Header Keywords

This section describes the FITS header keywords used in the Tomo-e Gozen data. Header keywords used in the Tomo-e Gozen project are listed with data types (boolean, integer, real, and string) and comments. The header is composed of six sections: Observation, Data, Observatory, Weather, Instrument, and WCS sections.

This document is based on the FITS header version 0.730.

Observation Section

OBJECT: string; Object name.
EXPTIME: real (positive); Total exposure time in seconds.
TELAPSE: real (positive); Elapsed time to obtain the data in seconds.
EXPTIME1: real (positive); Exposure time for a single frame in seconds.
TFRAME: real (positive); Frame-to-frame interval time in seconds.
TRLSTEP: real (positive); Interval of reset line feeding in seconds.
TRLSTEP1: real (positive); Interval of reset line feeding for single line in seconds.
DATA-FPS: real (positive); Frame rate of the data in frames per second.
DATA-TYP: string, { OBJECT, FLAT, DARK }; Data type.
OBS-MOD: string, { Imaging }; Observation mode. Tomo-e Gozen only support the “Imaging” mode.
FILTER: string, { BLANK }; Filter name.
PROJECT: string; Project name.
OBSEVER: string; Observer’s name.
PIPELINE: string; Code names of the data reduction pipeline.
DATE: string in the ISO date format (ex. 2000-01-01T00:00:00.000000); Timestamp in UTC when the FITS file was generated.
DATE-OBS: string in the date format (ex. 2000-01-01); Date of the observation in UTC.
TIME-OBS: string in the time format (ex. 00:00:00.000000); Exposure starting time in UTC.
UTC: string in the ISO date format (ex. 2000-01-01T00:00:00.000000); Timestamp when the exposure of the first pixel started.
UTC-EXP: string in the ISO date format (ex. 2000-01-01T00:00:00.000000); Timestamp when the exposure sequence started.; CAUTION: UTC-EXP should precede UTC. Otherwise the timestamp may corrupted.
GPS-UP: string in the ISO date format (ex. 2000-01-01T00:00:00.000000); GPS trigger timestamp of the rising edge.
GPS-DOWN: string in the ISO date format (ex. 2000-01-01T00:00:00.000000); GPS trigger timestamp of the falling edge.
TIMESYS: string, { UTC }; Time system used in the header.
RA: string in the Longitude format (hh:mm:ss.s); Right ascension of the telescope pointing.
DEC: string in the Latitude format (+dd:mm:ss); Declination of the telescope pointing.
RADESYS: string, { ICRS }; Coordinate system.
EQUINOX: real, { 2000.000 }; Equinox of the celestial coordinate system.

Data Section

EXP_ID: integer (positive, sequential); Exposure serial number.
QUAD_ID: integer, { 1, 2, 3, 4 }; ID number of the camera modules.
DET_ID: integer; Unique ID number of the detectors.
CMOS_ID: string (ex. FK1000123); Unique serial ID of the CMOS sensor.
FRAME_ID: string (ex. TMQ1201801010000000111); Unique ID of the FITS file.; The structure of the FRAME_ID is “TMQ” + QUAD_ID:1d + DATE:yyyymmdd + EXP_ID:08d + DET_LOCATION:2d. The DET_LOCATION is the last two digits of DET_ID.
RED_ID: integer; Unique serial number of data reduction.; The RED_ID is set -1 before data reduction.
DARK_ID: integer; Unique serial number of the dark frame used in data reduction.; The DARK_ID is set -1 if dark subtraction is not performed.
FLAT_ID: integer; Unique serial number of the flat frame used in data reduction.; The FLAT_ID is set -1 if flat-frame correction is not performed.
BUNIT: string, { ADU }; Unit of the pixel values.
SANITY: real; Standard deviation of reference pixels for the sanity check process.
WCSVALID: boolean; true if the WCS parameters are successfully optimized.
WCSORIG: string, { Gaia DR2, Gaia EDR3 }; Catalog name used for field calibration.
MAGZPT: real; Magnitude zero point.
MAGZERR: real; Standard error of the magnitude zero point (MAGZPT).
MAGZNOBJ: integer (non-negative); Number of objects used to obtain MAGZPT.
FWHM: real (positive); FWHM of point sources.
BGCOUNT: real; Average background counts.
BGMEDIAN: real; Median value of the background counts.
BGSTDDEV: real (positive); Standard deviation of background counts.
REDVER: integer (ex. master:a81d10f3); Version of the data reduction pipeline.
FMTTYPE: string; Data format type.
FMTVER: real; Version of the data format.
VERSION: real; FITS header version.

Observatory Section

OBSERVAT: string, { Kiso Observatory }; Observatory name.
TELESCOP: string, { Kiso Schmidt }; Telescope name.
INSTRUME: string (ex. Tomo-e Q1+Q2+Q3+Q4); Instrument name.
F-RATIO: real, { 3.100000 }; Monochromatic focal-ratio.
FOC-LEN: real, { 3300 }; Focal length of the telescope in millimeters.
FOC-VAL: real; Encoder value of the focus unit in millimeters.
OBSGEO-B: real; Telescope geodetic latitude in degrees in the WGS84 standard.
OBSGEO-L: real; Telescope geodetic longitude in degrees in the WGS84 standard.
OBSGEO-H: real; Telescope altitude in meters above the geoid surface.
AZIMUTH: real; Telescope azimuth position in degrees.
ZD: real; Telescope zenith distance in degrees.
ALTITUDE: real; Telescope altitude angle in degrees.
HA:: string in the hour angle format (ex. +00:00:00); Hour angle of the telescope pointing.
LST: string in the time format (ex. 00:00:00); Local sidereal time.
DOMEPOS: real; Dome position angle in degrees. The origin is the north. The angle increases toward east.
DOMESLIT: string, { OPEN, CLOSE }; Dome slit status.
TEL-MODE: string; Telescope operation mode.
MCOVER: string, { OPEN, CLOSE }; Mirror cover status.
FLATLAMP: string, { ON, OFF }; Dome flat lamp status.
FLAT-ND: string; Dome flat ND-filter name.

