18B TAC Report

by Dana Balser last modified May 30, 2018


A total of 149 proposals were submitted to NRAO's Karl G. Jansky Very Large Array (VLA) in semester 18B.  Proposals are reviewed on a competitive basis with a panel review system (see Proposal Review System).  Below are the statistics by proposal count and hours.  The oversubscription is the ratio of the number of submitted proposals to the number of approved proposals.  The pressure is the ratio of the requested time to the available time in hours.  Here we only include proposals submitted for the 18B semester that have been reviewed by the NRAO TAC.  We count HSA proposal hours that request the VLA as a VLBI station.

Statistics by Proposal Count
Submitted 149
Approved   59
Filler   56
Rejected   34
Oversubscription 2.5
Statistics by Proposal Hours
ProposalsVLA (C)
Requested 3746.14
Available 1721.50
Approved  1116.54
Filler 1527.29
Rejected  1102.31
Pressure       2.2

For the 18B semester, the NRAO had agreements with the Hubble Space Telescope (HST), the Swift Gamma-Ray Burst Mission, and the Chandra X-ray Observatory to submit joint proposals whereby the NRAO TAC could allocate time on these external facilities (see the 18B Call for Proposals).   The table below summarizes the results for the VLA only in 18B.  The time available on the external facilities is per year and includes the GBT and VLBA.


Joint External Proposals

HST (Orbits)

Swift (ks)Chandra (ks)


30 300 120
Requested  0 255  40
Approved  0   88    0


Telescope Pressure Plots

Pressure plots show the total hours of allocated time as a function of LST.   Also shown are how the hours are divided with respect to weather conditions and observing priority.  Click on the plot to enlarge.  The VLA has two weather categories: high frequency (above 12 GHz, light shading) and low frequency (below 12 GHz, dark shading). The figure below shows the pressure for the C configuration.  The black lines indicate the total time available for science (solid), the time available for K-band and higher frequencies (dashed), and the time available for Q-band (dotted).  The letters A, B, C, and N correspond to the priorities assigned by the TAC where A and B are approved time, C is filler time, and N is rejected time.

 VLA Pressure Plot 18B (C) - Updated


Observation Preparation

In semester 18B, daytime maintenance activities peak at about 16 hours LST for the C configuration, so observing pressure is highest there. For status of the VLA and links to the monthly schedules please see the schedsoc home page.  Proposals approved for priority A, B or C time become ineligible when the associated configuration ends, unless explicitly stated otherwise in the Comments from the TAC. Those allocated dynamic time should begin their scheduling block preparation about two weeks before the planned start of the configuration (see Configuration Plans).

Any approved time may be divided into multiple scheduling blocks as appropriate, considering the scheduling priority, observing frequency, LST range suitable for the target(s), and LST pressure. For advice, please consult the VLA Observing Guide.

Unless stated otherwise, any time allocated is only for the identified proposal, and no modification in the project should be made without obtaining permission from NRAO scheduling staff.  To seek permission, submit a ticket to the Proposal Review department of the NRAO Helpdesk.