In the tables below we give the approximately constant dispersion only. The spectral resolution will depend on the wavelength and on the projected slit width which depends on the collimator.

FORS2 standard grisms

Response curves are given in the User Manual.

(1) If used without or with the listed order separation filter, the orders will overlap above the given wavelength.

(2) An order separation filter (OG550) is cemented to the grism itself.

Identification of the arc lines

Please find a list of arc lines in the following table. There is noguaranty for the accuracy of the wavelengths. The optimum choice of lines will depend on the spectral resolution of the grisms and the data reduction method. In the long table for medium resolution grisms a preference column is included on the right hand side. Please have a look into the fitsheader for keyword INS.LAMP*.NAME and INS.LAMP*.TIME to see which lampsare on or off. In very rare cases broken lamps were not detected in time.

The following plots show the spectral line identification.The relative line strength maychange a lot since the switch on times for the lamps are changedfrom time to time. The 2nd order line identification plots are still tobe prepared.

Line identifications for FORS1 grisms (still with the old CCD) are given as well, to help with the reduction of old data.