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DrizzlePac is new software package for aligning and combining HST images, which brings an array of new features and algorithmic improvements, and we are recommending to use it as a successor to the older, widely used MultiDrizzle software.

Starting in July 2012, all drizzled data products obtained from MAST were produced with AstroDrizzle. An abbreviation for Astrometric Drizzle, AstroDrizzle was designed from the ground-up to substantially improve the handling of distortion in the image header World Coordinate System.

AstroDrizzle removes geometric distortion, corrects for sky background variations, flags cosmic-rays, and combines images with optional subsampling. Drizzled data products from MAST are generated for single visit associations only.

To combine data from additional visits, TweakReg may be used to update the image WCS using matched source lists. Once the full set of images of a given target are properly aligned, they may be combined using AstroDrizzle.

An all new ‘development’ version of the software, DrizzlePac 2.0, is now available for download from SSBX.

Current and recent known bugs in DrizzlePac/AstroDrizzle are listed on this page


  • To obtain the latest development version (DrizzlePac 2.0), users may install the Ureka-based SSBX build.
  • To obtain the same software used in the OPUS pipeline (currently 1.1.16), users may install Ureka.
  • To obtain only the new DrizzlePac software while maintaining the official version of Ureka, users may install an add-on following instructions linked on this page.

SUPPORT FOR AUTOMATED MOSAIC BUILDING Align sets of images into a large mosaic in one step Read more
IMPROVED SKY MATCHING Produce seamless mosaics using new sky matching techniques. More details can be found in an example where these techniques are compared.
ACS TIME-DEPENDENT DISTORTION CORRECTION Supports the new ACS distortion calibration: Only DrizzlePac 2.0 is able to interpret and apply the latest ACS/WFC distortion reference files Read more
MITIGATION OF FALSE DETECTIONS Select point-source targets for alignment based on sharpness/roundness and use of DQ masks to limit inclusion of artifacts/cosmic-rays. Read more
ALIGN DIFFERENT HST CAMERAS Specify separate source finding parameters for input and reference images to optimize source detection from images taken with different HST cameras. Read more
ALIGN HST IMAGES TO NON-HST IMAGES Allows undistorted non-HST images to be used as references for aligning and drizzling HST data. Read more
NEW SUPPORT FOR EXCLUSION INCLUSION REGIONS Select specific areas of interest to use for alignment. We provide an example where these techniques are discussed.
FULL SET OF UPDATES Please see the DrizzlePac 2.0 release notes

More examples coming in 2015 !



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