Hamburg Observatory Research Articles

Early experiences on the OLCF Frontier system with AthenaPK and Parthenon‐Hydro

SummaryThe Oak Ridge Leadership Computing Facility (OLCF) has been preparing the nation's first exascale system, Frontier, for production and end users. Frontier is based on HPE Cray's new EX architecture and Slingshot interconnect and features 74 cabinets of optimized 3rd Gen AMD EPYC CPUs for HPC and AI and AMD Instinct 250X accelerators. As a part of this preparation, “real‐world” user codes have been selected to help assess the functionality, performance, and usability of the system. This article describes early experiences using the system in collaboration with the Hamburg Observatory for two selected codes, which have since been adopted in the OLCF test harness. Experiences discussed include efforts to resolve performance variability and per‐cycle slowdowns. Results are shown for a performance portable astrophysical magnetohydronamics code, AthenaPK, and a mini‐application stressing the core functionality of a performance portable block‐structured adaptive mesh refinement framework, Parthenon‐Hydro. These results show good scaling characteristics to the full system. At the largest scale, the Parthenon‐Hydro miniapp reaches a total of zone‐cycles/s on 9216 nodes (73,728 logical GPUs) at 92% weak scaling parallel efficiency (starting from a single node using a second‐order, finite‐volume method).

The study on transiting systems HAT-P-13, HAT-P-16, and WASP-32 through combining ground-based and TESS photometry

ABSTRACT High-precision transit photometry supplies ideal opportunities for detecting new exoplanets and characterizing their physical properties, which usually encode valuable information for unveiling the planetary structure, atmosphere, and dynamical history. We present revised properties of three transiting systems (i.e. HAT-P-13, HAT-P-16, and WASP-32) through analyzing TESS photometry and ground-based transit observations, which were obtained at the 1-m and 2.4-m telescopes of Yunnan Observatories, China, and the 1.2-m telescope of Hamburg Observatory, Germany, as well as the data in the literature. During modelling the transit light curves, Gaussian process is employed to account for the potential systematic errors. Through comprehensive timing analysis, we find that both HAT-P-13b and HAT-P-16b show significant timing variations (TTVs) that can be explained by apsidal precession. TTVs of WASP-32b may be led by a decaying orbit due to tidal dissipation or apsidal precession. However, the current observations can not rule out the origins of three systems’ TTVs from gravitational perturbations of close planetary companions conclusively.

Repsold Company as a Global Player: From the First Meridian Circle in 1802 to the Modern Computerized in 1967

The first modern meridian circle after Rømer’s Rota Meridiana (1704) was constructed by Johann Georg Repsold (1770-1830) in 1802, used in the first Hamburg observatory, restored for Göttingen, 1818. A new meridian circle, made by A. & G. Repsold for the Hamburg-Millerntor Observatory (1825), was installed in 1836. The large 19-cm-meridian circle for the new Hamburg Observatory in Bergedorf, was made by Adolf Repsold & Sons (1909) with impersonal micrometers, levels, mires. In 1967 the Hamburg meridian circle was equipped with photoelectric reading and computerized, and used in Perth, Australia, for a catalogue of stars of the southern hemisphere (until 1987). The topic is discussed in the context of Repsold meridian circles all over the world — the Repsold company as a global player.

GIER: A Danish computer from 1961 with a role in the modern revolution of astronomy - II

AbstractA Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the measurement of stellar positions by means of a meridian circle, at that time the fundamental instrument of astrometry. An expedition to Perth in Western Australia with the instrument and the computer was a success. This method was also implemented in space in the first ever astrometric satellite Hipparcos launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized astrometry with an impact in all branches of astronomy from the solar system and stellar structure to cosmic distances and the dynamics of the Milky Way. In turn, the results paved the way for a successor, the one million times more powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a Gaia successor in twenty years are making progress.

Learning by Doing: Science Education at the Hamburg Observatory

In my contribution I would like to offer three different examples: the activities of the association “Forderverein Hamburger Sternwarte”, science education in the “astronomy workshop”, and the teaching of the history of science and technology for university students.

