C/2012 V1 (PANSTARRS) was discovered by the PANSTARRS survey using a 1.8-m f/4.4 reflector from Haleakala, HI.
Larry Denneau, Richard Wainscoat and Henry Hsieh noted a diffuse, non-stellar appearance on four 45 seconds w-band images, and subsequently it was posted on the NEO Confirmation Page under the temporary designation P104XVd, with also a 100% NEO score.
At first I was able to confirm its cometary appearance with the 2.0-m Faulkes Telescope North, from the same site, under very good seeing conditions (stars FWHM 0.9″-1.0″). In the image below (stack of 9×45 seconds with Bessel R filter) its nature is clear, with a diffuse 4″ coma, and a FWHM 70% larger than stars nearby.
The weather was good also at Schiaparelli Observatory on the same day, so I was able to image it with a 0.38-m f/6.8 reflector. Visually (i.e. on the screen) its aspect was stellar, but the “FWHM method” clearly revealed its nature: profile 30% larger than stars nearby, and a coma 8″ wide.
Also ARI Observatory (H21) detected it on Nov. 05.26, and in the image below, taken with the very good 0.81-m f/4 astrograph stacking 30×60 seconds images, the FWHM method revealed a profile 30-35% larger than stars, and a coma 11″x7″.
This is again a demonstration of how good is the FWHM method (used largely in our T3 project) in discerning comets among asteroids.
Results were published in CBET 3289 (subscription required) and astrometry, together with preliminary parabolic orbital elements, in MPEC 2012-V40.
204 image (and FWHM boxes):