Soft X-ray (0.2 - 3.5 keV) measurements for all normal, massive, o-type stars surveyed with the Einstein Observatory are presented as a catalog containing 89 detections and 176 upper bounds, together with a detailed discussion of the reduction process. Values of L[x]/L[bol] listed for most stars, range from 10e-5.44 to 10e-7.35; l[x] spans more than 3 orders of magnitude, ranging from 1.5 x 10e31 to 2 x 10e34 ergs se-1. It is noted that at least 30% of o-type stars are variable in X-rays, but that there is little evidence for new objects whose X-ray emission might be significantly enhanced by accretion processes onto a neutron star. For further information, please contact the HEASARC. This is a service provided by NASA HEASARC .

The IPCPHOT database contains information from the Imaging Proportional Counter aboard HEAO-2, the Einstein Observatory, in Event List Format. Einstein incorporated a high-resolution X-ray telescope and a focal plane assembly capable of positioning at its focus one of four instruments: a high-resolution imaging detector (HRI), a broader-field imaging proportional counter (IPC), a solid state spectrometer (SSS), and a Bragg crystal spectrometer (FPCS). Einstein (HEAO-2) was launched on November 13, 1978, and operated successfully until April 1981. This is a service provided by NASA HEASARC .

This database contains information on sources detected with the Einstein Observatory Image Proportional Counter (IPC), assembled for the Einstein Observatory Catalog (EOSCAT) of IPC X-ray Sources (2E) and containing over 4000 unique sources (with 6539 separate detections) which were detected with the IPC at a level of significance greater than 3.5 sigma in the broad band (0.2-3.5 keV). This database also contains the list of 277 sources which are known not to have been included in the Einstein Observatory Source Catalog (flagged by supplement = 'Y' in this database). Those which were not detected during the standard Rev1B processing were typically discovered upon visual inspection of the contour diagrams in the Catalog. Others were detected with Rev1B standard processing but left out of the Catalog because of short exposure times or other reasons listed in the "missed_code" field. 258 of these 277 additional sources have no valid signal to noise ratio (SNR) estimate (values of 0.0), while 3 others have SNR values of 3.2 and 3.3, notice. This IPC database is based on NASA Astrophysics Data System (ADS) tables that were created in 1991 and 1993 and were themselves derived from tables provided by Dr. D. E. Harris of the Center for Astrophysics at Harvard-Smithsonian. The HEASARC has a similar catalog in its database called EINSTEIN2E which comprises a more recent version of the IPC source list as archived at the NASA Astronomical Data Center (ADC) and the Center for Astronomical Data at Strasbourg (CDS). EINSTEIN2E has 868 fewer detections than the IPC catalog, notice, for reasons that the HEASARC is unsure of, but that may imply that some of the detections in IPC are not reliable. We have retained the IPC database for reasons of completeness, but caution that detections listed here which have no counterpart in the EINSTEIN2E Catalog should be treated with caution. This IPC database was recreated by the HEASARC in December 2000 to replace a previous version in which we discovered some transcription errors. It is based on NASA Astrophysics Data System (ADS) tables that were created in 1991 and 1993 and were themselves derived from tables provided by Dr. D. E. Harris of the Center for Astrophysics at Harvard-Smithsonian:

 The Einstein IPC Source List From EOSCAT (ADS Creation Date: 26-Dec-1990; ADS Last Revision Date: 04-Nov-1993), D.E. Harris, CfA The EOSCAT List of Missed IPC Sources (ADS Creation Date: 26-Oct-1990; ADS Last Revision Date: 17-Sep-1991), D.E. Harris, CfA 

This is a service provided by NASA HEASARC .

