In principal every gamma ray burst is followed by an afterglow. However, we do not always see these afterglows for several reasons. First, prior to 1997 and the launch of the BeppoSAX satellite (see question 15) it was impossible to find the position of gamma ray burst accurately enough to detect the afterglow. Second, even after 1997 the afterglows from some gamma ray bursts are too faint to detect from Earth.

The study of several thousand bursts has shown that there are two main classes of gamma ray bursts: those shorter than 2 seconds, and those longer than 2 seconds. In addition, it was found that the short bursts release more of their energy in very energetic gamma rays relative to the longer bursts. Therefore the terminology that is used to describe the two classes is "short and hard" and "long and soft". All of all bursts that have been studied in detail so far are "long and soft".

It is now thought that the "long and soft" gamma ray burts come from the collapse of massive stars, while the "short and hard" bursts come from the merger of binary systems. This result comes from computer simulations which show that the merger of neutron star or black hole binaries occurs much faster than the collapse of the iron core of a massive star.

The first step in the detection of afterglows is always the detection of a new gamma ray burst by a satellite such as the IPN, BeppoSAX, and HETE-II (see qeustion 4). The information from the satellite is quickly sent down to Earth and is distributed to gamma ray burst astronomers by email, pagers, and cellular phones. When astronomers get the information, they observe the part of the sky where the gamma ray burst occured, and look for an object which fades quickly.

The twinkling of radio waves from afterglows (see question 23) has shown that afterglows start very small (about the size of the Earth's orbit around the Sun), and then expand and become larger than the Solar system.

The naming system for gamma ray bursts is very simple: "GRB yymmdd". For exmaple, a gamma ray burst which occured on July 4, 1999 is called GRB 990704. If there is more than one gamma ray burst on the same day, the letter a, b, c, etc. are added to the name (for example, the second gamma ray burst on July 4, 1999 is called GRB 990704b).

Up until the 1990s and the launch of the Compton Gamma Ray Observatory (CGRO; see next question) there was a heated debate in the astronomical community about the source of, and distance to gamma ray bursts. One group claimed that gamma ray bursts occur in our own galaxy (the Milky Way), while others claimed that they occur in very distant galaxies.

Based on almost 30 years of observing gamma ray bursts, we now think that on average there is one gamma ray burst per day somewhere in the Universe. However, recent developments in the study of gamma ray bursts indicates that the true number of these events may be 500 times larger. This means that we only see one out of every 500 gamma ray bursts.

Gamma ray bursts are detected by satellites orbiting the Earth and travelling through the Solar system. They can only be detected from space because the Earth's atmosphere absorbs gamma rays and therefore we cannot observe them from the ground. The first gamma ray bursts were detected by the Vela satellites, which were launched in the 1960s to ensure compliance with the Nuclear Test Ban Treaty.

There are many popular level and scientific articles about gamma ray bursts. For popular level discussion of gamma ray bursts try looking for articles in Scientific American. Scientific articles can be found on the astro-ph preprint server and ADS.

Gamma ray bursts (GRBs for short) are intense and short (approximately 0.1-100 seconds long) bursts of gamma-ray radiation that occur all over the sky approximately once per day at very large distances from Earth. Gamma rays are very energetic photons (E>10^5 eV), which represent the most extreme portion of the electromagnetic spectrum (ranging from radio waves at the lowest energies through visible optical light at higher energies, to gamma rays at the highest energies).

The distribution of several thousand bursts which were detected primarily by the Burst And Transient Source Experiment (BATSE) on CGRO is uniform across the sky. This means that there is no prefered direction from which we detect more gamma ray bursts. This distribution was the first indication that gamma ray bursts occur in bery distant galaxies and not in our own galaxy.

Gamma ray bursts release extremely large amount of energy - approximately 10^52 ergs (or 10^45 joules), with the most extreme bursts releasing up to 10^54 ergs. This is the equivalent of turning a star like the Sun into pure energy (using Einstein's famous equation E=mc^2).

In the first years of gamma ray burst research there were more proposed sources (or progenitors) for gamma ray bursts than the actual number of gamma ray bursts detected! However, ever since it was determined that gamma ray bursts occur at very large distances (and therefore release huge amounts of energy) the list of proposed progenitors shrunk into two main classes: very massive stars, and binary (2 star) systems composed of neutron stars or black holes.

Astronomers now think that the iron cores of some very massive stars (at least 30 times more massive than the Sun) can collapse into black holes several million years after they form. The energy released in the formation of the black hole emerges out of the collapsed star in the form of a gamma ray burst. Gamma ray burst astronomers call this the "collapsar" model. Other names are "hypernova" or "failed supernova" models.

