Description of Keywords

Description of Keywords & Configuration Parameters

Primary Header Keywords

Keyword Comment

DATE Creation date of FITS file (UT): format DD/MM/YY

FILENAME Name of this Spectral & Visible Light (SPVL) data file

TLM FILE Name of original telemetry file

EXT Name of Binary Table Extension

ORIGIN Organization creating FITS file

TELESCOPE Spacecraft identifier

INSTRUMET Instrument

DETECTOR Detector Identifier

EXCON Experiment computer

EXPCOUNT Total number of exposures on file

TAI_OBS Observation start time in TAI seconds^(*)

TAI_END Observation end time in TAI seconds^(*)

DATE_OBS Observation start date/time in UTC:"dd-mon-year hh:mm:ss.ss" (IDL format)

DATE_END Observation end date/time

STATUS Calibration status

SC_STAT S/C Pointing Calibration Status

FLT_FILE Name of Flat Field Data file (or 'None')

DRK_FILE Name of Dark Count Data file (or 'None')

CAL_FILE Name of Calib. Parameter file (or 'None')

ORB_FILE Name of SOHO Orbit Data file (or 'None')

ATT_FILE Name of SOHO Attitude Data File (or 'None')

OBS_NUM Parameter identifying the Table ID and Fixed Parameter Set of the top-level observation sequence

OBS_TYPE Observation Type parameter (OTYPE):'SunCenter', 'Offset', 'Disk'

NPANEL¹ Original number of DATA panels (1-5)

ROWNGRP ¹ Number of row groups in original data (1-360)

ROWFRST ¹ First active row in original data (0-359)

ROWACT ¹ Number of active rows in original data (1-360)

ROWSPC ¹ Number of space rows in original data (0-359)

COLNGRPn ¹ Number of column groups for panel n in original data (1-1024)

COLFRSTn ¹ First active column for panel n in original data (0-1023): n=0, ..., NPANEL - 1

COLACTn ¹ Number of active columns per group for panel n in original data(1-1024)

COLSPCn ¹ Number of spacer columns between groups for panel n in original data (0-1023)

UVOFST ¹ Image RAM offset address

UVBCNT ¹ Image data byte count

UVTABL ¹ Detector mask table ID

INS_ZR ² z-coordinate of the line-of sight to a reference point on the entrance slit (UV channels) or center of entrance aperture (VL channel) in the instrument reference frame

NDATA ¹ Current number of DATA panels (1-5)

Txxxx³ Other keywords

1 Present only for Spectral Data files.

2 The INS_ZR parameter is present only after the Calibrate Instrument Configuration Function has been performed: STATUS = 'sp_raw_conf', 'sp_flat_conf', 'sp_wave', 'sp_rad', 'vl_raw_conf' or 'vl_rad'.

3 Other keywords such as: TIDMm, TDESCm, TRVAL, TDELTm, TSIZEm, TRCALm.

^(*)The parameters TAI_OBS and TAI_END give the observation start and end times in International Atomic Time (TAI).This is the time used on the SOHO spacecraft, and is defined as the number of standard seconds since Oh on 1 January 1958.

UVCS uses the IDL format for date/time strings (e.g. "18-JAN-!996 17:20:34.12").

The two tables below show the configuration parameters for the UV channel and the VL channel. Note that the configuration parameters in the shaded area are also same for the VL channel data.

Basic ConfigurationUV Data

Keyword Comment

DAT_XORB Exposure start date/time in UTC

DAT_XEND Exposure end date/time in UTC

OBLK Observation science block counter

BUFFER REU Image Buffer used

FLTPOS Filter position (O=ENGAGE,1=DISENG,2=CLEAR)

ROLL Raw roll mechanism position

PTGX1 Raw X1 pointing mechanism position

PTGX2 Raw X2 pointing mechanism position

SUNVT Raw sun sensor TOP diode signal

SUNVB Raw sun sensor BOTTOM diode signal

SUNVR Raw sun sensor RIGHT diode signal

SUNVL Raw sun sensor LEFT diode signal

MIRPOS Raw mirror mechanism position

OCCPOS Raw occulter mechanism position

SC_Y
SC_Z (SC-Y, SC-Z) is the angular offset of the spacecraft optical axis relative to the solar reference frame

SC_ROLL Roll angle of the spacecraft reference frame relative to the solar reference frame

ROLANGL¹ Roll angle

POSX1 ¹ X1 Pointing Mech. linear position

POSX2 ¹ X2 Pointing Mech. linear position

MIRANGL¹ Intermediate point between Ly-alpha and OVI slits

OCCWDTH¹ Width of unocculted portion of telescope mirror

INS-ROLL ¹ Roll angle of the instrument reference frame y-axis relative to the spacecraft reference frame z-axis

INS-YR ¹ Distance from Sun center to the nearest point on the slit. (Differs from MIRANGL by +10 arcsec for VLD and Lya-alpha channel and by -27 arcsec for the OVI channel). A postscript file illustration of the FOV can be found here.