Bernhard Schmidt and the Schmidt Telescope for Mapping the Sky

Abstract Bernhard Voldemar Schmidt (1879-1935) was born in Estonia. He ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, working freelance in Hamburg Observatory, he developed a short focal length optical system with a large field of view. He succeeded in inventing the “Schmidt Telescope” in 1930, which allows the imaging a large field of the sky without any distortions. Shortly after Schmidt’s death, the director of the observatory published details on the invention and production of the Schmidt Telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope was built in 1948, the “Big Schmidt” (126 cm), Mount Palomar, USA. Schmidt telescopes are also important tools for cosmology. The result of the Palomar Observatory Sky Surveys (1949-1958, 1985-1999) is a data base of about 20 million galaxies and over 100 million stars, supplemented in 1971 by the ESO Schmidt for the southern sky. Also high resolution spectrometers can be fitted to the Schmidt telescope. The 80 cm Schmidt telescope of Hamburg Observatory, planned since 1936, finished 1955, is on Calar Alto, Spain, since 1975. Combined with two objective prisms, it was used for a Quasar survey project.

Multi-band transit observations of the TrES-2b exoplanet

We present a new data set of transit observations of the TrES-2b exoplanet taken in spring 2009, using the 1.2m Oskar-Luhning telescope (OLT) of Hamburg Observatory and the 2.2m telescope at Calar Alto Observatory using BUSCA (Bonn University Simultaneous CAmera). Both the new OLT data, taken with the same instrumental setup as our data taken in 2008, as well as the simultaneously recorded multicolor BUSCA data confirm the low inclination values reported previously, and in fact suggest that the TrES-2b exoplanet has already passed the first inclination threshold (i_min,1 = 83.417) and is not eclipsing the full stellar surface any longer. Using the multi-band BUSCA data we demonstrate that the multicolor light curves can be consistently fitted with a given set of limb darkening coefficients without the need to adjust these coefficients, and further, we can demonstrate that wavelength dependent stellar radius changes must be small as expected from theory. Our new observations provide further evidence for a change of the orbit inclination of the transiting extrasolar planet TrES-2b reported previously. We examine in detail possible causes for this inclination change and argue that the observed change should be interpreted as nodal regression. While the assumption of an oblate host star requires an unreasonably large second harmonic coefficient, the existence of a third body in the form of an additional planet would provide a very natural explanation for the observed secular orbit change. Given the lack of clearly observed short-term variations of transit timing and our observed secular nodal regression rate, we predict a period between approximately 50 and 100 days for a putative perturbing planet of Jovian mass. Such an object should be detectable with present-day radial velocity (RV) techniques.

The development of the Schmidt telescope

AbstractBernhard Schmidt (1879–1935) was born in Estonia. After a few years of studying engineering he ran an optical workshop in Mittweida, Saxonia, between 1901 and 1927. Astronomers appreciated the quality of his telescopes. Starting in 1925, on behalf of the Hamburg Observatory, he developed a short focal length optical system with a large field of view. For this purpose, Schmidt moved his workshop to the observatory. He succeeded in inventing the “Schmidt telescope” which allows the imaging of a large field of the sky without any distortions. Schmidt's first telescope (spherical mirror diameter 0.44 m, correction plate 0.36 m diameter, aperture ratio 1:1.75, and focal length 0.625 m) has been used since 1962 at the Boyden Observatory in Bloemfontein/South Africa. Apart from his 0.36m telescope, Schmidt produced a second larger one of 0.60m aperture. Shortly after Schmidt's death, the director of the observatory published details on the invention and production of the Schmidt telescope. After World War II, Schmidt telescopes have been widely used. The first large Schmidt telescope, the “Big Schmidt” (1.26 m), Mount Palomar, USA, was completed in 1948. The 0.80 m Schmidt telescope of Hamburg Observatory, planned since 1936, finished in 1954, is now on Calar Alto/Spain (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Cultural heritage of astronomical observatories

AbstractWe present the results of the ICOMOS international symposium “Cultural Heritage of Astronomical Observatories (around 1900) – From Classical Astronomy to Modern Astrophysics” (Oct. 2008). The objective of the symposium was to discuss the relevance of modern observatories to the cultural heritage of humankind and to select partner observatories which, due to the date of their construction or to their architectural or scientific importance are comparable to Hamburg Observatory, as international cooperation partners for a serial trans-national application.

