NUV Grating G230L

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Description

G230L is a low-resolution grating (R ~ 3000) with wavelength coverage extending from about 1650 to 3200 Å. The grating has four central-wavelength settings.

Special Considerations

G230L spectra consist of three 400 Å stripes separated by two 700 Å gaps. To acquire a complete spectrum requires the use of all four central-wavelength settings.

Only stripes A and B record first-order light, and even they may be contaminated by second-order light when central wavelength 3360 is used. See Table 5.4.
 

GratingResolving Power R = λ/ΔλDispersion (mÅ pixel−1)Spatial Resolution (milliarcsec pixel-1)Plate Scale (milliarcsec pixel−1)FP-POS Step (Å step−1)
Disp. AxisCross-Disp. Axis
G230L2,100–3,90039081 ± 124.324.020.3

Figure 13.26: Wavelength Ranges for the G230L Grating.

Dark lines represent wavelengths sampled by all four FP-POS positions. Wavelengths above 3200 Å may be contaminated by second-order light.

G230L Point-Source Sensitivity

Table 13.11: G230L Point-Source Sensitivity for PSA.

Wavelength (Å)ThroughputSensitivity (counts pixel−1 sec−1 per erg cm−2 sec−1 Å−1)Effective Area (cm2)
14007.061e−09

7.4e+06

3.19e−04
16001.419e−04

1.7e+11

6.42e+00
18001.020e−021.4e+13

4.61e+02

20001.447e−02

2.2e+13

6.55e+02
22001.612e−02

2.6e+13

7.29e+02
24001.550e−02

2.8e+13

7.01e+02
26001.294e−022.5e+13

5.85e+02

28009.680e−03

2.0e+13

4.38e+02
30005.195e−03

1.2e+13

2.35e+02
32001.389e−033.3e+12

6.29e+01

34003.252e−03

8.2e+12

1.47e+02


Figure 13.27: G230L Point-Source Sensitivity for PSA and BOA.


G230L Signal-to-Noise Ratio

Figure 13.28: Point-Source Signal-to-Noise as a Function of STMAG for G230L.

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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