Astronomical Plates Research Articles

Development and application of high-precision multifunction astronomical plate digitizers in China

Development and application of high-precision multifunction astronomical plate digitizers in China

Data processing pipeline for multiple-exposure photo-plate digital archives

Abstract Photo-plates are an invaluable historical legacy that have been used for over a hundred years to capture images of celestial objects. By digitizing these photo-plates and processing the images with digital image processing methods, scientists can study celestial objects that exhibit temporal variations. Multiple-exposure photo-plates are a unique type of observation data that can capture images of the same sky at different observation times in a single photo-plate. Such photo-plates can be used to discover flares or moving targets with rapid variations, but they are difficult to process automatically due to their complex observation strategies. This paper proposes a pipeline based on classical data-processing algorithms and machine-learning algorithms to detect flares or moving targets in multiple-exposure photo-plate images automatically. The pipeline was used to process several digitized multiple-exposure photo-plate images from the China Astronomical Plates Data, and preliminary results indicate that the pipeline is effective. In the future, we plan to use our method to discover more celestial objects with temporal variations from photo-plate digital archives.

New reduction of old glass astronomical plates of Pallas and Vesta in 1956–1994 based on Gaia DR3 catalogue

New reduction of old glass astronomical plates of Pallas and Vesta in 1956–1994 based on Gaia DR3 catalogue

Hen 3-860: new southern eclipsing symbiotic star observed in the outburst

ABSTRACT Brightening of Hen 3-860, previously classified as an Hα emitter, was detected by the All-Sky Automated Survey for Supernovae (ASAS-SN) survey at the end of the year 2016. We have obtained the first spectroscopic observations of the transient and supplemented them with photometric data from the Digital Access to a Sky Century at Harvard (DASCH) archive of astronomical plates, All-Sky Automated Survey (ASAS), and ASAS-SN surveys. Based on the results of our analysis, we can classify the object as a classical symbiotic star of the infrared type S, consisting of an M2-3 giant with a temperature of Tg ∼ 3550 K, a radius of Rg ∼ 60–75 R⊙, and a luminosity of Lg ∼ 540–760 L⊙, and a hot and luminous component (Th ∼ 1 × 105–2 × 105 K and $L_{\rm h}\, \sim 10^3\, L_\odot$). The system experienced at least four outbursts in the last 120 years. In addition to the outbursts, its light curves revealed the presence of eclipses of the hot component and its surrounding (relatively cool) shell, which developed during the outburst and redistributed a fraction of the radiation of the hot component into the optical, by the giant, classifying the object as a representative of a group of eclipsing symbiotic stars. The eclipses allowed us to reveal the orbital period of the system to be 602 d.

Armenian Astronomical Heritage and Big Data

AbstractAstronomy in Armenia was popular since ancient times and Armenia is rich in its astronomical heritage, such as ancient and medieval Armenian calendars, records of astronomical events by ancient Armenians, the astronomical heritage of the Armenian medieval great thinker Anania Shirakatsi, etc. Armenian astronomical archives have accumulated vast number of photographic plates, films and other careers of observational data. The Digitized Markarian Survey or the First Byurakan Survey, is the most important low-dispersion spectroscopic database. It is one of the rare science items included in UNESCO “Memory of the World” Documentary Heritage list. The Byurakan Astrophysical Observatory (BAO) Plate Archive Project (2015–2021) will result in digitization and storage of some 37,000 astronomical plates and films and in creation of an Electronic Database for further research projects. Based on these data and archives and development of their interoperability, the Armenian Virtual Observatory was created and joined the International Virtual Observatory Alliance.

THE ASTROMETRIC AND PHOTOMETRIC RESULTS OF DIGITIZED PLATES ON EPSON EXPRESSION 10000XL SCANNER WITH DIFFERENT RESOLUTIONS

This work was done to assess the accuracy of the plate processing method and to study in detail the Epson Expression 10000XL scanner, which is used to digitize the FON-Kitab astronomical plates from the photographic archive collection of the Ulugh Beg Astronomical Institute (UBAI) of the Uzbekistan Academy of Sciences. The glass archive of the UBAI has about 15 thousand photographic plates with images of various space objects. To process the plates the specially developed software in the LINUX/MIDAS/ROMAFOT was used. From comparing the results of processing digitized files with grayscale 8 and 16 bits, an assessment of the accuracy of the developed method for determining rectangular coordinates and photometry was made. The Epson Expression 10000XL flatbed scanner together with developed software can be used to digitize and process the astronegatives and obtain characteristics of objects (high, medium and moderate brightness) with an internal accuracy better than 0.05ʺ and 0.015 m for equatorial coordinates and B-magnitudes, respectively. To assess the repeatability of astrometric and photometric errors of the scanner, six consecutive scans of one plate with 600, 900, 1200, 1500, 1800, 2100, 2400 and 2540 dpi spatial separations were processed. The average accuracies of measurements were σ αδ =0.07ʺ for the equatorial coordinates and σ m =0.13 m for B-magnitudes. The results of the xperiments showed that a scan mode with a spatial resolution of 1200 dpi is the best option for plate digitization. Higher resolution scanning modes require a significant increase of digitizing and processing times of a plate, but they do not affect on an accuracy of the obtained results.

