A new B600 grating has been commissioned and is available for science use in GMOS-N. This grating replaces the original B600 grating which was damaged in December 2008. Active programs that are configured to use the original B600 grating will automatically use this new grating for any new observations executed.
Full characterization of this new grating is still on-going. Preliminary estimates based on daytime GCALflats indicate that the new grating is at least as sensitive as the old grating prior to the damage, and at most wavelengths is has significantly higher sensitivity (~ 20-30%). Spectrophotometric standard observations taken through the 5.0 arcsec longslit are planned and the derived full system throughput will be made available.
The scattered light in GCALflat data is comparable to that measured with the original grating. The GCALflat exposure times and configurations webpage will be updated with plots from the new grating. Some configurations may have to change to compensate for the increased flux.
Any PIs who had previously opted to change to another grating when the original B600 grating was damaged may now configure their programs back to use the B600 grating again if they choose. Please e-mail your Gemini contact scientist letting them know that you wish to edit your unexecuted observations.
Users wishing to employ the Gemini IRAF package to reduce their data will need to update their GMOSgratings.dat file in order for the scripts to recognize the new grating. This file resides in the gemini$gmos/data directory. This file must be edited to include the following two lines:
B600+_G5307 600 461 1688 276 300 1180 0.0 0.0
B600-_G5307 600 461 1688 276 300 1180 0.0 0.0