debug -prints out debugging information about the progress of the search.
max= - defines the maximum count level instead of using the very first measurement. maxsteps= - adjusts the maximum number of steps used to find the half intensity point. The default value is 10 steps. first measurement.
back= - defines a background count level which is subtracted from the data before the half way point is calculated. The default value is 0.
chan= is the photometer channel used to determine the mean count rate. The default is channel 0. step= is the angular step (in decimal degrees) which is used to make the search for the half way point. The default is .01 degree.
nsamples= sets the number of samples to be obtained and summed to get the counts. The default is 100.
rate= sets the counter rate in Hertz. The default is 100 Hz.