The Active Surface Manager FITS keywords for the SURFACE table conforms to the definition for common FITS headers as described in GBT Software Project Note 4.0 ``Device and Log FITS Files for the GBT.''
SURFACE Binary Table Extension: Header
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XTENSION= 'BINTABLE' / binary table extension
BITPIX = 8 / 8-bit bytes
NAXIS = 2 / 2-dimensional binary table
NAXIS1 = 25 / width of table in bytes
NAXIS2 = 2209 / number of rows in table
PCOUNT = 0 / size of special data area
GCOUNT = 1 / one data group (required keyword)
TFIELDS = 5 / number of fields in each row
TTYPE1 = 'HOOP ' / label for field 1
TFORM1 = '1J ' / data format of field: 4-byte INTEGER
TUNIT1 = 'none ' / physical unit of field
TTYPE2 = 'RIB ' / label for field 2
TFORM2 = '1J ' / data format of field: 4-byte INTEGER
TUNIT2 = 'none ' / physical unit of field
TTYPE3 = 'INDICATED' / label for field 3
TFORM3 = '1D ' / data format of field: 8-byte DOUBLE
TUNIT3 = 'm ' / physical unit of field
TTYPE4 = 'DELTA ' / label for field 4
TFORM4 = '1D ' / data format of field: 8-byte DOUBLE
TUNIT4 = 'm ' / physical unit of field
TTYPE5 = 'ENABLED ' / label for field 5
TFORM5 = '1L ' / data format of field: 1-byte LOGICAL
TUNIT5 = 'none ' / physical unit of field
EXTNAME = 'SURFACE ' / name of this binary table extension
END
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SURFACE Binary Tables Extension: Data (complete)
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HOOP RIB INDICATED DELTA ENABLED
1J 1J 1D 1D 1L
none none m m none
1 0 0 0.000000E+00 0.000000E+00 F
2 0 0 0.000000E+00 0.000000E+00 F
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The columns HOOP and RIB uniquely identify the location of an actuator on the surface of the GBT's dish.
The INDICATED column is the position reading, in meters, of the actuator.
The DELTA column is the residual between the commanded position and the indicated positions of the actuator in meters. It is the commanded position minus the current position.
The ENABLED column indicates whether or not an actuator was enabled or disabled for a given scan.