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Extrasolar Planet Observations and Characterization (EPOCh)

On January 12, 2005 NASA launched the Discovery class Deep Impact spacecraft with the primary mission of rendezvousing with and ejecting a probe into Comet P/Tempel 1. This phase of the mission was spectacularly carried out on July 4, 2005. This mission has been extended to rendezvous with Comet Hartley in late 2010. In between these events NASA funded a proposal to monitor several stars already known to host at least one exoplanet and to monitor the remote Earth and (results pending) Mars as a remote source in several visible and near-infrared photometric bands. This cruise science program is known as The Extrasolar Planet Observations and Characterization (EPOCh) program. Deep Impact and EPOCh have been folded under the common Project acronym "EPOXI." The Principal Investigator for EPOXI is Dr. Michael A'Hearn of the University of Maryland and the lead for the EPOCh component is Dr. Drake Deming of Godd ard Spaceflight Center. We have also constructed a timeline of the EPOXI mission.

The Earth was monitored as a remote rotating planet during three encounters with its two instruments, the Medium Resolution Imager (MRI) and the High Resolution Visible Imager (HRIV). The MRI observed in imaging mode through several intermediate-band filter centered at 750 nm. The HRIV observed either in imaging mode through seven 100 nm bandwidth filters and at other times in 2-5 micron infrared spectroscopic mode in a second focal plane. Users may want to consult a summary of the observation details for the Earth and exoplanet-star observations as well as calibrations. A Project-supplied high level summary of the observations of the exoplanet-hosting stars and remote Earth are handy references. Users interested in the details of the calibration procedures and result may consult the EPOXI calibration paper. Users who do not have a subscripton to the AIP journal "Review of Scientific Instruments," should contact the EPOXI Project at the University of Maryland for a copy of this paper.

The EPOXI Project has made available multi-wavelength videos of the Earth's diurnal rotation available on its site. Just for fun, users might wish to check out the Sun glint (spinning Earth) movies that have been posted on its site.

The stellar component of the EPOCh program consisted of the monitoring of stars during January-August of 2008 with the High Resolution Visible Imager (HRIV) through the clear (wideband) filter. These data are nonproprietary. Image data for the Earth observations, also nonproprietary, are available in the raw format and intermediate and final calibration stages. However, note that all the images are defocused and have not been deconvolved. Therefore, they may differ from the deconvolved images that the Project has used to construct videos for the rotating Earth. In addition to the MAST archive, all EPOCh data are archived at the PDS-SBN (Small Bodies Node at NASA's Planetary Data Systems), located at the University of Maryland.

EPOCh has accumulated 180,000 white light observations of eight original target stars, usually at a cadence of 50 seconds. The names of these stars, the periods of their first (pre-EPOCh) discovered planet, and number of transits are given in a summary table. Light curves for six of the observed stars were made available in the MAST release in May, 2010. The EPOCh Project will not generate a light curve for the stars X0-2 and X0-3 because their monitorings included few or no transits. The image data for these stars are located on the PDS-formatted site only.



Deep Impact Spacecraft

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