The observations are done for Side 1 and Side 2 separately. Program 5594 (GHRS Side 1 Sensitivity Monitor) contains a series of visits of the ultraviolet standard BD+28D4211. Identical instrumental configurations (except for exposure times) were used for all observations. The target was acquired into the Large Science Aperture with a 5 x 5 spiral search using mirror N1, followed by a peak-up. The science observations were done with grating G140L in the ACCUM mode at two central wavelengths: 1200 Å and 1500 Å.
We extended the baseline of the monitor by adding the results of SMOV program 5278 (GHRS N1 and G140L Sensitivity Calibrations). This program was used to reestablish the Side 1 sensitivity for the low-resolution grating G140L immediately after Side 1 had been restored. It executed on SMS 94098. Multiple wavelength settings centered on 1200 Å, 1400 Å, 1600 Å, and 1800 Å were included in this program. We are only using the observation centered on 1200 Å from this program, which has exactly the same instrumental parameters as their counterparts in 5594. In Table 1 we give details of the observing log for all Side 1 observations used in this report.
Observation log for Side 1 (proposals 5278 and 5594)
An example of a spectrum of BD+28D4211 is shown in GHRS ISR 69. Except at wavelengths below 1150 Å the spectrum has more than 1000 counts per diode so that the S/N becomes independent of photon statistics.
The Side 2 observations were done as part of program 5599 (GHRS Side 2 Sensitivity Monitor). BD+28D4211 was acquired into the LSA with a 3 x 3 spiral search using mirror N2, followed by a peak-up. Centering was confirmed by taking an image with the LSA. A series of spectra in the ACCUM mode were taken with gratings G160M, G200M, and G270M. Central wavelengths were 1200 Å, 1500 Å, 2000 Å, 2500 Å, 3000 Å. This sequence was repeated approximately every 3 months. Details of the observing log are in Table 2. All observations were successful except the spectrum at 1200 Å which was intended to be obtained on SMS 95123. No spectrum was taken due to a carrousel reset.
Observation log for Side 2 (proposal 5599)
