DAG-TGI: turbulence generator instrument for DAG (Eastern Anatolia Observatory)

07/2018, SPIE, DOI: 10.1117/12.2313500

DAG (East Anatolia Observatory) Telescope has 4 m mirror with active optics (aO) and adaptive optics (AO) systems. In order to evaluate DAG's focal plane instruments and their installation, calibration and laboratory performance, one must emulate the atmospheric turbulence condition on DAG site. Although atmospheric conditions of the site are gathered from various meteorological and astronomical instruments, a turbulence generator instruments (TGI) is designed and characterized to emulate the similar characteristics. The design of the TGI is based on the forcing of cold air and temperature controllable hot air at adjustable wind speeds within a confined chamber, where the atmospheric turbulence strength is altered. First results of the TGI have been presented in this article for DAG's AO system.

DAG-MAM: meteorological and astronomical data monitoring for DAG (Eastern Anatolia Observatory)

07/2018, SPIE, DOI:10.1117/12.2313420

DAG (Eastern Anatolia Observatory) project is an ongoing project of 4 m visible (VIS) and near-infrared (IR) class telescope with active optics on primary mirror and adaptive optics on the Nasmyth platform at 3170 m altitude in Erzurum, Turkey. The first light of DAG Telescope will be taken on 2020. Some meteorological and astronomical measurements have been taken from several devices (meteorology stations, all sky camera, seeing camera and seeing quality meter, GNSS receiver, etc.) placed on a platform at the top of a 7 m tall DIMM tower at DAG Site (Konakli;/Erzurum) since the beginning of project (2012). Every device produces many various types of big-data. In order to analyse and evaluate these data all together in real-time, we have planned to design a database and a controller-pipeline software. In this poster, we present the first plans of this effort on a WEB GUI which allows to control historical and current data via the related charts.

Times of Minima of Some Eclipsing Binaries

05/2017, IVBS, DOI:10.22444/IBVS.6209

We present new times of minima in the light curves of some eclipsing binaries

Results from the worldwide coma morphology campaign for comet ISON (C/2012 S1)

12/2015, Planetary and Space Science, Volume 118, p. 127-137, DOI:10.1016/j.pss.2015.10.006

We present the results of a global coma morphology campaign for comet C/2012 S1 (ISON), which was organized to involve both professional and amateur observers. In response to the campaign, many hundreds of images, from nearly two dozen groups were collected. Images were taken primarily in the continuum, which help to characterize the behavior of dust in the coma of comet ISON. The campaign received images from January 12 through November 22, 2013 (an interval over which the heliocentric distance decreased from 5.1 AU to 0.35 AU), allowing monitoring of the long-term evolution of coma morphology during comet ISON's pre-perihelion leg. Data were contributed by observers spread around the world, resulting in particularly good temporal coverage during November when comet ISON was brightest but its visibility was limited from any one location due to the small solar elongation. We analyze the northwestern sunward continuum coma feature observed in comet ISON during the first half of 2013, finding that it was likely present from at least February through May and did not show variations on diurnal time scales. From these images we constrain the grain velocities to ~10 m s-1, and we find that the grains spent 2-4 weeks in the sunward side prior to merging with the dust tail. We present a rationale for the lack of continuum coma features from September until mid-November 2013, determining that if the feature from the first half of 2013 was present, it was likely too small to be clearly detected. We also analyze the continuum coma morphology observed subsequent to the November 12 outburst, and constrain the first appearance of new features in the continuum to later than November 13.99 UT.

A GUI for Analyzing the Period Changes of Eclipsing Binary Stars: ANGORA

07/2015, ASP,2015ASPC..496..290T

We describe improvements in the Python-based analysis code ANGORA (Analyzing the period chanGes Of binaRy stArs), a useful tool for modeling the orbital period variations (O-C) of eclipsing binary stars. ANGORA can be used to reveal the underlying origin of such variations by taking into account well-known physical mechanisms (e.g., mass transfer, LITE) individually or in combination. We provide an overview of the ANGORA code, together with applications to a few eclipsing binary stars.

Times of Minima of Eclipsing Binaries and Mid-Transit Times of Transiting Exoplanets

12/2014, IBVS,2014IBVS.6125....1B

We present new times of minima in the light curves of some eclipsing binaries and mid-transit times of some transiting exoplanets.

High precision defocused observations of planetary transits

03/2014, COSKA,2014CoSka..43..402B

It is only possible to measure physical properties of extrasolar planets, if they transit their host stars. One can determine the masses and the radii of this kind of objects, and hence, have constraints on their chemical composition, internal structure, formation and evolution. The availability of high quality light curves of planetary transits is essential in determining these properties within a few percent. In order to obtain high-quality transit light curves, we apply the well-established defocus technique on meter and sub-meter class telescopes in our project. This technique allows longer integration times, and hence collecting more photons to build up a higher S/N ratio. In this study, we present our first photometric results with the 1m Turkish telescope (T100) located at TÜBITAK National Observatory (TUG) of Turkey, which proved to be a well suited instrument to these observations with its large field of view.

A Tale on Two Close Binaries in Pegasus

2014, BALTA, DOI:10.1515/astro-2017-0177

We present the simultaneous light and radial velocity curve analysis of two contact binaries in Pegasus using the Wilson-Devinney code. The following absolute astrophysical parameters are determined: masses, radii and effective temperatures. BB Peg is a W-subtype W UMa-type binary, components of which are main sequence stars with 0.50 M and 1.40 M. The radii of its components are R1 = 0.81 R and R2 = 1.28 R. V407 Peg is an A-subtype contact binary composed of two subgiant components with masses 1.70 M and 0.43 M, and radii R1 = 2.17 R and R2 = 1.25 R. Comparisons with the theoretical models for solar composition by Girardi et al. (2000) confirms our classification and supports the results.

The Dwarf project: Eclipsing binaries - precise clocks to discover exoplanets

10/2012, AN, DOI:10.1002/asna.201211722

We present a new observational campaign, Dwarf, aimed at detection of circumbinary extrasolar planets using the timing of the minima of low-mass eclipsing binaries. The observations will be performed within an extensive network of relatively small to medium-size telescopes with apertures of ˜20-200 cm. The starting sample of the objects to be monitored contains (i) low-mass eclipsing binaries with M and K components, (ii) short-period binaries with a sdB or sdO component, and (iii) post-common-envelope systems containing a WD, which enable to determine minima with high precision. Since the amplitude of the timing signal increases with the orbital period of an invisible third component, the timescale of the project is long, at least 5-10 years. The paper gives simple formulas to estimate the suitability of individual eclipsing binaries for the circumbinary planet detection. Intrinsic variability of the binaries (photospheric spots, flares, pulsation etc.) limiting the accuracy of the minima timing is also discussed. The manuscript also describes the best observing strategy and methods to detect cyclic timing variability in the minima times indicating the presence of circumbinary planets. First test observations of the selected targets are presented.