Comet P/2012 NJ (La Sagra)

This comet is discovered by J75 La Sagra on Jul 13 2012. However, initially no any cometary feature was detected but appeared asteroidal, whereby it was designated as an asteroid called 2012 NJ. Later, the object was found to show a narrow 35" tail in P.A. 235° by Gerhard J. Hahn, Department of Asteroid and Comet Research, DLR Institute of Planetary Research on stacked and single images through the 1.23-m telescope on Calar Alto on three consecutive nights from Jul 16 to Jul 18.

2012/07/14 2012/07/19

2012 Jul 14

Mouse-over to browse the image in 4-color sequels version.

This sequence of images is our confirmation on the discovery the object, although completely asteroidal. The first taken image was removed due to trailing stars because of tracking problem.

FWHM of the comet appears slightly larger than stars in similar magnitudes, yet it may well be attributed to the trailed image owing to its fast motion.

MPC observation computed with Astrometrica using both UCAC-3 and CMC-14 star catalogs -- the former for astrometric reduction and the latter for photometric work:

COD C42
CON M.-T. Hui
OBS M.-T. Hui, X.Gao
MEA M.-T. Hui
TEL 0.36-m f/6.9 Schmidt-Cassegrain + CCD
NET UCAC-3
    PK12N00J tC2012 07 14.77134 23 38 23.36 +12 59 51.5                      C42
    PK12N00J tC2012 07 14.77316 23 38 22.50 +13 00 03.3          14.3 N      C42
    PK12N00J C2012 07 14.77470 23 38 21.99 +13 00 12.3          14.4 N      C42
    PK12N00J C2012 07 14.77609 23 38 21.45 +13 00 21.0          14.5 N      C42
    PK12N00J C2012 07 14.77763 23 38 20.90 +13 00 30.2          14.5 N      C42
    PK12N00J C2012 07 14.77919 23 38 20.36 +13 00 39.4          14.6 N      C42
----- end -----

: Photometry result computed with FOCAS II, which processes images based upon the .LOG file of Astrometrica, by means of Multibox method:

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
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ---- ---
P/2012 NJ     14/07/2012 18:37:39 14.46 14.29 14.16 14.02 13.87 13.71 67.3 19.5 C42
P/2012 NJ     14/07/2012 18:37:39* 0.09 0.09 0.08 0.07 0.07 0.07     5 3.5 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

It surprised me when I saw the measured magnitude of the comet, suffering from a consistent decline in brightness gradually, if the first image was removed as the trailing was quite extravaggant. Does it indicate anything related to any cometary activity on the surface of the object?

2012 Jul 19

Mouse-over to browse the image in 4-color sequels version.

A mere hint of the tail is discernable in the stacked image. The 4-color sequels version seems to present the tail clearer.

The sequence was stacked with registration to stars so as to show the motion of the comet.

MPC observation computed with Astrometrica using both UCAC-3 and CMC-14 star catalogs -- the former for astrometric reduction and the latter for photometric work:

COD C42
CON M.-T. Hui
OBS M.-T. Hui, X.Gao
MEA M.-T. Hui
TEL 0.36-m f/6.9 Schmidt-Cassegrain + CCD
NET UCAC-3
    PK12N00J C2012 07 19.78605 23 05 36.52 +21 26 47.4          14.0 N      C42
    PK12N00J C2012 07 19.78681 23 05 36.19 +21 26 51.8          14.0 N      C42
    PK12N00J C2012 07 19.78749 23 05 35.90 +21 26 56.0          14.0 N      C42
    PK12N00J C2012 07 19.78819 23 05 35.59 +21 27 00.4          14.0 N      C42
    PK12N00J C2012 07 19.78889 23 05 35.27 +21 27 04.6          14.0 N      C42
    PK12N00J C2012 07 19.78959 23 05 34.96 +21 27 08.9          14.0 N      C42
    PK12N00J C2012 07 19.79028 23 05 34.67 +21 27 12.9          14.0 N      C42
    PK12N00J C2012 07 19.79094 23 05 34.38 +21 27 17.0          14.0 N      C42
    PK12N00J C2012 07 19.79164 23 05 34.07 +21 27 21.3          14.0 N      C42
    PK12N00J C2012 07 19.79231 23 05 33.76 +21 27 25.5          14.0 N      C42
    PK12N00J C2012 07 19.79303 23 05 33.46 +21 27 29.7          14.0 N      C42
    PK12N00J C2012 07 19.79372 23 05 33.15 +21 27 33.9          14.0 N      C42
    PK12N00J C2012 07 19.79443 23 05 32.85 +21 27 38.3          14.0 N      C42
    PK12N00J C2012 07 19.79506 23 05 32.57 +21 27 42.1          14.0 N      C42
    PK12N00J C2012 07 19.79575 23 05 32.25 +21 27 46.4          14.0 N      C42
----- end -----
: Photometry result computed with FOCAS II, which processes images based upon the .LOG file of Astrometrica, by means of Multibox method. Note that two images of the sequence was refused by FOCAS II, but analysis of the flux and corresponding zero point reveals the matching of the result near the time stamps obtained in FOCAS II.

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
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ---- ---
P/2012 NJ     19/07/2012 18:58:57 13.98 13.87 13.76 13.63 13.49 13.33 91.1 20.3 C42
P/2012 NJ     19/07/2012 18:58:57* 0.02 0.02 0.03 0.04 0.06 0.07    13 3.2 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

The measured magnitudes appear steady in this session.

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

Top

Back... -- Zurück...

Home