Version 2000 of the Catalogue of Galactic Planetary Nebulae

The "Catalogue of Galactic Planetary Nebulae (Version 2000)" appears in Abhandlungen aus der Hamburger Sternwarte, Band XII in the year 2001. It is a continuation of CGPN(1967) and contains 1510 objects classified as galactic PNe up to the end of 1999. The lists of possible pre-PNe and possible post-PNe are also given. The catalogue is restricted only to the data belonging to the location and identification of the objects. It gives identification charts of PNe discovered since 1965 (published in the supplements to CGPN) and those charts of objects discovered earlier, which have wrong or uncertain identification. The question "what is a planetary nebula" is discussed and the typical values of PNe and of their central stars are summarized. Short statistics about the discoveries of PNe are given. The catalogue is also available in the Centre de Données, Strasbourg and at Hamburg Observatory via internet.

SIM Grid Star Observations: Astrometry with a New High Dynamic Range Imaging Device

AbstractFirst astrometric and photometric applications of the logarithmically scaled HDRC4 imager (developed by the Institut für Mikroelektronik Stuttgart, IMS, Germany) are presented. To test the HDRC4 imager at the telescope, a cooled camera had to be constructed by modifying a camera designed by IMS. First observations were performed with various telescopes at Hamburg Observatory, Germany. These showed the dynamic range to exceed 14 mag and the sensitivity to be comparable to that of the Kodak KAF 4200 CCD at a chip temperature of –35°C.

Catalogue of H-alpha emission stars in the Northern Milky Way

The "Catalogue of Stars in the Northern Milky Way Having H-alpha in Emission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XI in the year 1997. It contains 4174 stars, range having the Hα line in emission. HBH stars and stars of further 99 lists taken from the literature till the end of 1994 were included in the catalogue. We give the cross-identification of stars from all lists used. The catalogue is also available in the Centre de Données, Strasbourg and at the Hamburg Observatory via internet.

Brightness Calibration of Digitized Objective-Prism Plates

Currently, IIIa-J objective-prism plates from the Calar Alto and ESO Schmidt telescopes are used at the Hamburg Observatory to search for and to identify new astronomical objects. Major projects are the Hamburg Quasar Survey, the Hamburg-ESO Survey, and the Hamburg-Munich collaboration to identify sources from the ROSAT All-Sky Survey (cf. contributions to this conference by Hagen et al., Wisotzki, and Voges). The objective-prism plates are digitized with a PDS microphotometer. To determine the brightness of the digitized objects, a method to calibrate the plates was developed, using an internally determined characteristic curve and its external calibration with photometric sequences. Having spectral information, we are able to synthesize the Johnson B-filter as this filter is fully covered by the spectra.

The Second Cape Photographic Catalogue: CPC2

Between 1962 and 1972 the southern hemisphere has been covered by a 4-fold overlap pattern on 5820 plates, taken with a scale of 100 arcsec/mm and using a visual bandpass. More than 2 million pairs of x,y coordinates of the 2 exposures from 276259 stars have been measured at RGO with the GALAXY machine. The conventional plate adjustment, carried out at Hamburg Observatory, is now complete. About 150 000 primary stars will achieve a catalogue accuracy of about 0.06 arcsec at epoch of observation.The rigorous FK4 and FK5 versions, using the SRS catalogue (C. Smith 1988), will be supplemented by preliminary new proper motions for those stars common with the SAOC. Finally, a rigorous block adjustment will be performed within the next year.

