Public Release: 

MSX Infrared Observations Of The Galactic Center

Johns Hopkins University Applied Physics Laboratory

The Science Team for the Midcourse Space Experiment (MSX) -- a Ballistic Missile Defense Organization satellite launched in April -- has released the highest resolution mid-infrared maps of the central 1° by 3° region of our galaxy.

The resolution of the MSX mid-infrared observation is about 15 times better than the previous best infrared observation taken by the Infrared Astronomical Satellite (IRAS). The raster scans which were used to create the Galactic Center image were among the first made with the MSX Spatial Infrared Imaging Telescope (SPIRIT III), built by the Space Dynamics Laboratory of Utah State University in Logan, Utah.

The observation was part of several MSX astronomy experiments directed by the MSX Celestial Backgrounds Principal Investigator, Dr. Stephan D. Price of the Air Force Phillips Laboratory. Dr. Price is one of eight MSX Principal Investigators. The MSX Project Scientist is Dr. John D. Mill of the Environmental Research Institute of Michigan and Dr. A.T. Stair, Jr. of Visidyne, Inc., is the MSX Chief Scientist.

The images are available on the World Wide Web from the official MSX homepage at, under the "Program News & Info: Press Releases" section. They are also available on the Johns Hopkins University Applied Physics Laboratory (JHU/APL) homepage at, under the "PR" section. Color prints of the images can be obtained from the JHU/APL Public Affairs Office.

Image 1 is a false-color composite of three separate MSX wavelength bands. SPIRIT III Band A (6-11 micrometers) is coded blue; bands C + D (11-16 micrometers when combined) is green; red represents the longest wavelengths, Band E (18-26 micrometers). The image is built up from 23 scans over the 1° by 3° region. The individual images are scaled to produce white for equal intensity in the three bands. Such a composite gives the viewer a sense of the temperatures in various parts of the image. Hot objects such as stars show as blue, while cool objects are red.

The center of the Milky Way is the bright spot at the center of the image, and the Galactic Plane runs horizontally. The infrared is the best spectral region for measuring the thermal or heat radiation from the cool dust found in interstellar clouds and HII regions, regions of ionized hydrogen. These cool objects produce the extended structured emission surrounding the center and the "blobs" that are discernable in the image.

Image 2 is a visible image of the same region taken from the digitized Palomar Observatory Sky Survey. Absorption of visible light by interstellar dust is so large that the Galactic Center is hidden from our view. However, infrared wavelengths are absorbed much less, with 10 percent or more of the infrared radiation from the Galactic Center actually reaching us. So the infrared is ideal for probing regions such as the Galactic Center which are heavily obscured by dust.

MSX is the first system demonstration in space of technology to characterize ballistic missile signatures during the "midcourse" flight phase between booster burnout and missile reentry. During its five-year lifetime, MSX will detect, track, and discriminate realistic targets against terrestrial, Earth limb, and celestial backgrounds. The satellite's imaging capabilities will also support a wide variety of "dual-use" research involving global atmospheric change, astronomy, and space contamination and debris.

The observatory-class MSX satellite was launched on April 24, 1996, from Vandenberg Air Force Base, Calif., into a high-inclination, circular, near sun-synchronous Earth orbit at 561 miles (903.5 kilometers) altitude. Round-the-clock operations are being conducted from JHU/APL in Laurel, Md.

All MSX instruments are now routinely acquiring data for the multiple objective investigations. In addition to the early-mission imaging of the Galactic Center, the Small Magellanic Cloud (a small companion galaxy to the Milky Way) and comet Hyakutake, MSX is scheduled to conduct a survey of the Galactic Plane and to observe the Antarctic ozone hole, lunar eclipse spectra, aurora, Space Shuttle plumes, and other satellites.

MSX observes over a wide range of wavelengths from the mid-infrared to the far ultraviolet. The combined MSX sensor suite is a pioneering space based application of hyperspectral imaging technology. The sensor suite incorporates five primary instruments consisting of 11 optical sensors. The sensors are precisely aligned so that simultaneous observations with multiple sensors can be made. This is essential for scenes or targets which change rapidly.

MSX Instruments include SPIRIT III, an infrared radiometer and interferometer/spectrometer; UVISI (Ultraviolet Visible Imagers and Spectrographic Imagers), built by JHU/APL; SBV (Space-Based Visible) Instrument, built by the Massachusetts Institute of Technology Lincoln Laboratory; OSDP (On-Board Signal and Data Processor), built by Hughes Aircraft Co.; and a suite of contamination sensors provided by JHU/APL.

MSX management for BMDO includes Lt. Col. Bruce D. Guilmain, Program Manager, and Maj. Peter Kurucz, Deputy Program Manager. Principal Investigators for the MSX mission are assigned according to major program experiment areas. In addition to Dr. Price, they include: Mr. Glenn Light, Early Midcourse; Mr. William T. Prestwood, Cooperative Targets; Dr. E. Michael Gaposchkin, Space Surveillance; Dr. Gerry J. Romick, Shortwave Terrestrial Backgrounds; Dr. O. Manuel Uy, Contamination; Dr. Thomas L. Murdock, Data Certification and Technology Transfer; and Mr. Robert R. O'Neil, Earthlimb/Auroral Backgrounds. The MSX program is supported by approximately 100 scientists from 30 institutions.

For more information, please contact the BMDO External Affairs Office at (703) 695-8743, or Luther Young, JHU/APL Public Affairs, at (301) 953-6268 / MSX mission updates can be accessed at

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