Welcome to the fourth issue of ISO INFO. This newsletter is published at irregular intervals to keep the astronomical community informed of the progress of the Infrared Space Observatory (ISO). The majority of observing time on ISO will be available to the astronomical community via submission and review of observing proposals. The Call for ISO Observing Proposals will be released in April 1994; ISO INFO is being published now to raise the awareness of the capabilities of ISO and to alert the community to the observing opportunity. Please circulate this newsletter to interested colleagues.
ISO is the next astronomical mission of the European Space Agency (ESA). It is being readied for launch during a September 1995 launch window atop an Ariane vehicle. ISO will be the major space-based Infra-Red astronomical mission this decade and, therefore, it is vital that the community prepares to make full use of it.
For those new to ISO, this newsletter contains an overview of the mission and a summary of each of the four ISO scientific instruments. Additionally, it outlines the Call for Observing Proposals, plans for operations and the guaranteed time observing programme. To help inform the community about ISO, a series of extended seminars is being given by ESA Astronomers; a list of these talks is included in this issue.
In the four years since the last ISO INFO, much progress has been made, with problems being encountered and solved. The current status is that the flight models of the scientific instruments and the telescope have been integrated and tested in the flight cryostat. Some of the significant changes that have occurred in the programme are: