New Comet P/2021 U3 (Attard-Mori) Discovered

On November 2, astronomers reported the discovery of a new comet (magnitude ~19) by A. Mori and G. Attard on CCD images obtained on October 24 using the 0.28-m f/2.2 Rowe-Ackerman-Schmidt astrograph in San Pedro de Atacama, Chile, during the MAP (W94) survey. 

The new comet was designated P/2021 U3 (Attard-Mori). This is the 4th amateur comet discovery of 2021. It is also the second comet detected using the synthetic tracking method (using TYCHO software).

The addition of 51 unfiltered exposures, 60 seconds each, obtained remotely on 2021, 27.10.3 with X02 (Telescope Live, Chile) through 0.61-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma with a diameter of about 6" arc seconds and a tail length of 6" in PA 275 (observers E. Guido, M. Rocchetto, E. Brissink, M. Fulle, G. Milani, K. Nassef, G. Savini, A. Valvazori).

The addition of 66 unfiltered exposures of 60 seconds each, obtained remotely on October 2021, 29.9 from G18 (ALMO Observatory, Italy) through a 0.30-m f/4 reflector + CCD, shows that this object is a comet with a compact coma with a diameter of about 5" arc and a tail length of 6" in PA 270 (observers A. Valvasori and E. Guido).

MPEC 2021-V21, assigns the following preliminary elements of an elliptical orbit to comet P/2021 U3 (Attard-Mori): T 2021 Oct. 25.43; e = 0.55; Peri. = 335.48; q = 1.88 ; Incl.= 70.05.

"The comet passed 0.59 AU from Jupiter in 1983 in October (although the orbital period is not defined for more than a month). A search for earlier observations in archival astrometry yielded nothing."