GBT Pointing summaries for VLBI projects

VLBI General Info Operator's checklist Aspen Vlbeer VLBA Schedules
Past Projects Present and Future Projects Resource Calendar Gain Curves GBT VLBA Status

Explanation


Experiment Date VLBI proj name GBT project dir
and link
2007-10-04 bb240a ABB240_01
2007-10-08 bb240b ABB240_02
2007-10-28 bb240c ABB240_03
2007-10-30 bb240d ABB240_04
2007-11-08 bb240e ABB240_05
2007-11-19 bb240f ABB240_08
2007-11-24 bb240g ABB240_09
2007-12-01 bb240h ABB240_10
2007-12-08 bb240i ABB240_11
2007-12-15 bb240j Not Observed.
2007-12-21 bb240k ABB240_12
2007-12-29 bb240l ABB240_13
2008-01-07 bb240m ABB240_14
2008-01-16 bb240n ABB240_15
2008-01-25 bb240o ABB240_16
2008-01-31 bb240p ABB240_17
2008-02-07 bb240q ABB240_18
2008-02-14 bb240r ABB240_19
2008-02-19 bb240s ABB240_20
2008-02-28 bb240t ABB240_21
2008-03-02 bb240u ABB240_22
2008-03-23 bm270 ABM270_01
2008-03-26 bb240x ABB240_23
2008-03-30 bb251 ABB251_01
2008-04-06 bm267a ABM267_01
2008-04-07 bb240y ABB240_24
2008-04-10 bb240z ABB240_25
2008-04-14 bb242e ABB242_06
2008-04-13 bb242f ABB242_05
2008-04-15 bb240aa ABB240_26
2008-04-16 bb242g ABB242_07
2008-04-19 bb242i ABB242_08
2008-04-20 bl156b ABL156_01
2008-04-21 bb242h ABB242_09
2008-04-23 bb240ab ABB240_27
2008-04-28 bb240ac ABB240_28
2008-04-29 bb240ad ABB240_29
2008-05-03 bb255b ABB255_01
2008-05-16 bb240ae ABB240_30
2008-05-15 bd120t ABD120_01
2008-05-17 bd120a ABD120_02
2008-05-17 bd120b ABD120_03
2008-05-17 bd120c ABD120_04
2008-05-18 bd120d ABD120_05
2008-05-18 bd120e ABD120_06
2008-05-18 bd120f ABD120_07
2008-05-23 bb242j ABB242_10
2008-05-24 bb240af ABB240_32
2008-05-30 bb240ag ABB240_33
2008-06-01 gm064 AGM064_01
2008-06-14 gb064a AGB064_01
2008-06-15 gb064b AGB064_02
2008-06-16 gs029 AGS029_01
2008-06-19 bm267b ABM267_02
2008-06-19 br125c ABR125_03
2008-06-20 br125d ABR125_04
2008-06-20 bb240ah ABB240_34
2008-06-22 bb250 ABB250_01
2008-06-28 bb240ai ABB240_35
2008-07-03 bb240aj ABB240_36
2008-07-04 bm267c ABM267_03
2008-07-08 bb240ak ABB240_37
2008-07-12 bm267d ABM267_04
2008-07-15 bb240xl ABB240_38
2008-07-19 bb240am ABB240_39
2008-07-19 bb253 ABB253_01
2008-07-21 bi035a ABI035_01
2008-07-24 bb240an ABB240_40
2008-07-27 bm267e ABM267_05
2008-08-01 bb240ao ABB240_41
2008-08-03 bo031 ABO031_01
2008-08-03 bh157 ABH157_01
2008-08-08 bb240ap ABB240_42
2008-08-11 bb240aq ABB240_43
2008-08-16 bb240ar ABB240_44
2008-08-17 bm267f ABM267_06
2008-08-18 bb240as ABB240_46
2008-08-23 bb240at ABB240_47
2008-08-29 bi035b ABI035_02
2008-08-31 bb240au ABB240_48
2008-09-03 bb240av ABB240_49
2008-09-08 bb240aw ABB240_50
2008-09-11 bb240ax ABB240_51
2008-09-17 bb240ay ABB240_52


Explanation

The peak/focus sequence consists of 5 scans, crossing the source in the +azimuth (AzF) and -azimuth (AzB) directions, then in the +elevation (ElF) and -elevation (ElB) directions. The final (Focus) scan remains pointed at the source while the subreflector is moved through its range of motion. After the azimuth scans, an azimuth correction is derived and added to the telescope LPC ("local pointing correction"); after the elevations scans the LPC is updated with the elevation correction. After the focus scan, the LFC ("local focus correction") is updated. These LPCs are added to the current pointing/focus model and persist until the next peak/focus observation.

The pointing report referenced in this page lists 2 lines for each scan, for LCP and RCP channels. The Az and El corrections are given in arcseconds, and the focus corrections in millimeters.

The table also lists :

  • the peak of the fitted gaussian -- this is the approximate antenna temp in Kelvin.
  • the HPBW of the fitted gaussian in arcseconds (in mm for focus scans).
  • the pointing or focus offset, and estimated error.
  • the system temperature in Kelvin

    Normally we do a peak/focus at the beginning of every run, before starting the user's schedule. Hence the first peak/focus scans will not correspond to what is in the schedule file.

    At the bottom of the page there is a summary giving the average azimuth, elevation, and focus correction for each complete peak/focus sequence.

    Note: the Tant and Tsys depend on our assumed values for the noise calibration. I believe our values for LCP at 8.4 GHz are bogus, so until we get that fixed, believe only the RCP information !


    Another note: to generate the pointing summary and update this table:

  • login as gbvlbi
  • cd public_html/vlbsetup/
  • pointingreport GBTprojectcode VLBAprojectcode
  • for example: pointingreport ABB240_51 bb240ax