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Topic: RHESSI

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Martin Philip Caton

Mayesville, South Carolina

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	Microflares could play macro role in heating corona
		RHESSI, launched by NASA in February 2002 to study X-ray and gamma-ray emissions from flares, has observed more than 10,000 microflares in the past year and a half.
		RHESSI has seen many Type III bursts, and they appear to be associated with microflares that do very little heating of the solar atmosphere.
		The RHESSI scientific payload is a collaborative effort among UC Berkeley, NASA Goddard Spaceflight Center, the Paul Scherrer Institut in Switzerland and the Lawrence Berkeley National Laboratory.
	www.eurekalert.org /pub_releases/2003-07/uoc--mcp071803.php (1088 words)

	RHESSI detection implies gamma-ray bursts driven by strong magnetic fields
		Berkeley -- University of California, Berkeley's RHESSI satellite, launched last year by NASA, was snapping X-ray pictures of solar flares in December when it caught an extremely bright background gamma-ray burst, revealing a novel physical feature of these gamma rays -- their polarization.
		RHESSI stares directly at the sun in order to catch gamma and X-ray emissions from solar flares, but can detect gamma rays from any direction on the sky since they pass through the mechanical structures of the satellite to the detectors.
		Both Boggs and Coburn plan to continue monitoring the RHESSI data to capture more gamma-ray bursts and determine whether strong polarization is characteristic of all bursts and how the polarization evolves during the burst.
	www.eurekalert.org /pub_releases/2003-05/uoc--rdi052903.php (1361 words)

	Top Story - RHESSI CAPTURES NEW LIGHT FROM SUN, REVEALS SURPRISES IN SOLAR FLARES - June 05, 2002
		RHESSI detects X-rays that are similar to those used in medical and dental X-rays on Earth.
		RHESSI also reveals that solar active regions, the strongly magnetized sources of solar flares and coronal mass ejections, constantly produce a multitude of tiny X-ray flashes, or "microflares," that last only a few minutes each.
		RHESSI uses nine pairs of special tungsten grids, with slits as fine as a human hair, at opposite ends of a 1.5-meter-long (5 foot) tube.
	www.gsfc.nasa.gov /topstory/20020605rhessi.html (986 words)

	RHESSI Major Events
		RHESSI was the only high-energy instrument observing during this interval, since the dedicated astrophysics missions cannot point close to the Sun.
		RHESSI data should not be used for any solar science during the period from 22:00 UT on 8 June to 22:00 UT on 25 June without special consultation with the instrument team.
		RHESSI data were obtained during the partial eclipse of the Sun, and both scientific and calibration use may be made of the changes in count rate as the Moon eclipsed one or more x-ray emitting regions.
	hessi.ssl.berkeley.edu /~dsmith/hessi/HME.html (3626 words)

	Extensive Destruction Powers Solar Explosions - Planetary (Site not responding. Last check: 2007-11-05)
		With RHESSI, we've now seen both ends of the dragon." Linhui is lead author of a paper on this research published October 20 in Astrophysical Journal Letters.
		The hot, X-ray emitting plasma initially appeared in the RHESSI images as a blob atop an arch of relatively cooler plasma protruding from the sun's surface.
		However, as RHESSI made images of the 20-minute long flare, over the course of about four minutes during the most intense part of the flare, the X-ray emitting blob exhibited two characteristics consistent with large-scale magnetic reconnection.
	www.okka.biz /Extensive_Destruction_Powers_Solar_Explosions-1623836-292-a.html (1387 words)

	SPACE.com -- The Heat is On: New Sun-watcher Finds Solar Flares Hotter than Hot
		The RHESSI spacecraft captured this sequence of X-ray images depicting the hot "blob" of high-energy particles within the solar flare observed on July 23, 2002.
		RHESSI scientists said the July 2002 flare is probably not going to be the hottest one ever detected, but it does indicate that solar flares can be dissected to find specific areas of higher energy release.
		RHESSI researchers said it could also be possible to adopt what they learn about the Sun's natural particle accelerator processes to the movements of particles near fl holes, active galactic nuclei and even manmade atom smashers on Earth.
	www.space.com /scienceastronomy/hotter_flares_030708.html (1016 words)

	Universe Today - Solar Flares Shuffle Antimatter Around
		RHESSI allowed the most detailed analysis to date of the gamma rays emitted when antimatter annihilates ordinary matter in the solar atmosphere.
		The clue that tipped scientists off to this surprising behavior was the RHESSI observation that gamma rays from the July 23 flare were not emitted from the same locations that emitted the X-rays, as theory predicts.
		RHESSI was launched February 5, 2002, with the University of California, Berkeley, responsible for most aspects of the mission, and NASA Goddard responsible for program management and technical oversight.
	www.universetoday.com /am/publish/printer_solar_flares_antimatter.html (1129 words)

