Decoding the 'S' Project Code Names

The NRAO has cooperative agreements with several observatories allowing astronomers to request time on the VLA, VLBA, or GBT.  Since these external proposals do not go through NRAO's Proposal Handling Tool, we create a unique project code allowing us to easily recognize as external and search via database queries and the archive access tool. These external proposals requesting VLA or VLBA time always start with the letter S. (The GBT has their own naming scheme.) Historically, the S stood for satellite/spacecraft since at the time, all of the external proposals came from orbiting telescopes.  We have since added at least one ground based telescope.  Below, we describe the naming scheme (in use starting around late 2023) of these external proposals we create in the VLA's Observation Preparation Tool (OPT) and the VLBA's Operations Management System (OMS).

Example Project Codes:

  • SC240108 (for VLA time through Chandra)
  • SC24395 (for VLBA time through Chandra)

S = we kept so these are easily recognizable as external and searchable

C = second letter indicates the telescope;

C = Chandra
A = ALMA
F = Fermi
H = HST
I = IXPE
J = JWST
N = NICER
S = SWIFT
X = XMM-Newton

24 = indicates the proposal cycle

0108 = last four digits of the original proposal code shared with NRAO (used for external telescope proposals requesting VLA time)

395 = last three digits of the original proposal code shared with NRAO (used for external telescope proposals requesting VLBA time) This allows us to append a segment code, i.e., A, B, C, etc., in the VLBA's OMS.

For older 'S' projects that do not use the above naming scheme, the second letter was the proposing cycle converted to a hexadecimal letter followed by the last four digits of the original proposal code, e.g., SL0102. This naming scheme did not provide an indicator of which external telescope was associated with the project code nor an obvious proposal cycle. Hence, the new naming scheme described above.

Note, the VLBA has also used SSnnn for the Summer Student projects (nnn = 001, 002, 003, etc.).  Not to be confused with 'S' projects related to a SWIFT proposal requesting VLBA time or the older naming scheme.

If you have any questions, please contact us via the NRAO Science Helpdesk using the VLA or VLBA Scheduling Support department.

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