As was done for all the HST instruments for past Cycles, we have
established a set of core scientific capabilities of NICMOS which will be supported. These capabilities cover an enormous range of science applications.
Three additional capabilities are “available”, but not supported for
Cycle 17. The use of these capabilities requires approval from STScI and detailed support for calibration will not be provided.
The use of this capability can be proposed upon consultation with a
NICMOS Instrument Scientist, and is useful only for target acquisition of extremely bright sources for coronagraphic observations. The use of this capability is strongly discouraged if the acquisition of a target for coronagraphic observations can be obtained with any of the supported capabilities. Proposals which include this unsupported NICMOS capability must include a justification of why the target acquisition cannot be done with a supported configuration, and must justify the added risk of using an unsupported mode in terms of the science payback.
Starting in Cycle 17 there will be an available observing mode for
de-focused observations. This mode is classified as "available but unsupported", which means that it is available to observers who request it, but it is not supported through a full calibration program, other than basic verification that the mechanism successfully moves to the commanded de-focused position. When in use, the PAM mechanism will move to a pre-determined position, leading to a decrease in the count rate. The amount of decrease depends on the filter in use. The de-focus mode can help prevent saturation when short exposures are necessitated by bright objects, but will suffer from a degraded image quality. To implement this mode, the observer should contact the Program Coordinator.ß
See Chapter 8
for a discussion of the problems that can be faced when using ACCUM