P2PP for Surveys

This page provides a quick overview of the enhancements to the functionality of P2PP for Surveys and provides links to the relevant documentation.

P2PP for Surveys User Manual and related documents

Time-linking of OBs

It is frequent that OBs must be executed within precise time windows, rather than any time when the external conditions (moon, seeing, transparency...) would allow the execution. The following types of time-dependencies can be recognized:

• Absolute time constraints, meaning that an OB must be executed at specific dates that can be predetermined. An example is the observation of a binary star at a precise phase of its period.
• Relative time links, implying that an OB must be executed within a time interval after the execution of a previous OB, but not necessarily at a fixed date. Examples of this are monitoring observations of a variable source at roughly constant intervals.

Within a Time Link container, the user can define a series of OBs, having the earliest and latest time when a given OB in the series must be executed with respect to the preceding OB. The time-related information is stored in a database, from where it is retrieved by scheduling tools available to the operator on the mountain in order to build up a short-term schedule that properly takes these constraints into account.

Concatenation of OBs

In some cases it may be desired to execute the OBs consecutively, with no other observations in between. This has been implemented in the P2PP for Surveys within the new "Concatenation" container. The concatenation container consists of two or more OBs that must be executed "back-to-back" without breaks. The sequence of the execution of OBs in a concatenation cannot be specified.

Definition of groups of OBs

It has been recognized nevertheless that such simple priority scheme is sometimes insufficient to deal with programmes containing large number of OBs, and especially for surveys containing large numbers of target fields observed in a number of instrumental setups. In such cases the need for a prioritization scheme above the individual OB level, which can take into account the past execution history of the programme, becomes clear. One can consider for instance the case of a survey of several target fields to be observed through several different filters, with each field and filter specified in a single OBs. Depending on the science goals of the programme it may be desirable to complete the observations of a given field in all filters before proceeding to the next field, or conversely to observe all the fields in a given filter before proceeding to the next filter, or even ensure that contiguous coverage among the fields takes priority.

The approach adopted to deal with such cases is the definition of groups of OBs, in which internal priorities within each group are reflected in the form of a contribution of each OB to the total group score. The short-term scheduling tools available on the mountain will take into account the current scores of each group of OBs, and will then apply a number of rules in order to prioritize the possible OBs to be executed according to them. Such rules will for instance give the highest execution priority to those OBs that set a new maximum of the score among the existing groups; and among those, the highest priority will be given in turn to those that produce the largest increase in group score. By assigning to the OBs the appropriate contributions to the scores of their respective groups, the users can make sure that the progress in the execution of the programme will take place in a way that is consistent with the scientific priorities of the observations. In addition, it will be possible to assign different priorities to each group.

Import of target fields produced by the Survey Area Definition Tool