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55-738: ROSAT (short for Röntgensatellit ; in German X-rays are called Röntgenstrahlen, in honour of Wilhelm Röntgen ) was a German Aerospace Center -led satellite X-ray telescope , with instruments built by West Germany , the United Kingdom and the United States. It was launched on 1 June 1990, on a Delta II rocket from Cape Canaveral , on what was initially designed as an 18-month mission, with provision for up to five years of operation. ROSAT operated for over eight years, finally shutting down on 12 February 1999. In February 2011, it

110-541: A wavelength range known as X-rays or Röntgen rays, an achievement that earned him the inaugural Nobel Prize in Physics in 1901 . In honour of Röntgen's accomplishments, in 2004, the International Union of Pure and Applied Chemistry (IUPAC) named element 111, roentgenium , a radioactive element with multiple unstable isotopes, after him. The non- SI unit of radiation exposure , the roentgen (R),

165-549: A bar of platinum - iridium alloy, kept at the BIPM in Paris in a carefully controlled environment. Reliance on that material standard had led to an early error of about one part in 6000 in the tabulated wavelengths. Ångström took the precaution of having the standard bar he used checked against a standard in Paris, but the metrologist Henri Tresca reported it to be so incorrect that Ångström's corrected results were more in error than

220-429: A cardboard covering was added to protect the aluminium from damage by the strong electrostatic field that produces the cathode rays. Röntgen knew that the cardboard covering prevented light from escaping, yet he observed that the invisible cathode rays caused a fluorescent effect on a small cardboard screen painted with barium platinocyanide when it was placed close to the aluminium window. It occurred to Röntgen that

275-666: A carousel within the focal plane turret of ROSAT. PSPC-C was intended to be the primary detector for the mission and was used for the bulk of the All-Sky Survey until it was destroyed during the AMCS glitch on 1991, January 25th. After the glitch, PSPC-B was used for all further observations. Two more PSPCs(PSPC-A and PSPC-D) were mounted on ROSAT for ground calibration. Each PSPC is a thin-window gas counter. Each incoming X-ray photon produces an electron cloud whose position and charge are detected using two wire grids. The photon position

330-614: A code point U+212B Å ANGSTROM SIGN for the angstrom symbol, which is accessible in HTML as the entity Å , Å , or Å . However, version 5 of the standard already deprecates that code point and has it normalized into the code for the Swedish letter U+00C5 Å LATIN CAPITAL LETTER A WITH RING ABOVE (HTML entity Å , Å , or Å ), which should be used instead. In older publications, where

385-538: A further four years before equipment failure forced an end to the mission. For some months after this, ROSAT completed its very last observations before being finally switched off on 12 February 1999. On 25 April 1998, failure of the primary star tracker on the X-ray Telescope led to pointing errors that in turn had caused solar overheating. A contingency plan and the necessary software had already been developed to utilise an alternative star tracker attached to

440-533: A hacking incident on an office computer not related to flight operations. IT security remains a significant issue for NASA. Other systems including the Earth Observing System have also been attacked. In 1990, the satellite was put in an orbit at an altitude of 580 km (360 mi) and inclination of 53°. Due to atmospheric drag, the satellite slowly lost height until, in September 2011,

495-595: A lecturer at the University of Strasbourg. In 1875, he became a professor at the Academy of Agriculture at Hohenheim , Württemberg . He returned to Strasbourg as a professor of physics in 1876, and in 1879, he was appointed to the chair of physics at the University of Giessen . In 1888, he obtained the physics chair at the University of Würzburg , and in 1900 at the University of Munich , by special request of

550-469: A material artifact, was not accurate enough for their work. So, around 1907 they defined their own unit of length, which they called "Ångström", based on the wavelength of a specific spectral line. It was only in 1960, when the metre was redefined in the same way, that the angstrom became again equal to 10 metre. Yet the angstrom was never part of the SI system of units, and has been increasingly replaced by

605-473: A need for a separate unit of comparable size defined directly in terms of spectroscopy. In 1965, J.A. Bearden defined the Angstrom Star (symbol: Å*) as 0.202901 times the wavelength of the tungsten κ α 1 {\textstyle \kappa _{\alpha 1}} line. This auxiliary unit was intended to be accurate to within 5 parts per million of the version derived from

