M81 Chandra X-Ray Point Source Catalog: 276 Sources from 2005 Observations

265 X-ray point sources and 11 borderline sources were cataloged from 15 Chandra observations of the spiral galaxy M81 taken over six weeks in May-July 2005. The HEASARC at NASA created this table in 2011 based on analysis from a reference paper, which includes spectral fits, variability analyses, and comparisons to other galaxies. Each observation reached a sensitivity of approximately 10^37 erg s^-1.

Use Cases

• Analyze X-ray source variability on timescales of days, months, and years based on the described time-series observations.
• Compare X-ray luminosity functions (XLFs) of different galactic regions based on the parametrization mentioned for M81, M31, and the Milky Way.
• Differentiate populations of X-ray sources based on their colors as described in the catalog.
• Study the statistical reliability of sources using the PROB_NO_SOURCE statistic for the 265 'master' and 11 'borderline' entries.

Strengths

• Contains 276 distinct sources with a high probability (99.9% for 265 sources) of being real astronomical objects.
• Derived from 15 coordinated Chandra ACIS observations over a six-week period, providing temporal coverage.
• Includes spectral fitting and variability analyses for individual sources as described in the reference paper.

Limitations

• Column-level documentation is absent; field semantics must be inferred after download.
• Row count is unknown, which may limit suitability assessment.
• For 5 sources (3 master, 2 borderline), only coordinates are listed due to limited field-of-view coverage.

Provenance

Source

NASA HEASARC, based on electronic tables from a reference paper published in ApJ.

Collection Method

Analysis of 15 Chandra ACIS observations; source list compiled using the AE tool's PROB_NO_SOURCE statistic.

Time Range

Observations from May-July 2005.

Freshness

Last updated 2026-03-13 17:55:16.047209; freshness should be verified.

Geography

Target: the nearby spiral galaxy M81.