Hello Uwe,
I have some images from 3 August 2021 that I had not processed yet of 17P, unfortunately thin clouds were moving thru the field. I have included a better image and an estimate by Astrometrica. On this night the comet had a coma of at least 20" and a tail at least 1' long at a PA of 270 degrees. The magnitude was G=15.6 and was about the same when the other few images were averaged together although an 18 magnitude star to the west of the comet was close to the comet in the stack. At least on the 3rd the comet was not magnitude 13 just by looking at it in this 300 second image, if it was it would be brighter than almost everything in the image which it certainly is not. The comet was about 1.5 magnitudes brighter than Seiichi Yoshida's expected magnitude curve for the comet of about magnitude 17 for the beginning of August where there were 11 estimates reported around magnitude 17 although at the same time there were several reports of the comet being magnitude 15+. Hope this data helps.
| Dateianhänge: |
|
17P_20210803_0959_molason.jpg [ 241 KiB | 817 mal betrachtet ] |