First Galactic Plane A (GPA) Survey Data Archive

Galactic center region at 8.35 GHz (left) and 14.35 GHz (right)

This Web Page/CDROM contains calibrated radio wavelength images of the Milky Way (our galaxy). These data have a number of uses, including:
  1. Study the physics of the black hole at the center of our galaxy.
  2. Study the birth of stars in molecular clouds.
  3. Your own project.
This CDROM contains FITS format images, which have all coordinate and calibration measurements, BUT you need a program to display and measured parameters from these images.
The steps required to start making progress are:
  1. Follow the steps to start up Sky Image Processor (SIP) (below) to load a JAVA-based image analysis system within your browser.
  2. Go to the GPA sub-directory and select a region of the galaxy for study.
  3. Publish your results and mention the use of the GPA data.


Robert Welsh has created a series of lessons plans geared to high school level students, that the students will enjoy. These lesson plans achieve the goals of:
  1. Present a real-life example of how scientific research is carried out.
  2. Teach how radio wavelength data shows a very different view of the galaxy (With radio waves we can see to the center of the galaxy.
  3. Show measurement and tabulation of science data.
  4. Distinguish star forming regions from supernovae remnants.

Galactic Center at 8.35 (red), 10.3 (green) and 14.35 (blue) GHz

Galactic Center at 8.35 (red), 10.3 (green) and 14.35 (blue) GHz

In the image above, the GPA images at 8.35 and 14.35 GHz have been combined with the Handa et al survey at 10.3 GHz (see below) to produce a false color image of the galactic plane in the region near the galactic center. The pixel range is 0 to 3 Jy for all three frequency bands, so sources brighter than 3 Jy in all three bands are shown in white. The hot molecular clouds and the galactic center are white in the image above, while supernova remnants and extended cooler clouds are redder.

Cygnus X-3 2000 April flare The Cygnus X-3 (a binary star system in our galaxy) exhibited transient emission on 2000 April 20. The binary stars appear as a red peak in the center of one of the images. The radio emission of this region is compared to the Galactic Plane A (GPA) Survey image taken on 1998 September. The brightest emission is in red and faintest emission is in blue. The 2000 April 20 image has a higher noise level than the GPA image. The green emission differences are not significant. The flux density range is 0 to 7 Janskies at 8.35 GHz. The maps show a complex region of our galaxy, called the Cygnus Loop. Cygnus X-3 is located at galactic latitude 0.7005d, longitude 79.8455 (J2000 Ra 20h32m25.70s, Dec 40d57'28.0", 308.1071d, 40.9578d)
Sky Image Processor The Sky Image Processor program written by John Simonetti at Virginia Polytechnic Institute and State University is very useful for viewing FITS images, and for measuring the intensities of radio sources. The latest version is available online from the author.

A copy of version 2.10 of the software is also contained on this disk.
M31 Galaxy from NVSS FITSview programs are available for displaying GPA data. These programs, written by Bill Cotton are available for a variety of platforms and are very useful for studying images provided in FITS format. For the convenience of WIN95/WIN98/WINNT users, copies of the executable and help file are placed in the fitsview top directory. For the convenience of RedHat Linux users, a copy of of the executable is placed in the fitsview top directory.

The Northern VLA Sky Survey provides FITS format images over the entire sky north of -40 degrees declination.

Screen Shot of Aladin The Aladin JAVA software is very useful for viewing FITS images, but must be down-loaded and installed to allow access of local FITS images. The binary files for Aladin are available on this disk for /95/98/NT

Green Bank Tracking Station The GPA observations were made using the Orbiting VLBI tracking station in Green Bank, West Virginia. The station is one of four NASA tracking stations dedicated to support of the space vlbi missions in Japan and Russia. The HALCA satellite is used to study the properties of jets of material ejected from the region surrounding black holes at the centers of distant galaxies.
Galactic Center Region from Handa 10GHz survey The 10 GHz survey of Handa, Sofue, Nakai, Hirabayashi and Inoue 1987, (Publ. Astron. Soc. Japan, Volume 39, pages 708-754) covers a region of the galactic plane, 355 < l < 56, -1.5 < b < 1.5, with high sensitivity at 10 GHz. Their FITS format images, calibrated in units of Jy/Beam are available in increments of two degrees galactic longitude. The fits files are centered on 356d , 358d , 0d , 2d , 4d , 6d , 8d , 10d , 12d , 14d , 16d , 18d , 20d , 22d , 24d , 26d , 28d , 30d , 32d , 34d , 36d , 38d , 40d , 42d , 44d , 46d , 48d , 50d , 52d , 54d and 56d .

Multi-Wavelength Milky Way site at GSFC has a good Galaxy Overview.

The GPA data are provided by the National Radio Astronomy Observatory (NRAO), a facility of the National Science Foundation operated under cooperative agreement with the Associated Universities, Inc. Last update: 2000 March 22