	Terrestrial gamma-ray flashes
		The RHESSI spacecraft studies radiation from the Sun in the form of x-rays and gamma rays.
		RHESSI, a NASA Small Explorer spacecraft, was launched in 2002 to study x-rays and gamma-rays from solar flares.
		Smith worked with RHESSI principal investigator Robert Lin at UC Berkeley and Christopher Barrington-Leigh, now at UBC, to plan ways they could use the satellite for a range of investigations in addition to studying solar flares.
	currents.ucsc.edu /04-05/02-21/flashes.asp (907 words)

	05.28.2003 - RHESSI uncovers secret to cataclysmic explosions known as gamma-ray bursts
		The RHESSI satellite captures a gamma-ray burst flashing just off the limb of the sun, measuring for the first time the polarization of these gamma rays.
		BERKELEY – University of California, Berkeley's RHESSI satellite, launched last year by NASA, was snapping X-ray pictures of solar flares in December when it caught an extremely bright background gamma-ray burst, revealing a novel physical feature of these gamma rays - their polarization.
		Boggs interprets the measurements to mean that the burst originates from a region of highly structured magnetic fields, stronger than the fields at the surface of a neutron star - until now, the strongest magnetic fields observed in the universe.
	www.berkeley.edu /news/media/releases/2003/05/28_gamma.shtml (1419 words)

	Spacecraft: RHESSI
		Glenn Creamer of NRL and I gave a paper on the Lyapunov magnetic control at the last Goddard Space Flight Mechanics Symposium (the next one is in October) but, I haven't gotten around to publishing it anywhere else.
		An interesting challenge on RHESSI was that, it was a major axis spinner only by virtue of the flexible solar array panels.
		RHESSI was launched on an Orbital Sciences Corporation Pegasus, a launch vehicle that is typically used for small payloads.
	www.aoe.vt.edu /~cdhall/Space/archives/000393.html (449 words)

	Spaceflight Now \| Breaking News \| New solar flare satellite gets renamed, now on line
		RHESSI also has seen several non-solar events, including a soft gamma ray burster and X-rays that may be from the fl hole binary Cygnus X-1.
		The immediate goal of the UC Berkeley RHESSI team, however, is to switch the spacecraft over to automatic operation, so that the operations team doesn't have to scramble every time the satellite passes over Berkeley and downloads data, which can be in the middle of the night.
		The RHESSI scientific payload is a collaborative effort among UC Berkeley, Goddard, the Paul Scherrer Institut in Switzerland and the Lawrence Berkeley National Laboratory.
	www.spaceflightnow.com /news/n0203/29rhessi (1041 words)

	RHESSI Completes On-Orbit Checkout
		Launched February 5, RHESSI was fully operational after only 2 weeks in orbit.
		RHESSI is a sun-pointed, inertial spinner spacecraft that is orbiting at an altitude of 600 km, inclined at 38 degrees.
		The RHESSI scientific payload is a collaborative effort among the University of California, Berkeley; Goddard; the Paul Scherrer institute in Switzerland; and the Lawrence Berkeley National Laboratory in Berkeley.
	www.spacedaily.com /news/solarstorm-02d.html (671 words)

	07.21.2003 - RHESSI satellite finds tiny microflares on sun are smaller versions of normal flares; could heat corona
		Solar flares, the largest explosions in the solar system, propel energetic particles into space and are thought to be the main source of heat pumping the sun's outer atmosphere to a few million degrees Celsius - hotter than the surface itself.
		Based on recent observations by RHESSI, the largest mass ejections - such as the one modeled here, which occurred on April 21, 2002 - appear to be triggered flares.
		These have allowed the RHESSI team to investigate the relationship between flares and coronal mass ejections, which are large stellar explosions that send shock waves into space.
	www.berkeley.edu /news/media/releases/2003/07/21_flares.shtml (1163 words)

	NASA - Top Story - ANTIMATTER FACTORY ON SUN YIELDS CLUES TO SOLAR EXPLOSIONS - September 02, 2003
		This superposition of RHESSI images of gamma-ray and X-ray emissions with a TRACE UV image (taken 90 minutes later) of the July 23, 2002, solar flare, clearly shows the large separation between the high-energy emissions.
		The RHESSI observations are overlaid on a movie of the event taken in the visible light emitted by the hot hydrogen gas in the solar atmosphere.
		RHESSI views of X-rays on the flare are overlaid on an amber-colored TRACE image.
	www.gsfc.nasa.gov /topstory/2003/0903rhessi.html (1882 words)

