Chromospheric Transit Routine

The following is an IDL routine to compute the transit of a spherical planet of a stellar chromosphere which is geometrically thin, based upon Schlawin, Agol, Walkowicz, Covey & Lloyd (2010). If you use this routines in your research, please cite this paper. If you find any bugs in this routine, please let me know and I will make my best effort to correct them. This routine was created with support from NSF CAREER Grant No. 0645416.

Here is an example of using it to compute the chromospheric transit of planet with a radius that is 3% of the radius of the star:

IDL> p=0.03
IDL> b=0.5
IDL> t=-1.5+3*(dindgen(1000)+.5)*.001
IDL> x=sqrt(b^2+t^2)
IDL> chrom_exact,x,p,lc
IDL> plot,t,lc,ys=1,yr=[.995,1.001]

If you make use of this routine and would like to be informed of updates or bugs, please email me:
Eric Agol (agol AT