The Chandra X-ray Observatory is the U.S. follow-on to the Einstein
Observatory and one of NASA"s Great Observatories.
Chandra was formerly known as AXAF, the Advanced X-ray
Astrophysics Facility, but renamed by NASA in December, 1998.
Originally three instruments and a high-resolution mirror carried in
one spacecraft, the project was reworked in 1992 and 1993. The Chandra
spacecraft carries a high resolution mirror, two imaging detectors,
and two sets of transmission gratings. Important Chandra features are:
an order of magnitude improvement in spatial resolution, good
sensitivity from 0.1 to 10 keV, and the capability for high spectral
resolution observations over most of this range.
The Chandra Source Catalog (CSC) includes information about X-ray
sources detected in observations obtained using the Chandra X-ray Observatory.
Release 2.0 of the catalog includes 317,167 point, compact, and extended
sources detected in ACIS and HRC-I imaging observations released
publicly prior to the end of 2014.
Observed source positions and multi-band count rates are reported, as
well as numerous derived spatial, photometric, spectral, and temporal
calibrated source properties that may be compared with data obtained
by other telescopes. Each record includes the best estimates of the
properties of a source based on data extracted from all observations
in which the source was detected.
The Chandra Source Catalog is extracted from the CXC"s Chandra Data
Archive (CDA). The CXC should be acknowledged as the source of Chandra data.
For detailed information on the Chandra Observatory and datasets see:
http://cxc.harvard.edu/ for general Chandra information;
http://cxc.harvard.edu/cda/ for the Chandra Data Archive;
http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
The Chandra X-ray Observatory is the U.S. follow-on to the Einstein
Observatory and one of NASA"s Great Observatories.
Chandra was formerly known as AXAF, the Advanced X-ray
Astrophysics Facility, but renamed by NASA in December, 1998.
Originally three instruments and a high-resolution mirror carried in
one spacecraft, the project was reworked in 1992 and 1993. The Chandra
spacecraft carries a high resolution mirror, two imaging detectors,
and two sets of transmission gratings. Important Chandra features are:
an order of magnitude improvement in spatial resolution, good
sensitivity from 0.1 to 10 keV, and the capability for high spectral
resolution observations over most of this range.
The Chandra Source Catalog (CSC) includes information about X-ray
sources detected in observations obtained using the Chandra X-ray
Observatory. Release 2.0 of the catalog includes 317,167 point,
compact, and extended sources detected in ACIS and HRC-I imaging
observations released publicly prior to the end of 2014.
Observed source positions and multi-band count rates are reported, as
well as numerous derived spatial, photometric, spectral, and temporal
calibrated source properties that may be compared with data obtained
by other telescopes. Each record includes the best estimates of the
properties of a source based on data extracted from all observations
in which the source was detected.
The Chandra Source Catalog is extracted from the CXC"s Chandra Data
Archive (CDA). The CXC should be acknowledged as the source of Chandra data.
For detailed information on the Chandra Observatory and datasets see:
http://cxc.harvard.edu/ for general Chandra information;
http://cxc.harvard.edu/cda/ for the Chandra Data Archive;
http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
The Chandra X-ray Observatory is the U.S. follow-on to the Einstein
Observatory and one of NASA"s Great Observatories.
Chandra was formerly known as AXAF, the Advanced X-ray
Astrophysics Facility, but renamed by NASA in December, 1998.
Originally three instruments and a high-resolution mirror carried in
one spacecraft, the project was reworked in 1992 and 1993. The Chandra
spacecraft carries a high resolution mirror, two imaging detectors,
and two sets of transmission gratings. Important Chandra features are:
an order of magnitude improvement in spatial resolution, good
sensitivity from 0.1 to 10 keV, and the capability for high spectral
resolution observations over most of this range.
The Chandra Source Catalog (CSC) includes information about X-ray
sources detected in observations obtained using the Chandra X-ray
Observatory. Release 1.1 of the catalog includes about 138,000 point
and compact sources with observed spatial extents less than ~30 arcsec
detected in a subset of ACIS and HRC-I imaging observations released
publicly prior to the end of 2009.