It is known that most stars in the Universe reside in multiple systems of 2 (binary), 3 and even 4 stars. Some of the binary systems have two stars more massive than about ten times the mass of the Sun, and eventually after these stars die they leave behind neutron stars or black holes. Over time the two objects in the system spiral in toward each other and eventually they merge into a single black hole.

The Compton Observatory is one of NASA's four Great Observatories, with the mission of observing the sky in the light of gamma-rays. Gamma-rays are photons with greater energies than X-rays. The gamma-ray sky is variable and dynamic. Compton has observed many new sources with its four instruments: the Burst and Transient Source Experiment (BATSE), the Compton Telescope (COMPTEL), the Energetic Transient Experiment (EGRET) and the Oriented Scintillation Spectrometer (OSSE).

The luminance generated by a physical device is generally not a linear function of the applied signal. A conventional CRT has a power-law response to voltage: luminance produced at the face of the display is approximately proportional to the applied voltage raised to the 2.5 power. The numerical value of the exponent of this power function is colloquially known as gamma. This nonlinearity must be compensated in order to achieve correct reproduction of luminance.

Ray is one of the soldiers under the command of The General. He was thrown into a wall by a demon in Castle III part D as he ran through a corridor. Ray is the first character to make an appearance in Castle Repercussions.

The HEASARC's XANADU package supports spectral, temporal and spatial analysis of high-energy data and has been developed to be quite portable. You can use this immediately on the high-level products in the HEASARC archive. The FTOOLS provide more discrete analysis tools including mission-specific analysis pipelines. These two packages were recently merged into the HEAsoft package.

High-energy radiation damages plastics in a certain way. POM and some fluoroplastics such as PTFE are particularly sensitive.

The digital dose rate display takes some time (2 seconds to 6 minutes depending on the dose rate) to respond to changes in radiation levels. To locate the source of radiation, a more immediate feedback is often desired. By pressing and holding the mode button for 2 seconds the audio mode is turned on/off. In this mode, there is no delay. The unit emits a beep whenever a gamma ray is detected. The more frequent the beep, the closer you are to the source of the radiation.

YES, THIS IS POSSIBLE, WITH SOME PROBABILITY WHICH IS IN PRINCIPLE CALCULABLE, OR IT CAN BE MEASURED. YES, IT'S ALL HARD TO IMAGINE, BUT IT REALLY DOES HAPPEN ! WE CAN OBSERVE THESE PROCESSES USING POWERFUL ACCELERATORS AND OUR DETECTORS WHICH ACT LIKE MICROSCOPES TO THE SUBATOMIC WORLD! Yes, 1 electronVolt (or [eV], for short) is the energy gained as an electron crosses a potential difference of 1 volt. This gain in energy goes into increasing the electron's kinetic energy.

The RadWare matrix formats are very simple, just direct-access, unformatted integers, one record per row of 4096 channels. These integers can be either 2 Bytes per channel (for the .mat format) or 4 Bytes per channel (for the .spn / .m4b format). A standard matrix (.mat) file is 4096*4096*2 bytes, with one unformatted direct-access record of 8192 bytes per row. Subroutine rmat in src/libsutil/util.c reads such a file, but it's very simple to write.

In a video system, luminance of each of the linear-light red, green, and blue (tristimulus) components is transformed to a nonlinear video signal by gamma correction, which is universally done at the camera. The Rec. 709 transfer function takes linear-light tristimulus value (here L) to a nonlinear component (here E'), for example, voltage in a video system: The linear segment near black minimizes the effect of sensor noise in practical cameras and scanners. Here is a graph of the Rec.

Apple offers no definition of the nonlinearity - or loosely speaking, gamma - that is intrinsic in QuickDraw. But the combination of a default QuickDraw lookup table and a standard monitor causes luminance to represent the 1.8-power of the R, G, and B values presented to QuickDraw. It is wrongly believed that Macintosh computers use monitors whose transfer function is different from the rest of the industry. The unconventional QuickDraw handling of nonlinearity is the root of this misconception.

A burst is a weapon the Spider (3) and the Terrier (5) is equipped with. It spreads out a number of bouncing bullets out away from the ship that damages opponents. To activate a burst, press shift+del.

There are two kinds of afterglow effects: immediate and persisting. The immediate afterglow probably is due to the residual pharmacological effects of salvinorin A (some of which is presumably still present in the body for about an hour or longer after the primary effects have subsided). This immediate afterglow is often described as a vague sense of peaceful euphoria lasting an hour (or a bit longer) after the obvious intoxication has worn off.

This is extremely unlikely provided the balloon is not inflated beyond 10cm. Each single balloon has been tested up to the size of a football. The balloon is consists of medical silicone. Please treat the balloon carefully according to instructions for use.