STSDAS Users Guide
In addition to the instrument-specific applications and the general tools described in the previous two chapters, STSDAS includes seven general data analysis packages that can be used on essentially any astronomical data. These packages are grouped under the analysis package and include image restoration, various fitting routines, fourier analysis, access to the Guide Star Catalog, and statistics. This chapter provides an overview of the generic analysis facilities provided by STSDAS. Some of the features found in
analysis subpackages include:
Other tasks that may be useful to the HST observing community, but that are not yet complete are provided in the playpen package. Tasks that may be useful but that were written outside the STSDAS group are provided on a non-supported basis in the contrib package.
- Feature Fitting: There are two packages that contain general tasks for fitting image features:
isophote and fitting.
Both are layered on the IRAF icfit utilities.
The isophote package fits galaxy brightness profiles in two-dimensional images with elliptical isophotes. The fitting package fits elliptical Gaussians to two-dimensional images and can also fit one-dimensional Gaussians, Planck or powerlaw functions, and composite profiles to spectra or images.
- Fourier Analysis: The fourier package contains tasks for forward and inverse Fourier transforms as well as tasks for computing power spectra, cross-correlations, convolutions etc.
- Guide Star Analysis: The gasp package contains tasks for searching the Guide Star Catalog and extracting portions to STSDAS tables. Tasks can derive a plate solution for an image, determine celestial coordinates of objects, and write World Coordinate descriptors to an image header based on the plate solution.
- Image Restoration: The restore package contains several tasks for restoring images, especially those produced by HST with its aberrated mirror.
- Statistics of Censored Data: Statistical methods for the analysis of censored data are implemented in the statistics package, which was adapted from the ASURV v1.2 package developed at Pennsylvania State University. Upper and lower detection limits can be applied, excluding from analysis data meeting certain statistical criteria.
- Time Series: One-dimensional photometric time series analysis is provided by the
timeseries package. Tools are provided for coadding data over phase intervals and transforming flux measurements to instrument or standard magnitude systems. Auxiliary tools are available for other functions, such as calculating light travel time corrections to solar system barycenter, and subtracting sky background.
- Image Restoration
- Interactive Curve Fitting
- Fourier Analysis
- The Guide Star Catalog and Plate Solutions
- Isophote Fitting
- Other STSDAS Packages
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