Photographs of Comet C/2012 F6 (LEMMON)

This page contains photograph of the comet C/2012 F6 (LEMMON).

A photograph of Comet C/2012 F6 LEMMON on 28th February 2013
A photograph of Comet C/2012 F6 LEMMON on 28th February 2013. Taken with my Canon 7D DSLR at 1600ISO this is a stack of 8 x 60s exposures at F/5.6 using a 400mm lens.
A photograph showing the Evening twilight with comet C/2012 F6 LEMMON and C/2011 L4 PANSTARRS
Evening twilight with comet C/2012 F6 LEMMON and C/2011 L4 PANSTARRS. Taken on 28th February 2013.

As of the 13th January 2013 I included the comet in my nightly scripts to be imaged through my 12″ SCT. This is subejct to weather and horizon limitations as the comet moves through the sky.

Times shown are in UT, of the middle exposure of the exposure sequence from the given night/morning.

All photographs are taken using my 12″ SCT upon Paramount ME with SBIG ST8-XME camera using clear filter. Focal length started off at approx 2990mm with scale 1.26 arcsec/pixel at bin 2×2. I have since added a focal reducer bringing this down to 2200mm and f/7.4. Exposure times are 10 x 60 seconds unless otherwise stated.

I have been attempting to estimate the magnitude of this comet in my images. To do this I have tried using MaximDL’s aperture astrometry tool by specifying the magnitude of 6-8 known stars in each image then it calculating the magnitude, and by using CCDSoftv5 AutoAstrometry tool together with the “MPC Observation” magnitude estimate tool. So far the CCDSoftv5 estimate appears more consistent indicating it may be more reliable. CCDSoft AutoAstrometry is certainly the easier tool to use, two clicks and it’s done (plate solve then click the comet).

There is variation in the below processed results of my photographic observations is due to the following being individually processed in PhotoShop as well as being under different sky conditions (no moon vs moon for example). Individual reduced .FIT images are used for magnitude estimation.

Comet C/2012 F6 (LEMMON) 2013-02-07T19:55:52;
Comet C/2012 F6 (LEMMON) 2013-02-07T19:55:52; fl=220mm, scale=1.68”/pixel, 10x120s, ST8-XME, clear filter

On the night of 30th – 31st January I made my first attempt at an all-night video of this comet to show tail changes over that period. While it was cut short by focus problems this is the 166 minutes of exposure I did get:

Comet C/2012 F6 LEMMON Animation from Roger Groom on Vimeo.


Photograph of Comet C/2012 F6 (LEMMON) 2013-01-29T19:53:58
Comet C/2012 F6 (LEMMON) 2013-01-29T19:53:58; fl=2200mm scale=1.69”/pixel, clear, ST8-XME
Example of Comet C/2012 F6 (LEMMON) focal reduction comparison
Comet C/2012 F6 (LEMMON) focal reduction comparison. This shows the two different fields of view used for this comet so far.

All images below this point are taken at a focal length of 2990mm (approx f/10). All images above this point are taken at a focal length of 2200mm (approx f/7.4).

Photograph of Comet C/2012 F6 (LEMMON) 2013-01-28T19:58:50
Comet C/2012 F6 (LEMMON) 2013-01-28T19:58:50; fl=2990mm scale=1.26”/pixel, 10x120s, clear filter, ST8-XME. This image shows my best view yet of the tail, which extends like rays of sunlight toward the upper right.
Comet C/2012 F6 (LEMMON) at 2013-01-26T19:51:18
Comet C/2012 F6 (LEMMON) 2013-01-26T19:51:18; fl=2990mm, scale=1.26”/pixel, 20x60s, Clear filter, ST8XME
Photograph of C/2012 F6 (LEMMON); 2013-01-19T19:21:01
C/2012 F6 (LEMMON); 2013-01-19T19:21:01; fl=2990mm, scale=1.26”/pixel, 60sx7
Comet C/2012 F6 (LEMMON) 2013-01-17T19:24:15
Comet C/2012 F6 (LEMMON) 2013-01-17T19:24:15. The horizontal dark bar is due to processing which removed bright streaks from the image top and bottom caused by a nearby bright star (likely gama Crux).
Photograph of Comet C/2012 F6 (LEMMON)  2013-01-14
Comet C/2012 F6 (LEMMON) 2013-01-14T14:24:53; fl=2990mm, scale=1.26”/pixel. 10x60s