The NRAO 140 foot antenna is no longer in use. The GBT will be used for VLBI, but has not been tested as of January 2001. (But it has been in use by 2007 for a while and there is now a GBT section). This section will need a lot of work when it starts being used. It is expected that the Green Bank card type of output is now obsolete.
BELOW IS OLD INFORMATION ON USING THE 140’.
Frank Ghigo (email of 25 Mar 1997) asks VLBI and VSOP observers of the 140-foot at Green Bank to please allow enough time for pointing checks to be done during the schedule. For C-band (5 GHz) schedule 10 minutes of no observing about once every three hours. At K-band (22 Ghz) allow 10 minutes every two hours. At frequencies below 5 GHz no extra pointing checks are necessary.
Note that pointing can be specified through the use of the PEAK. However it is also possible for the local staff to insert the pointing observations if adequate gaps are left and the user’s intentions are made clear in the cover letter. Actually it is a good idea to make the user’s intentions clear in the cover information regardless.
Green Bank (140’) is the only station for which SCHED can still request automatic measurements of the antenna temperature of a source. The parameters TANT1 and TANTSTA1 are used to control this capability. Note that a Tant measurement takes about a minute and the antenna is off source part of the time so such measurements should be done before a recording scan starts.
Green Bank (140’) does not have computer control of the pcal injection. Therefore do not expect the pulse cal to be turned on and off on a per-scan basis. The support people will try to determine from your schedule or cover information if the pulse cal is desired and set it accordingly. It is wise to make your desires clear in the cover notes, especially if you want pcal off. Note that the pcal tones are injected in the IF, not at the receiver as at most sites.