The X-ray sources from observations made with the Einstein Observatory (HEAO-2) Imaging Proportional Counter (IPC) that have intensities of 2-sigma or more above the background are compiled in this catalog. This catalog covers more sky at fainter flux levels than the Einstein Medium Sensitivity Survey. Fields with diffuse emission sources such as bright Abell clusters of galaxies and supernova remnants were excluded. Thus, data within 10 degrees of the galactic plane as well as fields within the boundaries of the Magellanic Clouds were excluded. Regions crowded with galactic sources such as the Orion and Pleiades fiels were also excluded. Excluding redundant fields, this catalog covers 1850 sq. degrees of the sky. The generation of the Einstein Two-Sigma Catalog was described in detail by Moran et al. (1996). Please read this article carefully to ensure responsible use of the Catalog. Detailed scientific and technical questions on the contents and methodology of this catalog should be addressed to the first author, Ed Moran (edhed@igpp.llnl.gov). In particular, it should be noted that, by design, this catalog contains a significant number of spurious sources: only 28%, or about 13,000 sources, out of the 46,000 source in the 2-sigma catalog are `real` astrophysical sources, with the remainder of the sources being spurious ones. Moran et al. show in their paper that performing cross-correlations of 2-sigma sources with other catalogs is an effective way of selecting sources in this catalog that are probably real. This is a service provided by NASA HEASARC .

This database table is based upon the information contained in the Catalog of Galactic O-Type Stars (Garmany, Conti, and Chiosi 1982), which is a compilation from the literature of all O-type stars for which spectral types, luminosity classes, and UBV photometry exist. Most of the entries come from Cruz-Gonzalez, et al. (1974) and Humphreys (1978), with additional stars from Garrison and Kormendy (1976); Garrison, Hiltner, and Schild (1977); Garrison and Schild (1979); Feinstein, Marraco, and Muzzio (1973); Feinstein, Marraco, and Forte (1976); and Moffat, Fitzgerald, and Jackson (1979). As discussed below, the HEASARC has deleted 5 of the original 765 entries which we believe to be erroneous and/or redundant, and modified the names and/or positions of 14 other entries. As part of the checking process, the HEASARC created new, more accurate positions for all the entries using the SIMBAD database. The catalog contains 760 stars, for each of which designations (HD, DM, etc.), spectral types, V magnitudes, B-V magnitudes, cluster memberships, positional information, and source references are given. In addition, the authors have included derived values of absolute visual and bolometric magnitudes, and distances. The source reference should be consulted for additional details concerning the derived quantities. This is a service provided by NASA HEASARC .

This database table gives access to the IPC unscreened data set, which includes files in the event list format together with auxiliary files. This data set was generated by the Einstein Data Center and delivered to the HEASARC on CD-ROM. The Einstein Observatory (HEAO-2) operated from November 1978 to April 1981. Einstein carried the first fully imaging X-ray telescope in space and operated in pointing mode. The Imaging Proportional Counter had a bandpass of 0.2-3.5 keV and was one of two detectors onboard used for imaging. During the Einstein lifetime more than 4000 targets were observed with the IPC. This database table was last updated by the HEASARC in August 2005. Galactic coordinates were added and some parameters were renamed to adhere to the HEASARC's current parameter naming conventions. This is a service provided by NASA HEASARC .

The HRIPHOT database contains information from the High Resolution Imager aboard HEAO-2, the Einstein Observatory, in Event List Format. Einstein incorporated a high-resolution X-ray telescope and a focal plane assembly capable of positioning at its focus one of four instruments: a high- resolution imaging detector (HRI), a broader-field imaging proportional counter (IPC), a solid state spectrometer (SSS), and a Bragg crystal spectrometer (FPCS). Einstein (HEAO-2) was launched on November 13, 1978, and operated successfully until April 1981. This is a service provided by NASA HEASARC .

The IPCIMAGE database contains information from the Imaging Proportional Counter aboard HEAO 2, the Einstein Observatory. Einstein incorporated a high-resolution X-ray telescope and a focal plane assembly capable of positioning at its focus one of four instruments: a high-resolution imaging detector (HRI), a broader-field imaging proportional counter (IPC), a solid state spectrometer (SSS), and a Bragg crystal spectrometer (FPCS). Einstein (HEAO 2) was launched on November 13, 1978, and operated successfully until April 1981. This is a service provided by NASA HEASARC .