http://www.noao.edu/staff/mighell/qlwfpc2
This work is/was supported by grants from the
National Aeronautics and Space Administration (NASA)
  • Interagency Order No. NNG05EB61I (NRA 03-OSS-01)
  • Interagency Order No. S-13811-G (NRA 01-OSS-01)
  • which were awarded by the
    Applied Information Systems Research (AISR) Program
    of NASA's Science Mission Directorate.


    QLWFPC2: Quick-Look WFPC2 Stellar Photometry based on the Message Passing Interface

    QLWFPC2 is a new parallel-processing stellar photometry code which is designed to do quick-look analysis of two entire WFPC2 observations from the Hubble Space Telescope in under 5 seconds using a fast Beowulf cluster with a Gigabit-Ethernet local network. This program is written in ANSI C and uses MPICH implementation of the Message Passing Interface from the Argonne National Laboratory for the parallel-processing communications, the CFITSIO library (from HEASARC at NASA's GSFC) for reading the standard FITS files from the HST Data Archive, and the Parameter Interface Library (from the INTEGRAL Science Data Center) for the IRAF parameter-file user interface. QLWFPC2 running on 4 processors takes about 2.4 seconds to analyze the WFPC2 archive datasets u37ga407r.c0.fits (F555W; 300 s) and u37ga401r.c0.fits (F814W; 300 s) of M54 (NGC 6715) which is the bright massive globular cluster near the center of the nearby Sagittarius dwarf spheroidal galaxy. The analysis of these HST observations of M54 lead to the serendipitous discovery of more than 50 new bright variable stars in the central region of M54. Most of the candidate variables stars are found on the PC1 images of the cluster center --- a region where no variables have been reported by previous ground-based studies of variables in M54. This discovery is an example of how QLWFPC2 can be used to quickly explore the time domain of observations in the HST Data Archive.


    Figure 1. Typical QLWFPC2 performance results with two entire WFPC2 observations of a Local Group globular cluster running on a 5-node Beowulf cluster with 1.8 GHz CPUs connect with Gigabit Ethernet. The blue points show actural run times for 1 to 5 processors. The thin line shows a simple performance model based on measure cluster performance metrics (network bandwidth, disk I/O bandwidth, and performace with a single CPU). The thick line shows the theoretical limit of performance based on the system performace metrics. Note that the current version of QLWFPC2 already meets the ideal performance values for 1, 2, and 4 processors. QLWFPC2 running on 4 processors takes about 2.4 secons to anlyze the WFPC2 archive data sets u37ga407r.c0.fits (F555w; 300 s) and u37ga401r.c0.fits (F814w; 300 s) of M54 which is the bright massive globular cluster near the center of the nearby Sagittarius dwarf spheroidal galaxy. QLWFPC2 analyzed over 50,000 point source candidates and reported V, I, F555W, and F814W photometry of 14,611 stars with signal-to-noise ratios of 8 or better.


    ADASS XIII conference proceedings article:

  • adass2003_article.pdf (PDF format)
  • adass2003_article.ps (PostScript format)

  • AAS 203rd Meeting, January 2004
    Session 4 Computation, Data Handling and Image Analysis
    Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall

    [4.01] QLWFPC2: Parallel-Processing Quick-Look WFPC2 Stellar Photometry based on the Message Passing Interface

    K. J. Mighell (National Optical Astronomy Observatory)

    I describe a new parallel-processing stellar photometry code called QLWFPC2 which is designed to do quick-look analysis of two entire WFPC2 observations from the Hubble Space Telescope in under 5 seconds using a fast Beowulf cluster with a Gigabit Ethernet local network. This program is written in ANSI/ISO C and uses the MPICH implementation of the Message Passing Interface from the Argonne National Laboratory for the parallel-processing communications, the CFITSIO library (from HEASARC at NASA's GSFC) for reading the standard FITS files from the HST Data Archive and the Parameter Interface Library (from the INTEGRAL Science Data Center) for the IRAF parameter-file user interface. QLWFPC2 running on 4 processors takes about 2.4 seconds to analyze WFPC2 archive datasets u37ga407r.c0.fits (F555W; 300 s) and u37ga401r.c0.fits (F814W; 300 s) of M54 (NGC 6715) which is the bright massive globular cluster near the center of the nearby Sagittarius dwarf spheroidal galaxy. The analysis of these HST observations of M54 lead to the serendipitous discovery of more than 50 new bright variable stars in the central region of M54. Most of the candidate variables stars are found on the PC1 images of the cluster center --- a region where no variables have been reported by previous ground-based studies of variables in M54. This discovery is an example of how QLWFPC2 can be used to quickly explore the time domain of observations in the HST Data Archive.

