This comet was first reported by Robert D. Matson (Newport Coast, California, US) in SAWN imagery from Nov 2012. Terry Lovejoy (Thornsland, Queensland, Australia) managed to capture the comet on Nov 29.4 UT 2012 from ground-based, apparent diameter around 2', 10th magnitude. On Nov 30.4 UT 2012, Robert H. McNaught from Siding Spring confirmed the discovery through the 0.5-m Uppsala Schimdt. A 6' tail in P.A. 101° was also identified. However, it was not the ned of the story. Maik Meyer (Limburg, Germany) suggested the similarity between the orbit of the new comet and that of D/1827 M1 (Pons-Gambart). Syuichi Nakano (Somoto, Japan) attempted to establish the linkage, however, the residual was enormous provided that the orbital period is around half of a century. The comet was thereby designated C/2012 V4. More observations proved that the period is actually much longer than previously expected. Finally MPC announced the comet as 273P/2012 V4 (Pons-Gambart).
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| The final image was stacked in average method. Alas the focus was not accurate. Mouse-over to browse the images without special cometary processing techniques attached. Except the image processed by L-S filter, azimuthal median method and radial weighted method were applied to a final image stacked in median method. |
MPC observation computed with Astrometrica using both UCAC-4 and CMC-14 star catalogs -- the former for astrometric reduction and the latter for photometric work:
COD C42
OBS X.Gao, M.-T. Hui
MEA M.-T. Hui
TEL 0.36-m f/6.9 Schmidt-Cassegrain + CCD
NET UCAC-4
0273P KC2013 02 03.96889 18 27 59.49 +06 50 54.6 13.6 N C42
0273P KC2013 02 03.97108 18 27 59.31 +06 50 59.1 13.5 N C42
0273P KC2013 02 03.97328 18 27 59.20 +06 51 03.9 13.5 N C42
0273P KC2013 02 03.97550 18 27 59.11 +06 51 08.1 13.5 N C42
0273P KC2013 02 03.97770 18 27 58.97 +06 51 12.7 13.5 N C42
0273P KC2013 02 03.97988 18 27 58.88 +06 51 17.8 13.5 N C42
0273P KC2013 02 03.98207 18 27 58.69 +06 51 21.0 13.6 N C42
0273P KC2013 02 03.98428 18 27 58.60 +06 51 27.2 13.6 N C42
0273P KC2013 02 03.98649 18 27 58.49 +06 51 32.0 13.6 N C42
0273P KC2013 02 03.98868 18 27 58.36 +06 51 35.9 13.5 N C42
0273P KC2013 02 03.99088 18 27 58.28 +06 51 40.4 13.5 N C42
0273P KC2013 02 03.99307 18 27 58.20 +06 51 44.7 13.5 N C42
0273P KC2013 02 03.99553 18 27 58.05 +06 51 49.8 13.5 N C42
Photometry result computed with FoCAs, which processes images based upon the .LOG file of Astrometrica, by means of Multibox method:
OBJECT, DATE, TIME: refering to their original meanings respectivelyFisrt line:
The following is the plot of the magnitude enclosed by different square aperture boxes. The magnitude enclosed by infinite box was also calculated by the following equation:
$ m\left ( r \right )=m_\infty -2.5\log \left [ 1-\exp \left ( -\frac{r}{\rho} \right ) \right ] $,
where $ r $ is the radius of some aperture, $\rho $ is the apparent radius of the coma, and $ m_\infty $ is the magnitude obtained by an infinite aperture. In this case, I obtained $ m_\infty = 9.838 \pm 0.058 $, as it were measured by an infinite square box, which is consistent with what recent visual observers estimated.
