Baldone Schmidt Telescope Plate Archive and Catalogue

Alksnis, A.; Balklavs, A.; Eglitis, I.; Paupers, O.

doi:10.1515/astro-1998-0409

Cited by 6 publications

(3 citation statements)

References 2 publications

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“…We checked the Wide Field Plate Datebase 3 but found no entries for this time. Also the search in the plate archives of the Baldone Schmidt telescope (Alksnis et al 1998) and of the 100/300 cm Schmidt telescope of the Kvistaberg Observatory revealed no observations of M 31 during that time. It is useful to check also older historical observations of the Sharov 21 field which are not deep enough to detect the quasar in its faint stage but would allow discovering a previous outburst.…”

Section: Optical Photometry: Long-term Light Curvementioning

confidence: 99%

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

Meusinger¹,

Henze

Birkle

et al. 2010

A&A

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Aims. We announce the discovery of a quasar behind the disk of M 31, which was previously classified as a remarkable nova in our neighbour galaxy. It is shown here to be a quasar with a single strong flare where the UV flux has increased by a factor of ∼20. The present paper is primarily aimed at the remarkable outburst of J004457+4123 (Sharov 21), with the first part focussed on the optical spectroscopy and the improvement in the photometric database. Methods. We exploited the archives of photographic plates and CCD observations from 15 wide-field telescopes and performed targetted new observations. In the second part, we try to fit the flare by models of (1) gravitational microlensing due to a star in M 31 and (2) a tidal disruption event (TDE) of a star close to the supermassive black hole of the quasar. Results. Both the optical spectrum and the broad band spectral energy distribution of Sharov 21 are shown to be very similar to that of normal, radio-quiet type 1 quasars. We present photometric data covering more than a century and resulting in a long-term light curve that is densely sampled over the past five decades. The variability of the quasar is characterized by a ground state with typical fluctuation amplitudes of ∼0.2 mag aroundB ∼ 20.5, superimposed by a singular flare of ∼2 yr duration (observer frame) with the maximum at 1992.81. The total energy in the flare is at least three orders of magnitudes higher than the radiated energy of the most luminous supernovae, provided that it comes from an intrinsic process and the energy is radiated isotropically. The profile of the flare light curve is asymmetric showing in particular a sudden increase before the maximum, whereas the decreasing part can be roughly approximated by a t −5/3 power law. Both properties appear to support the standard TDE scenario where a ∼10 M giant star was shredded in the tidal field of a ∼2 . . . 5 × 10 8 M black hole. The short fallback time derived from the observed light curve requires an ultra-close encounter where the pericentre of the stellar orbit is deep within the tidal disruption radius. This simple model neglects, however, the influence of the massive accretion disk, as well as general-relativistic effects on the orbit of the tidal debris. Gravitational microlensing probably provides an alternative explanation, although the probability of such a high amplification event is very low.

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Section: Optical Photometry: Long-term Light Curvementioning

confidence: 99%

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

Meusinger¹,

Henze

Birkle

et al. 2010

A&A

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“…The purpose of the observations at the Baldone Observatory was to study the nonstationarity of stars at a late stage of evolution, especially carbon stars. Detailed description of photographic materials and filters used in observations and a list of observation objects are given in the works (Alksnis et al, 1998;Eglite and Eglitis, 2016). Most of the observations were obtained by the astronomers A.Alksnis, I.Daube, L.Duncáns, I.Eglitis, I.Jurǧítis, I.Platais, I.Pundure, A.Rudzinskis, P.Šimanskis and J.-I.Straume in the period from 1967 to 2005.…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays processing of large arrays of scanned plates has been successfully implemented, and catalogs of positions and stellar magnitudes of objects have been obtained for various observational programs: the FON program which processed 2260 plates of (MAN) and created the catalog of positions and Bvalues of 19.5 million stars and galaxies (Andruk et al, ,b, 2016a; the first epoch of observations to obtain proper motions in the vicinity of the scattered clusters 290 plates were photographed in Nikolaev observatory and a catalog of positions and B-values of 2.7 million stars was obtained (Protsyuk et al, 2014d); Saturn's satellites which processed 1385 positions from 250 astronegatives (Yizhakevych et al, 2015; other objects (Vavilova et al, 2014); observations of Uranus and Neptune where 1575 positions were obtained in different observatories , Pluto (59 positions) (Kazantseva et al, 2015) other Muminov et al, 2017). In 2015 started scanning and processing of 2200 plates -Kitab observatory part of FON program (from 0 to −20 degrees) Muminov et al, 2016) as well as over 1500 plates exposed in the U and V bands on 1.2 m Schmidt telescope (Alksnis et al, 1998;Eglite and Eglitis, 2016;Eglitis et al, 2016aEglitis et al, ,b, 2017. Stellar magnitudes of objects recorded in astronegatives are reduced to the Tycho2 catalog system or to the U, B, V system of photoelectric star measurements (Andruk et al, 1995;Kornilov et al, 1991;Mermilliod, 1991;Relke et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Processing of Digital Plates1.2m of Baldone Observatory Schmidt Telescope

