TECHNICAL DESCRIPTION

The First Byurakan Survey 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° prism (Markarian et al. 1989). 2050 Kodak IIAF, IIaF, IIF, and 103aF photographic plates in 1133 fields (4°x4° each, the size being 16cmx16cm) have been taken. FBS covers 17,000 deg² 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^m-19.5 ^m in V, however for the majority it is 17.5 ^m -18 ^m. The scale is 96.8"/mm and the dispersion is 1800 A/mm near H-g and 2500 A/mm near H-b (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° 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°<d<+29°, zone +63° has +61°<d<+65°, etc). The zones and the neighboring plates in right ascension overlap about 0.1 degree, as the exact size of a plate is 4.1°´4.1°, 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.

In 1988, Mickaelian continued the survey to low galactic latitudes to check if it is possible to work with the low-dispersion spectra in these crowded regions. Two regions of the Milky Way of the zones +39° and +43° have been covered. 28 Kodak IIaF, IIIaF and 103aF plates in 11 and 8 fields having 171 and 117 deg² surface respectively have been obtained. These plates are especially useful for discovery of white dwarfs and other galactic objects.

MAIN CHARACTERISTICS OF THE FBS OBSERVATIONAL MATERIAL

Sky coverage                            d>-15°, all RA except the Milky Way (|b|>15°)

Total area                                 17,000 deg²  

Number of fields                        1139 (each 16 deg²)

Number of plates                       1874 (at least one plate with m=17 in each field)

Size of the plates                      4°x4°, 16x16 cm

Photographic emulsion              Eastman Kodak IIAF, IIaF, IIF, 103aF

Spectral range                          3400-6900A, with a sensitivity gap at 5300A

Dispersion                                1800 A/mm near H-gamma, 2500 A/mm near H-beta

Spectral resolution                    50 A/pix in average

Scale                                       96.8 arcsec/mm

Limiting magnitude                    17.5-18.0 in V

REFERENCES

Markarian B.E., Lipovetski V.A., Stepanian J.A., Erastova L.K., Shapovalova A.I., 1989, Commun. Special Astrophys. Obs., 62, 5.