STScI Logo

Hubble Space Telescope
NICMOS Predefined Patterns

WHERE ARE THE PREDEFINED NICMOS PATTERNS?

NICMOS patterns are now supported for use by GOs for completing their Cycle 11 Phase 2 Proposals. A GO had reported that NICMOS patterns were not supported by the initial RPS2 release (version 11.0). It turns out that NICMOS patterns had not been switched from "restricted" to "supported" in the Phase 2 Proposal Instructions and RPS2. The Phase 2 Proposal Instructions and RPS2 (version 11.1) were updated to fix this on January 21, 2002.

HOW DO I SPECIFY A NICMOS PATTERN?

The easiest way to specify a NICMOS patterns is through the RPS2 proposal editor (PED), but you can also simply fill out the pattern form in the RPS2 template (and the syntax will be checked by the Syntax checker within RPS2). Regardless of how you choose to type the pattern syntax it is important to read Chapter 8 of the Phase 2 Proposal Instructions to understand how to use patterns. Additional information specifically about the NICMOS patterns can be found in Chapter 11 of the NICMOS Instrument Handbook.

HOW ARE THESE PATTERNS DIFFERENT THAN THE ONES I USED IN CYCLE 7?

The NICMOS predefined patterns are similar to those used by Cycle 7 NICMOS observers. In Cycle 7 the patterns were specified using Optional Parameters, but now they are specified in a separate pattern block and tied to a specific exposure through a new Special Requirement. The new pattern structure has extended the pattern capability to allow multiple exposures to execute at each pattern position. Thus observers can obtain multiple filter exposures at each pattern position without repeating the pattern for each filter. In addition, the new pattern structure allows the selection of the pattern coordinate frame: instrument (POS-TARG) or sky (Celestial), as well as selection of spacing size and orientation.

WHAT PREDEFINED NICMOS PATTERNS ARE THERE?

There are 12 supported NICMOS patterns. Seven patterns use the instrument POS-TARG coordinate frame: NIC-ONE-CHOP, NIC-TWO-CHOP, NIC-SPIRAL-DITH, NIC-SPIRAL-DITH-CHOP, NIC-SQUARE-WAVE-DITH, NIC-XSTRIP-DITH, and NIC-YSTRIP-DITH, and five patterns use the Celestial coordinate frame: NIC-MAP, NIC-SPIRAL-MAP, NIC-SKY-ONE-CHOP, NIC-SKY-TWO-CHOP, and NIC-SKY-SPIRAL-DITH-CHOP.

There are also a few nested patterns which use both a primary and secondary pattern. NIC-SKY patterns use the Celestial coordinate frame for both the primary and secondary patterns. However, pattern NIC-SKY-SPIRAL-DITH-CHOP has coordinate frame POS-TARG for the primary pattern and the celestial coordinate frame for the secondary pattern.

Three patterns, which are not supported for Cycle 11, are underdevelopment and will be supported for Cycle 12: NIC-XSTRIP-DITH-CHOP, NIC-YSTRIP-DITH-CHOP, and NIC-SKY-XSTRIP-DITH-CHOP.

The NICMOS predefined patterns have been implemented to assist the observer in preparing Phase 2 observations. It is recommended that NICMOS observers use one of the supported NICMOS patterns. However, if the predefined patterns are not sufficient for a particular set of observations, then observers can specify their own pattern using the generic line and spiral patterns.

The following is an example Phase 2 pattern specification for the NICMOS pattern NIC-SPIRAL-DITH:

Pattern_Data

Pattern_Number: 1
Primary_Pattern:
Pattern_Type: NIC-SPIRAL-DITH
Pattern_Purpose: DITHER
Number_Of_Points: 4
Point_Spacing: 9.766
Coordinate_Frame: POS-TARG
Pattern_Orient: 0.11
Center_Pattern: NO