    This work is supported by a grant from the National Aeronautics and Space Administration (NASA), Order No. S-13811-G, which was awarded by the Applied Information Systems Research Program (AISRP) of NASA's Office of Space Science (NRA 01-OSS-01).

    If you would like more information about this abstract, please follow the link to http://www.noao.edu/staff/mighell/qlwfpc2.

    203rd AAS meeting poster:

  • aas203_poster.pdf (PDF format)
  • aas203_poster.ppt (Microsoft PowerPoint format)

  • QLWFPC2 release: 2005OCT28

    Retrieve and build MX
    (^ click on this link and follow the instructions)

    Build QLWFPC2:

  • Go to the main mx directory

  • QLWFPC2 uses the Message Passing Interface (MPI) standard,
    so in order to build QLWFPC2 you will need to have a working implementation
    of MPI with a mpicc compiler command on your machine.
  • If you do not have MPI and the mpicc command on your machine,
    then you can build the Open MPI implementation of MPI,
    by typing the following command:

    make ompi

    now sip some espresso as this may take some time...

    After the build is done...

  • If you use the C shell (/bin/csh), then type the following commands:

    cp bin/.ompi.csh ~/
    source ~/.ompi.csh


    HINT: Add the last command to your ~/.cshrc file to make Open MPI always available.

  • If you use the BASH shell (/bin/bash), then type the following commands:

    cp bin/.ompi.bash ~/
    source ~/.ompi.bash


    HINT: Add the last command to your ~/.bashrc file to make Open MPI always available.

  • Congratulations! You have installed Open MPI on your machine.

  • Assuming that you have mpicc working on your machine,
    build QLWFPC2 by typing the following command from the main mx directory:

    make qlwfpc2
  • CHECK: If the file bin/qlwfpc2 exists, you have built QLWFPC2!

    Now try out QLWFPC2:

  • Go to the main mx directory

  • Go to the qlwfpc2 directory, by typing the following command:

    cd qlwfpc2

  • The simplest invocation with one processor:
  • Type the following command:

    ./qlwfpc2

    and accept the default values for the first and second WFPC2 image filenames.
    The program output is found in the following files:

    .qlwfpc2imag1
    .qlwfpc2imag2
    .qlwfpc2imag1.xml
    .qlwfpc2imag2.xml
  • Same results using the mpirun command:
  • Type the following command:

    mpirun -np 1 qlwfpc2
  • Now give the names of the images on the command line:
  • Type the following command:

    mpirun -np 1 qlwfpc2 data/v1.fits data/i1.fits

    Note that you are no longer prompted for the name of the WFPC2 image files.
  • If you want to be verbose...
  • Type the following command:

    mpirun -np 1 qlwfpc2 image1=data/v1.fits image2=data/i1.fits
  • Now try QLWFPC2 with 4 processes:
  • Type the following command:

    mpirun -np 4 qlwfpc2 data/v1.fits data/i1.fits

    The reported elapsed time should have gone down significantly
    -- if the 4 processes was run on 4 processors!
  • More to come...


    Kenneth Mighell
    Associate Scientist  
    Kitt Peak National Observatory
    National Optical Astronomy Observatory
    
    EMAIL: mighell at noao dot edu
     MAIL: P.O. Box 26732, Tucson, AZ  85726-6732
    FEDEX: 950 N. Cherry Ave., Tucson, AZ  85719
    PHONE: (520) 318-8391
      FAX: (520) 318-8360
      URL: http://www.noao.edu/staff/mighell/
    

    Updated: 2005 November 09 @ 17:04 MST