Standard Proposals
LCO's year is subdivided into two observing semesters, each 6 months long. Standard proposals from astronomers affiliated with LCO's Science Collaboration institutions are accepted every semester. The Science Collaboration partners allocate their shares of time according to their own TAC procedures. They may elect to assign some of their time to Key Projects (see below) with which they are involved.
For semesters 2025A-2026A, astronomers worldwide could submit standard proposals through the Open Access calls (supported by the Heising-Simons Foundation) each semester. For semester 2026B-2028B the Heising-Simons funding supports open access to Key Project proposals and continues to support open access to Director's Discretionary time for the entire astronomical community.
For LCO's own share of observing time, standard proposals are accepted from astronomers affiliated with LCO's non-guaranteed-time partners: the University of California at Santa Barbara and IPAC at Caltech. Proposals are also accepted from members of LCO's scientific family: current staff, astronomers who were postdocs at LCO in the last 5 years, astronomers who were graduate students at LCO in the last 3 years, and astronomers who served on our advisory and allocation committees in the last 2 years.
A Time Allocation Committee (TAC) returns a ranked list of proposals plus advice on scheduling. The Director assigns time to successful proposals and contacts the authors.
The most recent call for standard proposals is posted in the Announcement section of the website.
Key Project Proposals
Proposals for Key Projects are accepted every three years. Key Projects are large, coherent observing programs designed to take maximum advantage of the unique attributes of the LCO network to address important astrophysical problems. Key Projects are expected to have a duration of up to three years. For 2026B Key Projects all astronomers were eligible to submit letters of intent to propose for Key Projects with open access support provided by the Heising-Simons Foundation. All of the potential Key Projects that submitted letters of intent were invited to propose. You must have submitted a letter of intent and received an invitation to propose before submitting your proposal.
Key Projects generally acquire several hundred (perhaps several thousand) hours of observations, and large project teams are assembled to carry these out. These are LCO's premier science programs. Because LCO is contributing large amounts of telescope time to support Key Projects, collaborators on proposing teams from other institutions are required to commit significant resources to the effort. Such resources could be access to other facilities, or additional time on the LCO network from their own institution, or computing resources, or scientist time.
LCO is currently supporting seven Key Projects.
Guidelines for submitting 2026B Key Projects are here.
Director's Discretionary Time Proposals
LCO holds observing time in reserve, which may be allocated at the discretion of LCO's director. These discretionary hours are intended for observations of unforeseen targets-of-opportunity as well as high impact support of other space and ground-based facilities.
Eligibility:
Astronomers affiliated with an institution in LCO's Science Collaboration and investigators worldwide (through the Heising-Simons funded Open Access time) are eligible to submit proposals for discretionary time. Proposers must clearly justify why the observations must be carried out more immediately than the normal proposal/review cycle if they are eligible to submit standard proposals or have access to guaranteed time. Proposals for discretionary time may be submitted at any time, but the time expires at the conclusion of the current semester.
Discretionary time is not available to support education and outreach programs except under special circumstances by invitation.
Notification of Review Decision
Standard and Key Project proposals are reviewed by a Time Allocation Committee (TAC) panel whose members are selected from the astronomical community and are not employed by LCO. Proposals recommended for scheduling by the TAC are awarded time by LCO's director. PIs are notified of a standard proposal's acceptance approximately 6 weeks before the start of the semester. Proposals for discretionary time are reviewed by LCO's director often with consultation with subject matter experts. Notices of acceptance are issued as quickly as possible, but typically in less than one week.