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660-495: A real intrusion, there is a plausible "no attack" explanation for ROSAT's failure, and the report is claimed to link the two incidents as no more than "coincident." However, NASA officials in charge of the day-to-day operations of the ROSAT mission at Goddard, including GSFC Rosat Project Scientist Rob Petre, say definitively that no such incident occurred. Talleur's information appears to have come from one of his interns who exaggerated

715-608: A thin film of a metal such as aluminium. Röntgen published a total of three papers on X-rays between 1895 and 1897. Today, Röntgen is considered the father of diagnostic radiology , the medical speciality which uses imaging to diagnose disease. Röntgen was married to Anna Bertha Ludwig for 47 years until her death in 1919 at the age of 80. In 1866, they met in Zürich at Anna's father's café, Zum Grünen Glas. They became engaged in 1869 and wed in Apeldoorn , Netherlands on 7 July 1872;

770-550: A whole to benefit from practical applications of the phenomenon. Röntgen was also awarded Barnard Medal for Meritorious Service to Science in 1900. In November 2004, IUPAC named element number 111 roentgenium (Rg) in his honor. IUPAP adopted the name in November 2011. He was elected an International Member of the American Philosophical Society in 1897. In 1907, he became a foreign member of

825-412: Is about 0.5 angstroms. Visible light has wavelengths in the range of 4000–7000 Å. In the late 19th century, spectroscopists adopted 10 of a metre as a convenient unit to express the wavelengths of characteristic spectral lines ( monochromatic components of the emission spectrum ) of chemical elements . However, they soon realized that the definition of the metre at the time, based on

880-585: Is also named after him. He was born to Friedrich Conrad Röntgen, a German merchant and cloth manufacturer, and Charlotte Constanze Frowein. When he was aged three, his family moved to the Netherlands, where his mother's family lived. Röntgen attended high school at Utrecht Technical School in Utrecht , Netherlands . He followed courses at the Technical School for almost two years. In 1865, he

935-445: Is determined with an accuracy of about 120 micrometers. The electron cloud's charge corresponds to the photon energy, with a nominal spectral bandpass 0.1-2.4 keV. The US-supplied High Resolution Imager used a crossed grid detector with a position accuracy to 25 micrometers. The instrument was damaged by solar exposure on 20 September 1998. The Wide Field Camera (WFC) was a UK-supplied extreme ultraviolet (XUV) telescope co-aligned with

990-407: Is further reported as claiming that the ROSAT incident was "coincident with the intrusion" and that, "Operational characteristics and commanding of the ROSAT were sufficiently similar to other space assets to provide intruders with valuable information about how such platforms are commanded,". Without public access to the advisory, it is obviously impossible to comment in detail. Even if it did describe

1045-415: Is often used in the natural sciences and technology to express sizes of atoms , molecules , microscopic biological structures, and lengths of chemical bonds , arrangement of atoms in crystals , wavelengths of electromagnetic radiation , and dimensions of integrated circuit parts. The atomic (covalent) radii of phosphorus , sulfur , and chlorine are about 1 angstrom, while that of hydrogen

1100-544: Is reported to describe a series of attacks from Russia that reached computers in the X-ray Astrophysics Section (i.e. ROSAT's) at Goddard , and took control of computers used for the control of satellites, not just a passive "snooping" attack. The advisory stated: "Hostile activities compromised [NASA] computer systems that directly and indirectly deal with the design, testing, and transferring of satellite package command-and-control codes." The advisory

1155-690: The American College of Radiology . Up to 2023, 55 stamps from 40 countries have been issued commemorating Röntgen as the discoverer of X-rays. Röntgen Peak in Antarctica is named after Wilhelm Röntgen. Minor planet 6401 Roentgen is named after him. Angstrom The unit's symbol is Å , which is a letter of the Swedish alphabet , regardless of how the unit is spelled. However, "A" or "A.U." may be used in less formal contexts or typographically limited media. The angstrom

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1210-639: The Crookes–Hittorf tube , which had a much thicker glass wall than the Lenard tube, might also cause this fluorescent effect. In the late afternoon of 8 November 1895, Röntgen was determined to test his idea. He carefully constructed a black cardboard covering similar to the one he had used on the Lenard tube. He covered the Crookes–Hittorf tube with the cardboard and attached electrodes to a Ruhmkorff coil to generate an electrostatic charge. Before setting up

