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Hubble Space Telescope
Drizzlepac: Examples


Update

A detailed description on using AstroDrizzle to create mosaics is available at the Archive website. It is a cookbook on how the Horsehead Nebula image was created by Jennifer Mack.



Title Goal Data Description DrizzlePac Tasks
WFC3/UVIS: Optimizing Image Alignment for Multiple Visits Align and combine three images taken at different visits and orientations. Three full-frame UVIS F606W images of Omega Centauri, each with exposure time of 40 sec., each taken in a different visit with different roll angle and offset. Tweakreg AstroDrizzle
WFC3/IR: Optimizing Image Sampling for a Single Visit Optimize image sampling using final_pixfrac and final_scale settings in astrodrizzle, for WFC3/IR images. Spiral galaxy NGC 3370 in F160W, observed with a WFC3-IR-DITHERBOX-MIN pattern. All observations in the same visit with same orientation. AstroDrizzle
ACS/WFC: Optimizing Image Alignment for Multiple Visits Align and combine three images taken at different visits and orientations. Three F606W images of the dense star field NGC 104, each with exposure time 339 sec.. The images are CTE-corrected flat field-calibrated files with suffix flc.fits. Tweakreg AstroDrizzle
ACS/WFC: Optimizing Image Sampling for a Single Visit Optimize image sampling using final_pixfrac and final_scale settings in astrodrizzle, for ACS/WFC images. A two-point dither line with subpixel dithers at each point: four images of galaxy NGC 4449 taken with the F555W filter. The images are CTE-corrected flat field-calibrated files with suffix flc.fits. AstroDrizzle
WFC3/UVIS: Aligning Images in Different Filters by Defining an Output Reference Frame Two sets of drizzled images, each for a different filter, are aligned by WCS and in pixel space. Observations of galaxy M83 in F814W and F438W, each filter set taken in different visits. There are three images per filter. Tweakback Tweakreg AstroDrizzle
WFC3/UVIS: Alignment of Sparse Fields Using Headerlets Use headerlets to align and combine three images with a high degree of precision. Three full-frame 420-second UVIS F606W images of GRB-110328A observed in a 3-point dither pattern. Tweakreg AstroDrizzle Apply_headerlet
WFPC2: Aligning and Drizzling WFPC2 Images Strategies for dealing with severely undersampled WFPC2 images. Six dithered images of Messier 2. Most objects are in the WF chips (plate scale 0.1"/pixel). Tweakreg AstroDrizzle apply_headerlet_as_primary
SExtractor Catalogs to Align ACS/WFC Images Using External SExtractor (v2.8.6) Catalogs from *_crclean.fits Images to Align ACS/WFC Images With Drizzlepac/Tweakreg Alignment of four ACS/WFC images, about 60 pixels apart, using a catalog generated by SExtractor. The image contains a large number of extended sources, but relatively few point sources TweakReg TweakBack AstroDrizzle SExtractor

Some of these examples make use of configuration files (.cfg). A primer on working with configuration files can be found here.