	NASA - RHESSI's Lucky Break May Lead To Secret Of Ultimate Explosions
		The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite was snapping pictures of solar flares on December 6, 2002, when it caught an extremely bright gamma-ray burst in the background, over the edge of the Sun, revealing for the first time that the gamma rays in such a burst are polarized.
		He interprets the measurements to mean that the burst originates from a region of highly structured magnetic fields, stronger than the fields at the surface of a neutron star - until now, the strongest magnetic fields observed in the universe.
		The gamma rays measured by RHESSI were about 80 percent polarized, consistent with the maximum possible polarization from electrons spiraling around magnetic field lines.
	www.nasa.gov /home/hqnews/2003/may/HQ_03180_Rhessi.html (686 words)

	RHESSI Solar Flare Satellite
		But because RHESSI has the best energy resolution for such high-energy radiation of any satellite, Lin hopes the instruments can provide unique information on these and other X-ray and gamma ray sources by searching for emission and absorption lines and obtaining Doppler shifts indicative of chemical composition and motions, respectively.
		RHESSI also can study X-ray pulsars, which are stars that flash at regular intervals.
		RHESSI is the first NASA Small Explorer mission managed in the "principal investigator" mode, where Lin and his team are responsible for most aspects of the mission, including the science instrument, spacecraft integration and environmental testing, and spacecraft operations and data analysis.
	www.berkeley.edu /news/media/releases/2002/03/28_flare.html (790 words)

	RHESSI First Results -- Embargoed until 5-Jun-2002 (Site not responding. Last check: 2007-11-05)
		On 21-April-2002, a spectacular X-class (extremely large) solar flare exploded on the western limb of the Sun and was captured by RHESSI and the Transition Region and Coronal Explorer (TRACE) spacecraft, as well as many other spacecraft and ground-based observatories.
		``By combining RHESSI hard X-ray images with TRACE EUV data, we are able to follow the cascade of energy in the largest explosions in the solar system'', says UCB professor Robert Lin, principal investigator of the RHESSI mission.
		Surprisingly, RHESSI detects X-rays well in advance of the onset of the flare in the TRACE sequence.
	www.boulder.swri.edu /~deforest/hessi (1005 words)

	Imagine the Universe News - 10 June 2003
		Gamma-ray bursts are the most powerful explosions known in the universe, likely culminating in the creation of a fl hole, yet their origins still remain a mystery.
		RHESSI was doing what it was built for -- snapping pictures of solar flares when it caught an extremely bright gamma-ray burst in the background, over the edge of the Sun.
		RHESSI is not a gamma-ray burst satellite, but it does have an instrument capable of measuring polarization at X-ray and gamma-ray energies.
	imagine.gsfc.nasa.gov /docs/features/news/10jun03.html (774 words)

	[No title] (Site not responding. Last check: 2007-11-05)
		During the main peak of the flare the RHESSI spectroscopy detectors were saturated for ~0.5s after the rise, but observed the decay of the main peak and the 400-s long oscillatory component.
		After the giant peak, RHESSI recorded a series of 51 pulsations with a period of 7.56 s, similar to the INTEGRAL, KONUS, and Swift-BAT observations (Borkowski et al., GCN 2920; Mazets et al., GCN 2922; Palmer et al., GCN #2925).
		RHESSI observed the precursor during 21:28:03.44-21:28:04.49 UT, with a peak count rate in the spectroscopy detectors of ~30,000 cnt/s, and ~25,000 counts total.
	gcn.gsfc.nasa.gov /gcn3/2936.gcn3 (475 words)

	Scientists View Solar Flares in New Light - The Daily Californian (Site not responding. Last check: 2007-11-05)
		The UC Berkeley-operated RHESSI satellite has produced the first ever gamma-ray images of solar flares, giant eruptions on the surface of the sun.
		A massive solar flare captured last year by the RHESSI team was large enough to allow images to be made from high-energy gamma-rays for the first time.
		Instead, the RHESSI images showed that the gamma-rays came from a region nearly an earth's diameter away from the origin of x-rays, at the feet of the large magnetic field loops, whereas x-rays come from smaller loops within.
	www.dailycal.org /article.php?id=12737 (590 words)

