Staying with the Ha filter due to the full moon, I took 4 15 minute exposures of the Seagull Nebula in a 2 frame mosaic. This picture covers almost 4 degrees by 4 degrees in an area close to the borders of Canis Major, Monoceros and Puppis.
GRAS-12 – Takahashi FSQ-106ED
SBIG STL-11000M-ABG
This is one that’s featured in previous images of mine but this time it’s in close up courtesy of GRAS-6, an RCOS 16? Ritchey-Chrétien Cassegrain with a focal length of over 3.5 metres. With a full moon in the sky I used an Ha filter on the camera and binned the pixels 2×2 to reduce the sub-frame exposure length to a manageable 5 minutes. This image is a stack of 6 exposures.
Set against the bright emission nebula IC434, the Horsehead is a cloud of cold, dark gas in the constellation of Orion.
Galaxies tend to come in groups, and, after the local group this is the next nearest with M81 being the primary galaxy at a distance of 12 million light years. Also in this picture are other members of the group; M82 and NGC 3077. With a more aggressive screen stretch it’s also possible to detect the background galaxy UGC 5336 just to the left of M81.
As Wednesday evening was clear and still, I took the opportunity to gather 2 and a half hours worth of 3 minute exposures at ISO 800 with my ZenithStar 70 and Williams Optics field flattener. Bias and flat frames were also used in the image processing but not dark frames.
As regular readers of both mine and Dan’s blogs will know, using the 20″ has been a constant struggle to produce untrailed images. The approach taken has been to keep exposures as short as possible and be prepared to throw away a high percentage that show bad tracking.
With the new servos and controller we decided to press the club’s old SBIG STV into service again as a guider using the supplied 100mm focal length e-finder scope. Despite the disparity in focal lengths between this and the main instrument the results from initial testing are impressive.
This being an Alt-Az mount we chose IC 405 as a suitable subject as it was below 40 degrees in the East, with a bright star in the nebula that could be used for guiding. After an initial test exposure we increased the time to 300 seconds and reduced the ISO to 800 and took 6 frames. The first was unusable due to instability in altitude but the remaining 5 frames showed remarkably little trailing. Dan’s result is here.
IC 405 is a combination of an emission and reflection nebula in the constellation of Auriga.
