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NOAO Newsletter - Kitt Peak National Observatory - September 1999 - Number 59


SQIID Returns in 2000

As anticipated, one of the results of the ALADDIN InSb array development program was useful devices with fewer than four working 512 512 quadrants. Simultaneous Quad Infrared Imaging Device (SQIID) was the intended home for such arrays, because SQIID's optics can illuminate the inscribed circle of one 512-quadrant in each of four wavelength bands. SQIID is currently being retrofitted with four ALADDIN arrays and the controller is being upgraded to run the four individual quadrants. SQIID is likely, but is not at all guaranteed, to be available for shared risk use on the Mayall 4-m and 2.1-m for Semester 2000A.

The increased sensitivity of SQIID with InSb arrays will be ~ 1.4 mag at J and ~ 1.8 mag at K over the successful PtSi arrays. The field-of-view will be twice that of the original configuration with 256 256 arrays (that's four times the area).

The retrofit of SQIID is now well along, with T&E time for the instrument currently scheduled for the 2.1-m just before Thanksgiving 1999. Propsosals in 2000A for IR imaging with ONIS or IRIM that could make use of the unique properties of SQIID should note this opportunity briefly in their proposal. If SQIID is your preference and is available, your successful proposal will be scheduled with it when possible.

The following are anticipated performance characteristics of the upgraded SQIID:

    KPNO telescope:     2.1-m       4-m
    Platescale:         0.68        0.39"/pixel
    Circular FOV:        348        200"

The plate scale represents a reasoned balance between FOV and image sampling appropriate to the delivered image quality.

The estimated limiting magnitude for S/N = 3 in 60s integration time for a point-source (pt: mag) and a diffuse-source (diff: mag/square arcsec) (temperature = 50F; 3mm PWV; midrange KPNO OH background)

                           2.1-m              4-m
                        pt      diff       pt     diff

                J     19.43    20.38     20.60    20.94
                H     18.55    19.55     19.72    20.07
                K     18.00    18.96     19.17    19.52
             3.28nb*  12.15    13.10     13.31    13.66

*0.074 m bandpass

Michael Merrill, Richard Green


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