The LRIS red and blue detectors characteristics are shown in the table below. The detectors used in the two guiders are described in the Guiders CCDs page

  Blue Side Red side
Type 2 x 2K x 4K Marconi (E2V) CCDs, backside 15 µm pixels, science grade  LBNL 4k x 4k CCD 500-micron thick deep-depletion 15 µm pixels, science grade (Mark IV, installed in May 2021)
Outputs 4 amplifiers 1,2,3,4 (A,B,C,D old label) 4 amplifiers L1, L2, U1, and U2
Read noise
[e-/rms] Most Recent Measurements
1 2 3 4
3.9 4.2 3.6 3.6
L1 L2 U1 U2
3.64 3.45 3.65 3.52
Conversion Factor[e-/ADU] (Gain). Most Recent Measurements
1 2 3 4
1.55 1.56 1.63 1.70
L1 L2 U1 U2
1.71 1.64 1.61 1.67
Plate scale 0.135"/pix 0.135"/pix
Bias level ~1000 ADU ~1000 ADU
Saturation 65535 ADU 65535 ADU
Linearity 62,000 ADUs & Saturates at 65,536 ADUs see Linearity page 59,000 ADUs & Saturates at 65,536 ADUs see Linearity page
Bad Pixel Map Not Mapped Not Mapped

CTE @ 40,000 e-
CTE @ 200 e-
0.9999997 0.9999997 0.9999997 0.9999997
0.9999992 0.9999997 >0.999999 >0.999999
Prepix/Postpix 4x51=204 real pre image area pixels,
4x80=320 electronically added post image area pixels
Not Defined
Not Defined
Erase time [sec] 8 10
Readout time [sec] 42 90
Shutter time (from trigger to last movement) ~40 ms ~60 ms
Orientation vs keywords

When the rotator mode is set to "Position Angle" mode the ROTPOSN keyword may be used to determine the image rotation. ROTPOSN is defined as the rotator user position.

Position Angle of "Up"
on the slit w.r.t North
270 West up 180
180 South up 90
90 East up 0
0 North up 270


These orientations apply only to the LRIS image displays at the telescope. On the blue side the image is rotated 270 degrees and has the x-axis flipped. On the red side, the image is rotated 270 degrees and has the y-axis flipped. The entry below shows the LRIS SPECIFIC ds9 display.

Orientation on images with PA=0 with the DISPLAY set to the LRIS SPECIFIC ds9 displays

As seen at the telescope.

From top to bottom, blue side amplifiers are numbered 4,3,2,& 1.

From top to bottom, red side amplifiers are numbered 3,4,1,& 2.

The standard longslit position as indicated by the star in the images is located on amplifier 3 on the blue side and on 4 for the red side.

Click on the image to enlarge

Orientation on images with PA = 0 and DISPLAY set to a normal ds9 display (no rotations or flips)

Shows the LRIS images without rotations or flips.

Click on the image to enlarge

Windowing/Binning See binning and windowing page for details Not Implemented

Old LRIS red detector specs

If interested in the LRIS detector specs for the Red side before the detector upgrade, please review the old detector specs.