Amateur X-ray astronomy

Amateur X-ray astronomy awaits the ingenious and determined amateur, as X-rays can only be observed by appropriate detectors placed at very high altitudes near the edge of or above the Earth's atmosphere. Collectively, amateur astronomers observe a variety of celestial objects and phenomena sometimes with equipment that they build themselves. Often these efforts yield discoveries that add to the knowledge of astronomy. With the continued improvement in equipment and the lowering of costs for specialized devices, the amateur astronomer of today can accomplish more than many early professional astronomers could only dream of.
There are major challenges to amateurs observing and reporting experiments in X-ray astronomy: the cost of building an amateur rocket or balloon to place a detector high enough and the cost of appropriate parts to build a suitable X-ray detector.
Amateur rocketry
The United States Air Force Academy (USAFA) has and continues to develop the FalconLaunch sounding rockets. In addition to any direct amateur efforts to put X-ray astronomy payloads into space, there are opportunities that allow student-developed experimental payloads to be put on board commercial sounding rockets as a free-of-charge ride.
The Reaction Research Society on November 23, 1996, launched a solid fueled rocket, designed by longtime member George Garboden, to an altitude of 80 km (50 miles) from Black Rock Desert in Nevada.
On May 17, 2004, the Civilian Space eXploration Team (CSXT) successfully launched the first amateur high-power rocket into space, achieving an altitude of 115 km (72 miles).
Such sounding rockets, including those that can be purchased, have certain advantages even over satellites for X-ray astronomy. They are usually much simpler, far fewer interfaces to match up, and the launch facilities are less elaborate. Some basic space research efforts that can be accomplished by amateurs need to successfully explore the region of the atmosphere above balloon altitudes (about 40 km) and below satellite orbits (about 160 km). Convenient to the effort is the informality. For most payloads, only one experimenter (or a small group) is involved so there is no need for formal, time-consuming reviews to ensure compatibility with other experimenters. In addition, there is low cost - some sounding rockets cost as little as $10,000; then, there is recoverability, geographic flexibility, and temporal flexibility. It was launched on July 17, 1991, on an Ariane rocket along with four microsatellites, one of which is an amateur astronomy satellite called "SARA". For normal incidence or glancing angle incidence, the main cost limitation is the telescope X-ray optics. An overview and details which especially pertain to the use of CCDs in X-ray detectors can be coupled with practical books on the assembly of CCD cameras for amateur astronomy. Even for low-end amateur astronomy CCDs there are techniques well suited to X-rays such as for optical diffraction microscopy that do not depend on the use of focusing devices available at these very short wavelengths (which may have limited quality and resolution).
Simultaneous observation
Although presently the number of active X-ray astronomy satellites is only about eight, the controlling agency is fully aware of the pointing and slewing targets and time-table. Astute coordination of amateur astronomers using optical telescopes during imaging of the nearest star systems, for example, can result in simultaneous observations of phenomena in X-rays and the visual band.
Efforts to study the origin of X-rays from non-magnetic cataclysmic variables using ROSAT benefitted from simultaneous ultraviolet and visual observations with the International Ultraviolet Explorer (IUE) and groundbased amateur observers.
By combining optical data of amateur astronomers from international amateur organizations (the American Association of Variable Star Observers, AAVSO, and the British Astronomical Association, BAA) with that available from professional observations, very complete light curves of X Persei are produced. Further combining the optical light curves with infrared photometric measurements and X-ray observations shows the last extended faint, non-variable phase (1990-present) is related to the loss of the circumstellar shell associated with such a Be/X-ray binary system.<ref name=Roche/>
X-ray source files
With so many successful X-ray astronomy satellites over the last forty years gathering data on upwards of half a million astronomical X-ray sources, there simply is not sufficient time nor skilled people to process and correlate this information with visible sources, among others. Here is an opportunity for amateur astronomers to contribute significantly.
Consider the Lockheed X-ray sources. Most of these twenty-three sources have no visible counterpart or counterpart at any longer wavelength than X-rays.
Visibly dark X-ray source
Many of the Lockheed X-ray sources may be visibly dark. Of the first X-ray sources discovered in each constellation (126 for 89 areas), some 63% are visibly dark. These X-ray sources can be radiative cosmic dust, hydrogen gas such as an H I region (HI) or H II region (HII) (e.g. the Orion Nebula), a molecular cloud (MoC), dark nebula (DNe), dark cloud or cloud (Cld), high-velocity cloud (HVC), or a coronal cloud such as interstellar medium (ISM), a reflection nebula (RNe), or a galactic nebula (GNe). Many of the visibly dark X-ray sources are also X-ray transients.

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