The Multimission Archive at STScI Newsletter
Table of Contents
Users requesting WFPC2 data from the MAST archive now receive an additional data product, a quick-look mosaic of the images from all four detectors. The new files, labeled *drz.fits, are produced by the program PyDrizzle, which was recently incorporated into the WFPC2 calibration pipeline. PyDrizzle uses the WFPC2 distortion corrections recently derived by Luigi Bedin. Output images have a plate scale of 0.1" per pixel. Because PyDrizzle is run on each WFPC2 exposure independently, it cannot perform sub-pixel sampling or cosmic-ray rejection. The DRZ files are provided in standard (multi-extension) FITS format, rather than the waivered FITS (GEIS) format used by the other WFPC2 files. The primary extension contains only header information; the first extension contains the drizzled image. A Space Telescope Analysis Newsletter (STAN) describing the DRZ files will be issued later this month. An Instrument Science Report (ISR) describing the new geometric distortion corrections will be issued in a few months. Because they lack cosmic-ray rejection, DRZ files are intended as quick-look images, rather than as science data products.
Over the next several months we will be reprocessing all of the WFPC2 data, using the best calibrations available, and archiving the fully calibrated datasets in both GEIS and FITS formats. More information will follow in the next newsletter.
The completed AIS (all sky) survey has been delivered and staged on the MAST GALEX website, thereby completing the imaging component of the GR4. Grism data is being ingested at this writing, and at 143 tiles will almost triple the MAST holdings of GALEXZ spectra. The GR4 imaging dataset is huge (11.6 TB, including its database of 1TB) and covers some 31,000 tiles (almost the same number of square degrees on the sky). The GR4 delivery completes what the GALEX project terms its "primary mission."
Users now have a choice to go to the old GR2/GR3 pages or to the new GR4 website. The default homepage will be switched shortly when images are created for the Map tool, which will also point to one or the other GR datasets.
The MAST GALEX team is pleased to announce the inauguration of the "galexView" web application. The galexView tool easily accommodates searches for tiles or objects. By using the new Adobe Flex technology, galexView gives the user the instantaneous "desktop feel" once the data are loaded. We have just rolled out version 1.2, and a snapshot is shown in the figure below. The galexView browser page may be divided into up to 3 separate panes that show the image for the tile the user has selected, a table giving information about each of the objects, and a search history, such that one can readily return to previous visits. Version 1.2 also provides an upload target list facility that allows one to collect search results for a large number of targets, specified by coordinates. Catalogued objects in the tile (or neighboring tiles) may be switched on, color coded by survey. The snapshot shows an example of a search on the GR4 dataset for the Sombrero galaxy. The orange circles in the snap are the objects from the Nearby Galaxy Survey returned from the request out to a designated search radius (red circle). A specific object may be 'clicked on', turning its circle green and bringing up an Objects Properties box, as shown in the snap to the lower left of the image. We are currently developing a new generation of this tool and also investigating ways to modify the Map tool (see article in the February 2008 newsletter) to exploit the best of its native Mapserver technology as well as the capabilities of Flex.
MAST has established the "MAST Forum" in response to suggestions from our user community. You can find a link to the Forum on the second line of the top navigation bar of most MAST web pages. It should be the right most link on each page.
The forum is a place for MAST users to post topics related to the MAST archive, either suggestions or questions on using MAST tools and services are welcome. Recently we have been considering changes to the MAST website to improve navigation. We have posted a topic related to this in the forum and are looking forward to seeing a discussion on this topic by our users. To avoid spam postings, you will need to register on the forum to post.
GOODS - Version 2.0
Coma Cluster Treasury
STIS Next Generation Spectral Library
UV images of the UDF and HDF fields
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