A Headers and Arrays in GSD DAS files

 A.1 GSD Headers
 A.2 GSD Arrays
 A.3 Dimensionality of GSD Arrays

The following is a list of the headers and arrays found in GSD format (version 5.3) files in the order in which they appear in the file. Listed is the NRAO name, JCMT name, data type, description for each element. In addition, the dimensionality of the arrays for various observation types (Normal, Total Power, Continuous Calibration, Cross Correlation) is given (for scalar headers, the table indicates for which observation types the headers were used).

A.1 GSD Headers






NRAO name

JCMT name

Data type

Description





C1TEL

TEL_NAME

char*

Telescope name





C1PID

PROJECT

char*

Identifies the observing program





C1OBS

PROJECT_OBS_1

char*

Name of the primary observer





C1ONA1

PROJECT_OBS_2

char*

Name of the support scientist





C1ONA2

PROJECT_OBS_3

char*

Name of the telescope operator





C1SNA1

CENTRE_NAME_1

char*

Source name part 1





C1SNA2

CENTRE_NAME_2

char*

Source name part 2 or altern. name





C4CSC

CENTRE_COORDS

char*

Character code of commanded centre or source coordinate system





C4CECO

CENTRE_CODE

int

Centre coords. AZ=1; EQ=3; RD=4; RB=6; RJ=7; GA=8





C4EPT

EPOCH_TYPE

char*

Type of epoch, JULIAN, BESSELIAN or APPARENT





C4MCF

CENTRE_MOVING

char

Centre moving flag (solar system object)





C4EPH

CENTRE_EPOCH

double

Date of the RA





C4ERA

CENTRE_RA1950

double

Right ascension of source for EPOCH





C4EDEC

CENTRE_DEC1950

double

Declination of source for EPOCH





C4RADATE

CENTRE_RA

double

Right Ascension of date





C4DECDATE

CENTRE_DEC

double

Declination of date





C4RA2000

CENTRE_RA2000

double

Right ascension J2000





C4EDEC2000

CENTRE_DEC2000

double

Declination J2000





C4GL

CENTRE_GL

double

Galactic longitude





C4GB

CENTRE_GB

double

Galactic latitude





C4AZ

CENTRE_AZ

double

Azimuth at observation date





C4EL

CENTRE_EL

double

Elevation at observation date





C4LSC

CELL_COORDS

char*

har. code for local x-y coord.system





C6FC

CELL_CODE

int

Local x-y AZ=1; EQ=3; RD=4; RB=6; RJ=7; GA=8





C4ODCO

CELL_UNIT

char*

Units of cell and mapping coordinates;offset definition code





C6DX

CELL_X

double

Cell x dim,; descriptive origin item 1





C6DY

CELL_Y

double

Cell y dimension; descriptive origin item 2





C6MSA

CELL_V2X

double

Scanning angle - angle from local vertical to x axis measured CW





CELL_V2Y

CELL_V2Y

double

Position angle of cell y axis (CCW)





C4AXY

CELL_X2Y

double

Angle between cell y axis and x-axis (CCW)





C4SX

CENTRE_OFFSET_X

double

Commanded x centre position (JCMT cells wrt to centre; NRAO abs. degrees)





C4SY

CENTRE_OFFSET_Y

double

Commanded y centre position (JCMT cells wrt to centre; NRAO abs. degrees)





C4RX

REFERENCE_X

double

Reference x position (JCMT cells wrt to centre; NRAO abs. degrees)





C4RY

REFERENCE_Y

double

Reference y position (JCMT cells wrt to centre; NRAO abs. degrees)





C1HGT

TEL_HEIGHT

double

Height of telescope above sea level





C1LONG

TEL_LONGITUDE

double

Geographical longitude of telescope (West +ve)





C1LAT

TEL_LATITUDE

double

Geodetic latitude of telescope (North +ve)





C1SNO

NOBS

double

Observation number





C6ST

OBS_TYPE

char*

Type of observation





C1RCV

FRONTEND

char*

Name of the frontend





C1FTYP

FE_TYPE

char*

Type of frontend





C1BKE

BACKEND

char*

Name of the backend





C1BTYP

BE_TYPE

char*

Type of backend





C3DAT

OBS_UT1D

double

UT1 date of observation





C3UT

OBS_UT1H

double

UT1 hour of observation





C3UT1C

OBS_UT1C

double

UT1-UTC correction interpolated from time service telex (in days)





C3LST

OBS_LST

double

Local sidereal time at the start of the observation





C3CAL

OBS_CALIBRATION

char

Calibration observation?





