Purpose: This code calculates the predicted SNR of a transit given the 2MASS K band magnitude of the source, the spectral type of the source, the IRAC channel of interest, and the depth of the transit.

Author: Jessica Krick
Date Contributed: 29 Jan 2015
System Requirements: IDL

Information and Download

Download SNR.tar (18 KB)

The code assumes a relation for how the noise of the source decreases with increasing number of frames which is based on an empirical relation taken from the literature. After data reduction, on average the literature is finding that the poisson noise limit is routinely achieved for ch1 on binning scales less than 30 frames and for ch2 on binning scales less than 100 frames. Ch1 data are able to achieve 2 times the poisson noise on binning scales greater than 30 frames and a factor of 1.5 times poisson on binning scales greater than 100 frames for ch2.

Required functions include convert_Kmag_IRAC, find_exptime, mjy_to_electron, sigfig. The main code is called exoplanet_SNR.pro, and an example of how to call it is:

SNR = exoplanet_snr(12.0, 'M0','2', 1E-3)