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Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 14: ImagingReference Material > 14.8 MAMA Imaging Bright Object Limits

14.8
As described in Section 7.7, the MAMA’s are subject to absolute brightness limits, above which sources cannot be observed or they would potentially damage the detectors. In Table 14.40, we present the complete set of bright object point source and integrated magnitude screening limits for the MAMA imaging modes. These screening magnitudes are presented as a guide. Whether or not an individual source can be observed is determined by whether the desired configuration and the spectrum of that source is predicted to exceed the global and local absolute observing count rate limits, as described in Chapter 7. Remember, sources cannot be observed in configurations where they exceed the absolute bright object limits. The information presented here should be used in conjunction with the material presented in Chapter 7.
A few important points to note.
Table 14.40: MAMA Bright-Object limits (V magnitudes and cgs units). V magnitudes include NO additional safety factor to account for extrapolation uncertainties from the optical to the UV spectral range.
Flat, point source1
9.6 10-15
1.7 10-14
5.1 10-14
4.5 10-13
2.1 10-15
2.4 10-15
2.5 10-15
2.5 10-14
1.9 10-13
1.6 10-14
8.5 10-14
Flat, extended, peak2
4.0 10-12
7.5 10-12
2.1 10-11
1.9 10-10
9.0 10-13
1.0 10-12
1.0 10-12
1.0 10-11
8.0 10-11
7.0 10-12
3.5 10-11
O5 V3
G2 V4
G8 V5
K2 V6
KM III7
Integrated V magnitude8
Flat, extended, all detector9
7.2 10-15
1.4 10-14
4.1 10-14
3.6 10-13
1.7 10-15
1.9 10-15
2.0 10-15
2.0 10-14
1.5 10-13
1.3 10-14
6.7 10-14
1
Maximum allowed flux for a point source in erg/s/cm2 /.
2
Maximum peak allowed flux for an extended source in erg/s/cm2//arcsec2.
3
V magnitude limit for unreddened single stars. O5 V through F8 V are based on Kurucz models.
4
The magnitudes listed for G2 V are for the Solar template in the STIS ETC.
5
The magnitudes listed for G8 V are from IUE data for the star Tau Ceti.
6
The magnitudes listed for K2 V are from IUE data for the star Epsilon Eri.
7
The magnitudes listed for KM III are from IUE data for 9 stars of these types.
8
Maximum integrated V magnitude for stars in the field assuming all are of O5 V spectral type.
9
Maximum allowed flux for an extended source which covers the full detector in erg/s/cm2//arcsec2


Space Telescope Imaging Spectrograph Instrument Handbook for Cycle 22 > Chapter 14: ImagingReference Material > 14.8 MAMA Imaging Bright Object Limits

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