1265-700: The Federal Polytechnic Institute in Zürich (today known as the ETH Zurich ), he passed the entrance examination and began his studies there as a student of mechanical engineering . In 1869, he graduated with a PhD from the University of Zurich ; once there, he became a favourite student of Professor August Kundt , whom he followed to the newly founded German Kaiser-Wilhelms-Universität in Strasbourg . In 1874, Röntgen became

1320-510: The International Astronomical Union ) defined the international angstrom as precisely 1/6438.4696 of the wavelength of that line (in dry air at 15 °C (hydrogen scale) and 760  mmHg under a gravity of 9.8067 m/s ). This definition was endorsed at the 7th General Conference on Weights and Measures (CGPM) in 1927, but the material definition of the metre was retained until 1960. From 1927 to 1960,

1375-805: The Royal Netherlands Academy of Arts and Sciences . A collection of his papers is held at the National Library of Medicine in Bethesda, Maryland . Today, in Remscheid-Lennep , 40 kilometres east of Röntgen's birthplace in Düsseldorf , is the Deutsches Röntgen-Museum. In Würzburg , where he discovered X-rays, a non-profit organization maintains his laboratory and provides guided tours to

1430-671: The Röntgen Memorial Site . World Radiography Day: World Radiography Day is an annual event promoting the role of medical imaging in modern healthcare. It is celebrated on 8 November each year, coinciding with the anniversary of the Röntgen's discovery. It was first introduced in 2012 as a joint initiative between the European Society of Radiology , the Radiological Society of North America , and

1485-552: The Wide Field Camera . ROSAT was soon operational again, but with some restrictions to the effectiveness of its tracking and thus its control. It was severely damaged on 20 September 1998 when a reaction wheel in the spacecraft's Attitude Measuring and Control System reached its maximum rotational speed, losing control of a slew, damaging the High Resolution Imager by exposure to the sun. This failure

1540-430: The solar physics community, which adopted the unit and named it after him. It subsequently spread to the fields of astronomical spectroscopy , atomic spectroscopy , and then to other sciences that deal with atomic-scale structures. Although intended to correspond to 10  metres, that definition was not accurate enough for spectroscopy work. Until 1960 the metre was defined as the distance between two scratches on

1595-721: The Bavarian government. Röntgen had family in Iowa in the United States and planned to emigrate. He accepted an appointment at Columbia University in New York City and bought transatlantic tickets, before the outbreak of World War I changed his plans. He remained in Munich for the rest of his career. During 1895, at his laboratory in the Würzburg Physical Institute of the University of Würzburg, Röntgen

1650-619: The US National Institute of Standards and Technology (NIST). However, it is not mentioned in the 9th edition of the official SI standard, the "BIPM Brochure" (2019) or in the NIST version of the same, and BIPM officially discourages its use. The angstrom is also not included in the European Union's catalogue of units of measure that may be used within its internal market. For compatibility reasons, Unicode assigns

1705-555: The US-supplied High Resolution Imager (HRI). The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84 cm (33 in) diameter aperture and 240 cm (94 in) focal length. The angular resolution was less than 5 arcsec at half energy width. The XRT assembly was sensitive to X-rays between 0.1 and 2 keV. There are two Position Sensitive Proportional Counters (PSPC), PSPC-B and PSPC-C, mounted on

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1760-530: The X-ray sky, extending the energy range to 10keV, increase the sensitivity by a factor of 25 and improve the spatial and spectral resolution. Wilhelm R%C3%B6ntgen Wilhelm Conrad Röntgen ( / ˈ r ɛ n t ɡ ə n , - dʒ ə n , ˈ r ʌ n t -/ ; German: [ˈvɪlhɛlm ˈʁœntɡən] ; 27 March 1845 – 10 February 1923) was a German physicist , who, on 8 November 1895 , produced and detected electromagnetic radiation in

1815-638: The XRT and covered the wave band between 300 and 60 angstroms (0.042 to 0.21 keV). ROSAT was originally planned to be launched on the Space Shuttle but the Challenger disaster caused it to be moved to the Delta platform. This move made it impossible to recapture ROSAT with a Shuttle and bring it back to Earth. Originally designed for a five-year mission, ROSAT continued in its extended mission for

