Instrument Performance

Overheads

When estimating the total time required for a programme it is recommended to include about 3min on average for each target acquisition and around 30% of the estimated integration time for instrument overheads. Larger overheads may be justified for programmes requiring many short integrations and/or complex target acquisition (e.g faint sources for spectroscopy in which case time should be allowed for first imaging the field and then offsetting the target into the slit).

Broad Band Limits


1 minute 1 minute 1 hour  1 hour
Filter Continuum 

10-16erg.s-1.cm-2.A-1 

Magnitude  Continuum 

10-16erg.s-1.cm-2.A-1 

Magnitude
J (1.25) 1.4 x 10-2  20.7 2 x 10-3 22.9 
H (1.65) 1.9 x 10-2 19.7   2.4 x 10-3 21.9 
Ks (2.16) 1.2 x 10-2 18.7   1.6 x 10-3  20.9
Table 5. Measured point source detection limits for s/n =5 in a 1.5" diameter aperture (seeing: 0.75"). Sky brightness was J = 16 mag/sq arcsec, H = 14.3, Ks = 13.

Narrow Band Limits


 1 minute  1 minute  1 hour  1 hour
Filter  Continuum 

10-16erg.s-1.cm-2.A-1 

 Emission Line 

10-16erg.s-1.cm-2 

  Continuum 

10-16erg.s-1.cm-2.A-1 

Emission Line 

10-16erg.cm-2.s-1 

1.083 6.3 x 10-2 9.3  8.1 x 10-3 1.2 
1.187  3.0 x 10-2 3.8  3.8 x 10-3 0.48 
1.215  7.5 x 10-2 14.5   9.5 x 10-3 1.9 
1.257  3.6 x 10-2 7.3  4.6 x 10-3 0.93 
1.282  7.4 x 10-2 15   9.5 x 10-3 1.9
1.644  6.3x 10-2 16.5   8.1 x 10-3 2.1
1.710
6.3 x 10-2 17.3   8.1 x 10-3 2.2 
2.058 3.0 x 10-2 9.3  3.9 x 10-3 1.2 
2.090  3.1 x 10-2 7.0  4.0 x 10-3 0.9
2.122 2.9 x 10-2 9.3  3.8 x 10-3 1.2 
2.166  3.2 x 10-2 9.7   4.1 x 10-3 1.3
2.195  3.6 x 10-2 11.4   4.6 x 10-3 1.5 
2.280  3.1 x 10-2 10   4.0 x 10-3 1.3 
2.248  3.2 x 10-2 9.3   4.2 x 10-3 1.2 
2.336
3.8 x 10-2 
12.4 
4.9 x 10-3 
1.6 
Table 6. Estimated point source detection limits for s/n =5 through narrow band filters.

Spectroscopic Limits

The sensitivity is a strong function of wavelength. For continuum sources, the sensitivity is plotted separately for the J, Hand Katmospheric windows.

For emission line sources, the sensitivity is plotted separately for the J, Hand Katmospheric windows.