Preparing a Proposal

  After composing the scientific justification and identifying the desired VLBI target source(s), select an appropriate VLBI array. Possibilities include:

1. The VLBA alone (SC, HN, NL, FD, LA, PT, KP, OV, BR, and MK), with the possible inclusion of the VLA. The VLA can be requested in either phased array or single antenna mode; consult Wrobel & Claussen (1996) for information on VLBI at the VLA. Proposal deadlines are February 1, June 1, and October 1. Observing periods for such projects are identical to those for the VLA and are advertised regularly in the NRAO Newsletter. Observing time is allocated by the VLA/VLBA Scheduling Committee. Approved VLBA projects are scheduled by the VLBA scheduler Barry Clark (see Section 26.4).
2. The European VLBI Network (EVN). Prospective proposers can consult Schilizzi (1995) and Alef & Mantovani (1995; the EVN Handbook hereafter) for information on EVN members and the capabilities of EVN antennas. The EVN Handbook can be obtained through account VLBINFO on ASTBO1; the Internet address is ``astbo1.bo.cnr.it'' (192.167.165.1). The EVN handles the proposing, refereeing, and scheduling mechanisms for such projects, which must all be run during a regular VLBI Network session. EVN proposal deadlines are February 1, June 1, and October 1. VLBI Network session dates and wavelengths are routinely announced by EVN mailings and in the NRAO Newsletter. Observing time is allocated by the EVN Program Committee. Approved EVN projects are scheduled by the EVN scheduler R. Schwartz. Any EVN proposal requesting the VLBA or two or more of the non-EVN VLBA affiliates identified in Item 3 below constitutes a global proposal, and must be submitted to both the VLBA and the EVN.
3. VLBA affiliates in addition to the VLA include Arecibo, Effelsberg, the Deep Space Network, Green Bank, Medicina, and Noto. A VLBA proposal requesting such affiliates is handled as described in Item 1 above, except that if two or more EVN institutes are requested, then it is a global proposal and must be submitted to both the VLBA and the EVN. A VLBA project involving affiliates other than the VLA might be run outside of a regular VLBI Network session, depending on which affilliates are involved. In particular, about 20 days of time per year, outside of regular VLBI Network sessions, has been reserved for joint VLBI projects involving the VLBA and Effelsberg; submit proposals for such joint time both to the NRAO and to the MPIfR.

Once the appropriate VLBI array is selected, run the NRAO SCHED program (or the related Caltech UPTIME program available with SCHED) (Walker 1997), or the Haystack PC-SCHED program (see Section 26.1) to determine the Greenwich Sidereal Time range during which the VLBI target source(s) is (are) up at the selected antennas. These programs can also be used to evaluate the u-v plane coverage provided by the selected antennas (see Section 9).

Those proposing observations in VLBA format should consult files

``std_modes.vlba'' and ``OK_modes.vlba''

in directory ``pub'' on host ``ftp.aoc.nrao.edu'' (146.88.1.103) to identify which VLBA setup(s) is (are) desired; these files are also available from the VLBA home page (see Section 26.3).

Global proposals requesting Mark IV format will use VLBA format at sites with VLBA systems and Mark IV format at sites with Mark IV systems. The VLBA correlator can play back both, with some restrictions, and correlate them together. As of this writing, only a very limited set of Mark IV modes and mode changes have been checked out and approved for use at the VLBA correlator. Mark IV recordings sent to the VLBA correlator, whether from EVN-only or from global projects, must involve only approved modes and mode changes. In the near future (1) a list of approved Mark IV modes will appear in file ``OK_modes.vlba'', available as mentioned in the previous paragraph; and (2) the scheduling program SCHED will limit observers to those approved Mark IV modes.

If the proposal requests use of the VLBA correlator, then the proposed observing strategies must adhere to the ``Guidelines for VLBA Observations'' summarized by Jon Romney (see Section 26.4) and available from the VLBA home page (see Section 26.3).

NRAO has recently adopted a policy regarding proposals for unusually large amounts of observing time. This policy can be accessed from the NRAO home page (see Section 26.3).