During the early stages of the ESA-sponsored NGST spectrograph study late in 1998, it was realised by the members of the ESA Study Science Team (SST) that the Multi-object and Integral Field options for the 1-5µm NGST spectrograph would have substantially different matching to the range of scientific programmes represented in the Design Reference Mission (DRM).
This issue was being addressed by the Study consortium and they decided to concentrate the later phases of their work on an image-sliced, integral field approach which has been described in detail in their final presentation. The motivation for this choice was two-fold: a scientific judgement that an integral field device would produce a richer scientific return from NGST and a perceived need to study a spectrograph design which was substantially different from those being developed by the US ISIM teams.
In parallel with the study consortium's work, the ESA SST set up a small working group - one of three to consider spectrographic, optical and mid-infrared aspects of NGST - with the brief to report to the ESA Astronomy Working Group (AWG) in April 1999 but then continue their considerations in preparation for the Woods Hole Exposition in September.
During the spring of 1999, the STScI took a similar initiative and set up an independent study of spectrograph options under the chairmanship of John Huchra. Guenther Hassinger, from the ESA AWG, is a member of both the Huchra committee and the ESA IF-MOS working group.