IRCS instrument parameters
| Camera | Spectrograph | ||
|---|---|---|---|
| Detector | ALADDIN III 10242 InSb array | ALADDIN II 10242 InSb array | |
| Pixel size | 27 um | ||
| Pixel scale | w/o AO |
22.606+/-0.100 mas 58.037+/-0.149 mas |
60.408+/-0.006 mas (along slit) x 75 mas (across slit) |
| w/ AO |
22.560+/-0.059 mas 57.997+/-0.019 mas |
60.348+/-0.006 mas (along slit) x 75 mas (across slit) |
|
| Field of view | 23.149'' square 59.430'' square |
3.8-10.0'' slit lengths | |
| Gain | 5.6 e-/ADU | 3.8 e-/ADU | |
| Dark current | 0.1 e-/s | 0.2-0.3 e-/s | |
| Read noise | 43 e- rms | 67 e- rms | |
| Saturation level | 123 000 e- | 136 000 e- | |
| Readout rate | 0.41 s (standard readout) | ||
| 0.12 s (fast) | 0.18s (fast) | ||
Important note: The pixel scale of the IRCS echelle along the slit has been measured at 0.060''/pixel and is substantially different from the previously-quoted nominal value of 0.075''/pixel. The difference in the pixel scales parallel and perpendicular to the slit is caused by anamorphic demagnification due to diffraction by the cross-disperser grating.
The gain of IRCS has been reduced since Semester S01A. This has the
effect of increasing the spectroscopic sensitivity for faint objects,
and reducing the effect of the +/-1 ADU noise in each readout.
Detailed IRCS array characteristics
Dependency of read noise on Non-Destructive-Readout (NDR)
The read noise can be reduced with NDR for the infrared arrays, which should theoritically be propotional to 1/sqrt(number of NDR).
Maximum number of NDR
The maximum number of NDR is limited by an integration time, following
the below equation.