Comet SWAN25B from Northern Hemisphere
Taken by Mike Olason on September 14, 2025 @
Tucson, Arizona
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Details:
On a clear evening of 2025 September 14 UT from the Northern Hemisphere managed to get some images of SWAN25B just above the horizon in a fading orange twilight sky. The comet was magnitude G=7.3 as calculated from 30x2 second images taken thru no filter in an aperture diameter of 3.5', this Astrometrica magnitude calculation was made from 17 reference stars in a hazy sky from images only 1.5 degrees above the horizon with lots of optical artifacts in the images, Astrometrica calculated the position of the comet very accurately from the ephemeris used, so it is up to others to determine how accurate they think this magnitude calculation may or may not be given all these variables. The measured coma was 3.5', the tail "visible" in the image is 15' at a position angle of 116 degrees from the comet coma. The wide field of view image shows Mars, Spica and the expected position of SWAN25B, in the middle of the circle is a very faint object which may or may not be SWAN25B, it is very close to where the comet should be, but not possible to guarantee it is indeed the comet. The comet will slowly over the next several weeks become an evening comet for observers in the Northern Hemisphere. Click on each large image to get the best resolution image.
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