New Comet C/2020 F7 (Lemmon)

CBET 4949 & MPEC 2021-F110, issued on 2021, March 25, announce that an apparently asteroidal object (magnitude ~21.0) discovered on CCD images obtained with the Mt. Lemmon Survey's 1.5-m reflector on 2020 Mar. 22 and designated A/2020 F7 (cf. MPEC 2020-G78) has been found to show cometary appearance by numerous other CCD observers over the past half year. The new comet has been designated C/2020 F7 (Lemmon).

Stacking of 19 unfiltered exposures, 120 seconds each, obtained remotely on 2021, March 23.9 from Z08 (Telescope Live, Oria) through a 0.7 m f/8 Ritchey Chretien + CCD, shows that this object is a comet with a compact coma about 15" in diameter elongated toward PA 50. (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott)

MPEC 2021-F110, assigns the following preliminary orbital elements to comet  C/2020 F7 (Lemmon): T 2021 Nov. 14.1; e= 0.99; Peri. =  227.97; q = 5.33 ;  Incl.= 93.95

Credit: MPC

by Ernesto Guido 

New Comet C/2021 D2 (ZTF)

CBET 4948 & MPEC 2021-F67, issued on 2021, March 22, announce the discovery of an apparently asteroidal object (magnitude ~19.5) on CCD images taken on Feb. 19.5 UT & Mar. 09-5 with the 1.2-m Schmidt telescope at Palomar in the course of the "Zwicky Transient Facility" (ZTF) search program  (the object was reported twice by the ZTF survey team as two different objects) . This object has been found to show cometary appearance by CCD astrometrists elsewhere. The new comet has been designated C/2021 D2 (ZTF).

Stacking of 20 unfiltered exposures, 60 seconds each, obtained remotely on 2021, March 15.2 from I89 (iTelescope, Nerpio, Spain) through a 0.32-m f/8.0 reflector + CCD, shows that this object is a comet with a diffuse coma about 8" arcsec in diameter (Observers A. Valvasori, E. Guido).

Stacking of 12 unfiltered exposures, 90 seconds each, obtained remotely on 2021, March 18.2 from Z08 (Telescope Live, Oria) through a 0.7 m f/8 Ritchey Chretien + CCD, shows that this object is a comet with a diffuse coma about 10" in diameter (possibly elongated toward PA 140). (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).

 

Credit: MPC

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott)

MPEC 2021-F67, assigns the following preliminary orbital elements to comet  C/2021 D2 (ZTF): T 2022 Feb. 4.17; e= 0.99; Peri. =  125.07; q = 2.94 ;  Incl.= 83.84

 

by Ernesto Guido

Apollo Asteroid 2020 UQ6: A Super Fast Rotator

In the latest issue of Minor Planet Bulletin (VOLUME 48, NUMBER 2, A.D. 2021 APRIL-JUNE), our work on determining the rotation period of asteroid 2020 UQ6 was published. This  asteroid  is  a  Near-Earth  object belonging  to  the  Apollo  group  discovered  at  Tokyo-Kiso Observatory (MPC code 381) on 2020 October 27.

You can read here our paper titled "ROTATIONAL PERIOD AND LIGHTCURVE DETERMINATION OF  2020 UQ6: A SUPER FAST ROTATOR"

CCD photometric observation of 2020 UQ6 were carried  out  in 2×2 binned format during the night between 2020 October 28 and 29 by using the main telescope of the Osservatorio Salvatore di Giacomo,  Agerola  (MPC  code  L07).  It  is  a  0.50-m  Ritchey-Chretien operating at f/8 equipped with an unfiltered FLI-PL4240 CCD camera (2048×2048array of 13.5-micron pixels). 

The software Tycho by D. Parrott, that now offers the ability to construct lightcurves and determine rotation periods, was used during the observing session to extract the light curve of this interesting asteroid almost in real time.

In order to take in account both the high speed of the object (ranging from 21.48  arcec/min  to  17.46  arcsec/min  during  the  measurements) exposure times were kept to 4 s for all sessions. Eight  observation  sessions  collected  1373  data  points  for lightcurve analysis. This led to a bimodal lightcurve with a period of 0.04521 h (162.76 s), or a frequency of 530.84 rev/d, and an amplitude of 0.57 magnitudes. This finding identifies this object as a super-fast rotator asteroid (P << 2 h).

Credit: Guido et al.; MPB

From the absolute magnitude value  of H  =  22.6  and  assuming  the  asteroid  to  be  a  spherical object with a uniform surface and albedo ranging from 0.05 and 0.30, one can gets an estimated diameter ranging from 80 and 180 m.  From  this,  it  is  possible  to  add  the  average  value  of  the estimated diameter, D = 130 m, to the frequency vs diameter plot from  LCDB. As it can be observed, 2020 UQ6 is located in an uncrowded  region  of  the  graph  (identified  by  a  yellow  point), making this object particularly noteworthy. (click on the image below for a bigger version)

Credit: Guido et al.; MPB

by Ernesto Guido, Antonio Catapano, Alfonso Noschese, Antonio Vecchione

New Comet C/2021 C4 (ATLAS)

CBET 4937 & MPEC 2021-D113, issued on 2021, February 26, announce the discovery of an apparently asteroidal object (magnitude ~19) on CCD images taken on Feb. 12.6 UT with a 0.5-m f/2 Schmidt reflector at Haleakala, Hawaii, in the course of the "Asteroid Terrestrial-Impact Last Alert System" (ATLAS) search program. This object has been found to show cometary appearance by CCD astrometrists elsewhere after the object was posted on the Minor Planet Center's PCCP webpage due to its orbit. The new comet has been designated C/2021 C4 (ATLAS).

We performed follow-up measurements of this object while it was still on the PCCP webpage.

Stacking of 5 unfiltered exposures, 90 seconds each, obtained remotely on 2021, February 22.2 from X02 (Telescope Live, Chile) through a 0.6-m f/6.5 astrograph + CCD, shows that this object is a comet with a compact coma about 8" arcsecond in diameter. (Observers E. Guido, M. Rocchetto, E. Bryssinck, M. Fulle, G. Milani, C. Nassef, G. Savini, A. Valvasori).

Our confirmation image (click on it for a bigger version; made with TYCHO software by D. Parrott):

Credit: Minor Planet Center

 

M.P.E.C. 2021-D113, assigns the following preliminary parabolic orbital elements to comet C/2021 C4 (ATLAS): T 2021 Jan. 21.04; e= 1.00; Peri. =  320.80; q = 4.50;  Incl.= 132.85


by Ernesto Guido