Copyright @ Man-To Hui 2013/02/07
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| The final image was stacked in median method. A jet feature is clearly visible in all of the three special-processed images, whereby ought to be authentic instead of artificial. Mouse-over to browse the images without special cometary processing techniques attached. |
MPC observation computed with Astrometrica using both UCAC-4 and CMC-14 star catalogs -- the former for astrometric reduction and the latter for photometric work:
COD C42
OBS M.-T. Hui, X. Gao
MEA M.-T. Hui
TEL 0.36-m f/6.9 Schmidt-Cassegrain + CCD
NET UCAC-4
0273P KC2013 02 18.92000 18 10 59.06 +16 43 18.8 14.5 N C42
0273P KC2013 02 18.92189 18 10 58.84 +16 43 23.7 14.5 N C42
0273P KC2013 02 18.92378 18 10 58.66 +16 43 29.4 14.5 N C42
0273P KC2013 02 18.92567 18 10 58.50 +16 43 34.7 14.5 N C42
0273P KC2013 02 18.92757 18 10 58.31 +16 43 39.9 14.6 N C42
0273P KC2013 02 18.92946 18 10 58.14 +16 43 45.5 14.4 N C42
0273P KC2013 02 18.93135 18 10 57.97 +16 43 50.6 14.4 N C42
0273P KC2013 02 18.93325 18 10 57.84 +16 43 56.0 14.5 N C42
0273P KC2013 02 18.93515 18 10 57.63 +16 44 01.6 14.5 N C42
0273P KC2013 02 18.93705 18 10 57.44 +16 44 06.0 14.5 N C42
0273P KC2013 02 18.93894 18 10 57.25 +16 44 12.7 14.6 N C42
0273P KC2013 02 18.94083 18 10 57.08 +16 44 17.7 14.5 N C42
0273P KC2013 02 18.94274 18 10 56.91 +16 44 22.3 14.5 N C42
0273P KC2013 02 18.94464 18 10 56.71 +16 44 27.3 14.5 N C42
0273P KC2013 02 18.94654 18 10 56.52 +16 44 33.4 14.6 N C42
0273P KC2013 02 18.94844 18 10 56.37 +16 44 38.4 14.5 N C42
0273P KC2013 02 18.95413 18 10 55.86 +16 44 54.5 14.5 N C42
0273P KC2013 02 18.95604 18 10 55.66 +16 44 59.9 14.5 N C42
0273P KC2013 02 18.95795 18 10 55.47 +16 45 04.5 14.5 N C42
0273P KC2013 02 18.95985 18 10 55.27 +16 45 10.2 14.5 N C42
0273P KC2013 02 18.96282 18 10 55.14 +16 45 15.3 14.5 N C42
0273P KC2013 02 18.97427 18 10 54.03 +16 45 48.3 14.5 N C42
0273P KC2013 02 18.97617 18 10 53.85 +16 45 53.4 14.5 N C42
0273P KC2013 02 18.97808 18 10 53.69 +16 45 59.0 14.6 N C42
0273P KC2013 02 18.97999 18 10 53.52 +16 46 03.6 14.5 N C42
0273P KC2013 02 18.98191 18 10 53.35 +16 46 10.1 14.5 N C42
0273P KC2013 02 18.98381 18 10 53.11 +16 46 14.7 14.5 N C42
0273P KC2013 02 18.98572 18 10 52.95 +16 46 20.6 14.5 N C42
0273P KC2013 02 18.98763 18 10 52.79 +16 46 25.1 14.4 N C42
0273P KC2013 02 18.98953 18 10 52.60 +16 46 31.2 14.5 N C42
0273P KC2013 02 18.99144 18 10 52.38 +16 46 36.6 14.5 N C42
0273P KC2013 02 18.99334 18 10 52.18 +16 46 42.6 14.4 N C42
0273P KC2013 02 18.99487 18 10 52.07 +16 46 46.2 14.4 N C42
Photometry result computed with FoCAs, which processes images based upon the .LOG file of Astrometrica, by means of Multibox method, can be visited in the above image.
Interpretation of the FoCAs table headings:
OBJECT, DATE, TIME: refering to their original meanings respectivelyFisrt line:
The following is the plot of the magnitude enclosed by different square aperture boxes. The magnitude fitting function is modified as follows:
$ m\left ( r \right )=m_\infty -2.5\log \left [ 1-\exp \left ( - \left ( \frac{r}{\rho} \right ) ^n \right ) \right ] $,
where $ n $ is a parameter related to the shape of the coma. When $ n=1.28 $ the residual decreased to the least. Hence $ m_ \infty = 11.553 \pm 0.018 $, in good accordance with reports from visual observers.
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Copyright @ Man-To Hui 2013/02/21
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| For color version please pay a visit to this page. As the resolution and SNR of this comet is insufficient, there is no cometary-processing. |
Only photometric work has been performed with this session of observation. It is my first personal successful observation of the comet as well. The catalog used is CMC-14.
Radius of aperture 0 = 3.0
Radius of aperture 1 = 6.0
Radius of aperture 2 = 9.0
Radius of aperture 3 = 12.0
Radius of aperture 4 = 15.0
Radius of aperture 5 = 18.0
Radius of aperture 6 = 21.0
Radius of aperture 7 = 24.0
Radius of aperture 8 = 27.0
Inner radius for sky annulus = 30.0
Outer radius for sky annulus = 45.0
Sky SkySig SkySkw Magnitudes
8885.34 21.20 0.09 14.075+-0.029 13.070+-0.022 12.540+-0.020 12.188+-0.019 11.963+-0.020 11.780+-0.021
11.609+-0.021 11.499+-0.023 11.414+-0.025
I applied my IDL routine for calculating the infinite aperture magnitude of this comet. I obtained $ m_ \infty = 11.111 \pm 0.014$, a good match to results from visual observations during this time.
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Copyright @ Man-To Hui 2013/03/
18Feel free to e-mail me with any doubts or questions.
