D7000 DSLR DSO Imaging: NGC1637, NGC2261, & NGC2217
Posted: 18 February 2012
The weather changed after my last report, with cloudy skies, some rain, and even a surprise snowfall. My "Live Webcam" captured the snow on Tuesday, 14 February, in this short time-lapse video. The sky finally cleared on Friday, 17 February, and I opened the observatory at 1816 MST, 50°F. The sky was mostly clear but there were a few clouds drifting by and there was a slight breeze blowing. My plan for the night was to acquire longer exposures of two faint DSOs that I had imaged on the previous session and to acquire some more DSO images.
At 1821 MST, viewed Mercury at 77X. However, it was too low in the western sky for good viewing. I then viewed Venus at 77X. Next, I viewed Uranus at 77X. The sky was still too bright for good viewing. Next, was Jupiter at 77X. The four Galilean Moons were in an interesting configuration. Seeing was not ideal so I did no higher magnification observing of the planet.
At 1845 MST, I slewed the 8" LX200-ACF to my first imaging target: NGC1637, a small faint galaxy. I began waiting for twilight to end and for the clouds to move on. I prepared the D7000 DSLR for prime focus imaging. I then SYNCed the AutoStar on the star Rigel. The galaxy became visible at 1904 MST in the 26mm eyepiece (77X). The clouds had moved on towards the east. I mounted the camera at prime focus using the Off-Axis Guider and did a focus test on Rigel using the Bahtinov Mask.
At 1930 MST, I did a framing test exposure of NGC1637. I found a good guide star and framing was good. The sky was finally dark enough at 1940 MST and I began a 10 minute, ISO 6400, guided exposure. This is the result, cropped from the full-frame image:
During the 10 minute exposure, while monitoring the guide star, I also had to monitor a band of clouds that was approaching the DSO from the southwest. Fortunately, the clouds stayed south of the DSO.
At 1956 MST, I did a framing test exposure of my next target, NGC2216, Hubble's Variable Nebula. Again, I found a good guide star and framing was good. I did a 10 minute, ISO 6400, guided exposure, with this cropped result:
At 2014 MST, I slewed to a new target for imaging, NGC2217, another small faint galaxy. I did a framing test exposure. Once again, I had a good guide star and good framing. I then did a 5 minute, ISO 6400, guided exposure. After I completed the 5 minute exposure, I saw that another band of clouds was approaching from the southwest. I debated whether I would be able to do a 10 minute exposure before they arrived at the target area of the sky. I decided to try. The clouds got close to the DSO but I was able to complete the 10 minute, ISO 6400, guided exposure. This is the cropped image:
I was surprised that I was able to capture the circular arms around the galaxy with a DSLR. Nice. All three of the above images are cropped to the same scale.
At 2048 MST, there were clouds over most of the sky. So much for the "clear" forecast at 7Timer! and Clear Sky Chart. I unmounted the camera and at 2057 MST, viewed Mars at 77X and 133X through a hole in the clouds. Seeing was lousy. Not only had the cloud cover increased, so had the humidity. But I did observe five planets this night and I was able to get some nice DSO images. I SYNCed on the star Regulus and then began closing up.
Closed the observatory at 2110 MST, 42°F, humidity 73%.
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