Mailman 3 February 2000 - AstroPy

Updates to AstroPy page
by W.T. Bridgman Feb. 26, 2000

Feb. 26, 2000

I've installed a number of updates to the Astronomical Python home page at http://lheawww.gsfc.nasa.gov/~bridgman/AstroPy/. I've added links to pages of support modules mentioned in recent posts. Please contact me with any corrections/additions. I've also re-installed the link to the cross-platform support matrix which somehow became disconnected. The server at ra.stsci.edu seems to be down. Thanks, Tom _____________________________________________________ AstroPy mailing list - astropy(a)stsci.edu http://lheawww.gsfc.nasa.gov/~bridgman/AstroPy/

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Astro-Py list
by Andrew Williams Feb. 24, 2000

Feb. 24, 2000

This list has been quiet since I joined - is there actually anyone out there? I'm at Perth Observatory in Western Australia, using Python for data reduction scripts, and to control an Apogee AP7 camera, through pipes to a low-level driver ('Ariel') written by staff at Ohio State University. The only code likely to be useful elsewhere is a FITS file class that reads and parses header cards into a dictionary, so you can do stuff like: import fits f=fits.FITSfile('/path/test.fits','h') et=float(f.headers['EXPTIME']) print 'Exptime=',et,' and comment was:',f.comments['EXPTIME'] print 'All history cards for ',f.filename,':' print f.comments['HISTORY'] Not fancy - no error checking yet to see if the file actually _is_ in FITS format, for example - but it's only 50 lines of python. So far it only handles 'h' mode, to parse headers and leave the file closed. I was planning to add 'r' and 'w' as for normal file classes when I need to actually get at the data. I also don't want to spend too much time duplicating something that's already been written. The code is at: http://www.physics.uwa.edu.au/~andrew/ Andrew Williams -- Dr Andrew Williams andrew(a)physics.uwa.edu.au Perth Observatory, andrew(a)ucc.gu.uwa.edu.au Walnut rd, Bickley, Western Australia. andrewW(a)cyllene.uwa.edu.au

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Fast FITS queries in Python
by Nicolas Devillard Feb. 24, 2000

Feb. 24, 2000

Yet another module to help making keyword queries in FITS headers, either in C or Python. 'qfits' is an ANSI C module that offers very fast keyword queries in FITS headers, through the use of the mmap() system call on Unix. 'qfits' is written in portable ANSI C and should compile on any Unix system that offers the mmap() call, i.e. any modern Unix :-). 'qfits' has been extracted from the eclipse library to build a stand-alone module, to make it accessible from Python. A wrapper module called 'qfits_wrap.c' has been generated using SWIG, making qfits.so a callable shared object from the Python interpreter. If you have SWIG, you can straightaway build a callable module for Perl or Tcl (see http://www.swig.org). A wrapper class called 'Qfits.py' is then offered on top of the shared object, to make the queries more Python-like. Here is an example of an interactive session using Qfits: >>> from Qfits import * >>> q = Qfits('vltframe.fits') >>> q.get('naxis') '2' >>> q.get('MJD-OBS') '51275.33002418' >>> q.get('DET.DIT') '20.0' >>> q.get('HIERARCH ESO DPR CATG') "'SCIENCE '" >>> q.get('dpr.catg', pretty=1) 'SCIENCE' >>> q.get('simple', 'naxis', 'naxis1', 'naxis2', 'bscale', 'bzero') ('T', '2', '1024', '1024', None, None) 'qfits' is a good solution if you only want to retrieve known keywords from a FITS header in a Python script, and you want to do it fast, without need for a complete FITS library with bells and whistles (the distribution tar file for 'qfits' is 12 kbytes). 'qfits' can be downloaded from the (bottom of the) following page: http://www.eso.org/~ndevilla/saft/ -- Nicolas

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