College Observatory Research Articles

Photometric study and absolute parameters of the short-period eclipsing binary HH Bootis

We present the results of our investigation on the geometrical and physical parameters of the W UMa type binary system HH Bootis from new CCD (BVRI) light curves and published radial velocity data. The photometric data were obtained in 2011 and 2012 at Ankara University Observatory (AUO). Light and radial velocity observations were analyzed simultaneously using the Wilson–Devinney (2013 revision) code to obtain absolute and geometrical parameters. The system was determined to be a W-type W UMa system of a type different from that suggested by Dal and Sipahi (2013). An interesting cyclic period variation in the time intervals between primary and secondary eclipses (“half-period variation”) was discovered and analyzed and its possible cause is discussed. Combining our photometric solution with the spectroscopic data we derived masses and radii of the eclipsing system to be M1=0.627M⊙,M2=1.068M⊙,R1=0.782R⊙ and R2=0.997R⊙. New light elements were derived and finally the evolutionary status of the system is discussed.

Equivalence Relations Between the Cortie and Zürich Sunspot Group Morphological Classifications

Catalogues of sunspots have been available with useful information about sunspots or sunspot groups for approximately the last 150 years. However, the task of merging these catalogues is not simple. In this paper, a method is suggested of converting the types of sunspot groups that were proposed by Cortie (1901) into the well-known Zurich types of sunspot groups. To achieve this, the sunspot catalogue of the Valencia University Observatory (from 1920 to 1928) was used in addition to the descriptions proposed by Cortie. To assess the quality of this conversion scheme, the Zurich type was computed from the Valencia catalogue, and the resulting contribution of each group type was compared to what can be found in other catalogues. The results show that the proposed scheme works well within the errors that are found in the different catalogues.

Two Observatories in Istanbul: from the Late Ottoman Empire to the Young Turkish Republic

From the 17 century onward, the Ottoman Empire entered a phase of weakening, as a consequence of many factors including the dissolution of political stability, the loss of territory and decreasing revenue. In the second half of the 19 century, as an attempt to reinforce power of the central authority, the Ottomans undertook major reforms called Tanzimat. During this period, individuals started to establish professional and learned associations similar to those in the West which eventually led to the creation of a Faculty of Science and to the Ottoman University (Darulfunun, 1900). In this context of reform and opening to the West, the Imperial Observatory (Rasathane-i Amire) was founded in 1868 with the support of France. Its primary aim was to exchange data between European and Ottoman meteorological stations. The Imperial Observatory occupied several locations before reaching its final setting in Kandilli (1911), on the Asian side of the Bosphorus where other activities were developed such as sismology, astronomy, meteorology and magnetic studies. Following the spirit of the newly founded Republic in 1923, a serious reform of the academic programmes and a purging of the staff of the Ottoman University led to the establishment of the Istanbul University in the historical quarter of Beyazit (1933). The Istanbul astronomical Observatory was founded in the same year and its construction started in 1935. The university reform was largely influenced by the presence of German and other European scholars, many of them Jewish, escaping from Nazi persecution. In particular, Erwin Finlay-Freundlich from Potsdam Observatory became the first director of Istanbul Observatory. Kandilli and Istanbul University observatories are briefly presented here, stressing the main steps of their creation and their astronomical heritage.

ASTROMETRY, MORPHOLOGY, AND POLARIMETRY OF COMET DONATI IN 1858

We present unpublished observations of Comet Donati 1858 VI recently recovered in an old storage facility at the University Observatory in Oslo. Carefully-made drawings reveal temporal changes in the appearance of this comet. Fine structures in the tail were noted, some of which were short-lived. Envelopes in the comet's head, apparently due to outgassing from the nucleus, were monitored over several days. Astrometric positions of the comet's head derived by various combinations of telescopes and micrometers reveal a standard deviation of ± 6″. Visual polarimetry of the coma and tail revealed polarized light and determined that the polarization plane contained the comet and the Sun. Thus the polarized light from the comet was reflected sunlight. The observations are discussed in relation to contemporary publications.

Absolute and geometric parameters of contact binary BO Arietis

We present the results of our investigation on the geometrical and physical parameters of the W UMa type binary system BO Ari from analyzed CCD (BVRI) light curves and radial velocity data. The photometric data were obtained in 2009 and 2010 at Ankara University Observatory (AUO) and the spectroscopic observations were made in 2007 and 2010 at TUBITAK National Observatory (TUG). These light and radial velocity observations were analyzed simultaneously by using the Wilson–Devinney (2013 revision) code to obtain absolute and geometrical parameters. The system was determined to be an A-type W UMa system. Combining our photometric solution with the spectroscopic data we derived masses and radii of the eclipsing system to be M1=0.995M⊙,M2=0.189M⊙,R1=1.090R⊙ and R2=0.515R⊙. Finally, we discuss the evolutionary status of the system.

