Overall source/type of data: ASTRO = Astronomical
observation; CALIBRATION = calibration data; LAB = Laboratory data;
TEST = Test data; FIRSTPOINT = SOFIA first pointing observation;
OTHER = Any other source not listed here.
ASTRO, CALIBRATION, LAB, TEST, OTHER, FIRSTPOINT
'ASTRO'
Data Source
The type of observation such as an astronomical exposure or a particular type of calibration exposure: OBJECT = astronomical object; STANDARD = Astronomical flux standard for calibration; LAMP = Calibration lamp; FLAT = Flat-field exposure for calibration; DARK = Dark current exposure for calibration.
OBJECT, STANDARD, LAMP, FLAT, DARK
'OBJECT'
Observation type
Status of the observation: OK = observation performed successfully; ERROR = Observation completed but with an error.
OK, ERROR
'OK'
Observation status
SOFIA keyword dictionary version in use, in the form 'VX.X'.
'V1.2'
SOFIA Keyword dictionary, in the form 'VX.X'
The is a unique identifier for any given data file, meant
to provide ready timing and sequencing information at a glance to the user.
It is created at the same time that the data file is first written, in a
format common to all instruments (and thus mandated by the observatory).
The OBS_ID is assigned to saved datasets only. Some test data may be taken
during a flight for immediate diagnostic purposes, but not saved (e.g.,
a snapshot to verify pointing), in which case there would be no point in
assigning an OBS_ID, but we note that the default should almost always be
to save the data and thus assign this keyword.
The OBS_ID number is distinct from the AOR_ID. The AOR_ID is the unique
identifier for an AOR which can, in principle, generate multiple files
to be saved. Each of these files would have a unique OBS_ID. The mapping
from AOR_ID to OBS_ID is one-to-many, i.e., one AOR can produce
multiple data files. Note that the converse is not true -- one data file
cannot be the product of multiple AORs. Files generated by PI instruments
will generally not have an AOR_ID and so OBS_ID (along with FILENAME) becomes
the only way to track PI observations for SOFIA.
We suggest the following as a format for the OBS_ID keyword: yymmdd_MMM_LLINnnn.
Where: yymmdd = UT datestamp for time of observation;
MMM = Mission sequence number (e.g. 065) as defined by the MCS -- Data not
taken as part of a SOFIA mission should set MMM = 000;
LL = Mission leg number (e.g. 06) as defined by the MCS -- Again, data not
taken as part of a SOFIA mission would enter LL = 00. Pre- and post- flight
data would be marked with 00 and 99 respectively;
IN = Two letter instrument code (FL = FLITECAM; FO = FORCAST; HA = HAWC;
EX = EXES; CA = CASIMIR; SA = SAFIRE; FI = FIFI-LS; GR = GREAT;
HR = HIPO-Red; HB=HIPO-Blue);
nnn = Observation sequence number -- The sequence should be reset at mission
start and advanced all the way through mission close-out (as defined my the MCS),
which should allow for capture of pre- and post-flight data -- This field
will have a minimum of three digits (typical expected length), but more
digits will be allowed as necessary.
'040101_077_05FL001'
SOFIA Observation Identification
Running count of observation number for observing session or flight, starting with 1. This value should be identical to the observation sequence number appended to the ObservationID.
1
Running count of observation number for observing session or flight.
The image identification when there are multiple images for an observation within the SAME file (e.g. images stored as FITS extensions).
1
Image identification index
Standard reference or catalog name for the target astronomical object(s). The name should follow IAU standards, if possible. The definition of this keyword differs slightly from ObservationTitle (FITS: OBJECT) - see description for ObservationTitle. The value of ObjectName *may not be known* (and hence cannot be required) before or duing the observation, whereas ObservationTitle is given by the observer.
ObservationTitle
'M42'
Target object name (IAU).
The observation title given by the observer. This will usually be the name of the astronomical target object but sometimes it is not or has additional information (e.g. filter names, etc...). The strict object name should be givein in ObjectName (FITS: OBJNAME). This is a little consuing since the FITS implementation of ObservationTitle is *traditionally* OBJECT.
'Orion Nebula - BNKL region'
Observation title
Unique Astronomical Observation Template (AOT) identifier. FSI instruments only -- assigned by the DCS. The value of this keyword should be equivalent to <AOR/Reference/AOT> in the AOR document.
