After the Peer Review, the Chandra Director's Office (CDO) sends a message to observers of approved programs, requesting that they confirm basic observing parameters for their targets.
After observers confirm basic parameters, a long-term schedule (LTS) can be generated. The LTS includes all observations for the given cycle. This consists of both targets that need to be assigned to specific weeks, plus targets assigned to a "pool". Pool targets are unconstrained observations that are used to fill out the weekly short-term schedules (STS).
The LTS is updated each week to incorporate changes as the cycle progresses.
After the initial LTS is built for a cycle, the Chandra uplink support Interface scientists ("USINT", or "uplink scientists") contact observers to requests a more detailed second confirmation of observation parameters. If these parameters are not confirmed in a timely fashion, the target may need to be rescheduled, sometimes after a considerable delay.
The final planned short-term schedule (STS) for the week is posted on the public web soon after the schedule is approved for upload to Chandra.
Targets are placed in the LTS according to constraints imposed by both science and spacecraft requirements. Observers should be aware that some targets may be scheduled early. During the transition period before the nominal start of a new cycle, the LTS usually includes a mix of targets from both cycles.
Observers can review observation parameters in the Chandra database at any time using either WebChaSeR or from the pages linked off the table returned by the Target Search Form.
Observers are encouraged to review these pages to confirm the observation setup well in advance of their LTS observation date and either submit changes or else confirm that the configuration is correct to their uplink contact scientist.
After the initial parameter confirmation done by CDO, each Chandra observation is assigned an uplink support (USINT) scientist from the DOSS or Calibration groups at the CXC based upon the selected instrument. The uplink scientist is responsible for contacting each observer to confirm their observation configuration in more depth in advance of releasing the observation for scheduling in an STS.
The support process includes a series of steps:
| Action | Usual Timing (days are counted back from the first day of the target's LTS week) |
| First Contact from the Director's Office | Within one month of the announcement of approved targets for the new cycle |
| USINT Contacts the Observer | Start of Cycle (earlier if targets are selected for early scheduling) |
| Observer Response to USINT contact required | 32 days (Failure to respond to USINT can cause significant delays in the scheduling of an observation, possibly as long as a year in extreme cases.) |
| Observing Parameters are finalized in the CXC database | 25 days |
| Observation request is submitted for scheduling | 23 days |
A generic form of the current contact letters and information can be found at one of the following links:
This is generated for each observing cycle. It places about 50% of the targets into one week bins, taking note of all observing constraints. In order to achieve an efficient final schedule, the remaining unconstrained targets are placed in the pool and are selected for observation by the Mission Planning team as they become visible to Chandra.
The LTS is updated roughly once a week, and is available on the LTS page. Pool targets, which are those most likely to move around, are labeled clearly in each schedule.
This is generated weekly in preparation for upload to Chandra on the Sunday of each week. It is also updated on the public web site soon after notification of final approval for an STS goes out.
This is the official observation plan but we note that unanticipated events, such as TOOs, increased solar activity, satellite problems (etc.), can interrupt the schedule - resulting in some of the observations not being completed. In this case, an updated STS is generated and posted on the web and affected observers are notified.
Due to the unpredictable nature of the observations, TOO and DDT targets are not usually assigned an uplink scientist until after a trigger has been approved. If they have not been assigned a USINT person before triggering an observation, the observers of these proposals may request help from the CXC through the HelpDesk.
