|Comet C/2012 S1 ISON captured on 8 November with iTelescope T5 at around 4:30 am local time in New Mexico, USA. The image is a stack of 10 x 60 second Luminance exposures. Images stacked then a MEDIAN Z project applied using ImageJ, then contrast enhancement used. click to embiggen.||Comet C/2012 S1 ISON captured on 15 November with iTelescope T4 at 5:05 am local time in New Mexico, USA. The image is a stack of 7 x 60 second Luminance exposures. Images stacked then a MEDIAN Z project applied using ImageJ, then contrast enhancement used. click to embiggen. click to embiggen.|
As mentioned before, Comet ISON is in outburst at the moment, looking to be around magnitude 5 at the moment after some reports it was around 4. The two images above show the comet on November 8, before the outburst, and November 15, after the outburst. Both are at the same scale. The former is heavily twilight affected, but you can still see the substantial increase in brightness and coma size.
What's more you can see the delicate streamers and structure in the tail that was not evident before. Click to embiggen to see the detail that you can't get with the small image.
T4 and T5 are both 0.25-m f/3.4 astrographs, CCD SBIG ST-10XME 1.65 arc-secs/pixel. North is to the top.
For earlier images in this series see here. Too see the comets development in the wide field T14 isntrument see here.