Flats and arcs are acquired in polarimetry mode for flat fielding and wavelength solutions. Below you will find two tables that list typical exposure times for flats with the dome used as the illumination source and for arc lamps on both the red and blue side. Note that all filters are not available on both the red and blue sides. Optimal exposure times differ significantly from normal LRIS observing modes.Currently, there are two slits available in LRISp mode. Typical exposure times are provided for both slits.
| Lamp | Exposure Time (sec) | |||
|---|---|---|---|---|
| Red side | Blue side | |||
| using 1.0" slit | using 1.5" slit | using 1.0" slit | using 1.5" slit | |
| Hg | 3 | 2 | 5 | 3 |
| Neon | 3 | 2 | - | - |
| Argon | 4 | 3 | - | - |
| Cadmium | 2 | 1 | 5 | 3 |
| Zinc | - | - | 5 | 3 |
| Internal Halogen lamp | 18 sec | 12 sec | 220 | 150 |
*be sure to let this lamp warm up before taking the exposure!
Warm up times listed here.
| Filter | Exposure time | |
|---|---|---|
| Red Side | Blue Side | |
| U | NA | ?? |
| B | 80 | ?? |
| V | 20 | ?? |
| R | 10 | NA |
| Rs | ?? | NA |
| I | ?? | NA |