'dcs-data:/forcast/modes/mosmap/aot'
Astronomical Observation Template Identifier
Unique Astronomical Observation Request (AOR) identifier. The AOR_ID is assigned during the creation of the final version of an AOR to be used in flight planning. This keyword applies to facility-class instruments only and is assigned by the DCS. The value of this keyword should be equivalent to the AOR/ID tag in the AOR document.
'dcs-data:/users/pat/observingPlans/0001/aors/0003'
Astronomical Observation Request Identifier.
Identifier for a group of images stored as seperate data files. This is the mechanism for associating multiple data files that should be considered together. Can be defined by the user -- not necessarily unique in the SOFIA mission. For example, suppose a map of Orion is made such that each individual map point is stored in a seperate file. The user could then set this keyword to something like "OrionMap_20040101" for each of the files so that they can be associated later.
'ORIONMAP_20040101'
File group identifier.
Name and version information for pipeline processing.
Additional information about the pipeline (e.g. individual steps) can be
logged in HISTORY comments.
'FDRP DitherCombine v1.0'
Pipeline name and version.
Status of any processing applied to the data, as defined in the SOFIA Project Data Management Plan:
LEVEL_0 = Raw engineering data for diagnostic purposes, generally not intended for archiving;
LEVEL_1 = Raw, uncalibrated science data in FITS or SDFITS format with complete header adhering to the SOFIA Keyword Dictionary;
LEVEL_2 = Pipeline-processed science data with NO flux calibration or astrometric solution;
LEVEL_3 = Flux-calibrated science data with astrometric solution and extinction corrected (if possible);
LEVEL_4 = Mosaiced maps produced from LEVEL_3 data.
LEVEL_0, LEVEL_1, LEVEL_2, LEVEL_3, LEVEL_4
'LEVEL_1'
Processing status
Data quality assessment - to be inserted by SSMOC staff (TBD). The value of this keyword should convey the utility of the data: USELESS = Data which convey no meaning and cannot be "fixed" (e.g. all data values equal 0); BAD = data which cannot be "fixed" but may be useful; PROBLEM = data which require some "fix" beyond standard calibration techniques for the given instrumnet; GOOD = Data appear normal for the given instrument; UNCLASSIFIED = Quality cannot be determined.
USELESS, BAD, PROBLEM, GOOD, UNCLASSIFIED
'GOOD'
Data quality flag.
The unique observatory proposal identification.
'Morris_2004A_001'
Proposal identification
The observing plan which contains all the AORs. The value of this keyword should be equivalent to <AOR/Reference/ObservingPlan> in the AOR document.
'dcs-data:/users/pat/observingPlans/0001'
Observing plan identification
Aircraft base of operations.
'Moffet Field - Ames Research Center'
Site deployment
The aircraft scheduling block during which the data were obtained.
'2002_01'
Scheduling block identifier
Flight number.
66
Flight Number
Flight leg for given flight number.
4
Flight leg
Title(s) of the observers.
none
'Jane Astro'
Observer(s)
Software task which wrote the FITS file.
'Mauna Kea IR'
File creation task
The telescope operator or responsible observer (if not associated with the proposal).
'Joe Astro'
Telecope operator
Name of host file. The FILENAME keyword allows for different
stages in the treatment of a dataset: raw, calibrated, custom reduced,
pipelined, or reduced at an intermediate stage. Files resulting from actions
taken upon a given raw dataset will all have the same OBS_ID, but could
have different values of the FILENAME keyword. For the FILENAME format, we
recommend using OBSID as a prefix, and attach qualifiers denoting the stage
of treatment and format. For example, yymmdd_MMM_LLIN###.fits for raw data
in FITS format, or yymmdd_MMM_LLIN###.p.3.fits for the third version of
the output from a standard pipeline acting upon the data having
OBSID = 'yymmdd_MMM_LLIN###'.
'040101_077_05FL001.fits'
Name of host file
Observatory identification for the site of the observation.
'SOFIA'
Observatory name
Date of file creation in time system (yyyy-mm-dd).
'2004-01-01'
Date of file creation
Date of observation in UT at the start of the exposure. The format follows the FITSdate standard (yyyy-mm-dd).
'2004-01-01'
UT Date of exposure start
UTC time at the start of the exposure.
