New Comet: C/2012 S1 (ISON)

September 29, 2012
Cbet nr. 3238, issued on 2012, September 24, announces the discovery of a new comet (discovery magnitude 18.8) by Vitali Nevski (Vitebsk, Belarus) and Artyom Novichonok (Kondopoga, Russia) on CCD images 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. The new comet has been designated C/2012 S1 (ISON).

Comet C/2012 S1 (ISON) will get to within 0.012AU of the Sun (extremely close) at the end of  November 2013 and then to ~0.4AU from Earth at the beginning of January 2014! According to its orbit, this comet might become a naked-eye object in the period November 2013 - January 2014. And it might reach a negative magnitude at the end of November 2013. 

We performed some follow-up measurements of this object, while it was still on the neocp. Stacking of 24 unfiltered exposures, 120-sec each, obtained remotely on 2012, September 22.4 from H06 (ITelescope network near Mayhill, NM) through a 0.25-m, f/3.4 reflector + CCD, shows that this object is slightly diffused, with a 5" coma. The FWHM of this object was measured about 15% wider than that of nearby field stars of similar brightness.

M.P.E.C. 2012-S63 assigns the following nearly parabolic (e = 0.999999964) orbital elements to comet C/2012 S1 (ISON): T 2013 Nov. 28.87; e= 0.99; Peri. = 345.56; q = 0.012 AU; Incl.= 62.36. (prediscovery observations were identified by G. V. Williams in MPC data from the Mount Lemmon Survey on 2011 Dec. 28 and from the 1.8-m f/4 Pan-STARRS reflector on 2012 Jan. 28)

Below you can see the orbit (Credit JPL) and current position of comet C/2012 S1 (ISON). The comet is at present of magnitude ~18 and it is located at 6.25 AU from the Sun.

Below you can see a graph generated using the software Orbitas and showing the predicted magnitude (in red) versus the elongation:

Below a star map (calculated for Latitude is 46 deg north, time about 45 minutes before sunrise) for 2013, Nov.10. showing the comet position (click on the image for a bigger version): 

While by clicking here, you'll see a daily animation from 2013, Nov. 10 to Nov. 25 (wait a few seconds for the video to load).

Ephemerides (for the geocenter) generated using the "Minor Planet Ephemeris Service" for the period November 2013 - December 2014. A word of caution: as always with comets, the future magnitudes reported here are only indicative at this stage. Next weeks will tell us something more about the future of this promising comet.

Date       R.A. (J2000) Decl.    Delta     r     El.    Ph.    m1                                                                           
2013 11 10 12 08 03.9 -01 01 00   1.003   0.768   45.3  66.5   4.9
2013 11 18 13 24 14.0 -10 43 12   0.871   0.528   32.2  86.2   2.9
2013 11 21 14 01 42.1 -14 51 28   0.856   0.423   25.3  95.1   1.9
2013 11 22 14 15 23.6 -16 13 08   0.856   0.386   22.7  98.2   1.5
2013 11 23 14 29 42.5 -17 32 40   0.860   0.346   20.1 101.2   1.1
2013 11 24 14 44 40.4 -18 48 53   0.868   0.304   17.4 104.1   0.5
2013 11 25 15 00 21.0 -20 00 30   0.880   0.260   14.6 106.9  -0.1
2013 11 26 15 16 52.8 -21 05 50   0.898   0.211   11.6 109.2  -1.0
2013 11 27 15 34 37.4 -22 02 15   0.922   0.156    8.5 110.4  -2.3
2013 11 28 15 54 44.1 -22 42 33   0.955   0.090    5.0 107.8  -4.6
2013 11 29 16 23 20.6 -20 31 20   0.985   0.022    1.3  93.0 -10.6
2013 11 30 16 22 02.5 -16 36 54   0.917   0.108    5.0 127.2  -3.9
2013 12 01 16 19 50.9 -14 12 38   0.872   0.170    7.8 128.2  -2.0
2013 12 02 16 18 02.1 -12 08 28   0.834   0.223   10.4 127.5  -0.9
2013 12 03 16 16 32.0 -10 12 48   0.801   0.271   12.8 126.3  -0.2
2013 12 06 16 13 22.7 -04 40 04   0.716   0.395   19.9 122.2   1.2
2013 12 07 16 12 40.2 -02 48 06   0.692   0.433   22.2 120.7   1.6
2013 12 08 16 12 06.2 -00 53 51   0.668   0.468   24.5 119.1   1.8
2013 12 09 16 11 39.8 +01 03 27   0.646   0.503   26.9 117.5   2.1
2013 12 20 16 13 50.5 +28 33 54   0.467   0.829   57.1  94.7   3.5
2013 12 21 16 14 41.8 +31 45 29   0.457   0.855   60.3  92.1   3.6

by Ernesto Guido, Giovanni Sostero & Nick Howes

Source:
http://remanzacco.blogspot.com/2012/09/new-comet-c2012-s1-ison.html