Article by: Andacs Robert Eugen, on 23 April 2022, at 09:05 am Los Angeles time

We are all waiting for this announcement!

The James Webb Telescope is nearing the beginning of its scientific observations. For this, STScI has prepared the scientific observation program for Cycle 1 JWST.

This is called a long-term plan or LRP.

Below, the Space Telescope Science Institute presents some of the frequently asked questions and answers (Q&A).

Q. What is the Long Range Plan (LRP)?
A. The JWST Long Range Plan lays out all the planned visits for a complete Cycle, including General Observer, Guaranteed Time, Early Release Science, and Calibration programs. Cycle 1 consists of more than 11,000 hours of approved time. Every visit is assigned one and only one plan window in the LRP, during which the visit may be scheduled. Typical plan windows have durations of 7-14 days, but may be both shorter and longer, depending on observing constraints and visibilities. Note that some visits are not currently placed in the LRP by design (e.g., Target of Opportunity visits).

 
Q. When will I know for sure that my visits are going to be observed in my assigned window?
A. JWST observations are sent to the observatory in one-week increments. Planning each weekly Short-Term Schedule (STS) begins 10 days before the first observation. The STS is usually completed on Fridays to begin execution Sunday evening (Eastern Time). Visits for the STS's are drawn from the LRP.

 
Q. How likely is it that my visit will be executed within the LRP window it was assigned?
A. The LRP may change throughout the Cycle, depending on external circumstances, such as Director's Discretionary programs, Target of Opportunity programs, failed observations, and differences between actual and assumed observing efficiencies during normal science operations. Consequently, it is possible that visits may be delayed, or pulled forward, in the LRP. Requests for schedule changes from Principal Investigators are only considered given a strong scientific rationale.

 
Q. Why are some of my visits scheduled more than a year after the start of Cycle 1?
A. For efficiency reasons, Cycle 1 is deliberately oversubscribed by ~30%. While STScI is committed to executing all approved programs, this means some visits will necessarily be scheduled more than a year after the start of the Cycle.

 
Q. Which factors determine when an observation is scheduled in the LRP?
A. LRP windows are assigned based on scheduling requirements requested by the program, as well as on data rate usage, number of visits within the field of regard, and momentum build-up. PI-directed special requirements (as set in APT) notably limiting or delaying visits in the LRP include orient constraints and timing constraints (schedule within, schedule after, etc.).

Q. Are Guaranteed Time Observation getting higher priority than General Observer programs?
A. GTO and GO programs receive equal priority for scheduling purposes. Only ERS programs are generally scheduled within the first 5 months of Cycle 1.

Q. What determines the fraction of time that can be filled by science visits in the LRP?
A. There are two primary factors: The total clock time available (8760 hours in a year) and the data volume produced by the visits. The data volume limit takes into account the data storage available on JWST and the average rate with which the Deep Space Network (DSN) can downlink the data during two daily contacts. The schedule also leaves space for unplanned observations, such as targets of opportunity.

Q. Where can I find the Long Range Plan?
A. Assigned plan windows for all approved programs are available via the Program Information Tool, under the Visit Status Information link.

Q. Where can I find the weekly Short Term Schedules?
A. The weekly Short Term Schedules will be posted on jwst.stsci.edu during normal science operations. Normal operations will begin after the end of JWST Commissioning, and after the ERO release, currently expected to be early July.

Source: STScl