Comet 213P/Van Ness

in 2011

2011/08/06 2011/08/07

2011 Aug 07

Mouseover to see the labeled version.

Alas the secondary fragment 213P-B was exactly superimposed with a faint star and moving extremely close to it when the images were being taken. Consequently, I was only able to detect the fragment in the final images stacked with all the overall 30 frames.

The above image was converted to 4 color sequels so as to display the fragment more clearly, as seen in the following image.

Mouseover to see the labeled version.

MPC observation computed with Astrometrica using UCAC-3 star catalog in R band:

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
0213P        KC2011 08 07.77094 23 18 09.45 +02 50 57.5          15.5 N      C42
0213P        KC2011 08 07.78242 23 18 09.16 +02 51 01.6          15.5 N      C42
0213P        KC2011 08 07.79388 23 18 08.88 +02 51 05.8          15.5 N      C42
0213P      b KC2011 08 07.78241 23 17 49.82 +02 48 15.3          18.3 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
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ---- ---
213P         07/08/2011 18:46:40 15.48 14.80 14.46 14.24 14.09 13.98 41.3 20.1 C42
213P          07/08/2011 18:46:40* 0.01 0.03 0.02 0.02 0.02 0.02     3 3.9 CMC
213P      b 07/08/2011 18:46:40 18.21 17.34 16.74 16.36 16.16 15.89 6.6 19.5 C42
213P      b 07/08/2011 18:46:40* 0.00 0.00 0.00 0.00 0.00 0.00     1 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

The photometric work with the fragment was problematic as a result of interference from an intimate star.

2011 Aug 06

I converted the above B/W image into four colors sequels in order to show the comet's tail as well as its secondary fragment more clearly. Since the total exposure was not long enough, the fragment appeared rather dim and ill-displayed. Only when a measure that a much longer exposure is taken will I certify that the fragment is evidently presented and therefore my satisfaction will be met.

MPC observation computed with Astrometrica using UCAC-3 star catalog in R band:

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
0213P        KC2011 08 06.71890 23 18 33.22 +02 44 23.0          15.4 N      C42
0213P        KC2011 08 06.72502 23 18 33.11 +02 44 25.1          15.4 N      C42
0213P        KC2011 08 06.73102 23 18 32.93 +02 44 27.5          15.4 N      C42
0213P      b KC2011 08 06.71890 23 18 14.83 +02 41 38.6          19.6 N      C42
0213P      b KC2011 08 06.72502 23 18 14.81 +02 41 42.9          19.7 N      C42
0213P      b KC2011 08 06.73102 23 18 14.37 +02 41 46.0          19.1 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
------------ ---------- -------- ----- ----- ----- ----- ----- ----- ---- ---- ---
213P          06/08/2011 17:23:58 15.41 14.64 14.25 13.98 13.78 13.61 28.9 20.0 C42
213P          06/08/2011 17:23:58* 0.01 0.01 0.02 0.03 0.02 0.02     3 3.8 CMC
213P      b 06/08/2011 17:23:58 18.72 17.64 16.95 16.36 15.88 15.51 3.6 20.0 C42
213P      b 06/08/2011 17:23:58* 0.01 0.08 0.03 0.06 0.09 0.10     3 3.8 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.

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