The First Byurakan Survey (FBS) have been carried out by Markarian, Lipovetski and Stepanian in 1965-1980 on the Byurakan Observatory 102/132/213cm (40"/52"/84") Schmidt telescope with 1.5 deg. prism (Markarian et al. 1989). 2050 Kodak IIAF, IIaF, IIF, and 103aF photographic plates in 1133 fields (4x4 degree each, the size being 16cmx16cm) have been taken. FBS covers 17,000 sq. degrees of all the Northern Sky and part of the Southern Sky (Delta>-15) at high galactic latitudes (|b|>15). In some regions, it even goes down up to Delta=-19 and |b|=10. The limiting magnitude on different plates changes in the range of 16.5-19.5 in V, however for the majority it is 17.5-18. The scale is 96.8"/mm and the dispersion is 1800 A/mm near H-gamma and 2500 A/mm near H-beta (mean spectral resolution being about 50A). Low-dispersion spectra cover the range 3400-6900A, and there is a sensitivity gap near 5300A, dividing the spectra into red and blue parts. It is possible to compare the red and blue parts of the spectrum (easily separating red and blue objects), follow the spectral energy distribution, notice some emission and absorption lines (such as broad Balmer lines, molecular bands, He, N1+N2 lines, broad emission lines of QSOs and Seyferts, etc.), thus making up some understanding about the nature of the objects. The FBS is made up of zones (strips), each covering 4 degrees in declination and all right ascensions except the Galactic plane regions. In all there are 28 zones, which are named by their central declination (ex. zone +27 covers +25<delta<+29, zone +63 has +61<delta<+65, etc). The zones and the neighboring plates in right ascension overlap about 0.1 degree, as the exact size of a plate is 4.1X4.1, thus making the whole area complete. Each FBS plate contains low-dispersion spectra of some 15,000-20,000 objects, and there are some 20,000,000 objects in the whole survey.
The Second Byurakan Survey (SBS) was carried out by Markarian, Stepanian, Erastova, Lipovetski, Chavushian, and Balayan in 1978-1991 on the Byurakan Observatory 102/132/213cm Schmidt telescope with 1.5, 3 and 4 degree prisms, in combination with hypersensitized Kodak IIIaJ and IIIaF plates and filters, giving different ranges of spectrum (3500-5400A, 4950-5400A and 6300-6950A, respectively) (Markarian & Stepanian 1983, Stepanian 1996). In all, 550 plates have been obtained in 65 fields, 4x4 degree each. SBS covers 965 sq. degrees area at high galactic latitudes (|b|>30) with 07h43m<alpha<17h15m and +49<delta<+61. The limiting magnitude differs in the range of 18-20 in V, and the survey is complete to 17.5. 7 fields (covering 112 sq. degrees) have limiting magnitudes 19.5-20 (so-called Selected Fields of the SBS), and are of special interest. The dispersion near H-gamma for spectra obtained with 1.5, 3 and 4 deg. prisms is 1800A/mm, 900A/mm, and 280A/mm, respectively (and 1000A/mm near H-alpha for 4 deg. prism). SBS covers 3 zones of the FBS, with central declinations +51, +55 and +59. In average, each SBS plate contains low-dispersion spectra of some 50,000 objects, and there are some 3,000,000 objects in the whole survey.
The FBS was conducted originally for search of galaxies with UV-excess. The discovery of 1515 UV-excess (UVX) galaxies by Markarian and colleagues (later called Markarian galaxies) was the first and the most important work based on the FBS plates (Markarian 1967, Markarian et al. 1989). There are more than 200 Seyferts, dozens of QSOs, few hundreds of starburst and HII galaxies, BL Lac objects, radio, IR and X-ray sources among them. During the last 30 years more than 2500 scientific papers have been published on study of these objects. There are many Markarian galaxies, which are subject of study for understanding of AGN phenomenon, starburst activity and evolution of galaxies, high-luminosity IR radiation, AGN variability, double and multiple structure of the nucleus, composite spectrum AGN, galaxy interactions and merging, connection between different types of active galaxies, early stages of evolution of galaxies (some Markarian galaxies are BCDGs), and other important topics of modern extragalactic astronomy. Study of Markarian galaxies brought to discovery of many new Seyferts and spectral classification of this type of objects (Weedman & Khachikian 1971).