Current Status Of The Second Cape Photographic Catalogue

Photography of the southern hemisphere for the Second Cape Photographic Catalogue (CPC2) was commenced in 1962 by R H Stoy, HM Astronomer at the Cape. During the following ten years nearly 6000 plates, each having two exposures and covering 4° × 4° with fourfold corner to centre overlap were obtained. All plates have been measured on the GALAXY measuring machine at the Royal Greenwich Observatory under the general direction of W Nicholson. A preliminary catalogue giving positions and magnitudes of more than 50 000 stars in the Cape Astrographic zone (−40° to −52°) has already been published (Nicholson et al. 1984), together with details of the programme. Measurement of the plates, initial identification of star images appearing on all overlapping plates, and photographic photometry have been carried out at RGO; the subseqent astrometric data reduction is being performed at Hamburg Observatory.

Optical Design with the Schmidt Concept: 1) Ground-Based Development: 2) The Space Schmidt Project for the 1990's ?

The basic principle of the camera described by Bernard Schmidt in 1932 is that a single concave mirror with a stop at its center of curvature has no unique axis and therefore yields equally good images at all points of its yield. The field is curved, and to correct the spherical aberration produced by the mirror, Schmidt introduced, in the stop at the center of curvature of the mirror, a thin non spherical corrector plate of glass. Around 1930 at the Hamburg Observatory and in spite of many difficulties, it was Schmidt's genius as an optician that succeeded - after several judiciously interpreted trials - in figuring a corrector plate by elastic relaxation, and thus demonstrated the optical performance of this new generation of instruments.

The current Hamburg Program of precise optical positions of radio sources in the FK4 System

In 1975 an observational program for the determination of precise positions of optical counterparts of extragalactic radio sources in the FK4 system has been started at the Hamburg Observatory. The sources have been selected from the recent radio lists by Elsmore and Ryle (1976), Wade and Johnston (1977) and Clark et al. (1976) to perform a comparison between the radio- and independent optical positions in the FK4 system. The results from a pilot program to be reported here partly, which includes 17 sources (de Vegt and Gehlich, 1978), encouraged us to extend the program to at present 34 extragalactic sources and 14 radio stars on the northern hemisphere; a list of these sources is given in the appendix.

Plan of sky coverage by using wide-angle astrographs

In this paper we present information on the Soviet project to photograph the sky (epoch 1980-1985) using wide-angle astrographs (Kolchinsky I.G., Onegina A.B., 1977). The feasibility of such modern surveys has been discussed earlier, especially by R.H.Stoy (1975). Detailed information on a similar program for the northern hemisphere to be made with the new zone astrograph of the Hamburg Observatory has been given by Chr.de Vegt (1974).

On the Project of a New Fourfold Coverage of the Northern Hemisphere

The fully inherent information of the AGK 2 plate material, covering the northern hemisphere down to δ= −2.5° with homogeneous epoch and limiting magnitude has not been used to establish the AGK2 catalogue. A new measurement will provide positions for all stars with at least mpg=2 in the FK4 system, yielding an estimated accuracy of σ = 0″.14.In March 1973 a newly developed zone astrograph for the yellow spectral-region has been set in operation at the Hamburg observatory which would be available about 1975 for a new fourfold coverage of the northern hemisphere. A technical description of the instrument is given. Details of the fourfold plate coverage and the observing program are discussed. As a suitable reference star system the AGK3R catalogue, updated with recently derived proper motions to that epoch, is adopted. A final positional accuracy σ = 0″.11 of the new catalogue is expected. The available epoch difference of 45 years up to that date will then provide proper motions in the FK 4 system with an estimated accuracy of at least 0″.005/a for all stars of the northern hemisphere down to mpg=2.

Irregularities in the Crab Pulsar Wobble

THIS article presents new measurements of the arrival times of optical pulses from the Crab pulsar, NP 0532. The observations were obtained at Hamburg Observatory (Bergedorf) with a 60 cm refractor and a data acquisition system with an on-line computer (PDP-8/S). Comparison of our results with those obtained by Boynton et al.1 and Richards et al.2 does not support the assumption of a periodic wobble with a period of 77 days (ref. 2).