Gratings
Below, for each grating mode of STIS, we provide the basic properties of the mode, wavelength ranges covered in each central wavelength setting, sensitivities and throughputs, dispersions and plate scales. Advice on use is provided where appropriate and comparisons of the G230L
, G230M
MAMA modes with their G230LB
, G230MB
CCD counterparts are shown.
Table 13.1: STMAG
as a Function of Wavelength for Stellar Objects. STMAG
is defined as the color-dependent correction from V magnitude to STMAG at wavelength
.
Spectrum |
Wavelength (Å) |
1500 |
2000 |
2500 |
3000 |
3500 |
4000 |
4500 |
5000 |
6000 |
7000 |
8000 |
9000 |
10000 |
O5 V |
-4.80 |
-3.84 |
-3.03 |
-2.35 |
-1.74 |
-1.24 |
-0.77 |
-0.34 |
0.41 |
1.05 |
1.61 |
2.10 |
2.54 |
B0 V |
-4.56 |
-3.47 |
-2.77 |
-2.10 |
-1.65 |
-1.20 |
-0.78 |
-0.37 |
0.43 |
1.03 |
1.57 |
2.04 |
2.48 |
B5 V |
-3.01 |
-2.02 |
-1.64 |
-1.29 |
-1.00 |
-1.02 |
-0.68 |
-0.30 |
0.34 |
0.91 |
1.38 |
1.80 |
2.19 |
Vega |
-0.75 |
-0.48 |
-0.13 |
0.01 |
0.17 |
-0.85 |
-0.60 |
-0.26 |
0.33 |
0.82 |
1.28 |
1.81 |
2.08 |
A0 V |
-0.83 |
-0.41 |
-0.02 |
0.09 |
0.19 |
-0.79 |
-0.59 |
-0.27 |
0.31 |
0.80 |
1.25 |
1.58 |
1.87 |
A5 V |
3.69 |
0.46 |
0.82 |
0.44 |
0.38 |
-0.57 |
-0.50 |
-0.22 |
0.27 |
0.72 |
1.10 |
1.40 |
1.67 |
F2 V |
8.86 |
2.00 |
1.66 |
0.62 |
0.42 |
-0.24 |
-0.28 |
-0.13 |
0.17 |
0.49 |
0.78 |
1.04 |
1.31 |
F5 V |
10.86 |
3.35 |
2.03 |
0.78 |
0.43 |
-0.16 |
-0.23 |
-0.09 |
0.13 |
0.43 |
0.70 |
0.96 |
1.21 |
G0 V |
13.82 |
5.63 |
3.32 |
1.25 |
0.62 |
0.13 |
-0.12 |
-0.05 |
0.10 |
0.29 |
0.52 |
0.76 |
0.98 |
Sun |
10.80 |
6.02 |
3.73 |
1.52 |
0.69 |
0.10 |
-0.11 |
-0.01 |
0.07 |
0.32 |
0.55 |
0.82 |
1.03 |
K0 V |
7.08 |
6.72 |
5.13 |
2.49 |
1.18 |
0.53 |
0.05 |
0.01 |
0.01 |
0.18 |
0.39 |
0.61 |
0.84 |
M0 V |
8.58 |
8.22 |
6.64 |
3.99 |
2.69 |
1.80 |
0.57 |
0.46 |
-0.22 |
-0.39 |
-0.49 |
-0.45 |
-0.38 |
B0.5 III |
-3.86 |
-2.90 |
-2.43 |
-1.88 |
-1.47 |
-1.14 |
-0.71 |
-0.32 |
0.39 |
0.99 |
1.52 |
1.98 |
2.41 |
A0 III |
-1.33 |
-0.76 |
-0.24 |
-0.12 |
0.05 |
-0.92 |
-0.60 |
-0.28 |
0.33 |
0.85 |
1.32 |
1.57 |
1.96 |
F0 III |
8.93 |
2.09 |
1.84 |
0.80 |
0.51 |
-0.31 |
-0.38 |
-0.18 |
0.21 |
0.58 |
0.92 |
1.15 |
1.43 |
O9.5 I |
-4.09 |
-3.20 |
-2.59 |
-2.01 |
-1.61 |
-1.19 |
-0.74 |
-0.33 |
0.40 |
1.02 |
1.57 |
2.04 |
2.48 |
B0 I |
-3.78 |
-2.91 |
-2.45 |
-1.88 |
-1.48 |
-1.10 |
-0.70 |
-0.31 |
0.37 |
0.94 |
1.43 |
1.87 |
2.27 |
B5 I |
-1.86 |
-1.33 |
-1.26 |
-1.11 |
-0.87 |
-0.92 |
-0.58 |
-0.26 |
0.31 |
0.85 |
1.34 |
1.63 |
2.06 |
.
Table 13.2: STMAG
as a Function of Wavelength for Non-Stellar Objects. STMAG
is defined as the color-dependent correction from V magnitude to STMAG at wavelength 
Spectrum |
Wavelength (Å) |
1500 |
2000 |
2500 |
3000 |
3500 |
4000 |
4500 |
5000 |
6000 |
7000 |
8000 |
9000 |
10000 |
Elliptical |
3.35 |
3.19 |
4.17 |
2.92 |
1.60 |
0.70 |
0.17 |
0.15 |
-0.04 |
-0.08 |
-0.07 |
-0.13 |
n/a |
S0 |
4.63 |
3.95 |
3.27 |
2.23 |
1.61 |
0.71 |
0.18 |
0.13 |
-0.03 |
-0.13 |
-0.02 |
-0.08 |
n/a |
Sa |
2.64 |
2.27 |
2.39 |
1.78 |
1.31 |
0.36 |
0.12 |
0.07 |
-0.06 |
-0.05 |
-0.00 |
0.02 |
n/a |
Sb |
1.70 |
2.59 |
2.04 |
1.32 |
1.12 |
0.43 |
0.17 |
0.10 |
0.02 |
-0.05 |
-0.01 |
-0.04 |
n/a |
Sc |
-0.18 |
0.44 |
-0.17 |
-0.68 |
-0.67 |
-0.51 |
-0.44 |
-1.25 |
0.18 |
0.40 |
n/a |
n/a |
n/a |
Starburst,E(B-V)<0.1 |
-1.71 |
-1.15 |
-0.68 |
-0.43 |
-0.13 |
-0.42 |
-0.23 |
-1.24 |
0.21 |
0.40 |
0.70 |
0.85 |
n/a |
Starburst,0.25<E(B-V)<0.35 |
-0.95 |
-0.87 |
-0.33 |
-0.10 |
0.08 |
-0.19 |
-0.19 |
-0.28 |
0.15 |
0.44 |
0.41 |
0.47 |
n/a |
Starburst,0.51<E(B-V)<0.60 |
-0.40 |
-0.18 |
0.01 |
0.23 |
0.03 |
-0.14 |
-0.12 |
-0.36 |
0.07 |
0.07 |
0.18 |
0.29 |
n/a |
Starburst,0.61<E(B-V)<0.70 |
0.05 |
0.31 |
0.31 |
0.15 |
0.27 |
-0.17 |
-0.13 |
-0.11 |
0.06 |
0.17 |
0.26 |
0.24 |
n/a |
How to Use The STMAG
Tables
- Interpolate in the table to get STMAG
for the spectral type and wavelength region of your target observation (e.g. G0 V @ 4300Å).
- Add the target V magnitude to the STMAG
derived from Step 1.
- Find the S/N plot for the grating you want to use.
- Locate V+STMAG
on the horizontal axis and read off the S/N for the desired exposure time (or read off the exposure time for the desired S/N).