Observed source positions and multi-band count rates are reported, as
well as numerous derived spatial, photometric, spectral, and temporal
calibrated source properties that may be compared with data obtained
by other telescopes. Each record includes the best estimates of the
properties of a source based on data extracted from all observations
in which the source was detected.
The Chandra Source Catalog is extracted from the CXC"s Chandra Data
Archive (CDA). The CXC should be acknowledged as the source of Chandra data.
For detailed information on the Chandra Observatory and datasets see:
http://cxc.harvard.edu/ for general Chandra information;
http://cxc.harvard.edu/cda/ for the Chandra Data Archive;
http://cxc.harvard.edu/csc/ for Chandra Source Catalog information.
The Chandra Source Catalog (CSC) is the definitive catalog of X-ray sources detected by the Chandra X-ray Observatory. By combining Chandra's sub-arcsecond on-axis spatial resolution and low instrumental background with consistent data processing, the CSC delivers a wide variety of uniformly calibrated properties and science ready data products for detected sources over four decades of flux. The Chandra Source Catalog version 2.1 (CSC 2.1) was released on April 2nd 2024; the current minor release is version 2.1.1, updated on 2024 October 18. (Refer to the <a href="https://cxc.cfa.harvard.edu/csc/versions.html">version history</a> for details.) This release of the catalog includes measured properties for 407,806 unique compact and extended X-ray sources in the sky, allowing statistical analysis of large samples, as well as individual source studies in the "Master Sources" table, provided herein. The extracted properties are provided for 1,304,376 individual observation detections, identified in Chandra ACIS and HRC-I imaging observations released publicly through the end of 2021, at the <a href="https://cxc.harvard.edu/csc/about.html">Chandra X-ray Center</a>. CSC 2.1.1 includes -- as an "alpha" release -- photometric properties for 1,717 highly extended (> ~30") sources, together with surface brightness polygons for several contour levels. The sensitivity limit for compact sources in CSC 2.1.1 is ~5 net counts, achieved by using a two-stage approach that involves co-adding multiple observations of the same field prior to source detection, and then using an optimized source detection method. For each X-ray detection and source, the catalog provides a detailed set of more than 100 tabulated positional, spatial, photometric, spectral, and temporal properties (each with associated lower and upper confidence intervals and measured in multiple energy bands). The catalog Bayesian aperture photometry code produces robust photometric probability density functions (PDFs), even in crowded fields and for low count detections. Releases beyond 2 use Bayesian Blocks analysis to identify multiple observations of the same source that have similar photometric properties, and these are analyzed simultaneously to improve S/N. The energy bands used to derive many of the CSC properties are defined in Table 4 of the reference paper: ultrasoft (u: 0.2-0.5 keV), soft (s: 0.5-1.2 keV), medium (m: 1.2-2.0 keV), hard (h: 2.0-7.0) and broad (b: 0.5-7.0 keV) for the ACIS energy bands, and wide (w: 0.1-10.0 keV) for the HRC energy band. The energy bands are chosen to optimize the detectability of X-ray sources while simultaneously maximizing the discrimination between different spectral shapes on X-ray color-color diagrams. Numerous source-specific catalog properties are evaluated within defined apertures. The authors define the "PSF 90% ECF aperture" for each source to be the ellipse that encloses 90% of the total counts in a model PSF centered on the source position. Because the size of the PSF is energy-dependent, the dimensions of the PSF 90% ECF aperture vary with energy band. They define the "source region aperture" for each source to be equal to the corresponding 3-sigma source region ellipse included in the merged source list, scaled by a factor of 1.5. Like the PSF 90% ECF aperture, the source region aperture is also centered on the source position, but the dimensions of the aperture are independent of energy band. This database table was last updated by the HEASARC in March 2025 and is based on a download of the online version of the Chandra Source Catalog, v2.1.1, at the CXC using the CLI. Refer to <a href="http://cxc.harvard.edu/csc/">http://cxc.harvard.edu/csc/</a> for details. This is a service provided by NASA HEASARC .
