ASM Glossary

ASM Glossary


Definitive Data - The complete time history of a particular source dating back to the beginning of the RXTE mission.


Galactic Coordinates - A coordinate system, much like the global one, using the plane of the Milky Way Galaxy as a zero reference. Galactic latitude and longitude coordinates are represented by l and b respectively.


mCrab (= milliCrab) - One thousandth of the intensity of the Crab nebula. X-ray astronomers use this unit when comparing observations from different x-ray detectors on different instruments. On RXTE, for example:

Instrument 1 mCrab=
PCA 1.36 counts/s
HEXTE 0.250 counts/s per cluster
ASM 0.075 counts/s per camera


parsec - A parsec is a unit of distance, equal to 3.26 light years. The Megaparsec, equal to a million parsecs, is another commonly used unit of astronomical distance.


Quasi-Periodic Oscillations

Pulses of X-rays that are not strictly periodic, but vary slightly from cycle to cycle are called "quasi-periodic oscillations" or QPOs. This just means that the pulses are almost, but not quite, periodic.


Real Time Data - The most recent data from RXTE. The Real Time Data archive logs only the most current two weeks worth.


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[an error occurred while processing this directive] This file was last modified on Tuesday, 26-Oct-1999 15:54:22 EDT