FORS External Calibration Units - ECUs
ECU Calibration Exposure Times with FORS
The following exposure times correspond to a flux of about 30000 ADU in high gain:
| GRISM | FORS1 | FORS2 |
| (s) | (s) | |
| 150I | 5.1 | 1.4 |
| 200I | - | 1.2 |
| 300V | 13.0 | 9.0 |
| 300I | 9.8 | 4.0 |
| 600B | 40.0 | 8.3 |
| 600V | 31.8 | - |
| 600R | 38.4 | - |
| 600RI | - | 3.8 |
| 600I | 34.0 | 7.0 |
| 600z | - | 5.2 |
| 1400B | - | 27.3 |
| 1200R | - | 11.5 |
| 1028z | - | 9.1 |
| 2nd order | ||
| 600z | - | 45.4 |
| 600I | - | 40.0 |
Wavelength Calibrated Flux for grisms 300V and 300I/OG590 (FORS1)
The bump in the blue is caused by the blue lamp which is used with a cut-off filter to reduce the red and IR flux, while having the highest possible flux levels in the blue.