Instrument Science Report 072: Recommendations

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3. Recommendations

Given that spectra produced by GHRS are tilted across the diode array and that there are drifts with time which, it is very important that the nominal SPYBAL not be frivolously omitted. While the possible negative effects of not performing SPYBALS can be minimal for some wavelength/grating combinations, these effects are not readily predictable since they appear to be correlated with the recent thermal history of the instrument. It should be noted that the detrimental effects are nearly impossible to avoid for case of the G140L grating. We recommend that the SPYBALs not be skipped - if they are skipped the observer should assume the liability if the observations are found to be degraded.