SWIRC Instrument Stats
SWIRC Optics

Detector: 2048 x 2048 pix, HgCdTe Hawaii-2
Pixel scale: 0.1500 arcsec/pix (optical layout)
Field-of-view: 5.12 x 5.12 arcmin^2
Electronics gain: 4.0 e-/DN
Read-noise: 31 e-
Full well: ~190,000 e-, or 48,000 DN
Linearity: Linear to 40,000 DN (linear to better than 0.1%)
Dark current: 16 e-/s/pix
Bias drifts: The bias changes by 400 DN over 20 sec, thus darks must be taken for every exposure time <20 sec.
Filters: Y (plot, data), J (plot, data), H (plot, data), and a dark positions D1.
Detected electrons:For 15th mag star (Vega-relative)
Y-band: 26,000 e-/s
J-band: 33,000 e-/s
H-band: 37,000 e-/s
Sky background: Y-band: 650 e-/s/pix = 14.9 mag/arcsec^2
J-band: 470 e-/s/pix = 15.5 mag/arcsec^2
H-band: 2600 e-/s/pix = 13.7 mag/arcsec^2
Exposure time...for sky to reach 20,000 DN (half the linear regime):
Y-band: 90 seconds
J -band: 120 seconds
H-band: 20 seconds
Distortion: Very small (predicted 0.01% center-to-corner).
Cross-talk: None between quadrants; very little in channels within a quadrant.
Flat-fielding: Sky flats give ~2% accuracy across chip, excluding high dark regions.
Known problem: Channel 4.5 suffers from RMS=19 DN bias variations.
Cosmetics: High dark-current region in upper corners. The "scratch" and spot" cosmetics mask out well.
Readout: 32 channels; 8 channels per quadrants.
Readout time: 0.7 sec per readout; 5 sec total overhead per exposure including telescope dither.
Exposure times: Must be integer seconds >= 1 sec.

Note: images with the Hawaii-2 are taken by differencing a pair of non-destructive reads.
There is no shutter in SWIRC; rather, each line is cleared before being read the first time.
The Hawaii-2 is put in a continuous clear mode in-between exposures.

bad pixel mask dark frame flat-field
Bad Pixel Mask: Save Link Target         Dark Frame (5 seconds)                        Twilight Flat (H band)

Questions? Contact wbrown@cfa.harvard.edu