It is not clear that the t_exp parameter in the WinterRaDecToO class is the total expusure and not the exposure time for one of the frames that go in the coadd.
I suggest
adding a message in the api_res 'msg' saying something like : 'Each exposure is %single_exp and the coadd total expusure is %t_exp' , where single_exp = t_exp/n_dither
Displaying the forementioned single_exp in the table produced by build_schedule_locally. I suggest to put the column before visitExpTime and maybe rename visitExpTime to CoaddExpTime
(not needed, but useful) Adding a single_exp variable that check that single_exp * n_dither = t_exp
It is not clear that the t_exp parameter in the WinterRaDecToO class is the total expusure and not the exposure time for one of the frames that go in the coadd.
I suggest