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Cosmic Origins SpectrographInstrument Handbookfor Cycle 21 > Chapter 10: Bright-Object Protection > 10.4 Source V Magnitude Limits
10.4
Source V Magnitude Limits
In the following tables, the screening limits in Table 10.1 are converted into V 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.
Table 10.2: V Magnitude Limits for PSA Spectroscopy  
Spectral Class
FUV
NUV
G130M
G160M
G140L
G185M
G225M
G285M
G230L
O5 V
14.7
14.0
15.1
10.1
9.5
8.7
12.5
O7 V
14.5
13.8
14.9
10.0
9.5
8.6
12.4
O9 V
14.2
13.6
14.7
9.9
9.4
8.5
12.3
B0 V
14.2
13.5
14.6
9.8
9.3
8.4
12.2
B1 V
13.8
13.1
14.3
9.4
9.0
8.2
11.9
B3 V
12.8
12.5
13.4
8.8
8.4
7.7
11.3
B5 V
12.0
11.9
12.7
8.3
8.0
7.4
10.8
B8 V
10.9
11.0
11.5
7.5
7.2
6.7
10.0
A1 V
8.5
8.9
9.3
6.4
6.2
5.8
9.0
A3 V
6.4
7.8
8.3
6.1
6.0
5.6
8.7
A5 V
2.9
6.9
7.3
5.8
5.8
5.5
8.5
F0 V
-0.1
4.9
5.7
4.8
5.2
5.2
7.8
F2 V
-1.2
4.0
5.0
4.5
5.0
5.2
7.6
F5 V
-3.4
1.9
3.2
3.7
4.4
5.0
7.3
F8 V
-4.8
0.5
2.0
3.2
4.1
4.8
7.1
G2 V (Solar)
1.8
-0.5
3.4
1.4
2.7
4.4
6.8
G8 V (Tau Ceti)
3.0
-0.4
4.7
0.5
2.2
3.9
6.4
K2 V (Epsilon Eri)
4.0
-0.1
5.8
-0.8
1.1
3.2
6.1
KM III (Eta Ser)
-1.5
-1.4
0.2
-0.7
1.0
2.9
5.7
KM III (Alpha Boo)
-0.8
-2.3
0.9
-3.1
-1.1
0.9
4.7
KM III (Gamma Aql)
-2.3
-4.5
-0.5
-5.4
-3.9
-2.3
3.8
KM III (HD 146051)
-3.1
-5.0
-1.4
-7.0
-5.1
-3.1
3.3
KM III (Alpha Cet)
0.2
-1.5
1.9
-4.2
-1.9
-1.0
3.3
KM III (HD 123023)
0.0
-1.0
1.6
-3.2
-1.2
-0.3
3.7
KM III (Beta Gru)
-0.2
-0.6
1.5
-2.9
-1.0
0.7
3.4
T~50,000 K Blackbody
14.6
14.0
15.0
10.1
9.5
8.6
12.5
Fλ ~ λ−1
11.0
10.6
11.5
7.2
7.2
6.7
9.9
Fλ= const surface brightness
11.1
10.9
11.8
7.7
8.0
7.6
10.7
Fλ= const point source
9.3
9.2
10.0
6.0
6.3
5.9
9.0
 
Table 10.3: V Magnitude Limits for BOA Spectroscopy  
Spectral Class
FUV
NUV
G130M
G160M
G140L
G185M
G225M
G285M
G230L
O5 V
9.4
8.5
9.8
4.6
3.8
2.8
6.9
O7 V
9.2
8.4
9.6
4.4
3.7
2.7
6.8
O9 V
9.0
8.2
9.4
4.3
3.6
2.7
6.7
B0 V
8.9
8.0
9.3
4.2
3.5
2.6
6.6
B1 V
8.5
7.7
9.0
3.9
3.3
2.4
6.2
B3 V
7.5
7.0
8.1
3.2
2.7
1.9
5.6
B5 V
6.7
6.5
7.4
2.7
2.2
1.5
