COS Instrument Handbook for Cycle 26
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Cosmic Origins SpectrographInstrument Handbook for Cycle 26 > Chapter 10: Bright-Object Protection > 10.4 Source V Magnitude Limits

10.4
In the following tables, the screening limits in Table 10.1 are converted into magnitude limits for a variety of sources. These values are not meant to be a substitute for the ETC, but rather an indication of whether a given object may be near the limit. The most sensitive spectroscopic setting and lowest rate limit (global or local) determine the listed values. Stellar spectra are assumed to be unreddened. Table 10.2 corresponds to spectroscopy through the PSA, Table 10.3 through the BOA, and Table 10.4 to NUV imaging for both apertures.
These tables were calculated for the Cycle 19 COS instrument handbook (Version 3.0; December 2010). Due to the decline in the sensitivity of COS over time (TDS), targets that are brighter than the given values by up to 0.5 mag (4.0 to 4.5 mag for the G285M grating) may be within the spectroscopic screening limits. (Limits for imaging are not expected to differ.) Users are required to use the ETC for the final assessment of whether their targets violate the brightness limits.
0.1
1.2
3.4
4.8
0.5
0.4
0.1
0.8
1.5
1.4
0.7
0.8
2.3
3.1
1.1
2.3
4.5
0.5
5.4
3.9
2.3
3.1
5.0
1.4
7.0
5.1
3.1
1.5
4.2
1.9
1.0
1.0
3.2
1.2
0.3
0.2
0.6
2.9
1.0
Fλ ~ λ1
Fλ = const surface brightness
Fλ = const point source
0.1
0.3
2.5
0.4
5.6
0.7
0.6
0.7
6.7
1.6
0.6
1.2
0.8
0.8
8.8
3.7
2.4
2.0
1.4
1.0
10.2
5.0
3.6
2.5
1.7
1.1
3.6
6.1
1.9
4.3
3.1
1.5
2.3
5.9
0.6
5.2
3.6
2.0
1.2
5.6
6.4
4.7
2.7
6.9
6.9
5.2
6.3
4.8
3.1
6.1
7.8
4.4
8.7
6.9
5.1
1.3
7.6
10.0
5.9
11.1
9.7
8.2
2.2
8.5
10.5
6.8
12.6
10.9
9.0
2.8
5.1
7.0
3.4
9.7
7.7
7.0
2.8
5.4
6.5
3.7
8.8
7.0
6.4
2.3
5.6
6.1
3.8
8.6
6.8
5.2
2.6
Fλ ~ λ1
Fλ = const surface brightness
Fλ = const point source
Table 10.4: V Magnitude Bright-Object Limits for Imaging.
Fλ ~ λ1
Fλ= const surface brightness
Fλ= const point source

Cosmic Origins SpectrographInstrument Handbook for Cycle 26 > Chapter 10: Bright-Object Protection > 10.4 Source V Magnitude Limits

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