'09:30:01.00'
UTC of exposure start
UTC time at the end of the exposure.
'09:30:01.00'
UTC of exposure end
Local siderial time at the start of the exposure.
'14:00:00.00'
LST of exposure start
Modified Julian date at the start of the exposure. The fractional part of the date is given to better than a second of time.
day
46890.394063
MJD of exposure start
Integrated precipitable water vapor to the zenith, running
average of previous 60 second
microns
0.0
0.156
Water vapor
Static air temperature, as returned by the SCL.
Degrees Celsius
-10.5
Static air temperature outside aircraft.
Primary mirror temp #1
C
-273.0
-10.5
Temperature of primary mirror
Primary mirror temp #2
C
-273.0
-10.5
Temperature of primary mirror
Primary mirror temp #3
C
-273.0
-10.5
Temperature of primary mirror
Temperature of secondary mirror.
C
-273.0
-15.2
Temperature of secondary
General format for temperatures.
K
0.0
250.0
Temperature of XXX
Aircraft altitude according to GPS system, as returned by the MCS.
Feet
35229
Aircraft altitude.
True aircraft airspeed, as returned by the MCS.
Knots
375.0
True aircraft airspeed.
Current ground speed of aircraft, as returned by the MCS.
Knots
350.0
Aircraft ground speed.
Current aircraft latitude, as returned by the MCS.
Degrees
35.2567
Aircraft latitude.
Current aircraft longitude, as returned by the MCS.
Degrees
35.2567
Aircraft longitude.
True aircraft heading, as returned by the MCS.
Degrees
10.7892
Aircraft heading.
Telescope used for the observation. Usually SOFIA but can also be telescope an another observatory.
'SOFIA 3.5m'
Telescope name
Telescope configuration. The configuration defines the mirrors, correctors, light paths, etc... On SOFIA, this should be controlled by the MCS.
'NASMYTH'
Telescope configuration
Telescope pointing right ascension, as returned by the telescope
control system -- ICRS for current equinox (DATE-OBS). Representation may be either decimal hours or HH:MM:SS.s.
Hours
0,24
9.023456
Hours
0,24
5:35:17.3
RA - as returned by TCS
Telescope pointing declination, as returned by the telescope
control system -- ICRS for current equinox (DATE-OBS). Representation may be either decimal degrees or DD:MM:SS.
decimal degrees
-90,90
47.345789
Degrees
-90,90
-5:23:28
Dec - as returned by TCS
Requested right ascension for the observation before any
manual "tweaking", either from the instrument control software or from an
AOR. This may be different from the actual object coordinates
and/or telescope coordinates. Representation may be either decimal hours or HH:MM:SS.s. Reference frame can be specified in the comment
field (ICRS recommended) and equinox specified using the Equinox keyword.
Hours
0,24
9.0230
Hours
0,24
5:35:17.3
RA - requested
Requested declination for the observation before any
manual "tweaking", either from the instrument control software or from an
AOR. This may be different from the actual object coordinates
and/or telescope coordinates. Representation may be either decimal degrees or DD:MM:SS. Reference frame can be specified in comment
field (ICRS recommended) and equinox specified using the Equinox keyword.
Degrees
-90,90
47.3465
Degrees
-90,90
-5:23:28
Dec - requested
Equinox for ObservationRA and ObservationDec. Does not apply
to TelescopeRA/Dec which are fixed to current equinox (DATE-OBS).
yr
2000.0
2000.0
Coordinate equinox for OBSRA and OBSDEC
Zenith angle of telescope pointing at start of acquisition.
decimal degrees
0,90
42.359
Zenith angle
Hour angle at start of acquisition. Representation may be either decimal hours or HH:MM:SS.s.
Hours
-90,90
-2.288390
Hours
-90,90
-2:00:00.0
Hour angle
Deviation of right ascension telescope tracking rate from siderial in arc seconds per second.
arcsec/sec
0
1.2
Offset of tracking rate from sidereal
Deviation of declination telescope tracking rate from sidereal in arc seconds per second.
arcsec/sec
0
-3.4
Offset of tracking rate from sidereal
Angular separation between telescope pointing and sun at start of acquisition.
decimal degrees
0,180
110.5
Sun angle
Angular separation between telescope pointing and moon at start of acquisition.
decimal degrees
0,180
45.8
Moon angle
The name of a user defined coordinate system. Used to define object coordinates and offsets. If the value is USER, then it is assumed a new coordinate system is being defined based on a translation and rotation of a reference coordinate system defined in USRREFCR.
