Comet C/2017 O1 ASASSN and Open Star Cluster NGC 188

Mike Olason
Location of photo
Denver, Colorado
Date/Time of photo
6 January 2018, 0902UT
11" SCT f/6.4 and STF-8300M CCD Camera
This average of 3 images each 180 seconds long shows Comet C/2017 O1 ASASSN near the background Open Star Cluster NGC 188. Comet ASASSN was about 4 degrees from the North Star Polaris. Comet ASASSN is now fading as it moves away from Earth and is magnitude 16.1 in this image, it has a fuzzy tail above the comet coma. NGC 188 is the large circle to the left in this image and Comet ASASSN is the smaller circle to the lower right in this image. The image FOV is about 1/3 degree by 1/3 degree.
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Mike Olason

About Mike Olason

I started imaging comets in 1994 with an ST-5 CCD Camera and an 11" SC Telescope. Since then the CCD cameras have changed (ST-7, ST-402ME and STF-8300M), but I am still using the 11" SC Telescope. Naturally I have used a lot of smaller telescopes to obtain larger fields of view. I live south of Denver at an elevation of 6150 feet which allows me to image comets down to almost magnitude 21 on a perfect night. Unfortunately ChemTrails have turned Denver cloudy and dry. I use the camera software CCDOps to process my images. All I do to each image is dark subtraction and flat field, stack images as required to show faint comets, contrast/bright adjust the final image and maybe use a median filter to reduce the image noise. The result is an image that reflects reality and will never win any picture of the day award. If you would like to use my images for a project or ask a question send me an email to "".
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