	Top Story - HESSI first light images - March 20, 2002
		During its planned two-year mission, RHESSI will study the secrets of how solar flares are produced in the Sun's atmosphere.
		RHESSI is the first NASA Small Explorer mission being managed in the "Principal Investigator" mode.
		The Principal Investigator, Robert Lin of the University of California, Berkeley, is responsible for many aspects of the mission, including the science instrument, spacecraft integration and environmental testing, and spacecraft operations and data analysis.
	www.gsfc.nasa.gov /topstory/20020320hessixray.html (1016 words)

	Spaceflight Now \| Breaking News \| Lucky break may lead to secret of ultimate explosions
		The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) satellite was snapping pictures of solar flares on December 6, 2002.
		Steven Boggs, assistant professor of physics, and Dr. Wayne Coburn, a postdoctoral fellow at the UCB Space Sciences Laboratory, are presenting their findings today during a press conference at the American Astronomical Society meeting in Nashville, Tenn. Their paper about this discovery was published in the May 22 issue of Nature.
		He interprets the measurements to mean the burst originates from a region of highly structured magnetic fields, stronger than the fields at the surface of a neutron star, until now, the strongest magnetic fields observed in the universe.
	spaceflightnow.com /news/n0305/31rhessigrb (991 words)

	RHESSI Satellite Captures Giant Gamma-ray Flare
		RHESSI Satellite Captures Giant Gamma-ray Flare (March 11, 2005) -- Astronomers around the world recorded late last year the brightest explosion ever of high-energy X-rays and gamma rays -- a split-second flash from the other side of our galaxy that was strong enough...
		The flash, called a soft gamma repeater flare, reached Earth on Dec. 27 and was detected by at least 15 satellites and spacecraft between Earth and Saturn, swamping most of their detectors.
		Co-authors with Hurley, Boggs, Duncan and Thompson were D. Smith of the UC Santa Cruz physics department, RHESSI and Wind principal investigator and Space Sciences Laboratory Director Robert Lin, and teams of U.S., Swiss, Russian and German scientists.
	www.sciencedaily.com /releases/2005/02/050222112537.htm (1609 words)

	RHESSI Satellite Completes Successful Second Year of Solar Flare Observation \| SpaceRef - Your Space Reference
		Some of its important results include the first imaging of a flare in gamma-rays, the discovery of strong polarization in a cosmic gamma-ray burst; the first detection of continuous glow from the sun at 3-15 KeV energies; and the first hard X-ray imaging spectroscopy of flares from thermal to non-thermal energies.
		RHESSI is the sixth Small Explorer (SMEX) mission and the first to be managed in the "principal investigator" mode.
		Professor Robert P. Lin of the University of California, Berkeley is the principal investigator for RHESSI, responsible for instrument and spacecraft development, mission operations, and data analysis.
	www.spaceref.com /news/viewpr.html?pid=13659 (559 words)

	RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager)
		RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager)
		It carries out simultaneous, high resolution imaging and spectroscopy of flares from 3 keV X-rays to 20 MeV gamma rays with high time resolution.
		RHESSI, known originally as just HESSI, is the fourth SMEX (Small Explorer) mission.
	www.daviddarling.info /encyclopedia/R/RHESSI.html (138 words)

	RHESSI Microflare Statistics (Site not responding. Last check: 2007-11-05)
		RHESSI is ideally suited for observing microflares due to its unprecedented sensitivity and spectral resolution of the low energy X-rays (3-15 keV) produced by the thermal and non-thermal electron bremsstrahlung emitted by microflares.
		We are also considering the effect of threshold selection bias on the observed microflare distributions and working on a semi-analytical technique to correct for the discrepancy between observed and intrinsic distributions - so far this has been tested on TRACE micro- and nanoflare observations.
		The improved sensitivity of RHESSI and consideration of bias in the microflare statistics will provide us with a more accurate estimate of the power input into the corona from microflares.
	www.astro.gla.ac.uk /cesra2004/abstracts/15.html (163 words)

	HEAD - Newsletter No. 81, November 2002 (Site not responding. Last check: 2007-11-05)
		RHESSI images solar flares down to 2.3 arcsec at hard x-ray energies and 1 arcmin at gamma-ray energies, with energy resolution of 1-6 keV over the range 3 keV to 17 MeV.
		Although RHESSI was not intended to point away from the Sun, we have been studying the possibility of off-pointing in order to image the Crab Nebula.
		All RHESSI data are immediately available to the public; anyone interested in working on RHESSI science should visit the RHESSI general web page and the RHESSI data and software center (http://hessi.ssl.berkeley.edu/ and http://rhessidatacenter.ssl.berkeley.edu/).
	www.aas.org /head/headnews/headnews.nov02.html (8772 words)

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