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 |
