Caltech-Internal Target of Opportunity (ToO) Policy
Caltech Optical Observatories (COO) supports a Caltech-internal
Target of Opportunity (ToO) program to enable its researchers
to acquire data on unexpected, transient events by allowing interruption
of regularly scheduled programs of Caltech observers at the Keck telescopes
and the Palomar 200-inch telescope. In such cases, the observer at the telescope
is obliged to set aside his or her program and make specific observations on
behalf of the ToO researcher. The COO-internal ToO program for Keck supplements
the WMKO partnership ToO program described in
this PDF document.
Note that WMKO partnership ToO interrupts have priority and override
Caltech-internal interrupts that are scheduled but have not yet started
observing. Furthermore, WMKO partnership interrupts may interrupt any
observer without the restrictions described below.
Caltech-Internal ToO Program Policies:
- Caltech-internal ToO projects are restricted to Caltech
(and Northwestern — see below) researchers as designated by the
appropriate selecting official.
- Such projects must be among the applicant's highest priority
requests for time on the telescope involved.
- Caltech-internal ToO interrupts may be invoked only when a Caltech
(or Northwestern — see below) observer is observing with the telescope.
All Caltech observers shall support requested interrupts from
authorized Caltech-Internal ToO program advocates; postdoc-led or small
projects are no longer exempt from internal ToO program participation.
- Caltech's collaborative agreement with Northwestern
includes Northwestern participation in Caltech's internal ToO
program on Keck Telescopes. Keck ToO requests from designated
Northwestern ToO program advocates shall be supported by all
Caltech observers, and Northwestern Keck observers shall
similarly honor authorized Caltech ToO requests
(up to negotiated program limits).
- Each Caltech internal ToO interrupt is restricted to 1 hour of
wall clock time. Subject to the limitations below, two Caltech
internal ToO interrupts may be used to obtain 2 hours of wall
clock time, per telescope per night. These two interrupts may
- Caltech internal ToO interrupts may not normally be used to interrupt
a telescope beyond 2 hours of wall clock time per night. For the Keck telescopes,
time lost to WMKO Partnership interrupts are counted in the total. Thus, if a given
Keck telescope experiences two 1-hour WMKO Partnership interrupts in a given night,
additional interruption on that telescope using Caltech internal ToO interrupts
will not be allowed.
- Under extraordinary circumstances, e.g. detection of an important new type of
transient or event, the interruption may exceed the 2 hour maximum. Both parties
(ToO and regular observer) are expected to use their best judgement in such cases,
and to report the details on any such extraordinary interruption to the COO Director.
- The ToO observer is responsible for the execution of the ToO observations.
The regularly scheduled observer may choose to perform the ToO observations
at the request and on behalf of the ToO observer, in exchange for appropriate,
mutually agreed compensation (e.g., co-authorship in any resulting publications).
- Northwestern is allowed to use its Caltech internal ToO interrupts to
"piggyback" on any WMKO Partnership ToO interrupt triggered by Caltech.
In this mode, Northwestern is invoking the data sharing clause specified
in the Caltech-Northwestern collaborative agreement, and no additional
observing time is added beyond that obtained through the Caltech-triggered
WMKO Partnership interrupt.
- For regularly-scheduled Caltech observers, the time lost due to ToO
interrupts will be tracked by COO (see reporting requirements, below). When
this accumulated burden exceeds the lesser of 6 hours or 50% of the total allocated
time, the COO Director will allocate Discretionary Time (DDT) as compensation.
Compensation will typically be at a 2:1 rate but depends on availability of DDT
and may take place in subsequent semesters.
- ToO interrupt authorization is granted only for a specific semester;
unused time assigned to a ToO program will not be
carried forward to subsequent semesters.
- All PIs who are allocated observing time will be given brief
details of the successful ToO programs from previous
- An interrupt may be activated only when the available equipment
and moonlight conditions are consistent with the TAC
recommendations. Seeing and photometric conditions are not a
condition for any interrupt.
- Caltech internal ToOs at Keck are activated following WMKO-established
procedures. Interrupts on Keck telescopes shall be entered using the
WMKO ToO Observing Request Tool (TORT). [The TORT tool is available
through the Keck Observer Login Portal.]
Palomar interrupts are activated by contacting the regularly-scheduled observer
(e.g., by telephone or email).
- In contrast to WMKO Partnership interrupts, instrument changes are
currently not supported for Caltech internal ToO interrupts.
- NEW for Semester 2024A: Similar to WMKO Partnership TOO policy, observers
may request and be granted "uninterruptable" status for regularly-scheduled
observations and thus be protected from TOO trigger interruption. Protected
status is granted at the COO Director's discretion.
- ToO reporting & data access requirements:
- The scheduled observer shall
send an e-mail to the ToO
PI [copies to C. Martin (martinc [at] caltech.edu) and A. Boden
(bode [at] astro.caltech.edu)] immediately upon completion of the
observing run, reporting on the time devoted to ToO
observations and other relevant comments.
- The observer shall deliver/make available
the necessary data to the ToO PI.
- Similarly, within 24 hours of an interrupt
the ToO PI shall document in e-mail to A. Boden
(bode [at] astro.caltech.edu) [copy to C. Martin (martinc [at] caltech.edu)]
reporting on the time used for each interrupt, with an account of
the status of the ToO project.
- Finally, the ToO PI shall also include a complete account of the status
of his/her ToO projects, time invoked, etc as a part of the supporting
material for subsequent observing proposals from this PI.
The log of active and past ToO projects, go to
COO ToO Log.
Please share your feedback on this page at the COO Feedback portal
COO ToO Policy / v 0.5.2
Last updated: 26 September 2023 JXZ/AFB/RJB/ACM