FUV Grating G130M with CENWAVE=1055 or 1096

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Description

When used with a central wavelength of 1055 or 1096 Å, grating G130M samples wavelengths between about 900 and 1200 Å. Its resolution and effective area are higher than those of the G140L grating, but lower than those of G130M when used at longer central wavelengths.

Special Considerations

The COS sensitivity rises steeply between 1070 and 1150 Å. To observe bright targets near the Lyman limit, turn off detector Segment A and use only Segment B.


GratingResolving Power R = λ/ΔλDispersion (mÅ pixel−1)Plate Scale (milliarcsec pixel−1)FP-POS Step (Å step−1)
Disp. AxisCross-Disp. Axis

G130M Segment A

3,000–8,0009.9722.91002.5
G130M Segment B5,000–12,0009.9722.91002.5

Figure 13.8: Wavelength Ranges for the G130M/1055 and 1096 Modes.



G130M/1055 and 1096 Point-Source Sensitivity


Table 13.5: G130M/1055 and 1096 Point-Source Sensitivity for PSA.

Wavelength (Å)ThroughputSensitivity (counts pixel−1 sec−1 per erg cm−2 sec−1 Å−1)Effective Area (cm2)

901

1.611e−04

3.3e+09

7.29e+00

950

4.736e−04

1.0e+10

2.14e+01

1000

2.709e−04

6.1e+09

1.23e+01

1050

6.355e−04

1.5e+10

2.87e+01

1100

5.538e−03

1.4e+11

2.51e+02

1150

3.076e−02

8.0e+11

1.39e+03

1200

4.216e−02

1.1e+12

1.91e+03

1237

4.389e−02

1.2e+12

1.99e+03


Figure 13.9: G130M/1055 and 1096 Point-Source Sensitivity for PSA.


The sensitivity through the BOA is not shown, as its MgF2 filter is very low at these wavelengths.

G130M/1055 and 1096 Signal-to-Noise Ratio

Figure 13.10: Point-Source Signal-to-Noise as a Function of STMAG for G130M at 1030 Å.

The top axis displays constant Fλ values corresponding to the STMAG units (V+STMAGλ) on the bottom axis. Recall that STMAG = 0 is equivalent to Fλ = 3.63E−9 erg cm−2 s−1 Å−1. Colors refer to exposure times in seconds. The edge of the shaded area corresponds to the bright-object screening limit. Use of the PSA is assumed.

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