211129 - C/2021 A1 Comet "Leonard"
ASTRO:
type=comet
mag=7.5
distance=(at closest encounter to Earth) 21M mi
size=5 mi (est.)
IMAGE:
location=EB driveway
exposure=DSLR OSC; 75x30s (38m), ISO1600
EQUIPMENT:
optics=ES102CF APO / Starizona "L" 0.65x rdcr, FL(eff.)=464mm, f(eff.)/4.55
camera=Nikon D90 (mod)
filter=Optolong L-Pro LPS
mount=Celestron AVX
guiding=Orion 60x240mm, ZWO ASi224MC
SOFTWARE:
acquisition=APT, PHD2, Stellarium
processing=DSS, Photoshop, LrC
click image to enlarge
C/2021 A1 (Leonard) was a long period comet that was discovered by G. J. Leonard at the Mount Lemmon Observatory on 3 January 2021 (a year before it reached perihelion) when the comet was appx 750 million km from the Sun. It had a retrograde orbit (directionally counter to the rest of the solar system). The nucleus was about 1 km (0.6 mi) across. It came within 2.5 million mi of Venus, the closest-known cometary approach to that planet.
On the 10th of October, the comet showed a short but dense dust tail. In early December it had an apparent magnitude (coma+nucleus) of around 6.0. The first reports of naked-eye observations by experienced observers started coming in on the 5th of December, 2021. Much like observing Messier 33, the low surface brightness of the comet made it difficult to observe near urban areas. On the morning of December 6th, 2021 the comet was about 5 degrees from the star Arcturus. On the 14th of December, 2021 it was 14.7 degrees from the Sun and quickly became better seen from the southern hemisphere.
On the 23rd of February, 2022 the comet was observed with the SLOOH telescope in Chile, operated by Martin Masek. The comet lacked a central concentration, which indicates that the nucleus of the comet disintegrated or evaporated completely. Further observations by NASA have confirmed the lack of concentration.