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Comet C/2014 Q2 (Lovejoy)

Posted: 4 January 2015

The forecast for Friday night, 2 January 2015, was for clear skies. Several times during the day the sky seemed to be trying to clear up, only to return to being completely overcast. Oh well, I was rather pooped out after shoveling snow from our driveway that morning. Most of the 4.75" of snow here had not yet melted. Saturday, 3 January, dawned clear and cold (25°F), with a forecast for clear skies that night.

Open: Saturday, 3 January 2015, 2130 MST
Temperature: 32°F
Session: 763
Conditions: Clear

This was a planned short session to photograph Comet C/2014 Q2 (Lovejoy). I wanted to do some piggybacked DSLR test exposures, even though the nearly full moon would interfere by brightening the sky quite a bit. But I figured this would be a good "dry run" for photographing the comet once the moon was out of the sky on Wednesday, 7 January. As it turned out, the session was longer than expected.

2136 MST: viewed the nearly Full waxing gibbous moon, 83X. Slight terminator was visible. Grabbed this handheld iPhone 5s afocal image, 83X:


2142 MST: slewed to the RA/Dec of Comet Lovejoy. The coma was visible at 83X. The comet was not visible to the naked eye due to the sky brightness. It was however easily visible in 12x70 binoculars (by knowing where to look). No tail was visible in the binoculars due to the bright sky.

I focused the D7000 DSLR camera with 105mm focal length lens on the moon and then mounted the camera piggyback on the 8" LX200-ACF. No stars or the comet were visible in the camera viewfinder or on the "Live View" screen at ISO 25600. Since my piggyback adapter is not very accurately optically aligned to the telescope, I had to do several framing test exposures (30 seconds, ISO 1600) to get the comet near the center of the camera field-of-view (FOV). Unfortunately, I must have accidently changed the focus (which had been set to Manual) as the stars were out of focus in the latter images. I reduced the lens focal length to 58mm, which allowed the star Rigel to be the FOV, turned on Live View, set the ISO to 25600, and focused the lens. Unfortunately, when I went back to 105mm FL, the stars ended up slightly out-of-focus again. I repeated this cycle several times but could not get a precise focus at 105mm. Fortunately, at the image scale below, the slightly out-of-focus stars are not a factor.

So, here is Comet C/2014 Q2 (Lovejoy), visible just left of center, taken with the D7000 DSLR piggybacked on the telescope, 30 seconds, ISO 1600, FL 105mm:


This photograph, 30 seconds, ISO 800, FL 18mm, more accurately shows the sky brightness with the comet at the center, Orion to the left, the star Sirius at the lower left corner, the 8" telescope tube at the bottom, and part of the observatory dome in the upper left corner:

Mouseover or tap on image
Mouseover or tap on image for comet marker

2232 MST: ended Comet Lovejoy imaging.

Although it would not have helped a lot this night, using a Bahtinov Mask on the camera lens would have been handy to ensure precise focusing on nights when a bright star is available in the camera FOV. OPT has such a Bahtinov Mask that fits both my 18-105mm and 70-300mm zoom lenses. I will be ordering one.

Close: Saturday, 3 January 2015, 2243 MST
Temperature: 33°F

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