In SBS all interesting types of objects have been selected by Markarian, Stepanian and colleagues: fainter UVX galaxies, QSO, Sy, and BCDG candidates, all emission-line galaxies and stars, UVX and other peculiar stars. The SBS revealed 2892 peculiar objects, including 1286 galaxies and 1606 stellar objects (Stepanian 1996, 1999). 355 QSOs and 109 Seyferts, 5 BL Lac objects, 135 BCDGs, 41 LINERs, 170 SBN, 50 HII region galaxies, some 150 double nuclei galaxies; in all 790 UVX galaxies, 490 emission-line galaxies without UVX, many double and multiple galaxies, and 626 blue stars (cataclysmic variables, white dwarfs, subdwarfs, etc.) have been discovered. QSOs include BALQSOs, DampQSOs, QSOs with L-alpha forest, absorption-line QSOs, gravitational lenses. Many objects are IR, radio, X-ray and Gamma-ray sources. Spectral, photometric and accurate positional data have been obtained on Russian 6m, 4.5m MMT, Byurakan 2.6m, and other telescopes for about half of the objects. Spectral classification has been made for 1477 SBS objects. 519 galaxies have been discovered in the Selected Fields of the SBS, making up a complete sample for statistical investigations (Hakopian & Balayan 1999). The sample of the SBS low-redshift QSOs and Seyferts may provide data for filling the luminosity gap between QSOs and Seyferts, thus linking these two types of AGNs, thought to be of the same nature.
The second part of the FBS was devoted to the discovery and investigation of the blue (UVX) stellar objects. It was carried out by Abrahamian and Mickaelian in 1987-1994 (Abrahamian & Mickaelian 1996, Mickaelian 1994, and references therein) in 278 FBS fields, in a 4009 sq. degrees area of the FBS (+33<delta<+45 and +61<delta<+90). The main purpose of this work was discovery of new bright QSOs (as Markarian's survey was aimed only on extended objects), Seyferts, other compact galaxies, planetary nebulae nuclei, cataclysmic variables (CV), white dwarfs (WD), subdwarfs, and other peculiar stellar objects. 1103 objects have been selected, including 716 new blue stellar objects. Subsamples of candidate QSOs, WDs, CVs have been made up and spectral observations have been carried out for identification of the objects. 11 new bright QSOs have been discovered already among these objects (Mickaelian et al 1999), proving that FBS can provide data for enriching our knowledge on Local Universe. The local density of QSOs and the completeness of the Bright Quasar Survey (BQS) is re-estimated.
A survey on late-type stars on the FBS plates is being carried out since 1987 by Abrahamian and Gigoyan (ex. Abrahamian et al 1997 and references therein). 518 late M-type and carbon stars have been selected already in an area of 4569 sq. degrees in 12 zones, including 355 new ones. Surveys on carbon stars at high galactic latitudes are very rare. Discovery and study of such objects is necessary for study of the kinematics and chemical composition of the Galactic halo. Besides, many objects with extended dust shells, as well as extremely rare two new dwarf carbon stars have been discovered.
Works on selection of galaxies, blue stellar objects (including QSOs and Seyferts) and late-type stars lead to a new program of optical identifications of IRAS sources on the basis of the FBS plates (Mickaelian 1995). Since 1995, 1577 previously unidentified IRAS point sources (IRAS 1988, 1989) have been optically identified in the area +61<delta<+90 with a surface of 1487 sq. degrees. In this area, FBS plates have better limiting magnitudes (in average: 18.1 in V). 1178 of the identified sources are galaxies. Observations revealed many interesting objects, including Seyferts and LINERs and composite spectrum AGNs (Mickaelian et al. 1998, Balayan et al. 2001). IRAS galaxies contain AGNs, high-luminosity IR galaxies (LIGs, ULIGs, HLIGs), groups of galaxies (including compact ones), interacting and merging galaxies, etc. The subsample of galactic objects is also interesting, as it contains new planetary nebulae, AGB stars, late M and carbon stars. Some of them have excessive IR fluxes, mentioning on extended dust shells, as well as a number of stars show evidence of variability. Study of the new sample of IRAS galaxies, especially the high-luminosity IR galaxies, may lead to understanding of interrelationship between AGN and starburst activity induced by galaxy interactions and merging.
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