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Photographer:

Mike Olason

Location of Photo:

Tucson, Arizona

Date/Time of photo:

2025 September 26, 0217UT

Equipment:

SeeStar S50

Description:

Comet C/2025 R2 (SWAN) has brightened from magnitude 7.0 on 9/24 to magnitude 6.5 in these images, confirmed by others on COBs (comet magnitude reporting site). In this image the comet is near several bright stars with the star magnitudes noted in the image, this gives a nice comparison of the brightness of the comet's inner coma to the brightness of the stars. The Astrometrica image and magnitude calculation (G=6.5) on the right image uses the circled area (aperture) to calculate the magnitude of the comet and its visible coma around the comet's nucleus by comparing this area to the magnitude of all stars visible in a larger image.