2.9 STIS Snapshot Program Policies

For Cycle 28 STIS MAMA imaging modes and the STIS NUV-MAMA PRISM will not be allowed in snapshot programs. Other spectroscopic STIS MAMA snapshots are allowed, but the combined total of STIS MAMA and COS snapshot targets accepted in Cycle 28 will be restricted. See the Call for Proposals for further details. The prohibition on MAMA imaging and PRISM snapshot targets was instituted because the labor-intensive field bright-object checking requirements, when combined with the low-execution probability for STIS MAMA snapshots, results in a very inefficient use of resources. Moving targets are not permitted for STIS MAMA snapshot visits. Variable STIS MAMA snapshot targets must have well-defined maximum UV fluxes, which will be used for the bright-object checking. There are no restrictions on the numbers or variability of proposed STIS CCD snapshot targets, as they do not require bright-object checking and have a significantly higher expected completion rate. Thus, use of the STIS CCD G230LB or G230MB gratings is encouraged as an alternative to the NUV-MAMA.

In addition, STIS MAMA snapshot proposals should be limited to one or a few straightforward configurations. Specifically, use of the F25NDQ filters will not be allowed in MAMA snapshot proposals. Use of the 0.2 × 0.2 echelle aperture is recommended for first-order programs without a scientific need for a long slit in order to expedite the field bright-object screening process; these configurations are now supported. Because of the limited resources available for bright-object checking combined with the relatively low expected completion rate, excessively complex STIS MAMA snapshot targets, fields, or instrumental configurations may not be implemented in Phase II. If you are in doubt on this issue, you may consult with a member of the STIS Team via the Help Desk.