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C/2012 S1 (ISON)  -  24 sept. 2012

Astrometric data for minor planet center

COD H06

CON iTelescope.net, Mayhill, New-Mexico

OBS E. Bryssinck

MEA E. Bryssinck

TEL 0.5-m f/4.5 astrograph + CCD

ACK MPCReport file updated 2012.09.24 17:38:07

AC2

NET PPMXL

     AS03D20  C2012 09 24.45044 08 14 00.44 +27 49 14.9          18.4 R      H06

     AS03D20  C2012 09 24.45275 08 14 00.47 +27 49 15.0          18.3 R      H06

     AS03D20  C2012 09 24.45737 08 14 00.61 +27 49 14.9          18.2 R      H06

     AS03D20  C2012 09 24.45969 08 14 00.65 +27 49 14.7           R      H06

----- end -----

Photometric data from FOCAS-II

COD B96

CON BRIXIIS Observatory - Eyckensbeekstraat 2, B-9150 Kruibeke, Belgium

CATALOG: USNO A2.0 / CMC-14 - BAND: R

                                   10x10  20x20  30x30  40x40  50x50  60x60   SNR   SB   COD

OBJECT        DATE       TIME        +/-    +/-    +/-    +/-    +/-    +/-     N  FWHM  CAT

------------  ---------- --------  -----  -----  -----  -----  -----  -----  ----  ----  ---

C/2012 S1     24/09/2012 11:01:18  17.57  17.29  17.12  16.89  16.70  16.55  24.5  22.7  H06

C/2012 S1     24/09/2012 11:01:18*  0.00   0.00   0.00   0.00   0.00   0.00     1   5.5  CMC

COMET C/2012 S1 (ISON)

     Vitali Nevski (Vitebsk, Belarus) and Artyom Novichonok (Kondopoga, Russia) report their discovery of a diffuse comet with an 8" coma on four 100-s CCD exposures obtained on Sept. 21.06 UT with a 0.4-m f/3 Santel reflector of the International Scientific Optical Network (ISON) near Kislovodsk, Russia (discovery observations tabulated below); Nevski and Novichonok first reported the object to the Minor Planet Center with no mention of cometary appearance, and it was posted on the MPC's NEOCP webpage as an apparently asteroidal object (their report to the Central Bureau of cometary appearance arrived nearly a day after NEOCP posting).  Follow-up observations obtained with a 1.5-m f/8 reflector at the Majdanak observatory in Uzbekistan by O. Burhonov (measured by Novichonok and Nevski) on Sept. 21.99 show an obvious elongation in p.a. 305 deg with a coma of size 9" x 11" and total mag about 17.1.

…...........

While the object AS03D20 was still on the NEOCP page (24 sept.2012 10:55 UT), I made some observations on 23/9 and 24/9. My astrometric data was send to the MPC. I could measure a higher FWHM of 5.7 arc.sec. for this object while other stars of the same magnitude have a FWHM of 4.1 arc.sec.  So this was probably a comet.  The diameter of this object was about 12 arc sec on my images.

Animation of 4 images

You can see in the center of the image  the very small movement (~0.2 arc.sec/min) of the

comet C/2012 S1 (ISON), on the right/center side , you can see

the minor planet Lecar (4417) at magnitude of 17.4 (movement : ~0.8”/min)

Lecar

C/2012 S1 (ISON)