1870-480: The angstrom remained a secondary unit of length for use in spectroscopy, defined separately from the metre. In 1960, the metre itself was redefined in spectroscopic terms, which allowed the angstrom to be redefined as being exactly 0.1 nanometres. After the redefinition of the metre in spectroscopic terms, the Angstrom was formally redefined to be 0.1 nanometres. However, there was briefly thought to be

1925-498: The barium platinocyanide screen to test his idea, Röntgen darkened the room to test the opacity of his cardboard cover. As he passed the Ruhmkorff coil charge through the tube, he determined that the cover was light-tight and turned to prepare for the next step of the experiment. It was at this point that Röntgen noticed a faint shimmering from a bench a few feet away from the tube. To be sure, he tried several more discharges and saw

1980-433: The delay was due to Anna being six years Wilhelm's senior and his father not approving of her age or humble background. Their marriage began with financial difficulties as family support from Röntgen had ceased. They raised one child, Josephine Bertha Ludwig, whom they adopted as a six-year-old after her father, Anna's only brother, died in 1887. For ethical reasons, Röntgen did not seek patents for his discoveries, holding

2035-509: The inflation following World War I, Röntgen fell into bankruptcy, spending his final years at his country home at Weilheim , near Munich. Röntgen died on 10 February 1923 from carcinoma of the intestine, also known as colorectal cancer . In keeping with his will, his personal and scientific correspondence, with few exceptions, were destroyed upon his death. He was a member of the Dutch Reformed Church . In 1901, Röntgen

2090-408: The nanometre ( 10 m) or picometre ( 10 m). In 1868, Swedish physicist Anders Jonas Ångström created a chart of the spectrum of sunlight , in which he expressed the wavelengths of electromagnetic radiation in the electromagnetic spectrum in multiples of one ten-millionth of a millimetre (or 10  mm .) Ångström's chart and table of wavelengths in the solar spectrum became widely used in

2145-592: The new metre. Within ten years, the unit had been deemed both insufficiently accurate (with accuracies closer to 15 parts per million) and obsolete due to higher precision measuring equipment. Although still widely used in physics and chemistry, the angstrom is not officially a part of the International System of Units (SI). Up to 2019, it was listed as a compatible unit by both the International Bureau of Weights and Measures (BIPM) and

2200-403: The new rays he temporarily termed "X-rays", using the mathematical designation ("X") for something unknown. The new rays came to bear his name in many languages as "Röntgen rays" (and the associated X-ray radiograms as "Röntgenograms"). At one point, while he was investigating the ability of various materials to stop the rays, Röntgen brought a small piece of lead into position while a discharge

2255-470: The same shimmering each time. Striking a match, he discovered the shimmering had come from the location of the barium platinocyanide screen he had been intending to use next. Based on the formation of regular shadows, Röntgen termed the phenomenon "rays". As 8 November was a Friday, he took advantage of the weekend to repeat his experiments and made his first notes. In the following weeks, he ate and slept in his laboratory as he investigated many properties of

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2310-611: The satellite was orbiting approximately 270 km (168 mi) above the Earth. On 23 October 2011 ROSAT re-entered the Earth's atmosphere sometime between 1:45 UTC and 2:15 UTC over the Bay of Bengal , east of India. There was no confirmation if pieces of debris had reached the Earth's surface. eROSITA launched on board the Russian-German Spektr-RG space observatory in 2019. It will provide an updated all-sky survey of

2365-518: The study of the structure of low surface brightness features, and for low-resolution spectroscopy. The ROSAT spacecraft was a three-axis stabilized satellite which can be used for pointed observations, for slewing between targets, and for performing scanning observations on great circles perpendicular to the plane of the ecliptic . ROSAT was capable of fast slews (180 deg. in ~15 min.) which makes it possible to observe two targets on opposite hemispheres during each orbit. The pointing accuracy

2420-611: The uncorrected ones. In 1892–1895, Albert A. Michelson and Jean-René Benoît , working at the BIPM with specially developed equipment, determined that the length of the international metre standard was equal to 1 553 163.5 times the wavelength of the red line of the emission spectrum of electrically excited cadmium vapor. In 1907, the International Union for Cooperation in Solar Research (which later became

2475-410: The view that they should be publicly available without charge. After receiving his Nobel prize money, Röntgen donated the 50,000 Swedish krona to research at the University of Würzburg . Although he accepted the honorary degree of Doctor of Medicine, he rejected an offer of lower nobility, or Niederer Adelstitel, denying the preposition von (meaning "of") as a nobiliary particle (i.e., von Röntgen). With

