& the reviewing process
The ISO Call for Observing Proposals was released at the end of April 1994
with due dates of 19
and 23
August for electronic and paper
proposal submission, respectively. A total of 1000 proposals was received.
Roughly one third of these proposals were for stellar/circumstellar topics,
another third for extragalactic studies and one quarter addressed the
interstellar medium. The rest of the proposals were split roughly equally
between solar system and cosmological subjects. Each proposal contained a
list of observations giving the planned time and instrument observing mode for
each. The two ``pie'' charts (Figures 1 and 2) show how the requested time
was distributed between the instruments on the basis of both time and number of
observations. [A similar analysis will be presented in a later ISO INFO for
the results of the Call once phase 2 data entry has been completed].
These proposals were assessed for technical feasibility by staff of the ISO Science Operations Centre and for scientific merit by the ISO Observing Time Allocation Committee (OTAC), which had been set up by the ESA Director of Science. The composition of the OTAC is contained in a later section of this newsletter.
During the technical feasibility assessment, there were some interactions with proposers in the cases where either there were insufficient technical details or where feasibility was doubted. All the assessments were sent to the OTAC, together with any additional comments from proposers. Each of the OTAC panels met individually at least once before the end of November. Following these meetings, the Panel Chairmen met to discuss large (>50 hours) proposals and to harmonize the results of individual panels. The results were then sent by the OTAC Chairman to the ESA Director of Science for review and release. Proposers were informed of the results in January.
Figure 1: Division of requests between four instruments on basis of time.
Recommendations were made for observations to fill 3000 hours of time (leaving
some to be allocated via Discretionary Time as well as by the planned
post-launch Supplemental Call for Observing Proposals) in 2 priority classes
(1 and 2) plus another 
3000 hours as priority 3 for the necessary
oversubscription in the Mission Data Base. The 1000 hours in priority 1
(classified as ``must be done'') correspond to the top 8% requested.
The 2000 hours in priority 2 correspond to the next 16%. In cases of
duplication, one proposal was chosen; thus, even some excellent proposals
failed to get time. Overall, the recommended observations are distributed
over a total of 619 proposals. The table below summarises the OTAC
recommendations for the autumn launch window.
Figure 2: Division of requests between four instruments on basis of number of observations.
In the notifications to proposers several caveats have been made. It has been emphasised that, due to operational constraints, no guarantee can be given that any particular observation will be carried out. Proposers have also been informed that the OTAC recommendations are based on the current pre-launch estimates of spacecraft, instrument and ground segment performances and that the actual performances will be measured during the first two months of ISO operations. Based on these Performance Verification results, there will be a review of the ISO observing programme, including OTAC members, and there may well be changes in recommended priorities. A full list of the proposals with recommended observations is given in the following sections.