Astronomical photographic data archives: Recent status

AbstractI briefly present and discuss the recent status (with emphasis on digitization and data access) of astronomical photographic data archives worldwide, both photometric and spectroscopic, including various digitization techniques, automated data evaluation pipelines, astrophysical use, and public access. Although there are two major astronomical plate digitization projects (Harvard DASCH USA and APPLAUSE representing German Bamberg, Potsdam and Hamburg plate collections), the majority of astronomical photographic data archives are still awaiting digitization. Numerous plate archives have been visited, and in many of them, the glass plates are affected by various degradation types such as gold decease, sometimes progressing so fast that digitization is of great importance, taking into account the enormous scientific value of these databases.

Searching for (data on) Cracow astroplates

We briefly describe the issues and problems related to gathering our astronomical plates in one place – and preserving them. For a variety of reasons, they have not been properly preserved or stored in the past, which led to significant damages and losses. The general condition of the plates is discussed here, together with our most recent findings and future plans to use them for science.

Astrophysics with digitized astronomical plate archives

We discuss the recent status of astrophysical analyses with digitized astronomical plate archives with emphasis on high‐energy and transient astrophysics. These data represent huge scientific, historical, and cultural value, but only the recent digitization has enabled their effective use in astrophysics.

Progress of the Chinese Plate-Digitizing Project

AbstractAbout 30,000 astronomical photographic plates were digitised between 2012–2017 with a special digitising machine that has high precision in both astrometry and photometry. All the images from the plates, together with plate information and measured coordinates of all the objects on the plates, have been stored in the Chinese Virtual Observatory.

Photographic observations of comet Hale–Bopp at the Zvenigorod Observatory

We describe the archive of scans of the astronomical plates obtained in the observations of comet Hale–Bopp. The observations were carried out from August 17, 1996, to April 29, 1997, at the Zeiss-400/2000 astrograph of the Zvenigorod Observatory of the Institute of Astronomy of the Russian Academy of Sciences (INASAN). The archive contains the images that can be used in astrometric, photometric, and astrophysical studies. In some of the plates, the size of the comet reaches 6.3° (23 cm). In many scans, the details of the cometary tail, including individual jets, vortexes, etc., are clearly distinguishable. The archive of the images is available free.

Digitizer of astronomical plates at Shanghai Astronomical Observatory and its performance test

Before CCD detectors were widely employed in observational astronomy, the main method of detection was the use of glass astrophotographic plates. Astronomical plates have been used to record information on the position and activity of celestial bodies for more than 100 years. There are about 30 000 astronomical plates in China, and the digitization of astronomical plates is of great significance for permanent preservation and to make full use of these valuable observation data. A digitizer with high precision and high measuring speed is a key piece of equipment for carrying out the task of digitizing these astronomical plates. A digitizer for glass astrophotographic plates was developed jointly by Shanghai Astronomical Observatory and Nishimura Co., Ltd of Japan. The digitizer’s hardware was manufactured by Nishimura Co., Ltd, and the performance test, error corrections as well as image processing of the digitizer were carried out by Shanghai Astronomical Observatory. The main structure and working mode of the digitizer are introduced in this paper. A performance test shows that brightness uniformity of illumination within the measuring area is better than 0.15%, the repeatability of digitized positions is better than 0.2 µm and the repeatability of digitized brightness is better than 0.01 instrumental magnitude. The systematic factors affecting digitized positions, such as lens distortion, the actual optical resolution, non-linearity of guide rails, non-uniformity of linear motors in the mobile platform, deviation of the image mosaic, and non-orthogonality between the direction of scanning and camera linear array, are calibrated and evaluated. Based on an astronomical plate with a size of 300mm × 300mm, which was digitized at different angles, the conversion residuals of positions of common stars on different images were investigated. The results show that the standard deviations of the residuals are better than 0.9 µm and the residual distribution is almost random, which demonstrates the digitizer has a higher precision for digitization.

