Papers by Milcho Tsvetkov
The data in the Wide-Field Plate Database for the archived photographic observations obtained wit... more The data in the Wide-Field Plate Database for the archived photographic observations obtained with the 0.38 m refractor and the 0.16 m camera of the Bucharest Observatory in the context of the their repeated use are being analyzed. A summary of the observational programs carried out with these two instruments since 1930 is presented. Results from the scanning of selected plates with the PDS 1010 of the Sofia Sky Archive Data Center are presented, too.
Balkan Meeting of Young Astronomers, 2001
We consider the collaboration in the archiving of wide-field photographic observations in the ast... more We consider the collaboration in the archiving of wide-field photographic observations in the astronomical observatories from the Balkan peninsula region. As a result of the collaboration the descriptive information for 49.2% of all existing wide-field observations in Bulgaria, Serbia and Romania (40 437 plates) is already included in the Wide-Field Plate Database (WFPDB). An on-line access to this information is organized in Strasbourg Data Center and in Sofia Sky Archive Data Center. A digitized plate archive is on the way to be created as a part of the WFPDB with the operating high-speed Epson Expression 1640XL flatbed scanner and high-precision PDS1010 microdensitometer in Sofia Sky Archive Data Center, as well as with UMAX Alfa Vista II flatbed scanner in Bucharest, which provide good opportunities for an effective processing of the archived observations. Another aspect of the collabration is the exchange of experience in development and application of astronomical databases (WFPDB and BELDATA) and organization of mirror sites of the databases.
The results of an investigation of the optical properties of the 50/70 cm Schmidt telescope at th... more The results of an investigation of the optical properties of the 50/70 cm Schmidt telescope at the Bulgarian National Astronomical observatory using the Hartmann method are presented. Two basic features of the optical system were investigated, by mapping the normal deviations of the telescope's real wavefront from the ideal one and by finding the energy distribution in the image. It
On a plate obtained on the 40arcsec-Schmidt telescope of the Byurakan Astrophysical Observatory w... more On a plate obtained on the 40arcsec-Schmidt telescope of the Byurakan Astrophysical Observatory with 4°-objective-prism 6 new and 3 known Halpha emission stars as well as the probable variability of 33 stars from Kun's list of the Halpha stars are detected.
International Astronomical Union Colloquium, 1984
The 50/70 Schmidt telescope at the National Astronomical Observatory (NAO), Bulgarian Academy of ... more The 50/70 Schmidt telescope at the National Astronomical Observatory (NAO), Bulgarian Academy of Sciences, is an example of the possibilities for a long-term operation and everlasting actuality of these types of telescopes. Originally, this telescope was constructed in the GDR in 1952 and mounted in the Potsdam Observatory, Academy of Sciences of the GDR (as such, it is on the list of West, 1974). In 1979, on the basis of a mutual agreement between the Bulgarian Academy of Sciences and the Academy of Sciences of the GDR, it was transferred to Rozhen, Bulgaria. The principal parameters of the instrument are as follows: I. Main mirror: diameter: 70cm; material: Tempax; thickness in the centre: 10 cm; radius of curvature: 344 cm.
International Astronomical Union Colloquium, 1995
The contemporary state of the Schmidt/Maksutov telescope plate archives and their unification in ... more The contemporary state of the Schmidt/Maksutov telescope plate archives and their unification in an Index Plate Catalogue as part of the Wide Field Plate Database is presented.
AIP Conference Proceedings, 2008
ABSTRACT This paper is dedicated to the first comparative study concerning position determination... more ABSTRACT This paper is dedicated to the first comparative study concerning position determinations of selected small bodies in the solar system observed with the Bucharest Observatory equatorial PRIN-MERTZ refractor (d = 0.38m, f = 6.0m) by means of the Carl-Zeiss ASCORECORD measurements and the processing of 5 photographic plates dating from 1971, digitized with the EPSON 1640XL flatbed scanner of the Sofia. The calculations were done with PC computer, with the same program for both cases using a double precision accuracy on the way to compare manual measurements and data processing using the digitized plates. The scan resolution used was 1600 dpi-14 bit grayscale up to 3.6 densities. With this scale 1 pix = 15.875 microns we had the extended field of 15184×15219 pix. The format of the scans was FITS using the standard twain driver for EPSON 1640XL and software developed by S. Mottola.
Astronomy and Astrophysics, Aug 30, 1985
... BR Pettersen 1 Department of Astronomy and National Astronomical Observatory, Bulgarian Acade... more ... BR Pettersen 1 Department of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 7 November Street 1, BG-1000 Sofia, Bulgaria 2 ... This conclusion is supported by the results of Asteriadis (1982) for another star with similar characteristics. ...
Information Bulletin on Variable Stars, Aug 1, 1989
Spisanie Na Bŭlgarskata Akademii͡a Na Naukite Bŭlgarska Akademii͡a Na Naukite, 1987
The Wide-Field Plate Database (WFPDB) gives an inventory of all wide-field (>~ 1 sq. deg) phot... more The Wide-Field Plate Database (WFPDB) gives an inventory of all wide-field (>~ 1 sq. deg) photographic observations archived in astronomical institutions over the world. So it facilitates and stimulates their use and preservation as a valuable source of information for future investigations in astronomy. At present WFPDB manages plate-index information for 25% of all existing plates providing on-line access from Sofia (http://www.skyarchive.org/search) and in CDS, Strasbourg. Here we present the new development of WFPDB as an instrument for searching of long term brightness variations of different sky objects stressing on the European photographic plate collections (from existing 2 million wide-field plates more than 55% are in Europe: Germany, Russia, Ukraine, Italy, Czech Republic, etc.). We comment examples of digitization (with flatbed scanners) of the European plate archives in Sonneberg, Pulkovo, Asiago, Byurakan, Bamberg, etc. and virtual links of WFPDB with European AVO, ADS, IBVS.
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Papers by Milcho Tsvetkov