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