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DEEP SKY SURVEYS WITH RATAN-600
Yu.N. Parijskij Sp ecial Astrophisical Observatory of RAS Nizhnij Arkhyz, 369167, Russia par@sao.ru Blind Sky surveys with RATAN-600 were suggested by the general PROJECT of AVP (1968). A Flat mirror was included into the main CIRCLE structure to carry out quick allsky survey, as successfully was made with the Kraus telescop e of Ohio University. In 1960th the Sky seemed to b e filled by first generation young ob jects with inverted and SSA sp ectra, which were missing in the meters wavelengths catalogs. The Sternb erg Astronomical Institute of the Moscow State University group have surveyed the sky zone DEC:0-14deg with sub-Jy sensitivity at the 2-8 cm wavelength and the first big (8500) list of ob jects detected at 4 GHz ob jects was published just b efore the famous 87GB catalog app eared (see the Zelenchuk survey catalog in CATS data base). The CMB anisotropy studies were early on included in the high priority scientific targets. The first deep blind sky survey was done at 4 cm wavelength in the winter 1975-1976 with sub-mK sensitivity, but only results interesting for CMB p eople were published, and they reject all available in 70-th variants of the theories of galaxies formation. The second ep o ch of deep blind surveys started after installation of the world b est cryo-receiver at 7.6 cm (with 2mK/s1/2 sensitivity). The first 17 Feb. 1980 24h- drift scan demonstrated that ab out 200 details may b e found on this record and may b e classified as radio sources, and we integrated p oint sources (PS) and CMB anisotropy tasks in the exp eriment. Several regions were selected for deep surveys, including the celestial Pole, the Declination of SS433 strip, and the Declination of 3C84 (near the RATAN zenith) strip. Weakness of the CMB anisotropy requires a great averaging (hundreds daily scans) and we observed some regions during many years. At all frequencies lower 10 GHz we see a confusion limit, and we prop osed ways to suppress this noise using sp ecific shap e of the RATAN-600 b eam. It helps us to reach the few mJy level at cm wavelengths and much b elow by P(D) analysis. The multi-frequency mo de of observations, imp ortant for SCREENS (foregrounds) cleaning in the CMB exp eriments, turned out to b e useful for a sp ectral classification of the PS app earing on the scans. Now it is clear for all CMB groups, that the depth of the CLEANING from PS is the real limit of CMB dedicated exp eriments, including the PLANCK mission. The problem with PS ob jects at CMB frequencies connects with an absolutely unknown Source Population (b etween IRAS and NVSS, or GB). At RATAN-600 we try to use SELF CLEANING mo de, using much higher resolution than required by CMB physics (sub-degree scales). A huge amount of data collected during the CMB exp eriments should b e used by PS p eople. I shall present the p ositive and negative exp erience, connected with the international BIG TRIO program, and problems with detection of a new p opulation at cm wavelengths. The present state of RATAN-600 "Cold" and RATAN-600 Zenith Field (RZF) blind surveys will b e mentioned, as well as the present-day situation with High Frequencies Sky Surveys. This presentation describ es results of several groups in SAO and in SPb-branch of SAO, and now is partially supp orted by the RFBR grant 05-02-17521, OF RAS, SPb Center of RAS.