ISAAC Spectroscopic Modes

ISAAC is equipped with 2 gratings, for low (Rs~500) and medium (Rs ~3000) resolution spectroscopy in both the SW and LW arms (s is the slit widthin arcsec).

SW Spectroscopy - Low Resolution (SWS1-LR)

The pixel scale is 0.147 arcsec/pixel. The slit length is 120 arcsec.

 

SW Spectroscopy - Low resolution  

 

 
Spectral domain (µm)
 
Order
Detector
spectral coverage  (µm)
Number of grating positions
 
R(2")
 
R(1")
 
R(0.6")
 
R(0.3")
0.98 - 1.1
5
0.29
1
270
550
900
1800
1.1 - 1.4
4
0.36
1
250
500
860
1700
1.42 - 1.82
3
0.48
1
250
500
840
1600
1.82 - 2.5
2
0.72
1
200
450
750
1500

Use the Exposure TimeCalculator(ETC) for performance estimates.

SW Spectroscopy - Medium Resolution (SWS1-MR)

The pixel scale is 0.146 arcsec/pixel. The slit length is 120 arcsec.

 

SW Spectroscopy - Medium resolution

 

 
Spectral domain (µm)
 
Order
Detector
spectral coverage  (µm)
Number of grating positions
 
R(2")
 
R(1")
 
R(0.6")
 
R(0.3")
0.98 - 1.1
5
0.046
3-4
1700
3400
5700
11500
1.1 - 1.4
4
0.059
5
1500
3100
5200
10500
1.4 - 1.82
3
0.079
5
1500
3000
5100
10000
1.82 - 2.5
2
0.122
6
1300
2600
4400
8900

Use the Exposure TimeCalculator (ETC) for performance estimates.

LW Spectroscopy - Low Resolution (LWS3-LR)

The pixel scale is 0.146 arcsec/pixel. The slit length is 120 arcsec.

 

LW Spectroscopy - Low resolution

 

 
Spectral domain (µm)
 
Order
Detector
spectral coverage  (µm) 
Number of grating positions 
 
R(2")
 
R(1")
 
R(0.6")
 
R(0.3")
2.55 - 4.2
1
1.4
1
180
360
600
1200
4.45 - 5.1
1
1.5
1
250
500
800
1600

Use the Exposure TimeCalculator (ETC) for performance estimates.

LW Spectroscopy - Medium Resolution (LWS3-MR)

The pixel scale is 0.146 arcsec/pixel. The slit length is 120 arcsec.

 

LW Spectroscopy - Medium resolution

 

Spectral domain (µm)
 
Order
Detector
spectral coverage  (µm) 
Number of grating positions
 
R(2")
 
R(1")
 
R(0.6")
 
R(0.3")
2.55 - 4.2
1
0.255
6(5)
1000
2000
3300
6700
4.45 - 5.1
1
0.237
3
1500
3000
5000
10000

Use the Exposure Time Calculator (ETC) for performance estimates.