On July 16, 2013 the STScI Office of Public Outreach released a blog (hubblesite.org/go/ison to gather inf
ormation about HST observations of Comet ISON together.
Hubble Heritage program 13229 imaged the comet on 8 May 2013, using a Wide Field
Camera 3 (WFC3) subarray which is half of one of the two CCDs (2K x 2K
subarray). Eight identical 171-second exposures were obtained, with one dither
step to mitigate bad pixels. The long-pass F350LP filter was used to maximize
the signal-to-noise in one orbit. A small offset from the nominal aperture was
applied to optimally position the comet and tail within the field of view.
Another orbit on 30 April 2013 obtained deep fixed-pointing images of a field
with Comet ISON in it, released July 16, 2013. Further details about the Heritage Comet ISON observing program are
contained in the Phase II observing program.
Observations on Oct 9, 2013 showed the comet was intact. The press release was released October 17, 2013. The data were taken in two filters and the HLSP were released Oct ?? 2013
On December 18, 2013, HST tried to observe Comet ISON one last time. There was no evidence of Comet ISON in these images. Please see details about the observations and conclusions in the Comet ISON blog.