EQUATORIAL, GALACTIC, ECLIPTIC, FOCAL PLANE, USER
'GALACTIC'
User defined coordinate system
Reference coordinate system used to define a new user coordinate system, when USRCRDSY =USER .
EQUATORIAL, GALACTIC, ECLIPTIC, FOCAL PLANE
'GALACTIC'
Reference coordinate system
Origin of user defined coordinate system, i.e. translation from the reference coordinate system defined in USRREFCR.
decimal degrees
-34.567
X origin of user defined coordinate system.
Origin of user defined coordinate system, i.e. translation from the reference coordinate system defined in USRREFCR.
decimal degrees
15.645
X origin of user defined coordinate system.
Rotation of user defined coordinate system from USRREFCR.
decimal degrees
85.879
Rotation of user coordinate system.
X coordinate of object in new user defined coordinate system.
decimal degees
0.155
Object coordinate in new user defined coordinate system
Y coordinate of object in new user defined coordinate system.
decimal degees
-1.278
Object coordinate in new user defined coordinate system
Equinox when equatorial coordinates are used.
yr
2000.0
2000.0
User coordinate equinox
Telescope focus value in available encoder units (TBD - Simple encoder units may not apply to SOFIA...).
encoder
1430
Telescope focus
Rotation angle of instrument rotator during observation.
According to SOFIA concept of operations, sky rotation is countered via the
"ROF freeze mode" so the instrument rotator will NOT change during an observation,
but discretely between observations to ensure the same sky rotation at the
instrument focal plane.
decimal degrees
-3,3
1.235
Rotation angle of instrument rotator.
Velocity correction (DeltaV_helio) to bring observations into the heliocentric reference frame
km/s
40.6
Heliocentric correction
Velocity correction (DeltaV_LSR) to bring observations into the local standard of rest (LSR) reference frame
km/s
32.8
LSR correction
Telescope control system software version.
'MCS V1.0'
Telescope control system
SOFIA Tracking mode: On-axis or offset.
OnAxis,Offset
'OnAxis'
SOFIA tracking mode
Name of guide star in use for SOFIA tracking mode.
'HD37022'
Guide star for tracking.
Chopping flag
F
T
Chopping flag
Nodding flag
F
T
Nodding flag
Dithering flag
F
T
Dithering flag
Mapping flag.
F
T
Mapping flag.
Scanning flag.
F
T
Scanning flag.
SOFIA tracking flag. This can be either on-source or offset tracking.
T
T
SOFIA tracking flag.
SOFIA rotation of field (ROF) freeze mode flag.
T
T
SOFIA rotation of field (ROF) freeze mode flag.
Comment keyword. This keyword does not normally have an equal sign. Any number of COMMENT records may be present from any legitimate source. This is a good place for <AOR/SpecialInstructions>.
These data on ORION are GRRRRREAAAT!
Comments may be placed anywhere throughout the header.
History keyword. This keyword does not normally have an equal sign. This keyword should be reserved for any processing of the data, especially pre-processing (i.e. instrument level). Any number of HISTORY records may be present.
FDRP - Redux0 (2004-01-01, 00:00:00) OUTPUT = FILENAME
Processing history information.
Error information *useful to a guest investigator*; this is not meant to be a catalog of system errors. Any number of Error messages may be present. In the FITS implementation, sequence numbers are used to order the information. Generally this keyword should only be used if OBSTAT=ERROR.
Guide star lost - reacquired
Error information. FITS: Suffix index can be used to order entries (1-999).
Instrument name.
'FLITECAM'
Instrument
Instrument mode - simple description. e.g. IMAGING, GRISM,
ECHELLE, POLARIMETRY, etc...
'IMAGING'
Instrument mode
Instrument hardware version.
'FLITECAM V1.0'
Instrument hardware version
Instrument software version.
