Update: Feb 19, 2010
It is necessary to select the most suitable according to the wavelength resolution and sensitivity required.
Resolution vs. Wavelength |
Efficiency vs. Wavelength | |
---|---|---|
VPH grisms | other grisms (incomplete) | |
Grism name | Links to figures of efficiency, etc. | Lines or Grooves (mm-1) | Order | Dispersion (A/pix) |
Center WL (A) |
Spectral Resolution with 0.4" slit | Order Cut Filter |
Wavelength Coverage (A) |
0th order? | 2nd order? | Targets/Comments |
---|---|---|---|---|---|---|---|---|---|---|---|
Very low |
Efficiency Design Drawing Holder |
75 | 1 | 5.46 | 6500 | 250 | SO58 | 5800-10000 | YES | NO | Red MOS survey even @ >9400A |
SY47 | 4700-9000 | YES | Overlap at >9000 | Red MOS survey @ 4700-9400 | |||||||
L600 | 3650-6000 | YES | YES | Blue MOS survey | |||||||
L550 | 3400-5500 | YES | YES | Blue MOS survey even @<3500A | |||||||
Low |
Efficiency Design Drawing [a] [b] [1] [2] [3] [4] |
150 | 1 | 2.72 | 6500 | 500 | SY47 | 4700-9000 | NO | Overlap at >9000 | Red Low disp. |
SO58 | 5800-10000 | NO | NO | No 2nd order contami. even @ >9500A | |||||||
L600 | 3650-6000 | NO | YES | Blue Low disp. | |||||||
2 | 1.4 | 700 | L550 | 3400-5500 | NO | YES | Highest sensitivity for <3800A | ||||
Middle Blue |
Efficiency Throughput1 Throughput2 Design Drawing Holder |
300 | 1 | 1.34 | 5500 | 1000 | SY47 | 4700-8300 | NO | YES |
- Red Mid disp - Higher sens. than 300R @ <7800A - >8400A out of CCD |
SY47 offset slit |
4700-9000 | NO | Overlap at >9000 | Larger spectral coverage | |||||||
L600 | 3650-6000 | NO | YES | Blue Mid disp | |||||||
LC50 | 3300-6000 | NO | YES(weak) | Sensitive even @ <3500A | |||||||
none | 3650-8300 | NO | Overlap at >7000 |
- Blue Mid disp - Higher efficiency - contamination by scattered light at <3800A |
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Middle Red |
Efficiency Throughput1 Throughput2 Throughput3 Design Drawing |
300 | 1 | 1.34 | 7500 | 1000 | SY47 | 4900-9000 | NO | YES |
- Red Mid disp - Higher sens. than 300B @ >7800A - 4700-4900A out of CCD |
O58 | 5800-10000 | NO | NO | No 2nd order contami. even @ >9500A | |||||||
2 | 0.67 | 3900 | 2000 | L600 | 3650-5250 | NO | --- | Higher sens. than 300B 2nd |
|||
L600 offset slit |
3650-5950 | NO | --- | ||||||||
L550 | 3400-5250 | NO | --- |
- Sensitive even @ <3500A - better blocking for 1st order contami. |
|||||||
Grism name | Links to figures of efficiency, etc. | Lines or Grooves (mm-1) | Order | Dispersion (A/pix) |
Center WL (A) |
Spectral Resolution with 0.4" slit | Order Cut Filter |
Wavelength Coverage (A) |
0th order? | 2nd order? | Targets/Comments |
High Echelle |
Efficiency Throughput Design Drawing Holder [1] [2] |
175 (Echelle) |
2 | -0.98 @9300A |
9720 | 2500 | Cross Disp. | 7900-10000 | NO | --- | opposite dispersion direction (Note 2) |
SDSS-z' | 8300-10000 | NO | --- | ||||||||
I offset slit |
7300-8700 | NO | --- | ||||||||
3 | -0.63 @6600A |
6550 | 2500 | Cross Disp. | 5400-7900 | NO | YES | ||||
I | 7300-7900 | NO | YES | ||||||||
R | 5900-7100 | NO | YES | ||||||||
4 | 4980 | Cross Disp. | 4200-5900 | NO | YES | ||||||
5 | 4040 | Cross Disp. | 3600-4600 | NO | YES | ||||||
High 450 |
Throughput Prism Drawing Holder [1] [2] [3] [4] [5] [6] |
1000 (VPH) |
1 | 0.376 | 4500 | 4000 | No filter | 3800-5250 | NO | NO |
peak efficiency @ 4000A x shift = +16 pixel (Note 1) |
No filter offset slit |
4200-5650 | NO | NO | ||||||||
High 520 |
Throughput Prism Drawing Holder [1] [2] [3] [4] [5] [6] |
1000 (VPH) |
1 | 0.394 | 5250 | 4000 | No filter | 4450-6050 | NO | NO | x shift = -47 pixel (Note 1) |
No filter offset slit |
4900-6500 | NO | NO | ||||||||
High 650 |
Throughput Prism Drawing Holder [1] [2] [3] [4] [5] [6] |
665 (VPH) |
1 | 0.61 (average) | 6500 | 2500 | SY47 | 5300-7700 | NO | NO | x shift = +222 pixel (Note 1) |
SY47 offset slit |
5950-8350 | NO | NO | ||||||||
2 | 0.28 @4000A |
3500 | L600 offset slit |
3650-4350 | NO | --- | |||||
LC50 | 3300-4350 | NO | --- | ||||||||
High 850 | 360 (VPH) |
1 | 1.18 | 8000 | 1700 | SO58 | 5800-10350 | NO | NO | x shift = -6 pixel (Note 1) | |
SO58 offset slit |
6850-11650 | NO | NO | ||||||||
High 900 | 555 (VPH) |
1 | 0.74 | 9000 | 3000 | SO58 | 7500-10450 | NO | NO | x shift = -120 pixel (Note 1) | |
SO58 offset slit |
8300-11300 | NO | NO | ||||||||
Very High 680 |
Throughput Prism Drawing Holder [1] [2] [3] [4] [5] [6] |
1600 (VPH) |
1 | 0.223 | 6900 | 8000 | SY47 | 6450-7350 | NO | NO | x shift = +41 pixel (Note 1) |
SY47 offset slit |
6700-7600 | NO | NO | ||||||||
Very High 800 |
Throughput Prism Drawing Holder [1] [2] [3] [4] [5] [6] |
1324 (VPH) |
1 | 0.282 | 8000 | 7000 | SY47 | 7500-8600 | NO | NO |
- not tested for polarimetry - x shift = -27 pixel (Note 1) |
SY47 offset slit |
7800-8900 | NO | NO | ||||||||
Very High 950 |
Efficiency Throughput Drawing Prism drawing Holder [1] [2] [3] [4] [5] [6] |
1095 (VPH) |
1 | 0.352 | 9500 | 6000 | O58 | 8860-10200 | NO | NO |
- Unavailable for polarimetry - x shift = -190 pixel (Note 1) |
Grism name | Links to figures of efficiency, etc. | Lines or Grooves (mm-1) | Order | Dispersion (A/pix) |
Center WL (A) |
Spectral Resolution with 0.4" slit | Order Cut Filter |
Wavelength Coverage (A) |
0th order? | 2nd order? | Targets/Comments |