Comet Holmes best placed for observing next week.

Do you want to be involved in observing Comet Holmes between Nov 24 - Nov 30 (12:00 - 15:30 UT)?

We need your help to detect the rotation of the comet nucleus using high-precision photometry.

Background: Comet 17P/Holmes exploded on 2007 October 24 and within 24 hours it had appeared looking like a bright star clearly visible to the unaided eye in the constellation of Perseus. Astronomers are unable to explain the reason(s) why it exploded and more information is required to understand the unusual nature of this mysterious object. The comet has since faded and is now 10 million times fainter making it accessible for study using large telescopes.

What you can do:

Book a session FT North (Hawaii) between Nov 24 - Nov 30 (12:00 - 15:30 UT)

Whilst the apparent motion of Comet Holmes is very low near its stationary point, obtain high-quality Sloan-R filter images of the comet in a single field of view using Faulkes Telescope North positioned at R.A. 9:21:43, Dec. +25:23:50. To be successful, we require good photometric conditions (no clouds!) and good seeing (sharp images of stars). Take as many 120-sec duration images as possible using the Sloan-R filter (not the ordinary R filter) during the observing session. The images should then be combined by tracking and stacking in Astrometrica. The brightness of the comet in the stacked image will be measured using concentric apertures of increasing size starting with a radius of 3 pixels. It may also be possible to analyse the distribution of light within the inner coma by accurately quantifying its point spread function.

Sunlight reflected by the comet's nucleus, which is embedded in the centre of the coma, currently contributes about 20% of the total light as measured in a 3-pixel radius photometric aperture. Comet nuclei are usually elongated so when they rotate the amount of light they reflect varies. We are looking for gradual changes in the brightness of the inner coma over periods of hours and days. Since it will be possible to use the selfsame comparison stars during the 7-day observing window, this project should provide a stringent test of the comet's variability. Comet nuclei typically rotate every 6-36 hours. There is reason to believe that this comet has a much slower rotation rate than normal.

Good luck!