Weather Section

TMP_TEL: real; Temperature of the telescope interior in degrees (Celsius scale).
TMP_DOME: real; Temperature of the dome interior in degrees (Celsius scale).
TMP_VWS: real; Temperature at the weather monitoring system in degrees (Celsius scale).
HUM_TEL: real (percentage); Humidity of the telescope interior in percentages.
HUM_DOME: real (percentage); Humidity of the dome interior in percentages.
HUM_VWS: real (percentage); Humidity at the weather monitoring system in percentages.
SKYTEMP: real; Temperature of the sky in degrees (Celsius scale).
VISRANGE: real (positive); Zenith visibility in meters.
WIND_VEL: real (positive); Wind velocity in meters per second.
WIND_DIR: real; Wind direction in degrees. The origin is north. The angle increases toward east.
ATMOS: real; Atmosphere pressure in hPa.

Instrument Section

GAINCNFG: string, { LOW, MIDDLE, HIGH }; Sensor gain setting.
GAIN: real; Inverse gain of the AD converter in electron/ADU.
ND: real; Electric ND filter factor. The value should be unity when obtained without ND filter.
RNOISE: real; Readout noise in electron.
FULLWELL: real; Saturation limit (full well) in electrons.
DCURRENT: real; Dark current in electrons/pixel/second.
DEBIAS: boolean; true if auto bias-subtraction process is enabled.
TRIMMING: boolean; true if the reference pixels are trimmed off.
BURST: boolean; true if the high-speed mode is enabled.
Q1_TBODY: real; Q1 camera module temperature in degrees (Celsius scale).
Q1_TELEC: real; Q1 electronics temperature in degrees (Celsius scale).
Q1_TAMB: real; Q1 ambient temperature in degrees (Celsius scale).
Q2_HUMID: real (percentage); Q2 camera module humidity in percentages.
Q2_TBODY: real; Q2 camera module temperature in degrees (Celsius scale).
Q2_TELEC: real; Q2 electronics temperature in degrees (Celsius scale).
Q2_TAMB: real; Q2 ambient temperature in degrees (Celsius scale).
Q2_HUMID: real (percentage); Q2 camera module humidity in percentages.
Q3_TBODY: real; Q3 camera module temperature in degrees (Celsius scale).
Q3_TELEC: real; Q3 electronics temperature in degrees (Celsius scale).
Q3_TAMB: real; Q3 ambient temperature in degrees (Celsius scale).
Q3_HUMID: real (percentage); Q3 camera module humidity in percentages.
Q4_TBODY: real; Q4 camera module temperature in degrees (Celsius scale).
Q4_TELEC: real; Q4 electronics temperature in degrees (Celsius scale).
Q4_TAMB: real; Q4 ambient temperature in degrees (Celsius scale).
Q4_HUMID: real (percentage); Q4 camera module humidity in percentages.
VOLA_7VA: real; Analog +7 V output voltage (line A) in Volts.
CURA_7VA: real; Analog +7 V output current (line A) in Amperes.
VOLA_5VA: real; Analog +5 V output voltage (line A) in Volts.
CURA_5VA: real; Analog +5 V output current (line A) in Amperes.
VOLA_7VB: real; Analog +7 V output voltage (line B) in Volts.
CURA_7VB: real; Analog +7 V output current (line B) in Amperes.
VOLA_5VB: real; Analog +5 V output voltage (line B) in Volts.
CURA_5VB: real; Analog +5 V output current (line B) in Amperes.
VOLD_5V: real; Digital +5 V output voltage in Volts.
CURD_5V: real; Digital +5 V output current in Amperes.

WCS Section

CTYPE1: string (ex. __RA—TAN-SIP_); Pixel coordinate system for NAXIS1
CTYPE2: string (ex. DEC–TAN-SIP); Pixel coordinate system for NAXIS2
CTYPE3: string (ex. TIME); Pixel coordinate system for NAXIS3.
CRPIX1: real; NAXIS1 pixel coordinate of the reference point.
CRPIX2: real; NAXIS2 pixel coordinate of the reference point.
CRPIX3: real; NAXIS3 pixel coordinate of the reference point.
CRVAL1: real; Right Ascension value in degrees at the reference point.
CRVAL2: real; Declination value in degrees at the reference point.
CUNIT1: string, { deg }; Units used in the CRVAL1 and CD matrix.
CUNIT2: string, { deg }; Units used in the CRVAL2 and CD matrix.
CUNIT1: string, { s }; Units used in the CRVAL3 and CD matrix.
CD1_1: real; WCS transformation matrix element.
CD1_2: real; WCS transformation matrix element.
CD1_3: real; WCS transformation matrix element.
CD2_1: real; WCS transformation matrix element.
CD2_2: real; WCS transformation matrix element.
CD2_2: real; WCS transformation matrix element.
CD3_1: real; WCS transformation matrix element.
CD3_2: real; WCS transformation matrix element.
CD3_3: real; WCS transformation matrix element.
LANPOLE: real, { 180.0 }; Native longitude of the celestial pole in degrees.
LATPOLE: real, { 0.0 }; Native latitude of the celestial pole in degrees.

Caution

The WCS section may contain more keywords when the field parameters are calibrated with astrometry.net, since astrometry.net applies a higher order correction using the SIP polynomial expression.