James Gregory, the University observatory and the early acquisition of scientific instruments at the University of St Andrews.

James Gregory, inventor of the reflecting telescope and Fellow of the Royal Society, was the first Regius Professor of Mathematics of the University of St Andrews, 1668-74. He attempted to establish in St Andrews what would, if completed, have been the first purpose-built observatory in the British Isles. He travelled to London in 1673 to purchase instruments for equipping the observatory and improving the teaching and study of natural philosophy and mathematics in the university, seeking the advice of John Flamsteed, later the first Astronomer Royal. This paper considers the observatory initiative and the early acquisition of instruments at the University of St Andrews, with reference to Gregory's correspondence, inventories made ca. 1699-ca. 1718 and extant instruments themselves, some of which predate Gregory's time. It examines the structure and fate of the university observatory, the legacy of Gregory's teaching and endeavours, and the meridian line laid down in 1748 in the University Library.

Absolute and geometric parameters of the W UMa type contact binary V546 And

We present the results of our investigation on the geometrical and physical parameters of the W UMa-type binary V546 And from analyzed CCD (BVRI) light curves and radial velocity data. The photometric data were obtained in 2010 and 2011 at Ankara University Observatory (AUO) and the spectroscopic observations were made in 2010 at TUBITAK National Observatory (TUG). Light and radial velocity observations were analyzed simultaneously by using the Wilson–Devinney (2013 revision) code to obtain absolute and geometrical parameters. The system was determined to be a W-type W UMa system. Combining our photometric solution with the spectroscopic data we derived masses and radii of the eclipsing system to be M1=0.275M⊙,M2=1.083M⊙,R1=0.661R⊙ and R2=1.229R⊙. We finally discuss the evolutionary status of the system.

Computer-aided measurement of the heliographic coordinates of sunspot groups

Heliographic coordinates are used to identify the positions of solar features, especially the sunspot groups on the Sun’s surface. Tracking the positions of sunspot groups provides information about solar rotation and the movement behavior of sunspot groups over Solar Cycles. Two heliographic coordinates are defined: Carrington and Stonyhurst. The calculations used here depend on three solar parameters, position angle P, latitude angle B 0 and the starting longitude L 0. These values are calculated by using Astronomical Almanac for the observation time. In this study, a computer program called Computer Aided Measurement for Sunspots (CAMS) is presented. The main aim of the program is to determine the heliographic latitude and longitude of the sunspot groups besides other features like the latitudinal and longitudinal length, rectangular area and the tilt angle. This is accomplished by generating the corresponding Stonyhurst disk for the P and B 0 angles of the time of observation and superimposing it onto the scanned drawing. Since 2009, CAMS is being used to process daily solar drawings at the Istanbul University Observatory.

Retrieval of orbital parameters of the Galilean satellites using small telescopes

The orbital motion of Jupiterʼs Galilean satellites can be studied using the medium-sized telescopes commonly found in college or school observatories. In this paper we show how it is possible to deduce the parameters of their orbits around Jupiter using a small number of well-planed observations. This allows the instructor to propose a complete student activity that involves planning an observation, the observation itself, processing and analysing the images, and deduction of relevant magnitudes.

Massive Star Astrophysics with the new Magellanic Cloud photometric survey MCSF

AbstractSurveys of the resolved stellar content of entire galaxies are the natural tool to study fast evolutionary phases of massive stars. Therefore we launched the Magellanic Clouds Massive Stars and Feedback Survey (MCSF) and periodically imaged for 3 years the entire Small and Large Magellanic Cloud in u, B, V, R, I and Hα, [Oiii], [Sii] using the twin telescope RoBoTT at the University Observatory of the Ruhr-University Bochum at Cerro Armazones, Chile. Observations with short exposure times are included to ensure brightest stars not to be saturated, yielding a full coverage in luminosity. With this unique dataset we can study the massive stellar populations up to MB ∼ −10 mag and their feedback. Upon completion a high quality photometric and spatially complete catalog of the Magellanic Clouds will be established which is be comparable (or even beyond) the quality of HST based photometry of nearby galaxies.

