Search and Study of UV-Excess Objects in the DFBS Database Authors:

DFBS is a digitized version of the famous Markarian survey (or the First Byurakan Survey, FBS). The project has been carried out by teams from Byurakan, Rome and Cornell, using an EPSON Expression 1680 Pro scanner. The DFBS will serve as a unique spectroscopic database for studies in large areas (total surface is 17,000 sq. degrees) at high galactic latitudes, approximate classification for objects (20,000,000 objects are present), selection of samples of objects for definite studies (UV-excess objects, extremely red objects, variables, etc.). A joint usage of the direct images and spectra give larger possibilities for various studies and more efficient use of the survey. Using the dedicated BSpec software written by one of the authors (GC), we have obtained a list of DFBS stars, their positions, B and R magnitudes, and preliminarily classification for DFBS zones with central DEC=+39° and DEC=+43°. The spectral length l>90pix (compared to the total length 10^7pix) was used as a criterion to search for UV-excess objects, as this corresponds to the criteria used during the 2nd part of the FBS. However, the spectra of objects with B<13 always occupy the full length, and they were excluded from the lists. On the other hand, for the fainter objects (near the plate limit), we weaken the criteria of selection (l>80pix), as their spectra are shorter. An additional point for the UV excess object classification is the following: the spectra of the UV-excess objects are divided into two parts by a sensitivity gap in green; the red-yellow part of the spectra must be weaker and the blue-ultraviolet part must be brighter and more extended. We started the project in the DFBS zone +39° and +43° to compare the results with those obtained before during the 2nd part of the FBS. Later on, cross-correlations with available catalogs and a multi-wavelength analysis was made for the found objects. The preliminary results of the search and studies will be reported.