NOISE

NOISE observations are designed to check that the bolometers are operating within specifications. This is achieved by calculating the power spectrum and looking at the mean power between two frequencies (usually 2 and 10 Hz). Excessively noisy bolometers are noted and a bad bolometer mask generated. The calcnoise command can be used to analyze any SCUBA-2 time series. It can be used to generate both a noise image (in pA/rt(Hz)) and a NEP image (in W/rt(Hz)) from raw data. The noise image will be the image in the main part of the data file and the NEP image will be in the .MORE.SMURF.NEP extension. If the data have been flatfielded the NEP image extension will not be written since the primary image will already be in power units. A noise ratio image (.MORE.SMURF.NOISERATIO) is also created to give an indication of the mean power relative to the power at a particular frequency.

Bad bolometer masks are supported by the flatfield, extinction, remsky, and makemap tasks through the BBM parameter. A mask can be generated from the noise images using the KAPPA thresh command.