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Kepler Guest Observer Program

Contributed Software - KEPIMAGES

Software: PyKE
Version: 1.0.0
Contributor:

NAME
kepimages -- create a series of separate FITS image files from a Target Pixel File

USAGE
kepimages   infile   outfix   ranges   clobber   verbose   logfile

PARAMETERS
infile = string
Filename for the input Target Pixel File.

outfix = string
Prefix for the filenames of the output FITS images. Individual filenames will be prefix_BJDddddddd.dddd.fits, where ddddddd.dddd is the mid-time of the exposure in units of BJD.

ranges = string
The user can choose here specific time ranges of exposures from which to export images. Ranges can be supplied using one of two methods.

  1. Time ranges are supplied as comma-separated pairs of Barycentric Julian Dates (BJDs). Multiple ranges are separated by a semi-colon. An example containing two time ranges is:
    '2455641.658,2455641.740;2455671.658,2455672.740'.
    If the user wants to correct the entire time series then providing ranges = '0,0' or ranges = 'all' or ranges = '' will tell the task to operate on the whole time series.
  2. The user can provide BJD time ranges within a pre-prepared ascii file containing one time range per line, e.g.:
    2455641.658,2455641.740
    2455671.658,2455672.740
    etc
    The file, named for example 'arbitraryname.txt', is provided to the task using ranges = '@arbitraryname.txt', where the '@' tells the task that a file is being provided. Files containing time ranges can be generated manually or with the aid of data inspection using the task keprange.

clobber = boolean (optional)
Option to overwrite all of the output image files. If clobber = no and an existing file has an identical name then the task will stop with an error.

verbose = boolean (optional)
Option for verbose mode, in which informative messages and warnings are written to the shell and a logfile.

logfile = string (optional)
Name of the logfile containing error and warning messages.

status = integer
Exit status of the script. It will be non-zero if the task halted with an error. This parameter is set by the task and should not be modified by the user.

DESCRIPTION
kepimages will create a series of FITS image files which copy the images stored within a Target Pixel File (TPF). One FITS image file will be created for each Kepler exposure. The user can request all images within a TPF or a subset by supplying a series of Barycentric Julian Date ranges. FITS keywords from the primary and first extensions of the TPF are propagated into the output image files. The mid-time of each exposure (MIDTIME), Barycentric time correction (BARYCORR), cadence number (CADENCEN) and data quality flag (QUALITY) are exported to the FITS images as keywords. The position of the target during each observation, relative to the mid-time of the quarter, in both pixel column and row directions are recorded in keywords POSCORR1 and POSCORR2. If a cosmic ray event was recorded during an individual exposure then the keyword COSM_RAY is flagged as true. The keywords TELAPSE, LIVETIME and EXPOSURE are overwritten and refer to the individual exposure times of each image.

The user can choose from six different images to extract:

  1. RAW_CNTS -- uncalibrated pixel count values
  2. FLUX -- calibrated pixel, background-subtracted, cosmic ray-removed fluxes in units of e-/s
  3. FLUX_ERR -- 1-σ errors on the FLUX image, as propagated through the pixel calibration
  4. FLUX_BKG -- the background that has been subtracted from the FLUX image in units of e-/s
  5. FLUX_BKG_ERR -- 1-σ errors on the FLUX_BKG image, as propagated through the pixel calibration
  6. COSMIC_RAYS -- the cosmic ray map that has been subtracted from the FLUX image in units of e-/s

We recommend the tools ds9 and fv for the inspection of the FITS image products. The intent of the kepimages tool is to convert the TPF content into a form from which images can be imported into the array of public photometry software available to the K2 and Kepler communities.

EXAMPLES

  • kepimages   kplr006932990-2011177032512_lpd-targ.fits   kplr006932990   ranges=all

  • kepimages   kplr006932990-2011177032512_lpd-targ.fits   kplr006932990   ranges=2455641.658363778952,2455641.7401009678   clobber=y   verbose=y   logfile=kepimages.log

  • kepimages   kplr006932990-2011177032512_lpd-targ.fits   kplr006932990   ranges=@times.txt   clobber=y   verbose=y   logfile=kepimages.log

TIME REQUIREMENTS
Execution of this program for 1 quarter of long cadence data using a 3.06 GHz Intel Core 2 Duo Mac running OS 10.6.4 takes a few minutes.

BUGS AND LIMITATIONS
Please send bug reports and suggestions to keplergo@mail.arc.nasa.gov.

HISTORY

Date
Version
Description
2014-07-14
1.0.0
Initial software release (MS)

 


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