First-Order Grating G430L

Description

G430L, used with the CCD, is a low resolution grating (R ~ 500) with a relatively high throughput. The grating has only a single setting.

Recommended Uses

This grating is designed for observations where high spectral resolution is not required, but efficient spectral coverage in the blue portion of the optical is desired.

Special Considerations

Notice, that by taking two observations, one with G750L and one with G430L, the full spectral region, from the NIR at 10000 Å through the optical at 3000 Å can be efficiently observed at an R ~ 500.


Grating

Spectral Range

Average
Dispersion
(Å per Pixel)

Plate Scale
(arcsec/pixel)

Tilts

Central
Wavelengths

Complete

Per Tilt

G430L

2900–5700

2800

2.73

0.05078

Prime

4300

Figure 13.10: Wavelength Ranges for the G430L Grating Setting.


G430L Sensitivities


Table 13.5: G430L Sensitivities & Throughputs for a Point Source.

λ

Sensitivity

% Throughput

3000

2.7E14

1.4

3250

6.8E14

3.4

3500

9.5E14

4.4

3750

1.3E15

5.7

4000

2.0E15

8.1

4250

2.5E15

9.2

4500

2.7E15

9.9

4750

2.8E15

9.6

5000

3.0E15

9.7

5250

3.1E15

9.5

5500

2.9E15

8.6

Figure 13.11: G430L Point Source (left axis), and Diffuse Source (right axis) Sensitivities.


Note:

Point source sensitivity assumes full transmission (zero slit losses). Diffuse source sensitivity assumes a 0.1" wide slit. To convert point source sensitivities to diffuse source sensitivities multiply the point source values by the grating spatial (cross dispersion) plate scale in units of arcseconds per pixel and by the width of the desired slit in units of arcseconds.

G430L Signal-to-Noise

Note:

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/cm2/s/Å. The curves are labeled with exposure times in seconds.



Figure 13.12: Diffuse Source Signal-to-Noise as a Function of STMAG for G430L. 


Figure 13.13: Point Source Signal-to-Noise as a Function of STMAG for G430L.