Encounter Observations from Earth
08.11.05

While most of the major observatories around the world observed the encounter with Tempel 1, two networks of amateur astronomers had their telescopes aimed at the comet. In fact, the 141 advanced observing teams participating in the mission's Small Telescope Science Program (STSP) have been imaging the comet since October 2004. As of the end of July 2005, about half the STSP teams have submitted over 360 sets of broadband red or unfiltered images of Tempel 1 to help us fill gaps in the dust production light curve as well as to monitor for other activity such as outbursts and jets.

The science team was not sure if Tempel 1 had outbursts because the comet was never heavily studied in the months before perihelion. However, several STSP observers recorded outbursts from Tempel 1 on June 22 and 29, 2005. While Deep Impact instruments also recorded the outbursts (and the navigation team reported the events first), it was good to confirm the outbursts with ground-based observations.

Our other network, the Amateur Observers' Program (AOP) encouraged amateurs to observe whether it was to collect "data" or for fun. While the majority of observations were from digital cameras, several observers also made sketches and some reported their observations in text. About 65 observers (of 365 registered) have submitted over 355 observations. Observations were sent in from all over the world -- Australia, Malaysia, Iran, Zimbabwe, Romania, Poland, Hungary, Austria, Germany, France, Italy, Spain, Portugal, UK, Puerto Rico, as well as from all over the USA. While the first half of the year favored observers in the northern hemisphere, the comet is now primarily visible to observers in the southern hemisphere.

Amateur Observers' Program This recent image from AOP observer Mike Holloway (Holloway Observatory Van Buren, AR) was taken on 2005-07-29/02:53 UT (28 July 9:53pm CDT) and shows the dim comet. The image was stacked on the comet so the stars appear as streaks in this image put together from 27 exposures each lasting about 40 seconds (for a total of 18 minutes).

Small Telescope Science Program This recent image from STSP observer Toni Scarmato (Italy) was taken on 2005-07-29/19:18 UT (effectively the next evening after Mike's image). Taken with a larger telescope with a narrower field of view, the image includes views processed with different methods to try to see different details in the dim comet. The image is a composite of thirty 60 second exposures stacked on the comet (so the stars appear as streaks).

The Small Telescope Science Program (STSP) Gallery is at http://deepimpact.umd.edu/stsp/search_action.cfm
and the Amateur Observers' Program (AOP) Gallery is at http://deepimpact.umd.edu/amateur/gallery.cfm .

Contributed by Stef McLaughlin and Elizabeth Warner

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