C/2023 P1 (Nishimura) at perihelion +1d Nick James (19 Sep 2023 08:54 UTC)
RE: [BAA Comets] C/2023 P1 (Nishimura) at perihelion +1d Andrew Robertson (19 Sep 2023 09:09 UTC)
RE: [BAA Comets] C/2023 P1 (Nishimura) at perihelion +1d Andrew Robertson (19 Sep 2023 09:58 UTC)

C/2023 P1 (Nishimura) at perihelion +1d Nick James 19 Sep 2023 08:54 UTC

Last night (Sept 18.83) I managed to get an image of this comet from
2100m altitude on La Palma when it was only 1 degree above the horizon.
The sky was very transparent and a stacked image shows stars to 8th
magnitude at the same elevation as the comet. Using a star of magnitude
6.9 I estimate the total magnitude of the comet as 3.4. This is probably
an underestimate given that much of the outer coma will be lost in the
very bright background sky but I think it is not far off.

This is consistent with the magnitude prediction from pre-perihelion
observations so I think this comet is performing as expected.

This is the cropped image:

https://britastro.org/observations/observation.php?id=20230918_231556_76d8b2a376760ba7

There was a very strong background gradient across the image which has
been removed.

The following link shows the observing setup. A very clear western
horizon with occasional cumulous blowing up the side of the mountain. My
thanks to the Vistor's Centre for giving us access.

https://nickdjames.com/Comets/2023/2023p1/DSC00750.jpg

Nick James. BAA Comet Section.