SUNSET: 
0
Photographer:
Mike Olason
Location of Photo:
Tucson, Arizona
Date/Time of photo:
3 August 2021, 1122 UT
Equipment:
11" SCT and STF-8300M CCD Camera
Description:
These images show Comet C/2021 O1 (Nishimura) on August 3 a couple days before it's close approach to Earth on August 5 when it will be 158 million miles from Earth. Unfortunately the images were collected thru clouds so the magnitudes calculated by the software appeared to show the comet fainter than expected at about magnitude 10. The images showed a visible coma at least 0.02 degrees wide and a fan tail at least 0.02 degrees long to the west of the coma. The image insets to the right were computed by Astrometrica which used stars visible in the images to calculate the magnitudes and position of the comet for the times shown in the insets, G is the calculated magnitude for each inset image. The comet will reach perihelion in it's orbit on 12 August 2021 when it will be 74 million miles from the Sun.
