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ACS dithering and drizzling

Drizzling ACS images (Circa 2004)

Click here for the January 2009 MultiDrizzle Handbook which supercedes some but not all of this information below. It should be your starting point for using the current version of MultiDrizzle, including understanding task parameters, current working philosophy behind the various software tasks, and for examples using the latest methods and versions of the software and its task parameters. The information below, from 2004, may still be applicable in some cases, but is mainly maintained here at present for historical background and for links to other relevant technical documentation related to the development of the task as it existed in earlier versions. (The original circa 2004 page complete with its old, original links is below this point, except the link to the PyDrizzle page has been removed since PyDrizzle documentation is now incorporated into the MultiDrizzle Handbook.)


Helix Nebula mosaic F658N

See the ACS dither web page for information on designing and using ACS pointing patterns. The following list of documents provide information about reducing dithered or mosaiced data:

Drizzling mechanics

MultiDrizzle implementation in the ACS pipeline
As of September 22, 2004, MultiDrizzle has been incorporated into the ACS data reduction pipeline. This page describes some details of the implementation and resulting image products.

The ACS Data Handbook
Mack et al., 2003, Chapter 3 describes pipeline processing, including PyDrizzle; Chapter 4 provides detailed drizzling guidance, including the rejection of cosmic rays and image registration with MultiDrizzle

The MultiDrizzle webpage
Hack & Jedrzejewski, 2002, MultiDrizzle is currently a stand alone IRAF/STSDAS task which must be downloaded and installed; requires PyRAF; does not yet include automated shift tweaking

Reduction of the Helix Nebula mosaic
Mutchler, 2003, a detailed example of drizzling a large ACS mosaic (the F656N WFC mosaic is displayed above), which can be reproduced with FITS data also provided

Drizzling reference

Andy Fruchter's dithering webpage
Fruchter, 1996

Drizzle: A Method for the Linear Reconstruction of Undersampled Images
Fruchter & Hook, PASP, 114: 144-152, 2002 February

Anton Koekemoer's MultiDrizzle webpage
Koekemoer, 2002 (describes use of the full-featured version with shift tweaking)

MultiDrizzle: An Integrated Pyraf Script for Registering, Cleaning and Combining Images (PDF)
Koekemoer, Fruchter, Hook, Hack, 2002, HST Calibration Workshop Proceedings (details about Multidrizzle steps and parameter settings)

HRC mosaic simulation (PDF)
Mutchler, 2001, previous version of this webpage; pre-flight testing of drizzle software with simulated data

Last modified October 8, 2004 by Anton Koekemoer