C3CEN

OBS_CENTRE

char

Centre moves between scans?





C3FLY

OBS_CONTINUOUS

char

Data taken on the fly or in discrete mode?





C3FOCUS

OBS_FOCUS

char

Focus observation?





C3MAP

OBS_MAP

char

Map observation?





C3NPP

NO_MAP_DIMS

int

Number of dimension in the map table





C3NMAP

NO_MAP_PNTS

int

Number of map points





C6XNP

NO_X_MAP_PNTS

int

X map dimension; number of points in the x-direction





C6YNP

NO_Y_MAP_PNTS

int

Y map dimension; number of points in the y-direction





C6XGC

X_MAP_START

float

X coordinate of the first map point





C6YGC

Y_MAP_START

float

Y coordinate of the first map point





C6REV

SCAN_REVERSAL

char

Map rows scanned in alternate directions?





C6SD

OBS_DIRECTION

char*

Map rows are in X (horizontal) or Y(vertical) direction





C6XPOS

X_MAP_POSITIVE

char

In first row x increases (TRUE) or decreases (FALSE)





C6YPOS

Y_MAP_POSITIVE

char

In first row y increases (TRUE) or decreases (FALSE)





C3NIS

NO_SCANS

int

Number of scans





C3NSAMPLE

NSCAN

int

Number of scans done





C3NO_SCAN_VARS1

NO_SCAN_VARS1

int

Number of scan table 1 variables





C3NO_SCAN_VARS2

NO_SCAN_VARS2

int

Number of scan table 2 variables





C3SRT

SCAN_TIME

int

Total time of scan (=total integration time if OBS_CONTINUOUS = .FALSE.)





C3MXP

NO_SCAN_PNTS

int

Maximum number of map points done in a phase





C3NCI

NO_CYCLES

int

Maximum number of cycles in the scan





C3NCYCLE

NCYCLE

int

Number of cycles done in the scan





C3CL

CYCLE_TIME

int

Duration of each cycle





C3NCP

NO_CYCLE_PNTS

int

Total number of xy positions observed during a cycle





C6NP

NCYCLE_PNTS

int

Number of sky points completed in the observation





C3NSV

NO_PHASE_VARS

int

Number of phase table variables





C3PPC

NO_PHASES

int

Number of phases per cycle





C5AT

TAMB

double

Ambient temperature





C5PRS

PAMB

double

Mean atmospheric pressure





C5RH

HAMB

double

Mean atmospheric relative humidity





C4AZERR

SDIS(7)

double

DAZ:Net Az offset at start (inc.tracker ball setting and user correction)





C4ELERR

SDIS(8)

double

DEL:Net El offset at start (inc.tracker ball setting and user correction)





UAZ

SDIS(36)

double

User az correction





UEL

SDIS(37)

double

User el correction





C7SZVRAD

SZVRAD

int

Number of elements of vradial array





C8AAE

APERTURE_EFF

double

Ratio total power observed





C8ABE

BEAM_EFF

double

Fraction of beam in diffraction limited main beam





C8GN

ANTENNA_GAIN

double

Antenna gain





C8EL

ETAL

double

Rear spillover and scattering efficiency





C8EF

ETAFSS

double

Forward spillover and scattering efficiency





C4SM

CHOPPING

char

Secondary mirror is chopping





C4FUN

WAVEFORM

char*

Secondary mirror chopping waveform





C4FRQ

FREQUENCY

float

Secondary mirror chopping period





C4SMCO

COORDS

char*

Secondary mirror chopping coordinate system





C4THROW

THROW

float

Secondary mirror chop throw





C4POSANG

POSANG

float

Secondary mirror chop position angle





C4OFFS_EW

OFFS_EW

float

Secondary mirror offset parallel to lower axis (East-West Tilt)





C4OFFS_NS

OFFS_NS

float

Secondary mirror offset parallel to upper axis (North-South Tilt)





