Optical identification and follow-up observations of SRGA J213151.5+491400 -- a new magnetic cataclysmic variable discovered with SRG Observatory

We report results of optical identification and multi-wavelength study of a new polar-type magnetic cataclysmic variable (MCV), SRGA J213151.5+491400, discovered by Spectrum Roentgen-Gamma ($SRG$) observatory in the course of the all-sky survey. We present optical data from telescopes in Turkey (RTT-150 and T100 at the T\"UBITAK National Observatory), and in Russia (6-m and 1-m at SAO RAS), together with the X-ray data obtained with $ART-XC$ and $eROSITA$ telescopes aboard $SRG$ and the $NICER$ observatory. We detect SRGA J213151.5+491400 in a high state in 2020 (17.9 mag) that decreases about 3 mag into a low state (21 mag) in 2021. We find only one significant period using optical photometric time series analysis which reveals the white dwarf spin/orbital period to be 0.059710(1) days (85.982 min). The long slit spectroscopy in the high state yields a power law continuum increasing towards the blue with a prominent He II line along with the Balmer line emissions with no cyclotron humps; consistent with MCV nature. Doppler Tomography confirms the polar nature revealing ballistic stream accretion along with magnetic stream during the high state. These characteristics show that the new source is a polar-type MCV. $SRG$ $ART-XC$ detections yield an X-ray flux of (4.0-7.0)$\times$10$^{-12}$ erg cm$^2$ s$^{-1}$ in the high state. $eROSITA$ detects a dominating hot plasma component (kT$_{\rm{max}}$ $>$ 21 keV in the high state) declining to (4.0-6.0)$\times$10$^{-13}$ erg cm$^2$ s$^{-1}$ in 2021 (low state). The $NICER$ data obtained in the low state reveal a two-pole accretor showing a soft X-ray component at (6-7)$\sigma$ significance with a blackbody temperature of 15-18 eV. A soft X-ray component has never been detected for a polar in the low state before.Comment: 16 pages, 4 Tables and 15 Figures. Accepted for publication in A&A as it stand

Probing transit timing variations of three hot Jupiters: HATP-36b, HATP-56b, and WASP-52b

We report the results of new transit observations for the three hot Jupiter-like planets, HATP-36b, HATP-56b, and WASP-52b, respectively. Transit timing variations (TTVs) are presented for these systems based on observations that span the period 2016-2020. The data were collected with the 0.6-m telescope at Adiyaman University (ADYU60, Turkey) and the 1.0 m telescope at TÜBCrossed D signTAK National Observatory (TUG, Turkey). Global fits were performed to the combined light curves for each system along with the corresponding radial velocity (RV) data taken from the literature. The extracted parameters (for all three systems) are found to be consistent with the values from previous studies. Through fits to the combined mid-Transit times data from our observations and the data available in the literature, an updated linear ephemeris is obtained for each system. Although a number of potential outliers are noted in the respective O-C diagrams, the majority of the data are consistent within the 3σ confidence level implying a lack of convincing evidence for the existence of additional objects in the systems studied

Ottoman forestry: socio-economic aspect and its influence today Otomano florestal: aspecto socioeconômico e sua influência hoje

Forestry is an important subject because it supplies wood and timber for direct human consumption, in addition to its positive effects on global warming and on bio-diversity, with a history dating back to antiquity. As a labor-intensive sector in developing countries, it maintains interactions with natural resources management, public relations and socio-economic structure. It can affect the prosperity of countries either positively or negatively. Hence, an analysis of the history of forestry bears importance because it not only sheds light on its past and present condition, but also explains the improvements for the protection of forests. Accordingly, in the first section of this study, general information on the Ottoman Land System and Ottoman Forestry Organization will be given. In the second section, we will treat 19th century westernization movements, as well as socio-cultural and economic changes. The third section will include significant regulations on forestry, forest management, and administration in the Ottoman Empire; as well as the influence of Ottoman forestry on the actual socio-economic structure. In the final section, under the title discussion and conclusion, Ottoman forestry will be examined regarding its consequences in terms of policy, economy and law.<br>A silvicultura é um assunto importante, pois o suprimento de madeira em geral e madeira para consumo humano direto, além de seus efeitos positivos sobre o aquecimento global e sobre a diversidade biológica, trata de uma história que remonta à antiguidade. Como um setor de trabalho intensivo nos países em desenvolvimento, mantém interações com a gestão dos recursos naturais, relações públicas e estrutura socioeconômica. Ela pode afetar a prosperidade dos países, seja positiva ou negativamente. Assim, uma análise da história da silvicultura tem importância, porque não só lança luz sobre a sua condição passada e presente, mas também explica as melhorias para a proteção das florestas. Assim, na primeira parte deste estudo, serão dadas informações gerais sobre o Sistema de Terras e Florestas e Organização Otomano. Na segunda seção, serão tratados movimentos da ocidentalização do século 19, bem como alterações socioculturais e econômicas. A terceira seção irá incluir regulamentos significativos na silvicultura, manejo florestal e administração no Império Otomano, bem como a influência da silvicultura Otomano na atual estrutura socioeconômica. Na seção final, no âmbito da discussão do título e conclusão, a silvicultura Otomano será analisada em relação as suas consequências em termos de economia, política e direito

Ground-based transit observations of the HAT-P-18, HAT-P-19, HAT-P-27/WASP40 and WASP-21 systems

As part of our ongoing effort to investigate transit timing variations (TTVs) of known exoplanets, we monitored transits of the four exoplanets HAT-P-18b, HAT-P-19b, HAT-P-27b/WASP-40b and WASP-21b. All of them are suspected to show TTVs due to the known properties of their host systems based on the respective discovery papers. During the past three years 46 transit observations were carried out, mostly using telescopes of the Young Exoplanet Transit Initiative. The analyses are used to refine the systems’ orbital parameters. In all cases we found no hints for significant TTVs, or changes in the system parameters inclination, fractional stellar radius and planet-to-star radius ratio. However, comparing our results with those available in the literature shows that we can confirm the already published values