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UCO home > Observing > Keck Observing > ToO Observations at Keck

Policy for UC Keck Time for Targets of Opportunity

Updated April 7, 2015 by Interim UCO Director Claire Max

Target of Opportunity (ToO) proposals are directed at objects with unpredictable appearance dates for which a short, timely observation (up to one hour) may be of great value. The UC TAC will evaluate all ToO proposals. The TAC will recommend a specific number of maximum hours for approved ToO programs and the actual interrupts will be tracked each semester.

All UC programs for which the TAC has allocated at least one night of total observing time in the relevant semester will be subject to donating up to one hour of each night to approved UC ToO programs. (However due to time constraints, individual quarter-night scheduled observations will be excluded.) The observers will be able to briefly negotiate when to take the observations (e.g., to delay until completion of a current exposure, if necessary), but regularly scheduled observers are discouraged from questioning the scientific merits of these TACapproved programs. The one hour per night is actual clock time from the termination of the observer's own program and includes the overhead for the observer to configure the instrument for the ToO observation and to reconfigure the instrument to resume the normal program.

Should a ToO event occur for a TAC- approved project, it is the responsibility of the ToO proposer to arrange with that night's scheduled observer for the observations to be made. Immediately following a TAC-approved ToO observation, the ToO PI must send an email to Paula Towle ( listing (1) the regularly scheduled PI who was interrupted, (2) the instrument used, (3) the total elapsed time actually used for the ToO observation, and (4) the total time allocated by the TAC to the whole ToO project.

There are two observing modes available for a ToO event: 1) The regularly scheduled observer carries out the observations. In this case it is desirable for the PI of the ToO project to send the abstract and a written list of instructions and contact information to the regularly scheduled observer. A phone or Skype or Google Hangout connection is highly desirable. 2) The ToO PI carries out the observations from one of the Keck Remote Observing Rooms. If this is the case, the ToO PI must be consistent with the pre-existing schedule for the Remote Observing Room, and must arrange for the Remote Observing Room's VPN connection to be fully operational and tested ahead of time. PIs of TAC-approved ToO projects who want to use option 2) should discuss in advance the implications with local staff in charge of their Remote Observing Room.

ToO proposals are due the same date as others and should be clearly indicated as such.

Co-authorship on a resulting paper will be offered to the regularly scheduled observer if the ToO observations are done by that observer.

Important note:This version of UC ToO Policy assumes that a UC TAC-approved ToO project can only interrupt UC's regularly scheduled observers. After considerably discussion in the Keck SSC, Caltech and UC have agreed that UC ToO observers can interrupt Caltech nights, and vice versa. The procedures under which this can happen are still being worked out and will be announced shortly.

Currently Approved UC ToO Projects at keck

To update this list, send an e-mail to

Updated July 15, 2015

Semester 2015A

Keck 1 U064Hr Filippenko
Keck 2 U064N2L Filippenko
Keck 2 U015N2 de Pater
Keck 2 U035N2L Max

Semester 2015B

Keck 1 U048Hr Filippenko
Keck 1 U028OL Max
Keck 2 U048N2L Filippenko