The instrument PIs and ISAS will calibrate their instruments before and after launch, create the original calibration files, and re-verify the calibrations as the mission progresses. The Astro-DGOF will validate the calibrations, make them available to GOs and perform trend analysis during the GO phase of the mission. A separate document ``Astro-D Calibrations" currently being written by C.S.R. Day (Astro-D GOF) deals with this issue in more detail.
Before the establishment of the HEASARC in 1991, no standards existed for the structure of calibration data files. The task of defining these standards is now underway, and the structure the Astro-D calibration data files distributed by the GOF will follow them. All calibration files will be in a FITS format. The standards will allow analysis software to access calibration data in a mission-independent way.
A three-tier hierarchy of calibration files will be established. The first tier, the Primary Calibration Data (PCD), comprises the raw results from the calibration experiments as provided by the hardware teams. Also included in this category are theoretical models of the instrument behavior. From the PCD, the second-tier Basic Calibration Files (BCFs) are produced. In most cases, these files are simply the PCD reformatted in FITS. An example is the read-out noise of an individual CCD in an SIS camera as a function of temperature. Updates to BCFs will be appended to the files. The third tier comprises Calibration Product Files (CPFs) which are built from BCFs using software which, if necessary, also consults the FSF and the HKF. An example is the response of an SIS/telescope pair which is constructed from the energy-dependent response of the telescope, from the read-out noise, gain, QE, CTE and resolution of the SIS, with reference to information in the FSF and the HKF.
We consider it of the utmost importance to ensure that all Astro-D investigators have access to the latest calibration data. The GOF will hold a definitive calibration dataset in an anonymous FTP account accessible to all Astro-Dinvestigators. The GOF will be responsible for collecting the calibration data and associated documentation from the hardware teams. All calibrations will be subject to configuration control, i.e. each release will be assigned a unique version number.
The original laboratory calibration data used to generate the ground calibrations will be made available as part of an early calibration release.