Data Set Overview
  =================
    This data set contains aperture photometry of known transiting planet
    systems GJ 436, HAT-P-4, HAT-P-7, TrES-2, TrES-3, and WASP-3 derived
    from radiance calibrated (RADREV), clear #6 filtered (350 to 950 nm
    bandpass) images acquired by the Deep Impact High Resolution Visible
    CCD from 22 January through 31 August 2008 during the EPOCh phase of
    the EPOXI mission.  The photometry data were derived from time series
    of continuous 50-second integrations used to observe each system for
    about three weeks, typically covering five or more transits as well as
    secondary eclipses.  Photometry of EPOCh targets XO-2 and XO-3 was
    not produced because transits were not observed due to spacecraft
    telecommunication problems.
 
 
  Data Reduction
  ===============
    The HRIV CCD detector had changed over time while in space, and the
    ground-based flat fields used by the EPOXI radiance calibration
    pipeline (see Klaasen et al. 2008 [KLAASENETAL2006]) were not adequate
    for precision stellar photometry.  Therefore the EPOCh team used an
    independent bootstrap procedure, fitting aperture photometry derived
    from the radiance images to a 2-D spline, to define corrections to the
    flat-field calibration.  For descriptions of this process as well as
    discussions about the photometric results, see Ballard et al. 2009
    [BALLARDETAL2009B], Christiansen et al. 2009 [CHRISTIANSENETAL2009],
    Ballard et al. 2010 [BALLARDETAL2010, BALLARDETAL2010B], Ballard et al.
    2011 [BALLARDETAL2011], and Christiansen et al. 2010
    [CHRISTIANSENETAL2010] & [CHRISTIANSEETAL2010B].  Additionally the
    EPOCh team summarized the calibration steps and photometric errors
    by target in EPOCH_TRANSIT_OBS_DESC.PDF found the DOCUMENT directory
    of this data set.
 
 
  Data Products
  =============
    The derived photometry for each target is provided in two different
    formats:  One product is a flat ASCII table (*.TAB) and the other is
    a FITS binary table (*.FIT) where the data are located in the first
    extension.  Each product has a detached PDS label (*.LBL) describing
    its file format.
 
    Each photometry table contains four columns.  The most relevant data
    are in column 1, the UTC Barycentric Julian Date at mid-observation,
    and column 2, the measured flux.  Column 3 gives the day of year in
    2008, and column 4 gives the name of the radiance calibrated (RADREV)
    image file from which the photometry flux point was extracted.  Fluxes
    are normalized such that the non-transit data points are near unity.
    Null photometry data points (for example, images where the star was
    not in the field of view because of pointing deviations) are not
    included in the tables.
 
    The UTC Barycentric Julian Date provides the time at which light from
    the mid-point of an observation (that is, a photometry point), reached
    the solar system barycenter.  The 'Report on the Calibration of EPOXI
    spacecraft timing and reduction to Barycentric Julian Date' in the
    DOCUMENT directory describes how the values were computed.
 
    Please note the START_TIME and SPACECRAFT_CLOCK_START_TIME keywords in
    each product label are set to the UTC time at the spacecraft and the
    spacecraft clock value at the beginning of the first observation in the
    photometry table.  Likewise, STOP_TIME and SPACECRAFT_CLOCK_STOP_TIME
    are set to the UTC time at the spacecraft and the spacecraft clock
    value at the end of the last observation in the photometry table.
 
 
  Related PDS Data Sets
  =====================
    The following PDS data sets, available online at http://pds.nasa.gov,
    are related to this one and may be useful for research:
 
      DIF-X-HRIV-3-EPOXI-EXOPLANETS-V1.0
        - This data set contains radiance calibrated HRIV extrasolar planet
          transit observations of GJ 436, HAT-P-4, HAT-P-7, TRES-2, TRES-3,
          WASP-3, XO-2, and XO-3 acquired during 2008.  The EPOCh team used
          the reversibly calibrated images (known as 'RADREV') to derive
          the aperture photometry in this data set.
 
      DIF-CAL-HRIV-2-EPOXI-CALIBRATIONS-V1.0
        - This data set contains the raw HRIV dark frames (image exposure
          IDs 9600000 and 9600001) and internal stimulator lamp images
          (exposure IDs 9600002 and 9600003) acquired to monitor changes in
          the CCD detector for EPOCh transit photometry purposes.  The time
          series for each EPOCh target was typically bracketed by a set of
          dark and internal stimulator lamp frames to monitor changes in
          the CCD detector and to aid transit photometry.
 
      DIF-CAL-HRIV-6-EPOXI-STELLAR-PSFS-V1.0
        - This data set contains one HRIV point spread function, produced
          by a drizzle method, for each of the EPOCh exoplanet transit
          targets.  The EPOCh photometry team used these PSFs to locate
          the stellar position and fit the aperture photometry.  See
          Barry et al. 2010 [BARRYETAL2010] for more information.
 
      DI-C-HRII/HRIV/MRI/ITS-6-DOC-SET-V3.0
        - Deep Impact and EPOXI documentation set provides overviews
          of the EPOXI mission.

Confidence Level Overview
  =========================
    The EPOCh photometry team presented these data in Ballard et al. 2009
    [BALLARDETAL2009B], Christiansen et al. 2009 [CHRISTIANSENETAL2009],
    Ballard et al. 2010 [BALLARDETAL2010], and Christiansen et al. 2010
    [CHRISTIANSENETAL2010] & [CHRISTIANSEETAL2010B].
 
 
  Review
  ======
    This data set was peer reviewed at the PDS Small Bodies Node (SBN)
    29 September 2010 with the stipulation that liens must be resolved
    before it could be certified for scientific use.  Liens were
    resolved in December 2010, and the data set was certified for
    scientific use on 26 January 2011.  This data set is archived at
    SBN and the Multi-Mission Archive at STScI (MAST).