urn:nasa:pds:context:instrument:flwo.2mass1m3.2massnorth 1.0 1.10.0.0 Product_Context 2020-02-18 1.0 Initial export from OLAF urn:nasa:pds:context:telescope:flwo.2mass1m3 instrument_to_telescope Milligan et al., SPIE Proceedings Volume 2863, p. 2, 1996. 2MASS Camera - North Imager Each 2MASS camera consisted of a liquid nitrogen cryostat which contained three 256x256 NICMOS3 arrays. Each array viewed the same region of the sky via beamsplitting dichroics. The light passed through both dichroics to the Ks-band array. The first dichroic reflection fed the light to the J-band array. All three optical paths shared the same first element located behind a cryogenic field stop. Each optical path had six other lenses. This set of six lenses was identical for each band. The lenses were composed of water-free fused silica (Infrasil) or calcium fluoride. All lens surfaces were spherical. All optical elements were anti-reflection coated and the integrated optical assembly transmitted ~70% of the incident light. A band-limiting interference filter located near a pupil image established the system bandpass. Table 1 summarizes the Survey's bandpasses: Table 1: 2MASS 50% Transmission Band[INVALID_PDS_CHARACTER]Optics and Camera[INVALID_PDS_CHARACTER]System + Atmosphere J 1.11 - 1.40 um 1.12 - 1.36 um H 1.51 - 1.79 um 1.51 - 1.78 um Ks [INVALID_PDS_CHARACTER]2.00 - 2.31 um 2.02 - 2.30 um This instrument catalog refers to the 2MASS camera used at the northern hemisphere 2MASS facility, at the Whipple Observatory in Arizona.