INS-YO ¹
INS-ZO ¹ (INS-YO, INS-Z0) is the angular offset of the UVCS roll axis (origin of ?rotating? instrument reference frame) relative to the spacecraft reference frame

SC-YR ¹
SC-ZR ¹ (SC_YR, SC_ZR) is the angular offset of the spacecraft optical axis relative to the rotating instrument reference frame

SUN-YR ¹
SUN-ZR ¹ (SUN_YR, SUN-ZR) is the angular offset of solar disk center relative to the instrument reference frame (from sun sensor)

TAI-XORB Exposure start time (in TAI seconds)

GRTPOS Raw grating mechanism position

EXPTIME Exposure duration

SLTPOS Raw slit mechanism position

SLTWDTH ¹ Entrance slit width

MCPV Raw MCP voltage

MCPVOLT ¹ UV Detector MCP Voltage

WRVAL(2) Wavelength corresponding to first column on detector (WRVAL(0) is for primary and WRVAL(1) for redundant path).

WDELT(2) Wavelength interval per column pixel (after distortion correction). For OVI, WDELT(0) is the dispersion in primary in units of Angstrom per pixel. The Ly-alpha has just WDELT(0) which is not equal to zero.

1 These parameters are present only for STATUS ='sp_raw_conf', 'sp_drk_conf', 'sp_flt_conf', 'sp_wav', 'sp_rad', 'vl_raw_conf' or 'vl_rad'.

VL Channel Data

TTYPE Comment

VLHV Raw VLD high Voltage

VLHVOLT Calibrated VLD high Voltage

pB Fraction of polarized VL as determined relative to the center of the disk

pB_ERR Error in the fraction of polarized VL as determined relative to the center of the disk

ANGLE Angle of polarization

ANGLE_ERR Error in angle of polarization

STOKES_I2
STOKES_Q2
STOKES_U2
Calibrated Stokes parameters I, Q and U as derived from 3-8 VLCNT measurementswith different polarizer positions

VLENUM Number of sub-exposures (=r) in range 1 - 8

VLCNT Raw VLD photon count for each sub-exposure

VLEXP Sub-exposure duration

POLPOS Raw polarizer position for each sub-exposure

POLANGL¹ Polarizer angle for each sub-exposure

VLMODE VLD readout mode (0=count, 1=diode)

VLRAD¹ Raw VLD analog radiance 1 for each sub-exposure

VLRAD2 Raw VLD analog radiance 2 for each sub-exposure

VLSTRT Sub-exposure start time (in TAI seconds)

1 Present only for STATUS = 'vl_raw_conf' or 'vl_radf'

2 Present only for STATUS = 'vl_radf'

Keyword	Comment
DATE	Creation date of FITS file (UT): format DD/MM/YY
FILENAME	Name of this Spectral & Visible Light (SPVL) data file
TLM FILE	Name of original telemetry file
EXT	Name of Binary Table Extension
ORIGIN	Organization creating FITS file
TELESCOPE	Spacecraft identifier
INSTRUMET	Instrument
DETECTOR	Detector Identifier
EXCON	Experiment computer
EXPCOUNT	Total number of exposures on file
TAI_OBS	Observation start time in TAI seconds^(*)
TAI_END	Observation end time in TAI seconds^(*)
DATE_OBS	Observation start date/time in UTC:"dd-mon-year hh:mm:ss.ss" (IDL format)
DATE_END	Observation end date/time
STATUS	Calibration status
SC_STAT	S/C Pointing Calibration Status
FLT_FILE	Name of Flat Field Data file (or 'None')
DRK_FILE	Name of Dark Count Data file (or 'None')
CAL_FILE	Name of Calib. Parameter file (or 'None')
ORB_FILE	Name of SOHO Orbit Data file (or 'None')
ATT_FILE	Name of SOHO Attitude Data File (or 'None')
OBS_NUM	Parameter identifying the Table ID and Fixed Parameter Set of the top-level observation sequence
OBS_TYPE	Observation Type parameter (OTYPE):'SunCenter', 'Offset', 'Disk'
NPANEL¹	Original number of DATA panels (1-5)
ROWNGRP ¹	Number of row groups in original data (1-360)
ROWFRST ¹	First active row in original data (0-359)
ROWACT ¹	Number of active rows in original data (1-360)
ROWSPC ¹	Number of space rows in original data (0-359)
COLNGRPn ¹	Number of column groups for panel n in original data (1-1024)
COLFRSTn ¹	First active column for panel n in original data (0-1023): n=0, ..., NPANEL - 1
COLACTn ¹	Number of active columns per group for panel n in original data(1-1024)
COLSPCn ¹	Number of spacer columns between groups for panel n in original data (0-1023)
UVOFST ¹	Image RAM offset address
UVBCNT ¹	Image data byte count
UVTABL ¹	Detector mask table ID
INS_ZR ²	z-coordinate of the line-of sight to a reference point on the entrance slit (UV channels) or center of entrance aperture (VL channel) in the instrument reference frame
NDATA ¹	Current number of DATA panels (1-5)
Txxxx³	Other keywords