5.1
B8 V
5.5
5.5
6.2
1.9
1.5
0.8
4.3
A1 V
3.1
3.4
3.8
0.8
0.4
-0.1
3.3
A3 V
1.0
2.2
2.8
0.5
0.2
-0.3
3.0
A5 V
-2.5
1.4
1.8
0.2
0.0
-0.4
2.8
F0 V
-5.6
-0.7
0.1
-0.8
-0.6
-0.7
2.0
F2 V
-6.7
-1.6
-0.6
-1.2
-0.8
-0.8
1.7
F5 V
-8.8
-3.7
-2.4
-2.0
-1.4
-1.0
1.4
F8 V
-10.2
-5.0
-3.6
-2.5
-1.7
-1.1
1.2
G2 V (Solar)
-3.6
-6.1
-1.9
-4.3
-3.1
-1.5
0.8
G8 V (Tau Ceti)
-2.3
-5.9
-0.6
-5.2
-3.6
-2.0
0.3
K2 V (Epsilon Eri)
-1.2
-5.6
0.5
-6.4
-4.7
-2.7
0.1
KM III (Eta Ser)
-6.9
-6.9
-5.2
-6.3
-4.8
-3.1
-0.4
KM III (Alpha Boo)
-6.1
-7.8
-4.4
-8.7
-6.9
-5.1
-1.3
KM III (Gamma Aql)
-7.6
-10.0
-5.9
-11.1
-9.7
-8.2
-2.2
KM III (HD 146051)
-8.5
-10.5
-6.8
-12.6
-10.9
-9.0
-2.8
KM III (Alpha Cet)
-5.1
-7.0
-3.4
-9.7
-7.7
-7.0
-2.8
KM III (HD 123023)
-5.4
-6.5
-3.7
-8.8
-7.0
-6.4
-2.3
KM III (Beta Gru)
-5.6
-6.1
-3.8
-8.6
-6.8
-5.2
-2.6
T~50,000 K Blackbody
9.3
8.5
9.7
4.5
3.7
2.8
6.9
Fλ ~ λ−1
5.7
5.1
6.2
1.6
1.4
0.8
4.2
Fλ= const surface brightness
5.8
5.4
6.4
2.2
2.2
1.7
5.0
Fλ= const point source
4.1
3.7
4.6
0.5
0.5
0.0
3.3
Table 10.4: V Magnitude Bright-Object Limits for Imaging
Spectral Class
PSA+MirrorA
PSA+MirrorB
BOA+MirrorA
BOA+MirrorB
O5 V
19.2
16.3
13.5
10.7
O7 V
19.1
16.1
13.4
10.5
O9 V
19.0
16.0
13.3
10.4
B0 V
18.9
15.9
13.2
10.3
B1 V
18.6
15.6
12.9
10.0
B3 V
18.1
15.0
12.4
9.3
B5 V
17.6
14.5
11.9
8.9
B8 V
16.9
13.7
11.1
8.0
A1 V
15.8
12.6
10.1
6.9
A3 V
15.6
12.3
9.9
6.6
A5 V
15.3
12.0
9.6
6.2
F0 V
14.7
11.3
8.9
5.5
F2 V
14.4
11.0
8.6
5.2
F5 V
14.0
10.6
8.1
4.7
F8 V
13.7
10.3
7.8
4.4
G2 V (Solar)
13.0
9.6
7.1
3.7
G8 V (Tau Ceti)
12.6
9.1
6.6
3.2
K2 V (Epsilon Eri)
11.8
8.3
5.8
2.4
KM III (Eta Ser)
11.4
8.0
5.5
2.0
KM III (Alpha Boo)
9.6
6.1
3.6
0.2
KM III (Gamma Aql)
7.1
3.6
1.1
-2.3
KM III (HD 146051)
6.2
2.7
0.2
-3.3
KM III (Alpha Cet)
8.0
4.6
2.1
-1.3
KM III (HD 123023)
8.7
5.2
2.7
-0.7
KM III (Beta Gru)
8.9
5.5
3.0
-0.4
T~50,000 K Blackbody
19.2
16.2
13.5
10.6
Fλ ~ λ−1
16.8
13.6
11.0
7.9
Fλ= const surface brightness
10.9
8.0
5.1
2.3
Fλ= const point source
15.8
12.6
10.1
6.9
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