Semester Observing Opportunities

Semester proposing opportunities are announced through a Call for Proposals. The observing proposal submission deadlines for Observatory facilities are the closest date to 01 February and 01 August that fall on a Wednesday¹ each year. The February deadline applies to requests for observing time from 1 August–31 January; the August deadline applies to requests for time from 1 February–31 July. The Call for Proposals contains the implementation parameters and procedures and is available online at https://science.nrao.edu/observing/call-for-proposals.

In response to a semester Call for Proposals, three proposal types can be submitted for the standard semester deadlines each year:

• Regular proposals are for modest total time requests on Observatory facilities. The Call for Proposals specifies the maximum number of hours a Regular proposal is allowed, which may depend on the capabilities of a facility.
• Triggered proposals are for pre-planned observations of transients whose event times are unknown a priori.
• Large proposals are for large total time requests on Observatory facilities. The Call for Proposals specifies the maximum number of hours a Large proposal is allowed, which may depend on the capabilities of a facility.

Joint proposals with non-AUI facilities and commensal observing are proposed for within the scope of these proposal types, see Section 3.2.3 and Section 7.4, respectively. Note, Large proposals can have triggering criteria; users should specify the proposal type as “Large” in the PST.

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. When a facility, such as the VLA or GBT, is requested as part of the VLBI/HSA or GMVA, its time is categorized under the VLBI/HSA or GMVA facility for the purpose of meeting the criteria of a Large Proposal. However, if the same facility (like VLA or GBT) 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.

Proposals submitted to a semester call must contain capabilities offered in that semester call. An exception is for a PI who is a graduate student, who may propose up to one semester in advance for capabilities offered on the GBT, HSA, and VLBA. For the VLA, a PI who is a graduate student may propose for any array within one VLA configuration cycle (see Section 7.1 for definition). For other exceptional cases, please seek guidance from the NRAO Science Helpdesk. Submission of such cases will be subject to the NRAO's discretion.

¹ The exact call period will be announced in the Call for Proposal.