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Last modified: 16 December 2016


FAQ for Multi Cycle Observations

Proposer Threads (Cycle 19)


What is a Multi-Cycle Observation Proposal (MCOP)?

Proposers whose science calls for constrained observations over a period longer than one year, may include requests for up to a 3-year time period in a single proposal. This will be useful, for example, for long-term monitoring programs. Proposals must request time in the upcoming cycle, and justify both the requirement for multi-cycle observations and the allocation of time across the multiple cycles.

Refer to "Multi-cycle Observing Proposals" in the Call for Proposals for the maximum amount of observing time allocated to MCOPs in the upcoming cycle.

The proprietary period for data from multi-cycle targets begins when 90% of the data for any given target (as allocated to each cycle) has been made available to the observer.

RPS form for MCOPs

I am writing a proposal for a multi-cycle observation and I want a target to be observed for 200 ksec in the upcoming cycle, then again in the following two cycles for the same amount of time (for a total of 600ksec). How do I fill out the RPS form?

In the RPS Cover Page the question Is this a multi-cycle observing proposal? should be answered YES (Y).

In the RPS Target Page the total observing time for all cycles combined (600 ksec in this example) should be entered, in addition to the projected time for future cycles (200 ksec each in this example).

Note: The total observing time will be calculated by the RPS from the individual Target Pages and indicated on the RPS cover page.

If multi-cycle observations are requested for a given target, the proposer must specify the observing constraints that require the observations to extend into future cycles (see the following FAQ).

Observing Constraints

How do I specify the observing contraints in future cycles?

All observing contraints for the upcoming cycle and for future cycles should be specified in the Target page in the RPS form.

Multi-cycle observations may not be requested as a preference.

Constraints must be well-justified scientifically in the proposal.

The PI must estimate based on these constraints the amount of time required in future cycles for each such target, assuming the earliest feasible start date for the first target observations.

VLP proposals and MCOPs

I am writing an VLP proposal with no specific time constraints for which data can be accumulated over more than one cycle. I would like to exploit MCOPs to minimize the impact of exposure time per cycle. Does such a proposal qualify as a MCOP in the upcoming cycle?

No, it does not.

An VLP proposal can be a MCOPs only if it is time constrained, and the constraint is needed to achieve well defined science goals. MCOPs cannot be defined as such to minimize the impact in terms of exposure time per cycle. That is not a valid reason.

If approved, an VLP might well be scheduled over 2-3 cycles for technical reasons, but this is up to the Chandra mission planners.


I am proposing to observe a variable source and would like to observe it in a future cycle only if the flux is brighter than a specified value. Can I propose for a TOO in future cycles?

No, this is not possible. A scientific trigger can only be requested from the upcoming cycle. Only follow-up observations are allowed in future cycles.

Joint Time in MCOPs

Can I ask for joint time in future cycles?

For Cycle N, up to 10% and 5% of the available joint time in Cycles N+1 and N+2 respectively may be allocated to multi-cycle observing proposals if scientifically justified and subject to the continued availability of that time (see "Requirements and Conditions Common to All Joint Proposals" in the CfP).

More Information on MCOPs

I read all the FAQs about multi-cycle observations, but I still have questions. Where can I find more information?

The Call for Proposal is the definitive document where MCOPs are defined and explained. For further questions please contact the Chandra HelpDesk.

Last modified: 16 December 2016
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