C.8	Near Infrared Camera and Multi-Object Spectrometer (NICMOS)

This camera provided near-infrared imaging through three independent channels. NICMOS was installed in February 1997 and had operated with a cryogenic cooling system since March 2002. NICMOS continued to operate until September 2008, when the NICMOS Cooling System (NCS) failed to cool down the instrument, following a warm-up due to a planned safemode. The instrument was not successfully restarted after Servicing Mission 4. The NCS, which was required to maintain NICMOS at its nominal operating temperature for science observations, is currently disabled.

Although the NCS was not restarted, NICMOS proposals were solicited for Cycles 18 and 19. Based upon assessments of those proposals and the efforts required to recommission NCS and NICMOS, no proposals were selected and the NCS has remained off. NICMOS proposals are not being solicited for Cycle 21.

The three NICMOS channels (NIC1, NIC2, and NIC3) provided adjacent but not spatially contiguous fields of view of different image scales; they each covered the same wavelength range from 800 nm to 2500 nm. The foci of NIC1 and NIC2 were close enough that they could be used simultaneously, whereas NIC3 had to be used by itself. NICMOS was superseded by the WFC3/IR for most infrared imaging, except for a few specialty or unique modes.

The NICMOS Camera 3 (NIC3), had the lowest spatial resolution of the three channels with a 51.2" x 51.2" field of view. The detector was a 256 x 256 HgCdTe array with 40 x 40 μm pixels. The plate scale was 0.2 arcsec/pixel. The camera did not provide diffraction-limited imaging and was operated slightly out of focus. The camera had 19 filters and one blank on a single filter wheel. Well-dithered observations with the NIC3 led to a reconstructed PSF FWHM of approximately 0.24 arcsec at 1.6 μm, increasing slightly with wavelength.

The intermediate field channel (NIC2) had a 19.2" x 19.2" field of view. The detector was a 256 x 256 HgCdTe array with 40 x 40 μm pixels. The plate scale was 0.075 arcsec/pixel. The camera provided diffraction-limited imaging at 1.75 μm and longer. The camera had 19 filters and one blank on a single filter wheel. Well-dithered observations with the NIC2 led to a reconstructed PSF FWHM of approximately 0.19 arcsec at 1.6 μm, increasing slightly with wavelength.

The narrow field channel (NIC1) had the highest spatial resolution of the three with an 11" x 11" field of view. The detector was a 256 x 256 HgCdTe array with 40 x 40 μm pixels. The plate scale was 0.043 arcsec/pixel. The camera provided diffraction-limited imaging longward of 1 μm. The camera had 19 filters and one blank on a single filter wheel. Well-dithered observations with the NIC1 led to a reconstructed PSF FWHM approximately 0.14 arcsec at 1.6 μm, increasing slightly with wavelength.

In the near-infrared, NICMOS was unique in providing imaging polarimetry and coronagraphy. NICMOS also provided HST’s only capabilities longward of 1700 nm including access to the Pa line and K band. Furthermore the ability to defocus the NICMOS grisms had enabled spectroscopy of bright targets. NICMOS had grisms for slitless spectroscopy.