the mask, and slewed to the location of Comet C/2012 ISON as provided by SkySafari 3 Pro on my iPhone. I had to slew around guite a bit to locate a good guide star, so the comet was no longer well placed in the camera FOV. The comet is still about Magnitude +16. I took two 10 minute, guided, ISO 6400, exposures; the first at 2052 MST and the second thirty minutes later. This is the second image, slightly cropped, showing the comet at the lower right, with a magnified image of the comet in the inset:

I combined the two exposures to create this animated image showing the comet's movement in 30 minutes:

I removed the camera at 2134 MST, and at 2142 MST, I began a visual search using 364X for Sirius B (the "Pup" star), Magnitude +8.4. I had previously tried to view the "Pup" on 16 October 2009, 21 January 2011, and 30 January 2013, without success. This image from Wikipedia shows the orbit of Sirius B:

This night, I again used the techniques described by Dr. Clay Sherrod in his Sirius B article on my ETX Site. At 2146 MST, I finally saw Sirius B. It was a difficult star to see due to the brightness of Sirius A. I decided to try to image Sirius B using the D7000 DSLR and eyepiece projection using 222X and 444X. I did several images at various shutter speeds, ISO 1600. This 10 second exposure, 444X, best captured Sirius B, almost lost in the glare of Sirius A:

At 2224 MST, viewed Jupiter, 77X. Four moons were now visible. At 364X, the Great Red Spot was nicely visible. At 727X, the disks of all four of the Galilean moons were very obvious.

The humidity was now 54% and the paper in my logbook was getting slightly damp, so I ended this session. The observatory was closed at 2243 MST, 50°F.

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