2530-509: Was 1 arcminute with stability less than 5 arcsec per sec and jitter radius of ~10 arcsec. Two CCD star sensors were used for optical position sensing of guide stars and attitude determination of the spacecraft. The post facto attitude determination accuracy was 6 arcsec. The ROSAT mission was divided into two phases: The main assembly was a German-built imaging X-ray Telescope (XRT) with three focal plane instruments: two German Position Sensitive Proportional Counters (PSPC) and

2585-440: Was a joint German, U.S. and British X-ray astrophysics project. ROSAT carried a German-built imaging X-ray Telescope (XRT) with three focal plane instruments: two German Position Sensitive Proportional Counters (PSPC) and the US-supplied High Resolution Imager (HRI). The X-ray mirror assembly was a grazing incidence four-fold nested Wolter I telescope with an 84-cm diameter aperture and 240-cm focal length. The angular resolution

2640-528: Was awarded the first Nobel Prize in Physics . The award was officially "in recognition of the extraordinary services he has rendered by the discovery of the remarkable rays subsequently named after him". Shy in public speaking, he declined to give a Nobel lecture. Röntgen donated the 50,000 Swedish krona reward from his Nobel Prize to research at his university, the University of Würzburg . Like Marie and Pierre Curie , Röntgen refused to take out patents related to his discovery of X-rays, as he wanted society as

2695-431: Was initially attributed to the difficulties of controlling the satellite under these difficult circumstances outside its initial design parameters. In 2008, NASA investigators were reported to have found that the ROSAT failure was linked to a cyber-intrusion at Goddard Space Flight Center . The root of this allegation is a 1999 advisory report by Thomas Talleur, senior investigator for cyber-security at NASA. This advisory

2750-411: Was investigating the external effects of passing an electrical discharge through various types of vacuum tube equipment—apparatuses from Heinrich Hertz , Johann Hittorf , William Crookes , Nikola Tesla and Philipp von Lenard In early November, he was repeating an experiment with one of Lenard's tubes in which a thin aluminium window had been added to permit the cathode rays to exit the tube but

2805-597: Was less than 5  arcsecond at half energy width (the "angle within which half of the electromagnetic radiation" is focused). The XRT assembly was sensitive to X-rays between 0.1 and 2 keV (one thousand Electronvolt ). In addition, a British-supplied extreme ultraviolet (XUV) telescope, the Wide Field Camera (WFC), was coaligned with the XRT and covered the energy band from 0.042 to 0.21 keV (30 to 6  nm ). ROSAT's unique strengths were high spatial resolution, low-background, soft X-ray imaging for

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2860-503: Was occurring. Röntgen thus saw the first radiographic image: his own flickering ghostly skeleton on the barium platinocyanide screen. About six weeks after his discovery, he took a picture—a radiograph —using X-rays of his wife Anna Bertha's hand. When she saw her skeleton she exclaimed "I have seen my death!" He later took a better picture of his friend Albert von Kölliker 's hand at a public lecture. Röntgen's original paper, "On A New Kind of Rays" ( Ueber eine neue Art von Strahlen ),

2915-564: Was published on 28 December 1895. On 5 January 1896, an Austrian newspaper reported Röntgen's discovery of a new type of radiation. Röntgen was awarded an honorary Doctor of Medicine degree from the University of Würzburg after his discovery. He also received the Rumford Medal of the British Royal Society in 1896, jointly with Philipp Lenard , who had already shown that a portion of the cathode rays could pass through

2970-402: Was reported that the 2,400 kg (5,291 lb) satellite was unlikely to burn up entirely while re-entering the Earth's atmosphere due to the large amount of ceramics and glass used in construction. Parts as heavy as 400 kg (882 lb) could impact the surface. ROSAT eventually re-entered the Earth's atmosphere on 23 October 2011 over the Bay of Bengal . The Roentgensatellit (ROSAT)

3025-405: Was unfairly expelled from high school when one of his teachers intercepted a caricature of one of the teachers, which was drawn by someone else. Without a high school diploma, Röntgen could only attend university in the Netherlands as a visitor. In 1865, he tried to attend Utrecht University without having the necessary credentials required for a regular student. Upon hearing that he could enter

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