Main Proposer Page

What's New in Cycle 22

Bright Sources

Observations of extremely bright sources (> 5 Crab) carry significant risk to the detectors and will only be considered in exceptional cases. Proposers who wish to observe sources that are known to reach these flux levels must contact the CXC Helpdesk before submitting a proposal.

Resource Costs

We are developing a new metric accounting for the complexity/ease of scheduling each non-TOO observation which will encompass most of our previous constraint-related allocations: Resource Cost (RC). See Section 4.3 of the CfP for more details.

At the time of writing (December 2019) the RC metric is being finalized and we anticipate that it will be ready in February 2020. Proposers will be informed by 15 February 2020 if the RC metric is not ready for use. If the RC metric is not implemented the old constraint categories will be used. Assuming that the new RC metric is implemented, proposers will be able to estimate RC associated with their proposed targets via CPS no later than 15 February 2020. Examples of RC for different targets (e.g. high ecliptic latitude, a simple window constraint etc.) will be posted on the Cycle 22 Proposers webpage. PIs of proposals that are submitted prior to the RC algorithm becoming available will be contacted with estimates of the total RC for their proposal should they wish to update their proposal based on the new RC.

Prior to Cycle 22, constraints were classified into "easy", "average" and "difficult" categories. If the new RC metric is implemented by 15 February 2020 these categories will no longer be used in Cycle 22.

Observing Preferences

Prior to Cycle 22, observing preferences (e.g. time windows, roll angles etc) were allowed to enhance the science return of proposed observations. Due to the increasing complexity of keeping the spacecraft within acceptable thermal limits, preferences will not be accepted in Cycle 22 and beyond. Coordination with ground-based observatories must now be entered as a constraint.

Roll and/or offset adjustments after LTS placement

Some proposers ask to adjust the roll and/or pointing of an observation once the observation is placed in the Long Term Schedule and the nominal roll angle known. This request is frequently made to ensure an extended target is optimally positioned on the detectors. From Cycle 22, these requests must be specified on the CPS forms. Observations constrained in this way will incur a higher RC (or a constraint if RC are not implemented).

TOO Follow-ups

From Cycle 22, all TOO follow-up observations (observations following an initial trigger observation) will count as TOOs for the purposes of counting triggers at the peer review - see Section 4.6 of the CfP for more details.

TOO Response Times

TOO response times and the number of available triggers within each response category have changed. Please see Table 6 of the CfP. The total number of triggers (all response categories) has not changed.

High Ecliptic Latitude Targets

Targets at high ecliptic latitude (> 55 degrees) heat the Aspect Camera Assembly and are always at a thermally unfavorable pitch angle. A maximum of 2.5 Ms of observing time on targets situated above 55 deg or below -55 deg ecliptic latitude will be available at the Cycle 22 peer review. Proposers are encouraged to favor low ecliptic latitude objects unless key science goals require high latitude targets. See Section 4.5 of the CfP for details.