Digitization and reduction of old astronomical plates of natural satellites

Old astrophotographic plates are precious sources of historical data for astronomical studies, especially regarding the improvement of natural satellite orbits. Today, with the advent of new, accurate techniques, these old data can be re-processed so as to give positions that are much more accurate than those initially obtained. Various recent projects, including our Chinese project, have involved measuring and reducing these old plates again. Here we present a method for measurement and reduction that involves the digitization of plates using an advanced commercial scanner, namely the EPSON 10000 XL. We selected a set of 27 plates of the satellites of Jupiter, Saturn and Uranus taken from 1987 to 1990. A total of 125 satellite positions were derived from the new measurement and reduction of these plates using the UCAC4 catalogue. A comparison of the new observed positions with recent ephemerides has shown a general consistency with satellite theory of about 100 mas. The new positions present an accuracy equivalent to the most recent CCD observations, and better than the original positions. Moreover, nearly 30 per cent of the 125 positions obtained in this work are published for the first time here. This paper is a preliminary contribution to the larger project of new measurements and reductions of all the old Chinese plates of natural satellites, which should allow further improvements in the knowledge of the orbits of these satellites.

US Astronomical Photographic Data Archives: Hidden Treasures and Importance for High-Energy Astrophysics

We report here on an ongoing investigation of US astronomical plate archives and tests of the suitability of transportable scanning devices for in situ digitization of archival astronomical plates, with emphasis on application in high-energy astrophysics.

New variable stars on digitized plates of the Moscow collection. Field SA9

The new stage of work on digitizing the astronomical plates of the Sternberg Astronomical Institute’s collection and searching for new variable stars using the digitized photographic plates includes a considerable improvement of the automated search techniques for objects with variable brightnesses. In particular, the technique for taking into account the non-linear response of the photographic light detector has been improved. Applying the improved techniques to 182 digitized images of a 10° × 10° field centered at SA9, obtained from scanning photographic plates taken with the Sternberg Astronomical Institute 40-cm astrograph, has enabled the discover and study of 77 new variable stars (MDV 519–595). These include 3 Cepheids, 2 probable BY Draconis stars, 65 eclipsing binaries, 3RR Lyrae stars, 1 high-amplitude δ Scuti star (HADS), and 3 irregular variables. Special CCD observations have confirmed the presence of brightness variations in 7 of the 77 variables that were initially considered uncertain.

ASTRONOMICAL PLATE ARCHIVES AND SUPERMASSIVE BLACK HOLE BINARIES

The recent extensive digitisation of astronomical photographic plate archives, the development of new dedicated software and the use of powerful computers have for the first time enabled effective data mining in extensive plate databases, with wide applications in various fields of recent astrophysics. As an example, analyses of supermassive binary black holes (binary blazars) require very long time intervals (50 years and more), which cannot be provided by other data sources. Examples of data obtained from data mining in plate archives are presented and briefly discussed.

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.

Finding Hidden Treasures: Investigations in US Astronomical Plate Archives

We report here on an ongoing investigation of US astronomical plate archives and tests of the suitability of transportable scanning devices for in situ digitization of archival astronomical plates.

UkrVO Joint Digitized Archive and Scientific Prospects

Abstract The UkrVO (Ukrainian Virtual Observatory) database consists of about 200 000 astronomical photographic plates and 500 000 CCD frames containing unique astronomical information for formulating important scientific tasks. This database is compiled from observations conducted in 1898-2011 at the observing sites of 8 Ukrainian observatories, with about 60 instruments. This paper deals with some principal scientific projects where the UkrVO databases are used, namely, the creation of the Joint Digitized Archive (JDA); compilation of new stellar catalogues; search for optical counterparts of gamma-ray bursts; spectroscopic study of solar flares and solar active formations; development of software for searches for new small bodies of the solar system.

The Wide-Field Plate Database: Development and Access via Internet

The motivations and results from the first 1.5-year period of the project “Wide-field Plate Database (WFPDB): Development and Access via Internet” (DO-02-273/18.12.2008), approved for funding through a competition held by the Bulgarian National Science Fund in the field of Promotion of Research in Priority Areas, are described. The main direction of the development of the project is digitization and preservation of, and web access to, the astronomical plate archives of the 2-m RCC and the 50/70 cm Schmidt telescopes of the Rozhen National Astronomical Observatory received in the period 1979–1998. The basis of the work is set out in Tsvetkov (2006) [1] and Tsvetkova & Tsvetkov (2006) [2], motivating the project over the past 10 years. The WFPDB (www.wfpdb.org) represents a unique virtual instrument in astronomical research, which allows obtaining information on existing astronomical observations of celestial objects over the past 130 years with the professional astronomical telescopes at observatories around the world. Briefly, this is a unique virtual telescope working as a “Time Machine” for obtaining information on historical observations of minor planets, comets, stars and galaxies. The project also aims to continue and expand the successful work initiated during the past 15 years by extending the provision of technical work on the base, and improving and extending the internal LAN (www.skyarchive.org), which ensures rapid online access to data, based on international standards of the International Virtual Observatory Alliance (IVOA) and the European Virtual Observatory (EURO-VO). The main results of this paper are described in detail in the annual report project of July 15, 2010: http://trillian.magrathea.bg:8181/DATABASE FNI 273 2010July/