'FLITECAM Control System V2.2'
Instrument software version
Total on-source exposure time of the observation. This is the total time during which photons from the object of interest are collected by the detector. It includes any shutter corrections (which may not apply for most (all?) SOFIA instruments), and nodding/chopping corrections. For FITS, EXPTIME should be used instead of the FITS specification EXPOSURE. ExposureTime should be specified for all images in a data file.
s
600
On-source exposure time
PassBand specification: This name is the astronomical standard name if applicable; i.e. J, H, K, etc.... Specific filter info will be kept in instrument-specific keywords. Values can also be NONE, GRISM, or a combination of names, if multiple filters are in use.
none
'H'
Passband specification
Central wavelength of observation for imaging modes. This is a rough figure only, intended to be used for archive searches across all SOFIA instruments.
Microns
none
2.2
Central wavelength of observation.
Bandwidth (wavelength) of observation: Filter bandwidth for imaging and wavelength range for spectroscopy. This is a rough figure only, intended to be used for archive searches across all SOFIA instruments.
Microns
none
'[2.2034,2.5333]'
Wavelength range (bandwidth) of observation.
Approximate spectral resolution of observation for spectroscopy modes, expressed as R = c/DeltaV = Lambda/DeltaLambda. This is a rough figure only, intended to be used for archive searches across all SOFIA instruments.
2500
Spectral resolution of observation.
Detector name.
'SBRC InSb'
Detector name
Unbinned detector size in pixels.
'(1024,1024)'
Detector size
Projected pixel scale on the sky.
arcsec
0.32
Pixel scale
Number of sub arrays used in data acquisition. Full array assumed if absent.
0 (full array)
2
Number of subarrays used
The log unbinned size of the n-th subarray in section notation.
'[0:255,0:255]'
Sub array size
The value field shall always contain a floating point number, regardless of the value of BITPIX. This number shall give the minimum valid physical value represented by the array, exclusive of any special values.
150000
Maximum data value
The value field shall always contain a floating point number, regardless of the value of BITPIX. This number shall give the minimum valid physical value represented by the array, exclusive of any special values.
0
Minimum data value
The value field shall always contain a floating point number, regardless of the value of BITPIX. This number shall give the approximate saturation value per raw frame of the array.
100000
Saturation data value
Position angle of detector y axis with respect to celestial North.
Usually reported as degrees east of north.
decimal degrees
-180,180
10.0
Detector plane rotation angle
Number of coadded raw detector frames. This could also be
number of coadds per chop position.
1
10
Number of coadds
Name of frontend device.
'CASIMIR_Frontend_Device'
Name of frontend device.
Name of backend device.
'CASIMIR_Backend_Device'
Name of backend device.
Total bandwidth of heterodyne backend (Hz).
Hz
300.547
Total bandwidth of heterodyne backend
Heterodyne system temperature.
K
10.5
System temperature.
Nominal frequency resolution -- may differ from channel spacing.
Hz
100.0
Nominal frequency resolution -- may differ from channel spacing.
The observed frequency (Hz) at the reference pixel of the frequency-like axis.
Hz
Reference frequency.
The image sideband freq (Hz) corresponding to ReferenceFrequency.
Hz
Image sideband frequency.
Rest frequency.
Hz
Rest frequency.
Velocity of reference channel.
m/s
300.547
Reference velocity
Nominal velocity resolution.
m/s
22.547
Resolution
m/s
Alternate velocity reference value.
m/s
203.45
Alternate reference value
Alternate reference pixel.
32
Alternate reference pixel
Rest frequency.
Hz
Rest frequency.
Local oscillator frequency.
Hz
Local oscillator frequency.
Intermediate frequency.
Hz
Intermediate frequency.
Image sideband frequency.
Hz
Image sideband frequency.
System temperature.
K
System temperature.
Header checksum value for verifying the data. This follows the proposed FITS checksum standard.
'0WDA3T940TA90T99'
Header checksum
Data checksum value for verifying the data. This follows the proposed FITS checksum standard.
'aMmjbMkhaMkhaMkh'
Data checksum
Version of checksum method used for the checksums.
Checksum version
'SOFIA SMU V1.0'
Chopper hardware version
'SOFIA SMU Control System V2.2'
Chopper software version
Measured TCM chop frequency
Hz
0.0, 20.0
15.0
Chop frequency
Indicates whether 2 or 3 point chopping profile is being used. For 3-point chopping, the center position usually contains the object of interest.
2 POINT, 3 POINT
'2 POINT'
'2 POINT'
2 or 3 point chopping mode?
