Detectors

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

Bias level

~1000 ADU

Saturation

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

CTE @ 40,000 e-
CTE @ 200 e-

A	B	C	D
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]

Readout time [sec]

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		ROTPOSN
PA	direction	ROTPOSN
270	West up	180
180	South up	90
90	East up	0
0	North up	270

PA = ROTPOSN + 90

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.