For sentimental reasons I  have been trying to get a last image of the Great Comet of 2024 but it is clearly much fainter than the current ephemeris magnitude of 18 and it is in a very crowded field near the Milky Way in Hercules. The comet is now more than 6au out from the Sun.

The MPC last comet observations page has a detection at 21.0 R from C23 (an observatory in Belgium) on 2026 May 27 however the astrometry residuals from that station on that date are poor and the reported magnitudes range from 18.6 to 21.0. I suspect that the measurements were affected by nearby stars. Prior to that the next oldest astrometry is from Denis Buczynski (I81) on 2025 Nov 20 with magnitudes of 19.7 and 20.3. These residuals are good. The last image in our section archive is from 2025 September.

I took a 1hr stack on June 11/12 from Chelmsford with the 0.28m, f/10 SCT in very good conditions (for here). The sky background was 19.1 mag/square arcsec and the stack gets to an unfiltered stellar LM of around 21.2 (for an SNR of 3, measured using Tycho's image evaluation tool). I was lucky that the comet was in a patch of sky with no star interference but there is no sign of it. I suspect that the recent C23 photometry is wrong and the comet was even fainter than reported.

Does anyone want the challenge of imaging this comet to a deeper LM. You would need a long stack with dark skies on a night when the comet was in a clear patch of sky. It is well placed near the meridian at local midnight. It would be nice to see it again for one last time!