Further identification of ROSAT all-sky survey sources in Orion We report on the identification of 22 ROSAT All-Sky Survey (RASS) X-raysources distributed in the general direction of the Orion star-formingregion. The X-ray sample contains sources from the ROSAT bright sourcecatalogue and from previous detections. The optical identifications arebased on intermediate-resolution spectroscopy and UBV Johnson photometryusing a 1m-class telescope. The strengths of the Hα , Na I D_2 andlithium lines for the stellar counterparts are evaluated applying thespectral subtraction technique, using templates of the same spectraltype. Radial velocities of the optical counterparts are also reported.Thirteen of the optical counterparts show the lithium absorption line intheir spectra and have radial velocities consistent with the Orion starforming region. Four of these objects can be classified as new bona-fideT Tauri stars.Based on observations collected at Catania Astrophysical Observatory,Italy.
Walraven photometry of nearby southern OB associations Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars inthe regions of five nearby southern OB associations: Scorpio Centaurus(Sco OB2), Orion OB1, Canis Major OB1, Monoceros OB1, and Scutum OB2.Derived V and (B - V) in the Johnson system are included.
