Chandra X-Ray Observatory

Chandra Instruments and Calibration

The Chandra X-ray Observatory (CXO) is designed for high resolution (≤ 1/2 arcsec) X-ray imaging and spectroscopy. The High Resolution Mirror Assembly (HRMA) focuses X-rays onto one of two instruments, ACIS or HRC. Only one detector (HRC or ACIS) is in the focal plane at any given time. Two grating spectrometers (LETG or HETG) can be placed in the optical path behind the HRMA. The dispersed spectrum is read out by either ACIS or HRC. A high level overview of the instruments on-board the Chandra X-ray Observatory can be found on the About Chandra pages and a more detailed description can be found in the Proposers' Observatory Guide.

Current calibration data products for use in CIAO and other analysis systems can be found in the CALDB pages. A complete listing of all calibration products in the CALDB and a brief description of these products can be found in the Calibration Data Products.

Advanced CCD Imaging Spectrometer

The ACIS has two arrays of CCDs, one (ACIS-I) optimized for imaging wide fields (16x16 arc minutes) the other (ACIS-S) optimized as a readout for the HETG transmission grating. One chip of the ACIS-S (S3) can also be used for on-axis (8x8 arc minutes) imaging and offers the best energy resolution of the ACIS system.

High Resolution Camera

The HRC comprises two micro-channel plate imaging detectors, and offers the highest spatial (<0.5 arc second) and temporal (16 msec) resolutions. The HRC-I has the largest field-of-view (31x31 arc minutes) available on Chandra. The HRC-S is most commonly used to read out the dispersed spectrum from the LETG.

High Energy Transmission Grating

The HETG is optimized for high-resolution spectroscopy of bright sources over the energy band 0.4-10 keV. It is most commonly used with ACIS-S. The resolving power (E/ΔE) varies from ~800 at 1.5 keV to ~200 at 6 keV.

Low Energy Transmission Grating

The LETG provides the highest spectral resolving power (E/ΔE > 1000) on Chandra at low energies (0.07 - 0.2 keV). The LETG/HRC-S combination is used extensively for high resolution spectroscopy of bright, soft sources such as stellar coronae, white dwarf atmospheres and cataclysmic variables.

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The Chandra X-Ray Center (CXC) is operated for NASA by the Smithsonian Astrophysical Observatory. 60 Garden Street, Cambridge, MA 02138 USA.   Email: Smithsonian Institution, Copyright © 1998-2014. All rights reserved.