Comet C/2023 A3 Tsuchinshan-Atlas is the brightest comet in 27 years (brighter than Neowise, and brightest since Hale-Bopp in 1997). However, Comet A3's observance, starting on October 12 (closest to the earth and first day visible in the Northern Hemisphere), has been overpowered by its competition with the moon. The observation of a comet varies between a new moon and a full moon. The difference in detail and the number of visible stars is striking and speaks volumes about the impact of lunar phases on astronomical observations.
Zero Moon Interference over the next few days! Even though Comet A3 is now getting further away from the earth and getting smaller in size, it will soon have zero competition from the brightness of the moon.
Past and Future Moon Interference on Comet A3:
Oct 12 - 73% waxing moon
Oct 13 - 83% waxing moon
Oct 14 - 91% waxing moon
Oct 15 - 96% waxing moon
Oct 16 - Full Supermoon
Oct 17 - 99% waning moon
Oct 18 - 97% waning moon
Oct 19 - 91% waning moon *
Oct 20 - 84% waning moon †
* On this night, the moon will begin to rise about 10 minutes before the Astronomical Dusk — allowing for several minute of Astronomical Twilight photography of the comet before it is impacted by the moon.
† On this night, the moon will not begin to rise until about 40 minutes AFTER the Astronomical Dusk — allowing for plenty of time to do excellent comet photography. This scenario of no moon interference will continue as the comet become smaller and dimmer.
Even the Astronomical Twilight conditions on Oct 19 (with the moon below the horizon) will be better than what we have experienced so far (Oct 12 thru Oct 18). However, Oct 20 and beyond should be even better — until the comet gets smaller and dimmer (which is happening right now).
The SOONER you capture the comet under these conditions, the better!