The primary header contains all required GBT FITS keywords, for example:
SIMPLE = T / file does conform to FITS standard BITPIX = 8 / number of bits per data pixel NAXIS = 0 / number of data axes EXTEND = T / FITS dataset may contain extensions COMMENT FITS (Flexible Image Transport System) format is defined in 'Astronomy COMMENT and Astrophysics', volume 376, page 359; bibcode: 2001A\&A...376..359H ORIGIN = 'NRAO Green Bank' / INSTRUME= 'CCB' / device or program of origin GBTMCVER= '4.6 ' / telescope control software release FITSVER = '1.2 ' / FITS definition version for this device DATEBLD = 'Mon Sep 20 20:58:25 UTC 2004' / time program was linked SIMULATE= 0 / Is the instrument in simulate mode? DATE-OBS= '2004-10-09T07:50:01' / Manager parameter startTime TIMESYS = 'UTC ' / time scale specification for DATE-OBS TELESCOP= 'NRAO_GBT' / Green Bank Telescope (Robert C. Byrd 100m) OBJECT = '2230+114' / Manager parameter source PROJID = 'AGBT04C_018_04' / Manager parameter projectId OBSID = 'lineFSW ' / Manager parameter scanId SCAN = 305 / Manager parameter scanNumber END
In addition to the above standard keyword/value pairs, the following intrument-specific keyword/value pairs are recorded:
Keyword | Values | Related CCB Library Call | Units |
ACTPSW | A,B,Both,None | ccb_set_phase_switch_cnf.active_switches | |
NOTES: Designate active phase switches | |||
INPSWSTA | 0,1 | ".closed_switches | |
NOTES:Important if one switch is held constant so you know what it was | |||
INPSWSTB | 0,1 | ".closed_switches | |
NOTES:Important if one switch is held constant so you know what it was | |||
SMPPERST | integer | ".samp_per_state | 100 ns |
NOTES: number of ADC samples per phase switch state | |||
CALCYCLN | integer | ccb_set_cal_diode_cnf.ncal | |
NOTES: number of integrations in the calibration cycle | |||
CALOFFIG | integer | ".diode_times | |
NOTES:duration of the cal off step, integrations | |||
LCALONIG | integer | ".diode_times | |
NOTES:duration of the left cal on step, integrations | |||
BCALONIG | integer | ".diode_times | |
NOTES:duration of the both cal on step, integrations | |||
RCALONIG | integer | ".diode_times | |
NOTES:duration of the right cal on step, integrations | |||
INTGPD | integer | ccb_set_timing_cnf.integ_period | |
NOTES: number of phase switch cycles which go into one integration | |||
PSWDT | integer | ccb_set_timing_cnf.phase_switch_dt | 100 ns |
NOTES:phase switch transition blanking interval | |||
CRISEDT | integer | ".diode_rise_dt | 100 ns |
NOTES:Cal diode settling time after being switched on (determines # blanked integs) | |||
CFALLDT | integer | ".diode_fall_dt | 100 ns |
NOTES:Cal diode settling time after being switched off determines # blanked integs) | |||
RNDTRPDT | integer | ".roundtrip_dt | 100 ns |
NOTES:Internal hardware round trip delay | |||
HOLDOFF | integer | ".holdoff_dt | 100 ns |
NOTES:minimum interval between hardware interrupts | |||
INTEGRAT | integer | ccb_integration_time() | 100 ns |
NOTES: integration time per phase after blanking | |||
FAKESMP | logical | ||
NOTES: T indicates that data were generated from the CCB's fixed pseudorandom sequence. |