MOPEX User's Guide - IRSA

MOPEX User’s Guide
given below. On the command line, use the number indicated (e.g. Use_Photerr_for_SNR =
2).
0. no (default): This is APEX’s old SNR. The noise is the noise in the peak pixel, times
a scaling factor that takes into account that pixel’s contribution to the PRF for a centerof-pixel
hit. The noise should be from the Gaussnoise module (Use Data Uncertainties
for PRF-fitted SNR turned off in the APEX Settings. The estimate is poor (an
underestimate of noise) for undersampled pixels, e.g. IRAC channels 1 and 2.
1. yes, no gain: Use the sum (in quadrature) of the data uncertainties within a box
roughly the size of the core of the PRF (Use Data Uncertainties for PRF-fitted SNR
turned on in the APEX Settings. This is usually best.
2. yes, with gain: Use the background noise estimate from the Gaussnoise module
within a box roughly the size of the core of the PRF, and add the photon noise calculated
from the flux and the gain factor (Use Data Uncertainties for PRF-fitted SNR turned off)
Gain_for_SNR (float): The gain factor (electrons per data units) for use in the SNR estimate
(above). For Spitzer data, the data units are given in MJy/sr. This is the gain for a single
image. It will take into account the coverage to estimate an effective gain. In the case of
integration-time weighting, it should be for unit time.
COMMAND LINE INPUT
&SOURCESTIMATE
InputType = 'image_list',
Fitting_Area_X = 5,
Fitting_Area_Y = 5,
Max_Number_PS = 1,
Chi_Threshold = 3,
N_Edge = 4,
Max_N_Iteration = 1000,
Max_N_Success_Iteration = 0,
MinimizeFtol = 0.001,
MinimizeFtolSuccess = 0.00001,
DitherPixelFraction = 0.1,
DitherFluxFraction = 0.8,
DeblendDitherPixelFraction = 1.,
Background_Fit = 0,
Random_Fit = 0,
Chi2_Improvement = 1.,
PRF_ResampleX_Factor = 4,
Point Source Extraction (APEX) 149
APEX Modules