The 7-year MAXI/GSC Source Catalog of the Low-Galactic-latitude Sky (3MAXI)

<jats:title>Abstract</jats:title><jats:p>We present the first MAXI/GSC X-ray source catalog in the low-Galactic-latitude sky<jats:inline-formula><jats:tex-math/><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsaaa89cieqn1.gif" xlink:type="simple"/></jats:inline-formula>outside the Galactic center region (<jats:inline-formula><jats:tex-math/><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="apjsaaa89cieqn2.gif" xlink:type="simple"/></jats:inline-formula>,<jats:italic>l</jats:italic> < 30°, and<jats:italic>l</jats:italic> > 330°) based on 7-year data from 2009 August 13 to 2016 July 31. To overcome source confusion in crowded regions, we have accurately calibrated the position-dependent shape of the point-spread function of the MAXI/GSC by analyzing onboard data. We have also taken into account the Galactic ridge X-ray emission. Using a maximum likelihood image fitting method, we have detected 221 sources with a significance threshold >6.5<jats:italic>σ</jats:italic>, 7 of which are transients only detected in 73-day time-sliced images. The faintest source has a flux of 5.2 × 10<jats:sup>−12</jats:sup>erg cm<jats:sup>−2</jats:sup> s<jats:sup>−1</jats:sup>(or an intensity of 0.43 mCrab) in the 4–10 keV band. We have identified the counterparts for about 81% of the detected sources, by cross-matching with the<jats:italic>Swift</jats:italic>,<jats:italic>Uhuru</jats:italic>,<jats:italic>RXTE</jats:italic>,<jats:italic>XMM-Newton</jats:italic>, MCXC, and<jats:italic>ROSAT</jats:italic>all-sky survey catalogs. Our catalog contains the source name, position and its error, flux and detection significance in the 3–4 keV, 4–10 keV, and 10–20 keV bands, hardness ratios, and information on the likely counterpart for the individual detected sources. We have obtained 73-day bin light curves of all the cataloged sources over 7 years and have calculated their periodograms. On the basis of the mean properties of time variability and spectral hardness, we suggest that the majority of the unidentified sources are low-mass X-ray binaries or blazars. Finally, we present the log<jats:italic>N</jats:italic>–log<jats:italic>S</jats:italic>relations at different Galactic longitudes and for different source populations.</jats:p>