KOOLS Exposure Time Calculator(β)

For Point Sources

grism:

slit(arcsec):

Object Magnitude: Mag. at:

No.5: 500 nm
No.2: 700 nm
VPH495: 500 nm
VPH683: 680 nm

Target S/N:

Single Exposure Time: seconds

 

Results:

grism: no2
slit: 1.8
Object mag: 19.00 AB
Sky brightness: 19.00 mag/arcsec2 (fixed)
Single exp time: 1200
Seeing: 2.0 (fixed)
Slit loss: 29%
Sys. transmission: 0.10 at 700 nm
Binning: 2x2 (fixed)
Sampling: 0.38 nm/pix with 2bin
Read-out noise: 14.9 e- (fixed)

Required number of exposures to achieve S/N=5.00 for a point-source with 19.00 mag. : 3 

 exp num | source e- | background e- | noise e- | S/N
       1   1.3094e+02  6.6448e+02     3.8420e+01  3.41
       2   2.6187e+02  1.3290e+03     5.4334e+01  4.82
       3   3.9281e+02  1.9934e+03     6.6546e+01  5.90

λeff and System transmissions:
No.5: 500 nm, 5%
No.2: 700 nm, 10%
VPH495: 500 nm, 10%
VPH683: 680 nm, 15%
Note that these calculations are for the peak wavelength of each grism. Sensitivity variations for different wavelengths can be referred at KOOLS sensitivity page. Peak wavelength can be adjusted by moving the position of the slit in field-of-view.

kools_etc1.cgi version 20100318