! VLBA GAINS FILE ! ! ! This is a KEYIN format file that contains calibration and sensitivity ! information for the VLBA as determined from single-dish pointing ! observations. ! ! The file contains one group of input records for each station/band. ! There is a time range associated with each group that corresponds to a ! period during which the calibration values should have been stable. A ! new group is begun whenever there is a receiver change or some antenna ! change (such as subreflector changes) that might alter the gains. ! The values for the gains and temperatures are averages of all data ! taken during the timerange. Typically one set of observations is made ! each week as part of system verification. Longer runs are made ! occasionally. The averages use a robust averaging technique that ! severely downweights discrepant points, which are typically the result ! of weather or system problems. ! ! Individual "GAIN" lines can be extracted from this file and used ! for data calibration with programs ANCAL (AIPS) or CAL (Caltech). ! The file is used as-is by a number of programs related to the ! derivation and display of VLBA performance parameters. (PTANAL, ! GAINTABLE, PLOTTS, PLOTSUM, and NEWGAIN). It is also used for ! the calibration transfer by the VLBA correlator. ! ! The parameters are: ! BAND Frequency band. Needed to distinguish sx. ! TIMERANG Range of times for which the parameters apply. ! (yr1,month1,day1,hour1,yr2,month2,day2,hr2). ! FREQ Frequency in MHz. ! COMMENT May contain a reason for new timerange. ! TS Average RCP and LCP zenith system temperatures. ! TR Average RCP and LCP receiver temperatures. This ! is TS minus atmosphere and the elevation ! dependent part of spillover. ! TCAL RCP and LCP cal value used to get Ts and gain. ! FT Scale factor for known poor Tcal. The DPFU given ! has been determined assuming that this correction ! has been made. Making the correction is ! especially important if the system temperatures ! are to be used to derive opacity corrections. ! Use this factor by including it on the "TSYS" ! card in ANCAL or CAL input. ! Station Name The two letter code for the station. ! GAIN A record type flag for ANCAL and CAL. ! ALTAZ Mount type for ANCAL and CAL. ! DPFU The RCP and LCP sensitivities (K/Jy). ! POLY Coefficients (up to 7) for a polynomial gain curve. ! These are relative to the zenith angle in degrees. ! / End of an input group. ! ! ! NOTES --- If the TCAL and TSYS values are 0, there were no ! data for this receiver/band/pol at the last update. ! The DPFU will be whatever was in the old file which ! is probably a reasonable default. ! ! Where the 1 cm gain curves are not flat, they show ! a linear decrease with zenith angle. For 2cm, we used to ! assume that the curves have the same form but that ! the magnitude of the decrease is one half that seen ! at 1 cm. More recently, and certainly by mid 2002, ! gain curves at 2cm, 1cm, and 7mm are the results of ! fits to pointing data. ! ! ! ----------------------------------------------------------------------------- ! Based on data up to 2015, day 59 ! The following are based on 2434 2327 (R,L) measurements from 148 144 projects. ! BAND = '18cm' TIMERANG = 1993,08,01,00, 1999,06,26,00 ! FREQ = 1658. COMMENT = 'Receiver S/N 19' ! TS = 25., 30. TR = 23., 28. TCAL = 0.81, 0.93 FT = 1.000, 1.000 SC GAIN ALTAZ DPFU = 0.081, 0.095 POLY= 1.000 / ! The following are based on 370 331 (R,L) measurements from 29 26 projects. ! BAND = '18cm' TIMERANG = 1996,07,18,00, 1998,03,12,00 ! FREQ = 1658. COMMENT = 'Tsys and gain changed, reason unclear' ! TS = 27., 27. TR = 25., 24. TCAL = 2.27, 2.27 FT = 1.000, 1.000 HN GAIN ALTAZ DPFU = 0.080, 0.073 POLY= 1.000 / ! The following are based on 2390 2397 (R,L) measurements from 150 150 projects. ! BAND = '18cm' TIMERANG = 1994,10,21,00, 2000,09,19,00 ! FREQ = 1658. COMMENT = 'New Subreflector' ! TS = 21., 20. TR = 18., 18. TCAL = 1.70, 1.81 FT = 1.000, 1.000 NL GAIN ALTAZ DPFU = 0.071, 0.070 POLY= 1.000 / ! The following are based on 617 648 (R,L) measurements from 49 51 projects. ! BAND = '18cm' TIMERANG = 1996,12,01,00, 1999,07,21,00 ! FREQ = 1658. COMMENT = 'Something changed. Approx date.' ! TS = 26., 24. TR = 24., 22. TCAL = 3.30, 3.41 FT = 1.000, 1.000 FD GAIN ALTAZ DPFU = 0.092, 0.089 POLY= 1.000 / ! The following are based on 8124 8029 (R,L) measurements from 545 545 projects. ! BAND = '18cm' TIMERANG = 1996,08,01,00, 2010,06,08,00 ! FREQ = 1658. COMMENT = 'New receiver S/N 5' ! TS = 31., 35. TR = 29., 32. TCAL = 2.94, 2.65 FT = 1.000, 1.000 LA GAIN ALTAZ DPFU = 0.120, 0.127 POLY= 1.000 / ! The following are based on 3334 3312 (R,L) measurements from 220 217 projects. ! BAND = '18cm' TIMERANG = 1995,06,19,00, 2003,02,25,00 ! FREQ = 1658. COMMENT = ' New receiver - S/N 17' ! TS = 26., 29. TR = 24., 27. TCAL = 1.67, 1.83 FT = 1.000, 1.000 PT GAIN ALTAZ DPFU = 0.093, 0.107 POLY= 1.000 / ! The following are based on 2666 2639 (R,L) measurements from 147 147 projects. ! BAND = '18cm' TIMERANG = 1985,01,01,00, 1998,07,17,00 ! FREQ = 1658. COMMENT = 'Receiver S/N 3' ! TS = 30., 32. TR = 28., 30. TCAL = 1.55, 1.53 FT = 1.000, 1.000 KP GAIN ALTAZ DPFU = 0.095, 0.103 POLY= 1.000 / ! The following are based on 1816 1840 (R,L) measurements from 102 102 projects. ! BAND = '18cm' TIMERANG = 1995,03,02,00, 1998,09,22,00 ! FREQ = 1658. COMMENT = 'New receiver - S/N 16' ! TS = 25., 24. TR = 23., 22. TCAL = 2.85, 2.88 FT = 1.000, 1.000 BR GAIN ALTAZ DPFU = 0.087, 0.087 POLY= 1.000 / ! The following are based on 1693 1679 (R,L) measurements from 122 120 projects. ! BAND = '18cm' TIMERANG = 1997,01,01,00, 2002,01,25,00 ! FREQ = 1658. COMMENT = ' Change in LCP recvr behavior' ! TS = 34., 36. TR = 32., 34. TCAL = 3.38, 3.53 FT = 1.000, 1.000 MK GAIN ALTAZ DPFU = 0.095, 0.098 POLY= 1.000 / ! The following are based on 12579 12613 (R,L) measurements from 835 839 projects. ! BAND = '18cm' TIMERANG = 1985,01,01,00, 2100,01,01,00 ! FREQ = 1658. COMMENT = '' ! TS = 31., 37. TR = 29., 34. TCAL = 2.81, 2.81 FT = 1.000, 1.000 OV GAIN ALTAZ DPFU = 0.085, 0.111 POLY= 1.000 /