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ASCALSS - ASCA Large Sky Survey

HEASARC
Archive

Overview

The ASCA Large Sky Survey (LSS) was the first wide-area unbiased survey with the ASCA satellite in the 0.7 - 10 keV band around the North Galactic Pole region covering a continuous area of 7 square degrees. To make the best use of ASCA's capabilities, the authors developed a new source detection method in which the complicated detector responses were fully taken into account. Applying this method to the entire LSS data independently in the total (0.7 - 7 keV), hard (2 - 10 keV), and soft (0.7 - 2 keV) bands, they detected 107 sources altogether, with sensitivity limits of 6 x 10^-14 (0.7 - 7 keV), 1 x 10^-13 (2 - 10 keV), and 2 x 10^-14 ergs/s/cm^2 (0.7 - 2 keV), respectively. The complete list of detected sources is presented in this table. The detection criteria that needed to be satisfied were: (i) the significance of the summed count rate of the GIS and the SIS should exceed 4.5, and (ii) the significance of either the GIS or the SIS should also exceed 3.5.

Catalog Bibcode

1999ApJ...518..656U

References

Ueda Y., Takahashi T., Inoue H., Tsuru T., Sakano M., Ishisaki Y., Ogasaka
Y., Makishima K., Yamada T., Akiyama M., Ohta K. 1999, ApJ, 518, 656
      =1999ApJ...518..656U      (SIMBAD/NED BibCode)

Provenance

This database was created by the HEASARC in December 2001 based on the ADC/CDS Catalog J/ApJ/518/656.

Parameters

Name
The name of the X-ray source using the prefix AX (for ASCA X-ray) and the J2000 equatorial coordinates.

Hard_Flag
This flag is set to 'E' for the source with the hardest X-ray spectrum, AX J131501+3141. The position of this source is taken from the results of deep X-ray observations by Sakano et al. (1998, ApJ, 505, 129).

RA
The Right Ascension of the X-ray source in the requested equinox. The position used was that determined in the energy band for which the maximum significance was obtained. The RA was given in J2000 coordinates in decimal degrees and with a precision of 0.0001 degrees (0.36 arcseconds) in the originating table. The actual typical positional uncertainty was about 0.7 arcminutes (radius of the error circle).

Dec
The Declination of the X-ray source in the requested equinox. The position used was that determined in the energy band for which the maximum significance was obtained. The Declination was given in J2000 coordinates in decimal degrees and with a precision of 0.0001 degrees (0.36 arcseconds) in the originating table. The actual typical positional uncertainty was about 0.7 arcminutes (radius of the error circle).

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

SNR_GIS_Total
The significance of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the total (0.7 - 7 keV) energy band.

SNR_SIS_Total
The significance of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the total (0.7 - 7 keV) energy band. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

SNR_GIS_Hard
The significance of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the hard (2 - 10 KeV) energy band.

SNR_SIS_Hard
The significance of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the hard (2 - 10 KeV) energy band. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

SNR_GIS_Soft
The significance of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the soft (0.7 - 2 keV) energy band.

SNR_SIS_Soft
The significance of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the soft (0.7 - 2 keV) energy band. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

Count_Rate_GIS_Total
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the total (0.7 - 7 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (8.5 arcminutes offset for the GIS) integrated within a radius of 6.0 arcminutes. Note that a GIS count rate of 1 ct/ks (0.001 ct/s) in this energy band corresponds to a flux of 6.4 x 10^-14 erg s^-1 cm^-2 for a power-law spectrum with a photon index of 1.7

Count_Rate_SIS_Total
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the total (0.7 - 7 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (7.0 arcminutes offset for the GIS) integrated within a radius of 4.0 arcminutes. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

Count_Rate_GIS_Hard
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the hard (2 - 10 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (8.5 arcminutes offset for the GIS) integrated within a radius of 6.0 arcminutes. Note that a GIS count rate of 1 ct/ks (0.001 ct/s) in this energy band corresponds to a flux of 1.1 x 10^-13 erg s^-1 cm^-2 for a power-law spectrum with a photon index of 1.7

Count_Rate_SIS_Hard
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the hard (2 - 10 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (7.0 arcminutes offset for the GIS) integrated within a radius of 4.0 arcminutes. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

Count_Rate_GIS_Soft
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Gas Imaging Spectrometers (GIS) in the soft (0.7 - 2 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (8.5 arcminutes offset for the GIS) integrated within a radius of 6.0 arcminutes. Note that a GIS count rate of 1 ct/ks (0.001 ct/s) in this energy band corresponds to a flux of 4.5 x 10^-14 erg s^-1 cm^-2 for a power-law spectrum with a photon index of 1.7

Count_Rate_SIS_Soft
The vignetting-corrected count rate in ct/s of the X-ray source as measured by the Solid-state Imaging Spectrometers (SIS) in the soft (0.7 - 2 keV) energy band, and as at the reference position in the X-Ray Telescope (XRT) coordinate (7.0 arcminutes offset for the GIS) integrated within a radius of 4.0 arcminutes. A null value for this parameter means that the source lay outside of the SIS field of view (FOV).

Spectral_Index
The photon index of the best-fit absorbed power-law model. This was obtained by the simultaneous fitting of the GIS and the SIS spectra in the 0.7 to 10 keV range. The absorption column density was fixed at the Galactic column density N_H of 1.1 x 10^20 cm^-2.

Spectral_Index_Error
The 1-sigma (for a single parameter) statistical uncertainty in the photon index of the best-fit absorbed power-law model to the spectrum of the X-ray source.


Contact Person

Questions regarding the ASCALSS database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 8-Nov-2004