Signal-to-Noise Estimates

Signal-to-Noise Estimates

For Vega, which is a telluric standard A0V star, the IGRINS Exposure Time Calculator (Version 2.11) gives the estimates shown in the figure below.  

The figure shows S/N estimates for 30 & 300 second exposure times with a quad (e.g. ABBA) exposure set.

Park et al. (2014; SPIE Proceedings) find that the observed S/N is ~83% of the predicted value. 

Based of IGRINS ETC v2.11 and the deviation from predictions of 83% from Park et al. (2014; SPIE Proceedings), a rough value for the S/N for an A0V star can be estimated using the following equation:

S/N ~ 273*sqrt(N*t)*10^(-0.2*Kmag)

where N = # of exposures, t = exposure time in seconds, Kmag = K-band magnitude.

 

As a rough guide, the peak counts in the continuum of a single exposure can be examined to guide the final SNR.

 

Peak counts in single frame continuum:

SNR (per res.) for one ABBA

for 2 ABBA quads

50

 55

80

100

80

115

150 

 100

140

200

115

160

250

130

180

300 

 140

200

400

160

230

500

180

255

600 

 200

280

800

235

320

1000 

 250

360