C4X

X

float

Secondary mirror absolute X position at observation start





C4Y

Y

float

Secondary mirror absolute Y position at observation start





C4Z

Z

float

Secondary mirror absolute Z position at observation start





C4EW_SCALE

EW_AMPL_SCALE

float

Secondary mirror ew chop scale





C4NS_SCALE

NS_AMPL_SCALE

float

Secondary mirror ns chop scale





C4EW_ENCODER

AMPL_E_SET

int

Secondary mirror ew encoder value





C4NS_ENCODER

AMPL_N_SET

int

Secondary mirror ns encoder value





C2FV

DX

float

Secondary mirror x displacement from nominal at observation start





C2FL

DY

float

Secondary mirror y displacement from nominal at observation start





C2FR

DZ

float

Secondary mirror z displacement from nominal at observation start





C4MOCO

TEL_COORDS

char*

Mounting of telescope; defined as LOWER





C3NFOC

NO_FE_O_CH

int

NO_FE_O_CH:No. of frontend output channels





C7VR

VELOCITY

double

Radial velocity of the source





C12TCOLD

T_COLD

float

Cold load temperature





C12TAMB

T_HOT

float

Ambient load temperature





C12VDEF

VEL_DEFN

char*

Velocity definition code - radio, optical, or relativistic





C12VREF

VEL_REF

char*

Velocity frame of reference - LSR, Bary-, Helio-, or Geo- centric





C3NRC

NO_BE_I_CH

int

Number of backend input channels





C3NCH

NO_BE_O_CH

int

Number of backend output channels





C3NRS

NO_BES

int

Number of backend sections





C7BCV

BAD_CHANNEL

float

Bad channel value





C12CAL

DATA_UNITS

char*

Units of spectrum data





C6MODE

SWITCH_MODE

char*

Observation mode





C12CALTASK

BE_CAL_TASK

char*

Calibration instrument used (FE, BE, or USER)





C12CALTYPE

BE_CAL_TYPE

char*

Type of calibration (THREELOADS or TWOLOADS)





C12REDMODE

BE_RED_MODE

char*

Way of calibrating the data (RATIO or DIFFERENCE)





C3NOIFPBES

NO_IF_PER_BES

int

Number of IF inputs to each section (2 for correlator, 1 for AOS)





C3CONFIGNR

DAS_CONF_NR

int

Backend configuration





C3DASOUTPUT

DAS_OUTPUT

char*

Description of output in DAS DATA (SPECTRUM, T_REC, T_SYS, etc.)





C3DASCALSRC

DAS_CAL_SOURCE

char*

DAS calibration source for backend calibration (POWER or DATA)





C3DASSHFTFRAC

DAS_SHIFT_FRAC

float

DAS calibration source for backend calibration (POWER or DATA)





C7TAU225

CSO_TAU

float

CSO tau at 225GHz





C7TAURMS

CSO_TAU_RMS

float

CSO tau rms





C7TAUTIME

CSO_YYMMDDHHMM

char*

CSO tau time (YYMMDDHHMM)





C7SEEING

SAO_SEEING

float

Seeing at JCMT





C7SEETIME

SAO_YYMMDDHHMM

char*

SAO seeing time (YYMMDDHHMM)





C3POLARITY

C3POLARITY

char*

Frontend Polarity





C3SBMODE

C3SBMODE

char*

Sideband mode





C55NPH

DAS_NO_PHASE

int

DAS number of phases for interferometry observing





C55NCYC

DAS_NO_CYCLES

int

DAS number of phases for interferometry observing





C55NINT

DAS_NINTCYCLE

int

DAS number of phases for interferometry observing





C55NCORR

DAS_NCORRCYCLE

int

DAS number of correlation cycles





C55DASPRBIT

DAS_PROC_BITS

int

DAS data processing done





C55DASPRLOC

DAS_PROC_LOC

char*

Description of where processing is done





C55LX

RXJ.LX

double

RXJ X length of projected baseline in metres





C55LY

RXJ.LY

double

RXJ Y length of projected baseline in metres





C55LZ

RXJ.LZ

double

RXJ Z length of projected baseline in metres





C55A

RXJ.A

double

RXJ Coefficient of sin term in expression for fringe rate (metres)





C55B

RXJ.B

double

RXJ Coefficient of cos term in expression for fringe rate (metres)





C55C

RXJ.C

double

RXJ Coefficient of constant term in expression for fringe rate (metres)





