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Welcome to the XQC sounding rocket experiment. XQC stands for X-Ray Quantum Calorimeter, a soft x-ray spectrometer used for suborbital astrophysical observations.
The XQC sounding rocket payload is designed to study the diffuse X-Ray background in the energy range from 0.05 to 1 keV at very high spectral resolution. The diffuse x-ray background is thought to emanate from a local region of hot interstellar gas. Previous experiments have implied that this gas is a hot, low density plasma but did not have the resolving power to distinguish individual emission lines over a broad spectral range. This experiment is able to resolve line emission from the hot plasma.
The XQC detector is composed of a 36 pixel microcalorimeter array attached to an adiabatic demagnetization refrigerator operating at 60 mK. Each pixel measures 0.5 x 2.0 mm to give a total detector area of 36 mm2. The entire detector has a mechanically defined 28 degree field of view through four infrared blocking filters.
The launch vehicle for the XQC detector is a Nike-Black Brant two stage sounding rocket. The rocket was assembled at White Sands Missile Range by NASA's Wallops Flight Facility. Sounding rocket flights are quite short in duration, approximately 15 minutes, but obtain an altitude above 220 km. The XQC experiment was designed to have an observing time of only 240 seconds during the flight, sufficient, however, to obtain a reasonable spectroscopic observation.
The XQC experiment has been launched three times from White Sands Missile Range in New Mexico; twice successfully. Successful observations were made on June 3, 1996 and March 28, 1999. Both times, the experiment observed a large portion of the northern sky for 240 seconds before landing via parachute about 80 miles up-range in the New Mexico desert. Preliminary results from these flights show emission lines from several highly ionized atoms in both the Wisconsin C and M spectral bands. Analysis of the flight data and calibrations of the flight detector and filters continue to be performed by the experiment team.
The sounding rocket program is an inexpensive way to test the technologies necessary to deploy microcalorimeters in orbital experiments such as XRS and Constellation-X. In addition, however, useful astrophysical observations can be performed. In future experiments, the XQC detector will observe other regions of the soft x-ray sky and will use new, more advanced microcalorimeter detectors. The goal is to understand the origin, composition, ionization state and temperature of the emitting region..
This project is a collaboration between the X-ray Astrophysics and Detector Development branches at NASA/GSFC and the University of Wisconsin.
This site contains a description of the experiment as well as pictures of the payload, detectors and launch vehicle assembies. Please enjoy your visit and if you have any questions just follow the "experiment team" link off the main page.
This page written and maintained by F. Scott Porter (email:
Responsible NASA official: F. Scott Porter (email: Frederick.S.Porter@gsfc.nasa.gov)