# Documentation for CalFUSE v3.0
# 
# Intermediate Data File (IDF)
# File Format, Archival Version
#
# Created 03/04/2003
# Van Dixon
#
# History:
#	03/06/2003 wvd	Incorporate suggestions from SDP meeting
#	03/13/2003 wvd	More suggestions from SDP meeting
#	03/31/2003 wvd	Add flag for photons in pot holes.
#	06/09/2003 wvd	Update list of arrays to compress.
#	10/02/2003 wvd	Exchange TEMPORAL_PHA and LOCATION_GTI flags.
#	05/04/2004 wvd	Add LOCATION_FILL to LOC_FLGS
#	02/14/2005 wvd	Correct typo in description of timeline table.
#	02/16/2005 wvd	Change FEC and AIC arrays to type float.
#	03/17/2005 wvd  Add "Arrival time unknown" to timeflag bit #6.
#	03/22/2005 wvd	Change TIME_SUNRISE and TIME_SUNSET to shorts.
#

The IDF is a FITS file with data stored as binary table extensions.

Contents of HDU 1 (primary HDU):

Header only.  Contains all exposure-specific information as keywords.


Contents of HDU 2:

Binary table extension.  The following quantities are recorded for each
photon event.  Note that data are stored as a series of arrays.  That
is, all TIME values are listed, then all XRAW values, etc.

TIME            FLOAT    photon arrival time
XRAW            SHORT    raw x position
YRAW            SHORT    raw y position
PHA             BYTE     pha value
WEIGHT          FLOAT    dead-time correction (value ~ 1.0)
XFARF           FLOAT    x position in geometrically-corrected frame
YFARF           FLOAT    y position in geometrically-corrected frame
X               FLOAT    final x position (after motion corrections)
Y               FLOAT    final y position (after motion corrections)
CHANNEL         BYTE     aperture ID for the photon
TIMEFLGS        BYTE     time flags - see below
LOC_FLGS        BYTE     location flags - see below
LAMBDA          FLOAT    wavelength of each photon
ERGCM2          FLOAT    flux-calibrated photon (ERG CM^-2)

Note: To conserve memory, all floating-point values are stored as
shorts (using the TZERO and TSCALE keywords) except for TIME, WEIGHT,
LAMBDA and ERGCM2, which will remain as floats.

CHANNEL: standard code for aperture number:

Not in an aperture: 0
LIF     HIRS        1
	MDRS        2
	LWRS        3
	PINH        4
SIC     HIRS        5
	MDRS	    6
        LWRS        7
        PINH        8

TIMEFLGS: in order from most- to least-significant bit:

        8 - User defined
        7 - Jitter
        6 - Not in an OPUS-defined GTI / Arrival time unknown
        5 - Bursts
        4 - High voltage reduced or FIFO overflow
        3 - SAA
        2 - Limb angle
        1 - Day/Night  (N = 0, D = 1)

LOC_FLGS: in order from most- to least-significant bit:

	7 - Fill data in HIST mode
	6 - Photon in known bad-pixel region
        5 - Photon pulse height out of range
        4 - Right stim pulse
        3 - Left stim pulse
        2 - Airglow feature
        1 - Not in detector active area


Contents of HDU 3:

Final good-time intervals (GTI's) stored as double-precision
floating-point numbers in a binary table:

	START0	STOP0
	START1	STOP1
	START2	STOP2


Contents of HDU 4:

A "timeline table" containing the following entries for each second during
the observation.  As in HDU 2, these are stored as a series of arrays.

TIME            FLOAT           seconds from EXPSTART
STATUS_FLAGS    BYTE            status flags - see below
TIME_SUNRISE    SHORT           seconds since sunrise
TIME_SUNSET     SHORT           seconds since sunset
LIMB_ANGLE      FLOAT           (degrees) limb angle
LONGITUDE       FLOAT           (degrees) spacecraft longitude
LATITUDE        FLOAT           (degrees) spacecraft latitude
ORBITAL_VEL     FLOAT           (km/s) component of velocity in
				 direction of target
HIGH_VOLTAGE    SHORT           (unitless) detector high voltage
LIF_CNT_RATE    SHORT           (counts/sec) LiF count rate
SIC_CNT_RATE    SHORT           (counts/sec) SiC count rate
FEC_CNT_RATE    FLOAT           (counts/sec) FEC count rate
AIC_CNT_RATE    FLOAT           (counts/sec) AIC count rate
BKGD_CNT_RATE   SHORT           (counts/sec) background count rate
YCENT_LIF       FLOAT           (pixels) Y centroid of LiF target spectrum
YCENT_SIC       FLOAT           (pixels) Y centroid of SiC target spectrum

Note: To conserve memory, floating-point values will be stored as
shorts (using the TZERO and TSCALE keywords) except for TIME, which
will remain a float.

The STATUS_FLAGS have the same meanings as the TIMEFLGS discussed above.