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Mike Olason

Location of Photo:

Tucson, Arizona

Date/Time of photo:

18 April 2021, 0349 UT


11" SCT and STF-8300M CCD Camera


In these images of Comet C/2021 C6 (Lemmon) the comet is very faint at magnitude 20.1 and 285 million miles from Earth. The comet will reach perihelion in it's orbit in November 2021 when it will be 303 million miles from the Sun and may brighten to magnitude 18 when it is 218 million miles from Earth in January 2022. Of interest in these images is magnitude 19 Asteroid 48365 moving in a little different direction than the comet and Galaxy 2MFGC 8590. I had to search the Sloan Digital Sky Survey to find a name for this galaxy and the galaxy magnitude. The magnitude for the galaxy was given in a "u g r i z" format where these 5 designations cover the light wavelengths seen by modern day ccd/cmos cameras from 300-10000 nm. Wavelength bands of ultra-violet/blue, green, yellow/orange, red and near red probably defines it best. The magnitudes were given as 18.5, 16.8, 15.9, 15.5 and 15.1 respectively and they have a formula to give you a final magnitude from these 5 magnitudes although I am not sure what it really means since there are a hand full of different such magnitude measuring systems out there, the one I described was what the SDDS uses. So bottom line, I am not sure what the magnitude of this galaxy really is but it sure is a lot brighter than the magnitude 20.1 comet which is easily measured from an image or is it, we are now starting to see this same banding magnitude measurements being used on comets, of course it is only as good as the filters being used to define the bands.


Image of Mike Olason

Mike Olason

May 1, 2021 at 6:40 am

I made a mistake above, the wavelengths covered are from 300-1000nm in these 5 bands. 10000nm would take one well into the infrared spectrum.

Mike Olason

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