; ; Define the basic 3-Helium internal data structure format ; ; IDL single dish package requires at least these variables ; total ; v3.0 19 June 2004 ; variables passed via SDFITS v1.1 release ; ; gbt = {gbt_data, $ ; # bytes -> # bytes source:bytarr(32), $ ; 32 32 source name observer:bytarr(32), $ ; 32 64 observer ID obsid:bytarr(32), $ ; 32 96 observation description scan_num:0L, $ ; 4 100 scan number last_on:0L, $ ; 4 104 last ON scan: PS last_off:0L, $ ; 4 108 last OFF scan: PS procseqn:0L, $ ; 4 112 procedure sequence # procsize:0L, $ ; 4 116 # scans in procedure pol_id:bytarr(4), $ ; 4 120 polarization ID string line_id:bytarr(32), $ ; 32 152 line ID via corr sampler scan_type:bytarr(32), $ ; 32 184 scan type ON/OFF etc lst:0.0D, $ ; 8 192 LST at scan start in sec date:bytarr(32), $ ; 32 224 date/time string frontend:bytarr(16), $ ; 16 240 frontend ID string ra:0.0D, $ ; 8 248 RA in degrees dec:0.0D, $ ; 8 256 DEC in degrees epoch:2000.0D, $ ; 8 264 EPOCH of ra/dec l_gal:0.0D, $ ; 8 272 l_gal in degrees b_gal:0.0D, $ ; 8 280 b_gal in degrees hor_offset:0.0D, $ ; 8 288 map horizontal offset pos'n ver_offset:0.0D, $ ; 8 296 map vertical offset position az:0.0D, $ ; 8 304 AZIMUTH in degrees el:0.0D, $ ; 8 312 ELEV in degrees vel:0.0D, $ ; 8 320 Source velocity m/sec sky_freq:0.0D, $ ; 8 328 center frequency Hz rest_freq:0.0D, $ ; 8 336 rest frequency at band center ref_ch:0.0D, $ ; 8 344 reference ('center') channel delta_x:0.0D, $ ; 8 352 delta freq of x-axis in Hz vel_def:bytarr(8), $ ; 8 360 velocity reference frame ID vframe:0.0D, $ ; 8 368 frame radial velocity m/sec rvsys:0.0D, $ ; 8 376 Vsource - Vtelescope m/s bw:0.0D, $ ; 8 384 bandwidth in Hz tsys:0.0D, $ ; 8 392 system temperature in Kelvin tsys_on:0.0D, $ ; 8 400 Tsys ON source/freq tsys_off:0.0D, $ ; 8 408 Tsys OFF source/freq tcal:0.0D, $ ; 8 416 cal value in Kelvin tintg:0.0D, $ ; 8 424 effective integ. time sec feed:0.0D, $ ; 8 432 signal feed number srfeed:0.0D, $ ; 8 440 reference feed number beamxoff:0.0D, $ ; 8 448 beam XEL offset in degrees beameoff:0.0D, $ ; 8 456 beam EL offset in degrees freqoff:0.0D, $ ; 8 464 sideband:bytarr(4), $ ; 4 468 resulting sideband U/L data_points:!data_points, $ ; 4 472 # data points in spectrum history:bytarr(552), $ ; 552 1024 annotation string data:fltarr(!data_points) $ ; 16,384 17,408 ; ; --> uses !data_points value to set size of data array ; --> size = 4bytes * !data_points : 4 x 4096 = 16,384 bytes ; --> SDFITS sends data as single float values ; ; --> correlator has 32,768 channels maximum = 64 x 512 ; 4 x 32,768 = 131,072 bytes ; } ; end of definition ; ; unformated read/write files and the ASSOC IDL command all need for ; the data to have fixed length records for maximum utility ; ; thus all string variables from SDFITS are stored here as byte ; arrays of ASCII codes with one ASCII character coded by each ; byte. note that we are keeping this structure aligned on ; 16 byte boundaries for obvious reasons ; ; all declariations match SDFITS precision ;