The Mt John University Observatory search for Earth-mass planets in the habitable zone of α Centauri

AbstractThe ‘holy grail’ in planet hunting is the detection of an Earth-analogue: a planet with similar mass as the Earth and an orbit inside the habitable zone. If we can find such an Earth-analogue around one of the stars in the immediate solar neighbourhood, we could potentially even study it in such great detail to address the question of its potential habitability. Several groups have focused their planet detection efforts on the nearest stars. Our team is currently performing an intensive observing campaign on the α Centauri system using the High Efficiency and Resolution Canterbury University Large Échelle Spectrograph (Hercules)at the 1 m McLellan telescope at Mt John University Observatory in New Zealand. The goal of our project is to obtain such a large number of radial velocity (RV) measurements with sufficiently high temporal sampling to become sensitive to signals of Earth-mass planets in the habitable zones of the two stars in this binary system. Over the past few years, we have collected more than 45 000 spectra for both stars combined. These data are currently processed by an advanced version of our RV reduction pipeline, which eliminates the effect of spectral cross-contamination. Here we present simulations of the expected detection sensitivity to low-mass planets in the habitable zone by theHerculesprogramme for various noise levels. We also discuss our expected sensitivity to the purported Earth-mass planet in a 3.24-day orbit announced by Dumusqueet al.(2012).

Wide‐Field Plate Archive of the University Observatory Jena

AbstractWe present the archive of the wide‐field plate observations obtained at the University Observatory Jena, which is stored at the Astrophysical Institute of the Friedrich Schiller University Jena. The archive contains plates taken in the period February 1963 to December 1982 with the 60/90/180‐cm Schmidt telescope of the university observatory. A computer‐readable version of the plate metadata catalogue (for 1257 plates), the logbooks, as well as the digitized Schmidt plates in low and high resolution are now accessible to the astronomical community.This paper describes the properties of the archive, as well as the processing procedure of all plates in detail. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

FLECHAS – A new échelle spectrograph at the University Observatory Jena

AbstractThe new échelle spectrograph FLECHAS (Fibre Linked ECHelle Astronomical Spectrograph) is in operation at the Nasmyth‐focus of the 0.9 m telescope of the University Observatory Jena. FLECHAS is equipped with a sensitive back‐illuminated and midband coated CCD‐detector, as well as with a calibration unit for flatfield and wavelength‐calibration. The spectrograph covers the spectral range between about 3900 and 8100 Å and exhibits a resolving power of R ∼ 9300. In this article all technical characteristics of FLECHAS are described and examples of the first astronomical observations obtained with the new instrument in July 2013 at the University Observatory Jena are presented, among them the first light spectra taken with FLECHAS, simultaneous imaging and spectroscopic observations, the determination of the detection limit of the instrument, the spectroscopy of stars of different spectral types and of faint extended objects, as well as the Li‐line detection in the spectra of young solar‐like stars. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Puoko-nui: a flexible high-speed photometric system

We describe a portable CCD-based instrumentation system designed to efficiently undertake high time precision fast photometry. The key components of the system are (1) an externally triggered commercial frame-transfer CCD, (2) a custom GPS-derived time source, and (3) flexible software for both instrument control and online analysis/display. Two working instruments that implement this design are described. The New Zealand based instrument employs a Princeton Instruments (PI) 1k x 1k CCD and has been used with the 1 m telescope at Mt John University Observatory, while the other uses a newer 1k x 1k electron-multiplying CCD supplied by PI and is based at the University of Texas at Austin. We include some recent observations that illustrate the capabilities of the instruments.

An international campaign of the 19th century to determine the solar parallax

In 1847 Christian Ludwig Gerling, Marburg (Germany), suggested the solar parallax to be determined by measuring the position of Venus close to its inferior conjunction, especially at the stationary points, from observatories on nearly the same meridian but widely differing in latitude. James M. Gilliss,astronomer at the newly founded U.S. Naval Observatory, enthusiastically adopted this idea and procured a grant for the young astronomical community of the United States for an expedition to Chile. There they were to observe several conjunctions of Venus and oppositions of Mars, while the accompanying measurements were to be taken at the US Naval Observatory in Washington D.C. and the Harvard College Observatory at Cambridge, USA. This expedition was supported by A. v. Humboldt, C.F. Gau{\ss}, J.F. Encke, S.C. Walker, A.D. Bache, B. Peirce and others. From 1849 to 1852 not only were astronomical, but also meteorological and magnetic observations and measurements recorded, mainly in Santa Lucia close to Santiago, Chile. By comparing these measurements with those taken simultaneously at other observatories around the world the solar parallax could be calculated, although incomplete data from the corresponding northern observatories threatened the project's success. In retrospect this expedition can be recognized as the foundation of the Chilean astronomy. The first director of the new National Astronomical Observatory of Chile was Dr. C.W. Moesta, a Hessian student of Christian Ludwig Gerling's. The exchange of data between German, American and other astronomers during this expedition was well mediated by J.G. Fl\"ugel, consul of the United States of America and representative of the Smithsonian Institution in Europe, who altogether played a major role in nurturing the relationship between the growing scientific community in the U.S. and the well established one in Europe at that time.