Keyword	Comment
DAT_XORB	Exposure start date/time in UTC
DAT_XEND	Exposure end date/time in UTC
OBLK	Observation science block counter
BUFFER	REU Image Buffer used
FLTPOS	Filter position (O=ENGAGE,1=DISENG,2=CLEAR)
ROLL	Raw roll mechanism position
PTGX1	Raw X1 pointing mechanism position
PTGX2	Raw X2 pointing mechanism position
SUNVT	Raw sun sensor TOP diode signal
SUNVB	Raw sun sensor BOTTOM diode signal
SUNVR	Raw sun sensor RIGHT diode signal
SUNVL	Raw sun sensor LEFT diode signal
MIRPOS	Raw mirror mechanism position
OCCPOS	Raw occulter mechanism position
SC_Y SC_Z	(SC-Y, SC-Z) is the angular offset of the spacecraft optical axis relative to the solar reference frame
SC_ROLL	Roll angle of the spacecraft reference frame relative to the solar reference frame
ROLANGL¹	Roll angle
POSX1 ¹	X1 Pointing Mech. linear position
POSX2 ¹	X2 Pointing Mech. linear position
MIRANGL¹	Intermediate point between Ly-alpha and OVI slits
OCCWDTH¹	Width of unocculted portion of telescope mirror
INS-ROLL ¹	Roll angle of the instrument reference frame y-axis relative to the spacecraft reference frame z-axis
INS-YR ¹	Distance from Sun center to the nearest point on the slit. (Differs from MIRANGL by +10 arcsec for VLD and Lya-alpha channel and by -27 arcsec for the OVI channel). A postscript file illustration of the FOV can be found here.
INS-YO ¹ INS-ZO ¹	(INS-YO, INS-Z0) is the angular offset of the UVCS roll axis (origin of ?rotating? instrument reference frame) relative to the spacecraft reference frame
SC-YR ¹ SC-ZR ¹	(SC_YR, SC_ZR) is the angular offset of the spacecraft optical axis relative to the rotating instrument reference frame
SUN-YR ¹ SUN-ZR ¹	(SUN_YR, SUN-ZR) is the angular offset of solar disk center relative to the instrument reference frame (from sun sensor)
TAI-XORB	Exposure start time (in TAI seconds)
GRTPOS	Raw grating mechanism position
EXPTIME	Exposure duration
SLTPOS	Raw slit mechanism position
SLTWDTH ¹	Entrance slit width
MCPV	Raw MCP voltage
MCPVOLT ¹	UV Detector MCP Voltage
WRVAL(2)	Wavelength corresponding to first column on detector (WRVAL(0) is for primary and WRVAL(1) for redundant path).
WDELT(2)	Wavelength interval per column pixel (after distortion correction). For OVI, WDELT(0) is the dispersion in primary in units of Angstrom per pixel. The Ly-alpha has just WDELT(0) which is not equal to zero.

TTYPE	Comment
VLHV	Raw VLD high Voltage
VLHVOLT	Calibrated VLD high Voltage
pB	Fraction of polarized VL as determined relative to the center of the disk
pB_ERR	Error in the fraction of polarized VL as determined relative to the center of the disk
ANGLE	Angle of polarization
ANGLE_ERR	Error in angle of polarization
STOKES_I2 STOKES_Q2 STOKES_U2	Calibrated Stokes parameters I, Q and U as derived from 3-8 VLCNT measurementswith different polarizer positions
VLENUM	Number of sub-exposures (=r) in range 1 - 8
VLCNT	Raw VLD photon count for each sub-exposure
VLEXP	Sub-exposure duration
POLPOS	Raw polarizer position for each sub-exposure
POLANGL¹	Polarizer angle for each sub-exposure
VLMODE	VLD readout mode (0=count, 1=diode)
VLRAD¹	Raw VLD analog radiance 1 for each sub-exposure
VLRAD2	Raw VLD analog radiance 2 for each sub-exposure
VLSTRT	Sub-exposure start time (in TAI seconds)