Fitting and Modeling in the ASC Data Analysis Environment

S. Doe, A. Siemiginowska, W. Joye, J. McDowell
SAO

Session ID: P10.08   Type: poster

Abstract:

As part of the ASC (AXAF Science Center) Data Analysis Environment, we will provide a Fitting Application to the astronomical community. We present a design of the Application in this paper. Our design goal is to give the user the flexibility to use a variety of optimization techniques (Levenberg-Marquardt, maximum entropy, Monte Carlo, Powell, downhill simplex, Cern-Minuit, and simulated annealing) and fit statistics ( , Cash, variance, and maximum likelihood); our modular design allows the user to easily add their own optimization techniques and/or fit statistics. We also present a comparison of the optimization techniques to be provided by the Application. The high spatial and spectral resolutions that will be obtained with AXAF instruments require a sophisticated data modeling capability. Models will be represented in both ``analytical'' form (i.e., as parameterized models, or functions) and ``digital'' form (as arrays of ``predicted'' data points, calculated over some data subspace). We will provide not only a suite of astronomical spatial and spectral source models, but also the capability to combine these models into source models of up to four data dimensions (i.e., into source functions f(E,x,y,t)). The ASC will provide users with detailed calibration files specifying the performances of the AXAF mirrors, gratings, and instruments; thus, we provide tools to create instrument response models which are appropriate for each observation.

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