Comet 186P/Garradd

Mike Olason
Location of photo
Denver, Colorado
Date/Time of photo
3 June 2018, 0409UT
11" SCT f/6.4 and STF-8300M CCD Camera
Comet 186P/Garradd is another comet that is just above the southern horizon this year as seen from Denver, only getting about 12 degrees above the horizon this year. 186P reaches perihelion in its 11.19 year orbit 5 May 2019 when it will be 408 million miles from the Sun and may reach magnitude 17, but unfortunately if you live from Denver (40N) north 186P will not rise above the horizon in 2019. This collection of 10 five minute images of 186P that resulted in this image was started when the comet was at 10 degrees above the horizon and were finished when the comet was just 6 degrees above the horizon. The comet appeared to be about magnitude 18.5 and was 361 million miles from Earth. The bright, fuzzy object to the right of 186P is magnitude 14.5 Galaxy PGC 39234. The comet was moving at only 0.0029 degrees per hour so I had to wait a 1/2 hour after it got dark for the comet to get far enough away from the star just to the upper left of the comet to start taking images that would show the comet and star as separate objects, hoping while I waited that the low horizon would stay clear enough to take these images. So this image may not be much to look at, but it took a lot of luck to get it.
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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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