Measured TCM chop amplitude bewteen mid and positive setpoints.
arcsec
-1125.0, 1125.0
300.0
Chop amplitude 1
Measured TCM chop amplitude bewteen mid and negative setpoints.
arcsec
-1125.0, 1125.0
300.0
Chop amplitude 2
Coordinate system in which CHPANGLE is defined. USER coordinate system (defined above) is allowed.
EQUATORIAL, GALACTIC, ECLIPTIC, USER
EQUATORIAL
'GALACTIC'
Coordinate system for CHPANGLE
Chop angle, clockwise from y axis defined by CHPCRSYS.
decimal degrees
-180,180
45.0
Chop angle
Chopper phase - '+' = Starting on-source; '-' = starting
off-source.
+,-
'+'
'+'
Chop phase
Indicates use of either internal or external chop signal.
INTERNAL, EXTERNAL
'INTERNAL'
'INTERNAL'
Chopper source signal
Indicates whether the Chopper is being driven digitally or via
the analog inputs.
CHOPAC, CHOPDC
'CHOPDC'
Digital or analog chopper input.
Chopper waveform function.
'SQUARE'
Chop function
Applied chopper settling time.
millisec
1.0, 100.0
2.04
Chop settle time
Total integration time per nod position -- not including nod
slew time and nod settle time (see NodSettleTime).
s
300.0
Nod time
Number of nod cycles.
1
30
Nod cycles.
Time required for telescope to settle after nod slew is complete.
Amount of time to wait between when telescope arrives at nod destination and
when to begin intergrating.
s
0.0556
Nod settle time
Nod amplitude on sky.
arcsec
30.0
Nod amplitude on sky.
Current nod beam (A or B), where beam A is usually assumed
to be for the object.
A,B
'A'
Current nod beam
Pointing sequence pattern for one nod cycle (there could be many
nod cycles in an observation). Beam A is usually assumed to contain
the object of interest.
AB,ABBA
'ABBA'
Nodding pattern, one cycle.
Coordinate system in which absolute nod positions (NODPOSX,Y)
and rotations are defined.
EQUATORIAL, GALACTIC, ECLIPTIC, USER
'EQUATORIAL'
'EQUATORIAL'
Coordinate system for Nod angle
Absolute nod offset position X in the coordinate frame specified by
NODCRSYS. Alternate specification to NODDIST when an absolute nod offset
position is required.
decimal degrees
32.123467
Nod X position
Absolute nod offset position Y in the coordinate frame specified
by NODCRSYS. Alternate specification to NODDIST when an absolute nod offset
position is required.
decimal degrees
-22.9873
Nod Y position
Nod angle, clockwise from y axis defined by NODCRSYS.
decimal degrees
-180,180
45.0
Nod angle
Approximate shape of dither pattern.
BOX5, BOX9, LINE, SPIRAL, CUSTOM
'BOX9'
Dither pattern
Number of dither positions.
9
Number of dither positions.
Coordinate system in which absolute map positions are defined.
EQUATORIAL, GALACTIC, ECLIPTIC, USER
EQUATORIAL
'GALACTIC'
Coordinate system for mapping/scanning.
Approximate map pattern shape.
RASTER, SPIRAL, SWEEP, CUSTOM
'RASTER'
Map pattern
Number of map positions in X coordinate as defined by MAPCRSYS.
4
Number of map positions in X
Number of map positions in Y coordinate as defined by MAPCRSYS.
4
Number of map positions in Y
Mapping step interval in X coordinate as defined by MAPCRSYS.
arcmin
8.5
Mapping step interval in X
Mapping step interval in Y coordinate as defined by MAPCRSYS.
arcmin
8.5
Mapping step interval in Y
Start of scan - RA.
decimal hours
0,24
9.023456
Start of scan - RA.
Start of scan - Dec.
decimal degrees
-90,90
47.345789
Start of scan - Dec.
End of scan - RA.
decimal hours
0,24
9.023456
End of scan - RA.
End of scan - Dec.
decimal degrees
-90,90
47.345789
End of scan - Dec.
Slew rate in arcsec/sec along path.
arcsec/s
10.0
Scan rate
Angle on sky in some coordinate system to scan from
ScanStartRA/Dec, alternative specification to ScanEndRA/Dec.
degrees
-35.5
Scan direction