Eglitis

Andruk

2017

Open Astronomy

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Abstract:The aim of this research is to evaluate accuracy of Plate Processing Method and to perform a detailed study of the Epson Expression 10000XL scanner, which was used to digitize plates from the database collection of the 1.2 m Schmidt Telescope installed in the Baldone Observatory. Special software developed in LINUX/MIDAS/ROMAFOT environment was used for processing the scans. Results of the digitized files with grey gradations of 8-and 16-bits were compared; an estimation of the accuracy of the developed method for rectangular coordinates determination and photometry was made. Errors in the instrumental system are ±0.026 pixels and ±0.024 m for coordinates and stellar magnitudes respectively. To evaluate the repeatability of the scanner's astrometric and photometric errors, six consecutive scans of one plate were processed with a spatial separation of 1200 dpi. The following error estimations are obtained for stars brighter than U< 13.5 m : σxy = ±0.021 to 0.027 pixels and σm = ±0.014 m to 0.016 m for rectangular coordinates and instrumental stellar magnitudes respectively.

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Astrometry and photometry of digitized plates of Baldone Schmidt telescope

Eglitis

Andruk

2021

Open Astronomy

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During the 40-year photographic period of astronomical observations, the Baldone Astrophysical Observatory has accumulated more than 22,000 direct and 2,500 spectral images. In 2018, the digitization of direct astrophoto images with a resolution of 1200 dpi was completed. A processing methodology for obtaining the equatorial coordinates and photometric characteristics of the objects recorded in digitized astronegatives using the LINUX/MIDAS/ROMAFOT environment has been developed at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. Program package with success already works in seven observatories. A description of the operation of this program complex in stages and analysis of the obtained results is given. The steps describe the astrometric and photometric reduction process of digital records, as well as the reduction of the obtained instrumental magnitudes to the Johnson UBVR photometric system. The methodology of characteristic curve construction in the case of one exposure is described in detail. From all digitized astrophotoplates to date Approximately 2200 V film negatives, 300 U plates and several R, B plates were processed. As a result, catalogs of the positions and magnitudes of Pluto, 1848 asteroids and comets were obtained. 31 new positions were recorded in the VizieR Pluto catalog VI/155. It was found that the root-mean-square errors of the reduction of the measured coordinates to the equatorial coordinate system of the Tycho-2 catalog have values σ RA , DEC = 0.1-0.2”, and the root-mean-square errors of the reduction of instrumental photometric quantities m to the Johnson system of stellar UBVR-values are also in within σ UBVR = 0.1 − 0.2 m .

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Baldone Schmidt Telescope Plate Archive and Catalogue

Abstract: Abstract.The article presents information on the archive and catalogue of the astrophotos taken with the Schmidt telescope of the Institute of

Cited by 6 publications

References 2 publications

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

J004457+4123 (Sharov 21): not a remarkable nova in M 31 but a background quasar with a spectacular UV flare

Processing of Digital Plates1.2m of Baldone Observatory Schmidt Telescope

Astrometry and photometry of digitized plates of Baldone Schmidt telescope

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