def __init__(self, jds, mags, magerrs, splitup=True, deltat=0.000001, sort=True, stab=False, 
		stabext=300.0, stabgap = 30.0, stabstep = 5.0, stabmagerr = -2.0, stabrampsize = 0, stabrampfact = 1.0):
		"""
		Constructor
		Always leave splitup and sort on True ! Only if you know that you are already
		sorted you can skip them.
		You cannot specify a mask, I do this myself. (could be done in principle).