GIRAFFE High Resolution Mode
High resolution mode 316 lines/mm, 63.5 blaze grating
These are the setups for the grating currently in used, which is a higher-efficiency version (installed October 10th 2003) of the original one. The resolving powers listed here also correspond to the most up-to-date measurements, after the intervention in the focussing procedure on February 2nd 2015. The corresponding values for the old focussing procedure (i.e. for observations taken between Oct 10 2003 and Feb 1 2015) are given here. The numbers for the OLD grating are given here.
From P84 in ARGUS/GIRAFFE, the settings HR01, HR02 and HR03 are available in VISITOR MODE ONLY due to the problem of obtaining sufficient counts in blue attached flats. For Medusa and IFU all settings are available in service and visitor mode.
From P73 a number of new settings were introduced. These are H447.1B,H484.5B, H525.8B, H651.5B, H737.0B and H836.6B. These have higher resolution but LOWER THROUGHPUT compared with the 'A' setups as they work in higher order where the diffraction grating diffraction angle is not matched to the peak efficiency of the grating. Additionally, a new setting H665.0 has been introduced that covers both H-alpha and Li6707. Bluewards of about 649 nm the response of this setting is only 50% of the peak.
Approximate efficiency ratios comparing the higher and lower-order settings with the same central wavelength are as follows;H447.1B/H447.1A=0.6, H484.5B/H484.5A=0.7, H525.8B/H525.8A=0.7,H651.5B/H651.5A=0.5, H737.0B/H737.0A=0.3, H805.3B/H805.3A=0.7, H836.6B/H836.6A=0.25, H920.5B/H920.5A=0.7
These values were measured by comparing the strength of flatfield data in the two settings and refer to the central wavelength only.They have been corrected for the fact that the 'B' settings have a lower wavelength coverage than the 'A' settings.
|Filter||Theta||Order||p2 name||ETC name||Wl start||Wl center||Wl end||Band||R IFU/Argus||R MEDUSA||Comments|
|15||--||8||H665.0||HR15N||647||665.0||679||32||30600||19200||Covers H-alpha and Li6707.|
- Filter is the filter number;
- Theta is the angle of diffraction with the grating normal;
- Order is the working echelle order;
- Wl start, center, end are wavelengths at the edges and center of the CCD in nm;
- Band is the covered spectral passband;
- resolving power, R, obtained in IFU/Argus mode;
- resolving power, R, obtained in MEDUSA mode.
Note that these are the values corresponding to the currently used grating and focussing procedure, i.e. for observations after February 2 2015. The corresponding values for the old focussing procedure (i.e. for observations taken between Oct 10 2003 and Feb 1 2015) are given here.
The numbers for the OLD grating (i.e. for observations taken before Oct 10 2003) are given here.