C/2010 G2 (Hill)

Comet C/2010 G2 (Hill)

IAUC 9134, issued on Apr 11 2010, announces the discovery of a new comet by R. E. Hill on Apr 10 2010, in the course of the Catalina Sky Survey. The cometary features include a 6" - 8" coma in diameter, as well as an 8" - 10" tail in length approximately in P.A. 200°. The central condensation is of around 19^m. The new comet has been designated C/2010 G2 (Hill).

2012 Jan 03

The comet is in outburst. Its FWHM is only slightly larger than stars in similar magnitudes. Interestingly, the L-S filtered image hints an elongated (NE to SW) feature (jets?) within the coma.

Mouseover to see the version without the two pseudocolor illustrations.

The following MPC observations were compiled with coordinates measured in Astrometrica by UCAC-3 star catalog and photometry by CMC-14 star catalog in R band. The first quadruplet is measured from images with exposure of 30-sec each whilst the last quadruplet from images with exposure of 120-sec each:

COD C42
OBS X.Gao, M.-T. Hui
MEA M.-T. Hui
TEL 0.36-m f/6.9 Schmidt-Cassegrain + CCD
NET UCAC-3
    CK10G020 KC2012 01 03.53002 03 02 50.65 +03 07 31.4          12.2 N      C42
    CK10G020 KC2012 01 03.53153 03 02 50.56 +03 07 29.2          12.2 N      C42
    CK10G020 KC2012 01 03.53301 03 02 50.47 +03 07 27.2          12.2 N      C42
    CK10G020 KC2012 01 03.53448 03 02 50.38 +03 07 25.4          12.2 N      C42
    CK10G020 KC2012 01 03.53591 03 02 50.30 +03 07 23.5          12.2 N      C42
    CK10G020 KC2012 01 03.53734 03 02 50.23 +03 07 21.6          12.2 N      C42
    CK10G020 KC2012 01 03.53880 03 02 50.12 +03 07 19.3          12.2 N      C42
    CK10G020 KC2012 01 03.54066 03 02 50.03 +03 07 17.2          12.2 N      C42
----- end -----

PSF in PhAst with one of the images in composite exposure of 75-sec.

I have not yet mastered the way to perform photometry of objects in PhAst, as by no means could I change the zeropoint magnitude. Perhaps PhAst will perform well in Linux. Nonetheless, the PSF of the comet is shown above.

Photometry result computed with FOCAS II, which processes images based upon the .LOG file of Astrometrica, by means of Multibox method. The results in multiboxes are very satisfactory due to sufficient SNR.

COD C42
CATALOG: USNO A2.0 / CMC-14 - BAND: R
                                   10x10 20x20 30x30 40x40 50x50 60x60 SNR SB COD
OBJECT        DATE       TIME        +/-    +/-    +/-    +/-    +/-    +/-     N FWHM CAT
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ---- ---
C/2010 G2     03/01/2012 12:50:42 12.19 11.86 11.72 11.64 11.58 11.52 108.2 17.5 C42
C/2010 G2     03/01/2012 12:50:42* 0.01 0.01 0.01 0.02 0.01 0.01     8 3.6 CMC

FoCAs II - 17/03/2010
www.astrosurf.com/cometas-obs
es.groups.yahoo.com/group/Cometas_Obs

Interpretation of the FOCAS II table headings:

Fisrt line:

OBJECT, DATE, TIME: refering to their original meanings respectively

10x10, 20x20 ... 60x60: the aperture sizes of photometry in term of rectangle in arcsec that are used to measure an object's magnitude

SNR: the Signal-to-Noise Ratio for aperture photometry

SB: stars of faintest magnitude on the images used in data reduction with the used star catalog in Astrometrica, rather than the stars of faintest magnitude in the images

COD: MPC Code of the observatory

Second line:

+/-: precisions of measurement

N: the number of used images for measurement

FWHM: Full-Width-Half-Maximum of total PSF, relevant to degree of seeing

CAT: the used star catalog in Astrometrica

Feel free to e-mail me with any doubts or questions.