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 2k x 4k CCDs frontside 15 µm pixels, science grade
Outputs 4 amplifiers 1,2,3,4 (A,B,C,D old label) 4 amplifiers 3,4,1,2
Read noise
[e-/rms] Most Recent Measurements
1 2 3 4
3.9 4.2 3.6 3.6
1 (19-3L) 2 (19-3R) 3 (19-2L) 4 (19-2R
4.64 4.76 4.54 4.62
Conversion Factor[e-/ADU] (Gain). Most Recent Measurements
1 2 3 4
1.55 1.56 1.63 1.70
1 (19-3L) 2 (19-3R) 3 (19-2L) 4 (19-2R
1.255 1.180 1.191 1.162
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
CCDDS9 Pane CoordinatesNotes
X pix Y pix
19-239063627Hot pixel
19-234062878Trap cluster
19-237963545Trap with tail
19-31314526 Hot pixel with tail
19-311881706Hot pixel with tail
19-310653471Hot pixel with tail
19-31979-19800-4096Column Stop Failure
19-31395-13960-4096Column Stop Failure
19-3613-6150-4096Column Stop Failure
19-311790-4096Column with low level trap
19-311810-4096Column with low level trap
19-222790-4096Column with low level trap
19-224990-4096Column with low level trap
19-227490-4096Column with low level trap
19-230460-4096Column with low level trap
19-232260-4096Column with low level trap
19-233860-4096Column with low level trap

A FITS image called bpm_red.fits maps the bad pixels. Hot pixels and traps are flagged as 1, Column stop failures are flagged as 2, and good pixels are 0 in the FITS map.

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
4x12=48 real pre image area pixels
4x80=320 electronically added post image area pixels
Erase time [sec] 8 10
Readout time [sec] 42
LRIS-R Mosaic Readout Times
CCDSPEED Binning Readout Time (s)*
Normal 1x1 127
Normal 1x2 (spectral) 78
Normal 2x1 (spatial) 83
Normal 2x2 58
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. 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 See binning and windowing page for details

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.