Recent measurements of signal-to-noise values on some coudé spectra have shown some of the integration times in the coudé spectrograph manual to be very conservative. For example, the manual lists 300s to achieve a S/N ratio of 100 for V = 6 using grating A in second order. At V = 10, this would imply an exposure of 12,000s for the same S/N. However, recent spectra indicate an integration time of about 1500s to reach a S/N of 100 at V = 10. We are updating the on-line manual as we acquire data for different camera and grating combinations. The undersigned may be contacted for more information on a particular combination. We urge users to send us their estimates for integration times taken under good conditions.
Daryl Willmarth, Sam Barden