simcado.nghxrg module¶
NGHXRG by Bernard Rauscher see the paper: http://arxiv.org/abs/1509.06264 downloaded from: http://jwst.nasa.gov/publications.html
-
class
simcado.nghxrg.HXRGNoise(naxis1=None, naxis2=None, naxis3=None, n_out=None, dt=None, nroh=None, nfoh=None, pca0_file=None, verbose=False, reverse_scan_direction=False, reference_pixel_border_width=None)[source]¶ Bases:
objectA class to generate HxRG noise frames
HXRGNoise is a class for making realistic Teledyne HxRG system noise. The noise model includes correlated, uncorrelated, stationary, and non-stationary components. The default parameters make noise that resembles Channel 1 of JWST NIRSpec. NIRSpec uses H2RG detectors. They are read out using four video outputs at 100.000 pix/s/output.
-
mknoise(self, o_file, rd_noise=None, pedestal=None, c_pink=None, u_pink=None, acn=None, pca0_amp=None, reference_pixel_noise_ratio=None, ktc_noise=None, bias_offset=None, bias_amp=None)[source]¶ Generate a FITS cube containing only noise.
- Parameters
- o_filestr
Output filename
- pedestalfloat
Magnitude of pedestal drift in electrons
- rd_noisefloat
Standard deviation of read noise in electrons
- c_pinkfloat
Standard deviation of correlated pink noise in electrons
- u_pinkfloat
Standard deviation of uncorrelated pink noise in electrons
- acn: float
Standard deviation of alterating column noise in electrons
- pca0float
Standard deviation of pca0 in electrons
- reference_pixel_noise_ratiofloat
Ratio of the standard deviation of the reference pixels to the regular pixels. Reference pixels are usually a little lower noise.
- ktc_noisefloat
kTC noise in electrons. Set this equal to sqrt(k*T*C_pixel)/q_e, where k is Boltzmann’s constant, T is detector temperature, and C_pixel is pixel capacitance. For an H2RG, the pixel capacitance is typically about 40 fF.
- bias_offsetfloat
On average, integrations stare here in electrons. Set this so that all pixels are in range.
- bias_ampfloat
A multiplicative factor that we multiply PCA-zero by to simulate a bias pattern. This is completely independent from adding in “picture frame” noise.
Notes
Because of the noise correlations, there is no simple way to predict the noise of the simulated images. However, to a crude first approximation, these components add in quadrature.
The units in the above are mostly “electrons”. This follows convention in the astronomical community. From a physics perspective, holes are actually the physical entity that is collected in Teledyne’s p-on-n (p-type implants in n-type bulk) HgCdTe architecture.
-
nghxrg_version= 2.3¶
-