Space Telescope Science Institute   4.6.1 Overview Chapter 5:  Imaging

4.6.2 Observational Limits


To ensure the safety of the SBC detector and the robustness of the observing timeline, we have established observational limits on the incident count rates. Observations which exceed the allowed limits will not be scheduled. The allowed limits are given in Table 7.3, which includes separate limits for nonvariable and irregularly-variable sources. The limits for irregular variable sources are a factor 2.5 more conservative than for sources with predictable fluxes. Predictable variables are treated as nonvariable for this purpose. Examples of sources whose variability is predictable are Cepheids or eclipsing binaries. Irregularly variable sources are, for instance, cataclysmic variables or AGN.

SBC observations of targets subject to large, unpredictable outbursts must be preceded by groundbased monitoring within the previous 24 hours, or by an HRC NUV observation a couple of orbits in advance. In the latter case, the HRC observation must be included in the Phase I orbit request.

For further information about checking for SBC bright object limits while planning your observations, please refer to Section 7.2.


 4.6.1 Overview Chapter 5:  Imaging
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