Table 1: SYSCAL: System calibration
SYSCAL: System calibration

Name

Format

Units

Measure

Comments

Columns

Key

ANTENNA_ID

Int

Antenna id

FEED_ID

Int

Feed id

SPECTRAL_WINDOW_ID

Int

Spectral window id

TIME

Double

s

EPOCH

Midpoint of time for which this set of parameters is accurate

INTERVAL

Double

s

Interval

Data

NUM_LOAD

Int

# Ncl of CAL or LOAD used

CALLOAD

Int(Ncl)

List of the Ncl LOADs used

(PHASE_DIFF) 

Float

rad

Phase difference between recepor 0 and receptor 1

SBGAIN  

Float

Relative gain of LO1 sideband.

(TAU  )   

Float(Nr)

K

Atmosheric optical depth

(TCAL) 

Float(Nr)

K

Calibration temperature

(TRX) 

Float

K

Receiver temperature see note 

(TSKY) 

Float(Nr)

K

Sky temperature

(TSYS) 

Float(Nr)

K

System temperature

(TANT) 

Float(Nr)

K

Antenna temperature

(TANT_TSYS) 

Float(Nr)

Tant/Tsys

(PWVPATH) 

Float

m

Water vapor pathlength.

(DPWVPATH) 

Float

m/K

Pathlength per K of radiometric emission

SBGAIN_SPECTRUM  

Float(Nf)

Relative gain spectrum.

(TAU_SPECTRUM  )   

Float(Nr,Nf)

K

Atmosheric optical depth spectrum

(TCAL_SPECTRUM)   

Float(Nr,Nf)

K

Calibration temperature spectrum

(TRX_SPECTRUM) 

Float(Nf)

K

Receiver temperature spectrum

(TSKY_SPECTRUM)   

Float(Nr,Nf)

K

Sky temperature spectrum

(TSYS_SPECTRUM)   

Float(Nr,Nf)

K

System temperature spectrum

(TANT_SPECTRUM) 

Float(Nr,Nf)

K

Antenna temperature spectrum

(TANT_TSYS_SPECTRUM) 

Float(Nr,Nf)

Tant/Tsys spectrum

(PWVPATH_SPECTRUM) 

Float(Nf)

m

Water vapor pathlength spectrum

(DPWVPATH_SPECTRUM) 

Float(Nf)

m/K

Pathlength increment spectrum

Flags

(PHASE_DIFF_FLAG) 

Bool

Flag for PHASE_DIFF

(SBGAIN_FLAG) 

Bool

Flag for SBGAIN

(TAU_FLAG) 

Bool

Flag for TAU

(TCAL_FLAG) 

Bool

Flag for TCAL

(TRX_FLAG) 

Bool

Flag for TRX

(TSKY_FLAG) 

Bool

Flag for TSKY

(TSYS_FLAG) 

Bool

Flag for TSYS

(TANT_FLAG) 

Bool

Flag for TANT

(TANT_TSYS_FLAG) 

Bool

Flag for Tant/Tsys

(PWVPATH_FLAG) 

Bool

Flag for PWVPATH


Notes: This table contains time-variable calibration measurements for each antenna, as indexed on feed and spectral window. Note that Nr = number of receptors and Nf = number of frequency channels.
ANTENNA_ID
Antenna identifier
FEED_ID
Feed number
SPECTRAL_WINDOW_ID
Spectral window identifier. In general this will be associated to spectral window identifiers corresponding to low spectral resolutions. .
TIME
Mid point of the time interval over which the data in the row are valid. Require to use the same TIME Measure reference as in MAIN 
INTERVAL
Time interval
NUM_LOAD
Number of loads Ncl used for this calibration. (e.g. 2 for the determination of TRX using a a cold and a hot load, 1 for determination of TCAL, a hot load when using the chopper wheel method, ...)
CALLOAD
List of the Ncl loads used for this calibration. (e.g. 2 for the determination of TRX using a a cold and a hot load, 1 for determination of TCAL, a hot load when using the chopper wheel method, ...)
PHASE_DIFF
Phase difference between receptor 0 and receptor 1.
SBGAIN
Sideband gain spectrum. Actual normalization to be defined.
TAU
Average opacity
TCAL
Calibration temperature (temperature used to convert the raw signals to Ta* scale.)  
TRX
Receiver temperature.  
TSKY
Sky temperature  
TSYS
System temperature  
TANT
Antenna temperature
TANT_TSYS
PWVPATH
Water vapor pathlength  
DWVPATH
Water vapor pathlength increment per K of radiometric emission  
SBGAIN_SPECTRUM
Sideband gain spectrum. The other SPECTRAL_WINDOW_IDfor the other sideband is know via ASSOC_SPW_ID 
TAU_SPECTRUM
Opacity spectrum
TCAL_SPECTRUM
  Temperature used to convert the raw signals to Ta* scale
TRX_SPECTRUM
Receiver temperature spectrum. Frequency dependency mandatory for ALMA  
TSKY_SPECTRUM
Sky temperature spectrum  
TSYS_SPECTRUM
System temperature spectrum  
TANT_SPECTRUM
Antenna temperature spectrum    
TANT_TSYS_SPECTRUM
Antenna temperature over system temperature spectrum
PWVPATH_SPECTRUM
Water vapor pathlength spectrum
DPWVPATH_SPECTRUM
Water vapor pathlength increment spectrum per K of radiometric emission
PHASE_DIFF_FLAG
True if PHASE_DIFF flagged
PHASE_DIFF_FLAG
True if PHASE_DIFF flagged
SBGAIN_FLAG
True if SBGAIN flagged
TAU_FLAG
True if TAU flagged
TCAL_FLAG
True if TCAL flagged
TRX_FLAG
True if TRX flagged
TSKY_FLAG
True if TSKY flagged
TSYS_FLAG
True if TSYS flagged
TANT_FLAG
True if TANT flagged
TANT_TSYS_FLAG
True if TANT_TSKY flagged
PWVPATH_FLAG
True if WVPATH flagged

COMMENT: For ALMA TSKY, TSYS, and TCAL would be filled only for associated spectral window of nature “CHANNEL-ZERO” (one per baseband. The CHANNEL-ZERO1  data would be put together in a single specific spectral window (see ASSOC_NATURE  in the SPECTRAL_WINDOW  table). The xxx_SPECTRUM data columns would be mandatory only for associated spectral windows of nature CAL-RESOLUTION (Spectral resolution for calibration)  . such spectral windows having typicaly CHAN_WIDTH=100 106 Hz and TOTAL_BANDWIDTH=2 109 Hz. With ALMA associated spectral windows with ASSO_NATURE =”CAL-RESOLUTION” would be mandatory for each baseband and sideband.