We present the properties of the discrete X-ray sources detected in our monitoring survey of the Antennae galaxies with Chandra ACIS-S. We detect ~70 sources down to a typical luminosity of 7x10^37^ergs/s in each of the six monitoring observations. In the co-added observation (which has a total exposure of 411ks) we detect a total of 120 sources down to a luminosity of (2-5)x10^37^ergs/s, depending on the local background. Fifteen sources have a strong extended component. Fourteen of the pointlike sources have luminosities above 10^39^ergs/s, at least in one exposure, which qualifies them as ultraluminous X-ray sources (ULXs). Ten of the ULXs show long-term variability, while one is observed only once, suggesting that it is a transient source. We find that 25 sources exhibit long-term variability clearly associating them with accreting compact objects. Twenty-one sources also show spectral variability. However, their variability patterns are diverse, indicating that they belong to different source classes. Finally, we find a weak excess of hard sources at the low luminosities that we tentatively associate with pulsar X-ray binaries.
We observed B1600+434 and B1608+656 with Chandra ACIS, detecting both quasar images in B1600+434 and three of four images in B1608+656. We also detected 157 serendipitous X-ray sources in the two Chandra fields and identified the brighter optical counterparts using the Sloan Digital Sky Survey and Palomar Digital Sky Survey.
Sensitive X-ray imaging surveys provide a new and effective tool to establish the census of pre-main-sequence (PMS) stars in nearby young stellar clusters. We report here a deep Chandra X-Ray Observatory observation of PMS stars in the Chamaeleon I North cloud, achieving a limiting luminosity of log L_t_~27ergs/s (0.5-8keV band) in a 0.8x0.8pc^2^ region. Of the 107 X-ray sources, 37 are associated with Galactic stars of which 27 are previously recognized cloud members.
We present the catalog of X-ray sources detected in a shallow Chandra survey of the inner 2{deg}x0.8{deg} of the Galaxy and in two deeper observations of the Radio Arches and Sgr B2. The catalog contains 1352 objects that are highly absorbed (NH>~4x10^22^cm^-2^) and are therefore likely to lie near the Galactic center (D~8kpc), and 549 less absorbed sources that lie within 6kpc of Earth.
We present catalogs and images of optical counterparts to the Chandra-selected X-ray sources found in the fields of the five clusters RX J0152-1357, RX J0849+4452, RDCS J0910+5422, MS 1054-0321, and RDCS J1252-2927, which were imaged with the Advanced Camera for Surveys as part of the ACS Guaranteed Time Observer programs. A total of 98 X-ray sources fall within the ACS mosaics, and positive identifications are made for ~96% of them, including confirmed cluster members. We classify the sources as active galactic nuclei (AGNs) or QSOs depending on their X-ray output.
We report here results from a Chandra ACIS observation of the stellar populations in and around the M17 HII region. The field reveals 886 sources with observed X-ray luminosities (uncorrected for absorption) between ~29.3ergs/s<logL_X_<32.8ergs/s, 771 of which have stellar counterparts in infrared images.
![To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to the catalogue of astrometric microlensing events. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice. .. image:: /static/img/cc0.png :alt: [CC0]](/registry-search/?f%5BcapabilityType_facet%5D%5B%5D=Simple+Cone+Search&f%5Brights_facet%5D%5B%5D=To+the+extent+possible+under+law%2C+the+publisher+has+waived+all+copyright+and+related+or+neighboring+rights+to+the+catalogue+of+astrometric+++microlensing+events.++For+details%2C+see+the+%60Creative+Commons+CC0+1.0+Public+Domain+dedication+%3Chttp%3A%2F%2Fcreativecommons.org%2Fpublicdomain%2Fzero%2F1.0%2F%3E%60_.++Of+course%2C+you+should+still+give+proper+credit+when+using+this+data+as+required+by+good+scientific+practice.%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fcc0.png%0A+++%3Aalt%3A+%5BCC0%5D%0A%0A){kind=link}