Development of an AutoFlat program for the acquisition of effective flat images in the automated observation system

The purpose of this study is to develop an observation program for obtaining effective flat images that are necessary for photometric observation. The development of the program was achieved by improving the existing method for obtaining twilight flat images. The existing method for obtaining twilight flat images acquires flat images by observing the sky light after sunset or light before sunrise. The decision of when to observe flat images at each night is solely dependent on the judgment of an observer, and thus the obtained flat images for particular nights may not be clean. Especially, in the case of the observatories where an automated observation system is in operation, there is a difficulty that an observer should pay attention during sunrise and sunset in order to obtain flat images. In this study, a computer program is developed to improve this inconvenience and to efficiently perform photometric observation in the observatories where an automated observation system is applied. This program can obtain flat images by calculating the time for obtaining flat images automatically and the exposure time using a numerically calculated function. When obtaining twilight flat images at dusk and at dawn, the developed program performs automated observation and provides effective flat images by acquiring appropriate exposure time considering the sunrise and sunset times that vary depending on the day of observation. The code for performing this task was added to Obs Tool II (Yoon et al. 2006), which is the automated observation system of the Chungbuk National University Observatory, and the usefulness of the developed program was examined by performing an actual automated observation. If this program is applied to other observatories where automated observation is in operation, it is expected that stable and high-quality flat images could be obtained, which can be used for the pre-processing of photometric observation data.

The historical 1900 and 1913 outbursts of the binary blazar candidate OJ287

We report on historical optical outbursts in the OJ287 system in 1900 and 1913, detected on archival astronomical plates of the Harvard College Observatory. The 1900 outburst is reported for the first time. The first recorded outburst of the periodically active quasar OJ287 described before was observed in 1913. Up to now the information on this event was based on three points from plate archives. We used the Harvard plate collection, and added another seven observations to the light curve. The light curve is now well covered and allows one to determine the beginning of the outburst quite accurately. The outburst was longer and more energetic than the standard 1983 outburst. Should the system be strictly periodic, the period determined from these two outbursts would be 11.665 yr. However, this does not match the 1900 outburst or other prominent outbursts in the record. On the other hand, the precessing binary black hole model of Lehto and Valtonen (1996) can explain these and other known outbursts in OJ287. Finally, we discuss the upper limits for the expected 1906 outburst and the 1910 outburst, which was observed.

University Students and Technologies

This paper presents and discusses data on the use of technology in general and of Web 2.0 platforms and services in particular by students at the University of Milano-Bicocca. The data was obtained from a survey on media consumption habits and usage of new web technologies conducted by the university's Observatory on New Media, NuMediaBiOs. Research of this kind provides a valuable basis for the development, adaptation and improvement of existing services and offerings involving new technologies in educational contexts, given that for new technologies to be successfully integrated it is critical to have access to detailed information about how they are currently deployed by users (in this case, undergraduate students on basic degree programmes). Such analyses have implications for a range of contexts, not least for the public educational institution in which they are carried out, namely the university.

Night sky photometry and spectroscopy performed at the Vienna University Observatory

We present night sky brightness measurements performed at the Vienna University Observatory and at the Leopold-Figl-Observatorium für Astrophysik, which is located about 35km to the southwest of Vienna. The measurements have been performed with Sky Quality Meters made by Unihedron. They cover a time span of roughly one year and have been carried out every night, yielding a luminance value every 7s and thus delivering a large amount of data. In this paper, the level of skyglow in Vienna, which ranges from 15 to 19.25magSQMarcsec−2 is presented for the very first time in a systematic way. We discuss the influence of different environmental conditions on the night sky brightness and implications for human vision. We show that the circalunar rhythm of night sky brightness is almost extinguished at our observatory due to light pollution.Additionally, we present spectra of the night sky in Vienna, taken with a 0.8m telescope. The goal of these spectroscopic measurements was to identify the main types of light sources and the spectral lines which cause the skyglow in Vienna. It turned out that fluorescent lamps are responsible for the strongest lines of the night sky above Vienna (e.g. lines at 546nm and at 611nm).

δ Scuti-type pulsation in the hot component of the Algol-type binary system BG Peg

AbstractIn this study, 23 Algol-type binary systems, which were selected as candidate binaries with pulsating components, were observed at the Çanakkale Onsekiz Mart University Observatory. One of these systems was BG Peg. Its hotter component shows δ Scuti-type light variations. Physical parameters of BG Peg were derived from modelling the V light curve using the Wilson-Devinney code. The frequency analysis shows that the pulsational component of the BG Peg system pulsates in two modes with periods of 0.039 and 0.047 d. Mode identification indicates that both modes are most likely non-radial l = 2 modes.