For Phase 1 proposals, the duration of each requested observation has to be estimated and entered into IRPSS by the proposer. IRPSS does not calculate the observing times. Instructions for calculating times are contained in the Observer's Manuals for ISO and the instruments; in some cases ``cookbooks'' are to be used and in other cases software time estimators may be available. Obviously, these only give approximations to the time that the observation will take. Observers should mention in their proposals how they calculated the observing times. Based on the received proposals, OTAC will recommend maximum times for proposals; these maxima must be respected during the Phase 2 data entry and thereafter. As observing times can vary fairly dramatically based on the fine details of the observations which will only be finalised during Phase 2, OTAC reserves the right to reconsider, after Phase 2, the priorities set and the times recommended.
In addition to the above, the ISO SOC will provide--on a ``best efforts'' basis--access by remote login to PGA in order that proposers may make spot checks of the ``real'' time for some of their observations; IPAC will provide a similar facility for US observers. Note that these times are ``real'' in the sense that they are calculated by the same software that is used to generate the commands to the instruments and that they include the overheads. However, they are based on current calibrations and might change as the understanding of the in-orbit performance of the instruments continues to increase.
To make use of this facility, an e-mail request should be sent to the ISO helpdesk (see section 5.2). You will be given a limited time period to use a specified PGA account, which will be set up initially with some typical AOTs, which you can modify to suit your proposed observations. These data bases will not be saved at the end of your session. This facility will close on 1 October, approximately one week in advance of the deadline. Depending on demand some access rules will be set. These are likely to include limiting each ``session'' to 24 hours and restricting the number of sessions that each OBSID (observer identification) may book in advance.