This program performs a noise analysis similar to pamela's noise. i.e. it makes local estimates of the noise using the mean of the absolute value of the differences of the values of each pixel and the mean of its 8 surrounding neighbours. The measn is taken over all pixels in boxes over the images. The idea here is not to take overall RMS values which are sensitive to image structure. To relate the mean of the absolute value to the variance a correction factor = sqrt(4*Pi/9) is applied. This accounts for the uncertainty in the mean of the 8 surrounding pixels and is based upon an assumption of gaussian white noise.
ncal device list nccd nwin rms gain grain
| device | --- | Plot device |
| list | --- | List of files to be analysed |
| window | --- | A windows file (e.g. as generated by setwin defining the regions to be evaluated. Each CCD is treated separately. Since one expects each half of the chips to behave differently in ULTRACAM, it is probably wise to avoid crossing the border. |
| nccd | --- | CCD number to analyse |
| xbox | --- | Size of box to average over (X dimension, binned pixels) |
| ybox | --- | Size of box to average over (Y dimension, binned pixels) |
| rms | --- | RMS counts readout to plot as a model |
| gain | --- | electrons/count factor |
| grain | --- | flat-field noise in percent |
This command is a member of the classes: Programs, Testing.
Author: T.R. Marsh
Created: 14 May 2002