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Instrument Capabilities

NICMOS, the Near Infrared Camera and Multi-Object Spectrometer, is an HST axial instrument, containing three cameras designed for simultaneous operation. The NICMOS optics present the detectors with three adjacent but not spatially contiguous fields-of-view of different image scales. The instrument covers the wavelength range from 0.8 to 2.5 microns, and contains a variety of filters, grisms, and polarizers. Each camera carries a complement of 19 optical elements, selected through independent filter wheel mechanisms, one per camera.

The basic capabilities of the instrument, and the chapters which discuss them are:

IR imaging: NICMOS provides its highest sensitivity from 1.1 to ~2 microns, where it is superior to that achievable on an 8m class telescope, and better sensitivity than the WFPC2 for all observations for wavelengths longward of 0.9 microns. Chapter 4 discusses the overall throughput of NICMOS and the optical elements available in each camera. The low background will allow deep photometry. Our estimates of limiting sensitivities per pixel to give a 5

detection in a 60 minute integration are given in Table 3.1.

Table 3.1: Limiting Sensitivities per Pixel in Janskys for 5 Detection in 60 -Minutes (assumes point source centered on pixel)
Camera	Filter
Camera	F110W	F140W	F160W	F240M
bandwidth (microns)	0.8 to 1.35	0.8 to 1.8	1.4 to 1.8	2.3 to 2.5
NIC1	2.4x10^-7 (J~23.9)	2.3x10^-7(J~24.6)	5.5x10^-7 (H~23.1)	-
NIC2	8.5x10^-8 (J~25.1)	-	1.8x10^-7 (H~24.3)	5.2x10^-6 (K~20.1)
NIC3	6.5x10^-8 (J~25.3)	-	7.8x10^-8 (H~25.2)	2.8x10^-6 (K~20.7)

Grism Spectroscopy: Camera 3, NIC3, has three grisms which provide a multi-object spectroscopic capability with a resolving power of R ~200 over the full field of view of the camera. Their wavelength ranges are 0.8 to 1.2 microns, 1.1 to 1.9 microns, and 1.4 to 2.5 microns. Because the grisms are slitless, the spectra of spatially resolved objects are confused and multiple objects can overlap.
Imaging Polarimetry: Three polarizing filters with pass directions of 0, 120, and 240 degrees are provided for the wavebands 0.8-1.2 microns in Camera 1, NIC1, and 1.9-2.1 microns in Camera 2, NIC2.
Coronography: A 0.3 arcsec radius occulting spot and cold mask, in the intermediate resolution Camera 2, NIC2, provides a coronographic imaging capability. Chapter 5 discusses these three special capabilities.

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Instrument Capabilities

Table 3.1: Limiting Sensitivities per Pixel in Janskys for 5 Detection in 60 -Minutes (assumes point source centered on pixel)

Camera

Filter

F110W

F140W

F160W

F240M