Joint Proposing Opportunities

There are a number of opportunities for joint proposals with external (non-Observatory) facilities and between the Observatory’s facilities. The time will be awarded only for proposals that require use of both observatories and shall not apply to usage of archival data. The observations are not required to be coordinated or simultaneous, and the programs may be subject to basic feasibility reviews. All joint proposals submitted through the PST must indicate the joint facility, specify the requested time for the joint facilities, and additional details. The Call for Proposals contains the most up-to-date opportunities and requirements for joint proposals.

Joint proposals between the Observatory’s facilities consist of observing programs that require combinations of the GBT, VLBA, and/or the VLA. For such requests, proposers should submit a proposal for each of the requested telescopes. The same Scientific Justification should be submitted with each proposal, and it should contain a clear justification for each telescope requested. VLBI proposals which request the GBT or VLA (or any other HSA telescope) as elements of the VLBI array do not need separate proposals as those telescopes can be selected as separate VLBI stations from a VLBA/HSA proposal. When determining whether a joint proposal qualifies for as a Large Proposal, the total time requests are evaluated per facility and not as an aggregate sum. For example when a facility is requested as an element of the VLBI array, its time is categorized under the VLBI facility for the purpose of meeting the criteria of a Large Proposal. However, if the same facility is simultaneously requested as a joint resource apart from being an element of the aforementioned facilities, their respective time requests remain distinct and are not compounded when assessing against the Large Proposal threshold.

For joint proposing opportunities with external facilities, one proposal should be submitted to the facility where more observing time is being requested; authors should not duplicate their request across the observatories in this case. Authors may re-submit the proposal if their previous submission was rejected (partially or fully), or if the outcome of the previous submission is unknown.

If the latter and a positive disposition is eventually received, it is expected that the duplicate proposal be withdrawn promptly. Proposing teams that are awarded time through an external Telescope Time Allocation Committee (TAC) must adhere to the policies of this document when applicable. If the policies of this document conflict with that of another facility, the Observatory will work with the proposing team and external facility to reach a suitable resolution.

Detailed information about the external joint proposing opportunities can be found within their corresponding Memorandum of Understanding. These documents are accessible online at Note, the agreements for Joint Observations with external facilities were made at different times across the boundaries when the Observatory was split into multiple observatories (NRAO, GBO, and LBO) in 2017, and when the Long Baseline Observatory (LBO) was reintegrated back into the NRAO in 2019. Therefore, the Memorandum of Understandings will sometimes mention various combinations of the NRAO, GBO, and LBO.

Table 2.1 summarizes the amount of time that may be awarded from either the Observatory TAC or the External TAC to an external joint proposal. Column 2 gives the amount of time an External TAC may award on an Observatory facility, and column 3 gives the amount of time the Observatory TAC may award on the external facility. Proposing teams should consult the Call for Proposals for the specific guidelines when preparing a joint proposal.

Table 2.1: Summary of Joint Proposing Opportunities
External Facility External TAC (Observatory Time)a Observatory TAC (External Time)
ALMA 5% 50 hrs per cycleb
Chandrac 3% 120 ks per year
Fermi 5%d 300 ks per year
HSTe 3% 30 orbits per years
NICER 5%f 250 ks per year
Swift 5%f 300 ks per year
XMM-Newton 3% 150 ks per year

a Percentage of observing time that is considered Open Skies.
b The Observatory can award up to 50 hours on the ALMA 12-m array, 50 hours on the 7-m array, and 50 hours on the Total Power array per cycle.
c Chandra ToO proposals are not supported under the Chandra-NRAO joint program.
d A maximum of 5% or up to 200-325 hours of Open Skies observing time per year is available on each telescope.
e HST Snapshots observations are not supported under the HST-NRAO Joint program.
f A maximum of 5% or up to 200-300 hours of Open Skies observing time per year is available on each telescope.