C55CSOSW

RXJ.CSO_SWITCH

int

RXJ Delay setting of RXJ micro for CSO side





C55JCMTSW

RXJ.JCMT_SWITCH

int

RXJ Delay setting of RXJ micro for JCMT side





C55SECOND

RXJ.NSECS

int

RXJ Number of the tick on which integration started





C55ABSORB

RXJ.ABSORB

char*

CSO Position of absorber IN or OUT





C55TAU

RXJ.CSO_TAU

float

CSO TAU value





C55DAZ

RXJ.DAZ

float

CSO Position offset in az (arcsec)





C55DEL

RXJ.DEL

float

CSO Position offset in elevation (arcsec)





C55RA

RXJ.RA

double

CSO RA





C55DEC

RXJ.DEC

double

CSO Dec





C55EPOCH

RXJ.EPOCH

double

CSO Epoch of CSO RA and Dec





C55PAZ

RXJ.PAZ

float

CSO Pointing offset in az (arcsec)





C55PEL

RXJ.PEL

float

CSO Pointing offset in el (arcsec)





C55TRACK

RXJ.TRACK

char*

CSO Track mode of telescope Y or N





C55FMODE

RXJ.FMODE

char*

CSO Focus mode of CSO





C55FX

RXJ.FX

float

CSO X position of focus





C55FY

RXJ.FY

float

CSO Y position of focus





C55FZ

RXJ.FZ

float

CSO Z position of focus





C55VLSR

RXJ.VLSR

float

CSO LSR velocity of source (km/s)





C55VOFF

RXJ.COFF

float

CSO velocity offset (km/s)





C55VRAD

RXJ.VRAD

float

CSO radial velocity (km/s)





C55PLOCK

RXJ.PLOCK

char*

CSO Phase lock status L or U





C55RFREQ

RXJ.RFREQ

double

CSO Rest frequency of line (GHz)





C55IFFREQ

RXJ.IFFREQ

double

CSO IF frequency (GHz)





C55LOFREQ

RXJ.LOFREQ

double

CSO LO frequency (GHz)





C55FREQOFF

RXJ.FREQOFF

double

CSO frequency offset (GHz)





C55SIDEBAND

RXJ.SIDEBAND

char*

CSO Sideband U or L





C55MHN

RXJ.MHN

int

CSO Multiplier Harmonic number





C55CSOSTATUS

RXJ.CSO_STATUS

int

CSO overall status 0 = bad 1 = good





C55TELAZ

TEL.SDIS(9)

double

CENTRE_AZ from tel sdis array





C55TELEL

TEL.SDIS(10)

double

CENTRE_EL from tel sdis array






A.2 GSD Arrays






NRAO name

JCMT name

Data type

Description





C55FENUOBS

FE_NUOBS

double

Observing frequencies





C55FESBSIGN

FE_SB_SIGN

int

FE sideband signs





C55FENULO

FE_NULO

double

FE LO frequencies





C7VRADIAL

C7VRADIAL

double

Array for computer radial velocities





C12SCAN_VARS1

SCAN_VARS1

char*

Names of the cols. of scan table1





C12SCAN_VARS2

SCAN_VARS2

char*

Names of the cols. of scan table2





C12SCAN_TABLE_1

SCAN_TABLE1

float

Begin scan table





C12SCAN_TABLE_2

SCAN_TABLE2

float

End scan table





C14PHIST

MAP_TABLE

float

List of xy offsets for each scan





C11VD

PHASE_VARS

char*

Names of the cols. of phase table





C11PHA

PHASE_TABLE

float

Phase table: switching scheme dependent





C12CM

BES_CORR_MODE

int

Correlation function mode





C12BM

BES_BITMODE

int

Correlation bit mode





C3OVERLAP

BES_OVERLAP

float

Subband overlap





C3MIXNUM

DAS_MIXER

int





C3BESCONN

BES_CONN

int

BE input channels connected to this section





C3BEINCON

BE_IN_CONN

int

IF output channels connected to BE input channels





C3LSPC

NO_BES_O_CH

int

Number of channels per backend section





C3BESSPEC

BES_SPECTRUM

int

Subsystem nr to which each backend section belongs.





