2011 FR143 was discovered by the Mt.Lemmon Sky Survey (part of the Catalina Sky Survey) on 2011 Mar. 29 and followed until Apr. 26. Its orbit was quite unusual (a=6.83 AU, e= 0.45 and a period of 17.9 yrs) and with a Tisserand parameter of 2.73 it was put in our special list of the T3 observing project.
Thanks to Sergio Foglia, who alerted me about this particular target, we successfully recovered it at mag. 20.3 R on 2012, Mar. 29 (exactly one year after its original discovery!). Stacking all images together (73 minutes of total exposure time) we noted its cometary appearance, with a 6″ coma and a tail 10″ in PA around 270°.
Soon after I alerted Tomas Vorobjov, who confirmed its cometary appearance with the 1.3-m f/13 RCT telescope of Western Kentucky University located at Kitt Peak (code 695) on the night of Mar. 31.
Another confirmation came from images obtained by Robert Holmes from ARI Observatory six days past (and measured by Sergio Foglia). Both observatories noted a coma 6″ wide and a tail 10-12″ long in PA about 270°.
I also observed it using the 2.0-m f/10 Faulkes Telescope North located at Haleakala, Hawaii: with a total exposure time of 15 minutes in good seeing the object was clearly diffuse respect to stars nearby, with a coma at least 5″ wide. The presence of the Moon just 25° away prevented me to see the tail, however.
After all these confirmations, MPC/CBAT staff released circulars CBET 3082 and MPEC 2012-G36 with the discovery circumstances and all the astrometry available.
This is my image:
and this is H21 image from Apr. 6 (0..81-m telescope, 45 minutes of total exp. time):