Chandra X-Ray Observatory

Main Proposer Page

What's New in Cycle 18

Large Programs:

The default boundary between General Observer (GO) and Large Projects (LP) is set at 400 ksec for Cycle 18 and future cycles. In recent cycles, the large number of LPs has resulted in an undue burden on the Big Project Panel (which makes the final recommendation on LPs) and also the Topical Panels (LPs are reviewed in two panels). As in previous cycles, an LP must be designated as such by the PI.

FAQ: Why change the LP boundary from 300 to 400 ks?

Answer: Read about this decision via the following link:

Joint Contingent Large Projects (JCLPs):

Programs that require substantial investments of observing time from Chandra and one or more other facilities (the Contingent Observatories or COs), where the observing requests are too large to be considered as a normal Joint proposal. Currently, COs are limited to NASA/ESA space facilities. The Chandra time is approved but not scheduled until time on the partner facilities is approved. If the relevant proposal is not awarded its full request by the CO Time Allocation Committee(s), the Chandra program is withdrawn. JCLPs must request ≥ 400 ksec of Chandra time. The minimum CO requests are: 35 orbits for HST, 20 hours for Spitzer, and 300 ksec for XMM, Swift and NuStar. The total time allocated to JCLPs ≤ 500 ksec in Cycle 18. JCLPs are reviewed via the same process as LPs. They can be multi-cycle, and/or contain time-constrained targets, but observations cannot be constrained to occur before October 2016. Full details are given in Section 5.1.

FAQ: Is only one JCLP going to be approved in this cycle?

Answer: The number of JCLP proposals to be approved is not pre-determined. The peer review will make recommendations via the usual process and may, for example, recommend more than one by including only part of the proposed time request(s).

Default Target Offsets:

The Chandra aimpoint has changed throughout the mission primarily due to thermal changes in the Aspect Camera Assembly. To compensate for these changes, default offsets were introduced to place the target away from chip edges or node boundaries and closer to the optical axis. In the past year, ACA temperatures have fluctuated more rapidly. To compensate for these changes, target offsets will be calculated and applied at the time a target is scheduled to be observed. Full details are given in the POG, Chapters 4 and 5.

Initial Proposal Parameter Sign-Off (IPPS):

In previous Cycles, there was a two-step checkoff process for approved targets. In the first step, observers were contacted and asked to confirm that basic target information was correct (the Initial Proposal Parameter Sign-off (IPPS)) so that the target could be inserted into the Long Term Schedule. The second step involved a detailed discussion of the observing set-up. In Cycle 18, observers will have the opportunity to sign off on targets as "flight ready" at the IPPS stage. Observers may request help from an instrument scientist at any time. All targets declared "flight ready" via IPPS will be reviewed by an instrument scientist before being scheduled.

Cycle 18 Scheduling:

The nominal start time for Cycle 18 is January 2017. To facilitate planning, a mix of Cycle 17 and Cycle 18 targets will be scheduled for some time before and after the nominal change-over month. We expect that Cycle 18 observations will take up greater than 50% of the available time from sometime in February 2017.

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