CBET 5064 & MPEC 2021-V21, issued on 2021, November 02, announce the discovery of a new comet (magnitude ~19) by A. Maury and G. Attard on CCD images taken on October 24.3 UT with the 0.28-m f/2.2 Rowe-Ackermann Schmidt astrograph at San Pedro de Atacama, Chile in the course of the MAP (W94) survey. The new comet has been designated P/2021 U3 (Attard-Maury). This is the 4th amateur comet discovery of 2021. It is also the second comet discovered using the synthetic tracking technique (using TYCHO software).
Stacking of 51 unfiltered exposures, 60 seconds each, obtained remotely on 2021, Oct. 27.3 from X02 (Telescope Live, Chile) through a 0.61-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 6" arcsecond in diameter and a tail 6" long in PA 275 (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).
Stacking of 66 unfiltered exposures, 60 seconds each, obtained remotely on 2021, Oct. 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 about 5" arcsec in diameter and a tail 6" long in PA 270 (Observers A. Valvasori & E. Guido).
MPEC 2021-V21, assigns the following preliminary elliptical orbital elements to comet P/2021 U3 (Attard-Maury): T 2021 Oct. 25.43; e= 0.55; Peri. = 335.48; q = 1.88 ; Incl.= 70.05.
According to CBET 5064 "the comet passed 0.59 AU from Jupiter in 1983 October (though the orbital period is uncertain by well over a month). A search for earlier observations in archival astrometry produced nothing".