PDS_VERSION_ID = PDS3 RECORD_TYPE = "STREAM" LABEL_REVISION_NOTE = "2007-01-09: Information loaded into OLAF by Matthew Knight" OBJECT = INSTRUMENT INSTRUMENT_ID = "SQIID" INSTRUMENT_HOST_ID = "OBS321T3" OBJECT = INSTRUMENT_INFORMATION INSTRUMENT_NAME = "SIMULTANEOUS QUAD INFRARED IMAGING DEVICE (SQIID)" INSTRUMENT_TYPE = "INFRARED IMAGER" INSTRUMENT_DESC = " Instrument Overview =================== The NOAO SQIID (Simultaneous Quad Infrared Imaging Device) infrared camera produces simultaneous images of the same field in the J, H, K, and narrowband L filters, using individual 512 x 512 quadrants of ALADDIN InSb arrays and is designed for use at the f/15 Cassegrain foci of the KPNO 2.1-m and 4-m telescopes. On the KPNO 2.1-m, the pixel scale is 0.69 arcsec/pixel and the unvignetteed field of view is 304 x 317 arcsec (440 x 460 pixels). Instrument Characteristics ========================= The physical and optical characteristics and estimated imaging performance of SQIID are provided below. These properties are reproduced from the SQIID User's Manual, available at http://www.noao.edu/kpno/sqiid/sqiidmanual.html. This guide is included as documentation for this archive with permission from NOAO/KPNO (/DOCUMENT/SQIIDMANUALDOC.PDF). Physical characteristics ------------------------ Detector type : Raytheon Infrared Operations ALADDIN InSb array Detector format : 1024 x 1024 pixels (only 512 x 512 are used) Pixel size : 27 microns Data format : Two-dimensional FITS file [X,Y] Filters : J, H, K, L Nominal operating : 30 K, cooled by Closed Cycle Cryogenic Coolers temperature (no dewar) Guiding system : none Estimated imaging performance ----------------------------- Field of view : 304 x 317 arcsec (unvignetted) Detector pixel scale : 0.69 arcsec/pixel Wavelength range : Name Bandpass in microns J 1.131-1.402 H 1.535-1.809 K (pre 02/2002) 2.027-2.421 K (post 02/2002) 1.95-2.30 L 3.262-3.336 Data pipeline flow : ~40 sec, roughly fixed Internal co-addition : 0.10 sec Observing efficiency -------------------- To optimize observing efficiency and avoid saturating the detectors while building up integration times, images are taken then coadded on the chip a number of times before being read out to the disc. Each internal coaddition requires only 0.10 ms while each read to disc requires ~40 seconds. For example, 8 second exposures with 10 coadditions results in a total integration time of 80 seconds. Including the readout time, this takes ~120 seconds, resulting in an observing efficiency of 0.67. However, reading to disc after each 8 second integration would require ~48 seconds, resulting in an efficiency of only 0.13. Array characteristics and system responsivity --------------------------------------------- Characteristic J H K L Response uniformity : +/-5% +/-5% +/-5% +/-5% Quantum efficiency : 95% 95% 95% 85% Bias (mv) : 700 700 700 800 Full well (electrons) : >200000 >160000 >200000 >300000 in situ read noise : 40 40 35 35 (electrons rms) in situ dark signal : 21 32 197 26 (electrons/sec) Conversion gain : 10 10 11 11 (electrons/ADU) Minimum integration time (sec) : 0.84 0.84 0.84 0.11 10 mag star within aperture : 3.25e4 2.90e4 1.78e4 ? (ADU/sec) Sky brightness level : 98 421 387 ? (ADU/sec/pixel) Limiting magnitude for S/N=3 in 60 sec integration time point source (mag) : 19.8 18.9 18.3 12.3 diffuse-source : 20.2 19.7 19.2 13.1 (mag/sq_arcsec) Sky brightness origin : Filter Origin J OH airglow, scattered light H OH airglow, scattered light K OH airglow, thermal emission L thermal emission Detector non-linearity ---------------------- The response of the SQIID detectors is non-linear. The model fitted function for the relative error is: ym[x] = a(1) * x**2 + a(2) * x**3 where ym = relative error = (input - observed) x = observed (adu) The fit is valid for values < Xmax. For values beyond Xmax, the array is rapidly approaching saturation. The fitted parameters for each channel are summarized below (from Table 10 in the SQIID Manual (/DOCUMENT/SQIIDMANUALDOC.PDF): Channel : J H K L Bias (mv) : 700 700 700 ? a(1) : 6.4864e-7 -1.3456e-8 1.2626e-6 ? a(2) : 4.4790e-10 6.1010e-10 2.9498e-10 ? Xmax (ADU) : 16000 16000 16000 ? Valid from : Jun 2000 Jan 2005 Jan 2005 ? Note that prior to 2005 the bias was 600 mv, requiring different linearity coefficients." END_OBJECT = INSTRUMENT_INFORMATION OBJECT = INSTRUMENT_REFERENCE_INFO REFERENCE_KEY_ID = "N/A" END_OBJECT = INSTRUMENT_REFERENCE_INFO END_OBJECT = INSTRUMENT END