C12CF

BES_NUOBS

double

Centre frequencies (rest frame of source) [GHz]





C12RF

BES_NUREST

double

Rest frequency [GHz]





C3BEFENULO

BES_FE_NULO

double

Copy of frontend LO frequency per backend section





C3BETOTIF

BES_TOT_IF

double

Total IF per backend section





C3BEFESB

BES_FE_SB_SIGN

int

Copy of frontend sideband sign per backend section





C12INFREQ

BE_NUIN

double

BE input frequencies [GHz]





C12FR

BES_DELTANU

float

Frequency resolution [MHz]





C12BW

BES_BANDWIDTH

float

Bandwidth [MHz]





C12RT

BES_T_REC

float

Receiver temperature





C12SST

BES_T_SYS

float

System temperature





C12TSKY

BES_T_SKY

float

Sky temperature at last calibration





C12TTEL

BES_T_TEL

float

Telescope temp. from last skydip





C12GAINS

BES_GAIN

float

Gain value (kelvins per volt or equivalent)





C12CT

BES_T_TEL

float

Calibration temperature





C12WO

BES_T_TEL

float

Water opacity





C12ETASKY

BES_ETA_SKY

float

Sky transmission from last calibration





C12ALPHA

BES_ALPHA

float

Ratio of signal sideband to image sideband sky transmission





C12GS

BES_G_S

float

Normalizes signal sideband gain





C12ETATEL

BES_ETA_TEL

float

Telescope transmission





C12TSKYIM

BES_T_SKY_IM

float

Frontend-derived Tsky, image sideband





C12ETASKYIM

BES_ETA_SKY_IM

float

Frontend-derived sky transmission





C12TSYSIM

BES_T_SYS_IM

float

Frontend-derived Tsys, image sideband





C12TASKY

BES_TA_SKY

float

Ratio of signal sideband to image sideband sky transmission





C3INTT

INTGRN_TIME

int

Scan integration time





C13DAT

DATA

float

Spectrum data





C55HOTPOWER

DAS_HOT_POWER

float

Total power measurement on hot load





C55SKYPOWER

DAS_SKY_POWER

float

Total power measurement on hot load (??)





C55SAM

SAMPLES

float

Samples to store for cross_correlation mode





C55POWER

DAS_POWER

float

Total power measurement per subband per integration






A.3 Dimensionality of GSD Arrays


C3NO_SCAN_VARS1
C3NO_SCAN_VARS2
C3NO_SCAN_VARS1 × C3NIS
C3NO_SCAN_VARS2 × C3NIS
C3NPP × C3NMAP
C3NSV
C3NSV × C3PPC
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRC
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRC
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NRS
C3NIS
C3NCH × C3MXP × C3NIS





NRAO name

Dims (normal)

Dims (total power)

Dims (cont. cal)

Dims (cross corr.)






C55FENUOBS

N/A

C3NFOC






C55FESBSIGN

N/A

C3NFOC






C55FENULO

N/A

C3NFOC






C7VRADIAL

C7SZVRAD

N/A

C7SZVRAD

N/A






C12SCAN_VARS1






C12SCAN_VARS2






C12SCAN_TABLE_1






C12SCAN_TABLE_2






C14PHIST






C11VD






C11PHA






C12CM






C12BM






C3OVERLAP






C3MIXNUM






C3BESCONN






C3BEINCON






C3LSPC






C3BESSPEC






C12CF






C12RF






C3BEFENULO






C3BETOTIF






C3BEFESB






C12INFREQ






C12FR






C12BW






C12RT






C12SST

C3NRS

C3NRS × C3NIS

C3NRS






C12TSKY

C3NRS

C3NRS × C3NIS

C3NRS






C12TTEL






C12GAINS






C12CT






C12WO






C12ETASKY

C3NRS

C3NRS × C3NIS

C3NRS






C12ALPHA






C12GS






C12ETATEL






C12TSKYIM

C3NRS

C3NRS × C3NIS

C3NRS






C12ETASKYIM

C3NRS

C3NRS × C3NIS

C3NRS






C12TSYSIM

C3NRS

C3NRS × C3NIS

C3NRS






C12TASKY

C3NRS

C3NRS × C3NIS

C3NRS






C3INTT






C13DAT






C55HOTPOWER

N/A

C3NRS × C3NOIFPBES






C55SKYPOWER

N/A

C3NRS × C3NOIFPBES






C55SAM

N/A

C3NCH × C55NPH × C3NCI






C55POWER

N/A

C3NRS C3NOIFPBES C55NPH C3PPC C3NCI

N/A

C3NRS × C3NOIFPBES × C55NPH × C3NCI