Small observatories for the UV

We describe concepts for small space telescopes that are able to provide significant UV science and can be realized with small (but realistic) budgets. The concepts are based on nano-satellites carrying small optics, with no redundancy, without producing intermediate models prior to flight model, and using COTS (custom off-the-shelf) components. We describe a few concepts of deployable optics that could provide large collecting areas and high angular resolution while packaged in the small volume of a nano-satellite. We point out areas where technological development is still required.     

System aspects of the EUDOXOS observatories network

The networking architecture of the EUDOXOS' robotic telescopes is presented. We have studied adopted and tested various software & hardware approaches for developing an observational facility equipped with the very high availability needed to achieve continuous operation, inherent capacity for effective multiuser support, fully robotic unattended operation, fast response to targets of opportunity and accommodation of tele‐operating instruments. Critical practical aspects and considerations of our operating implementation as well as the main points of an ongoing upgrade initiative expected to be of general interest, are discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Intercalibration of airglow observatories with the atmosphere explorer satellite

The visible airglow photometer on the Atmosphere Explorer C Satellite has been used to compare the calibrations of a number of ground-based airglow observatories. Discrepancies between different ground stations as large as a factor of six have been revealed. Efforts to account for these discrepancies have resulted in the discovery of differences as large as a factor of 2 in the standard light sources in use at different observatories. The participation of additional observatories in the intercomparison of standard sources is solicited. The project has also led to the discovery of a source of error that can amount to another factor of 2 in the procedure used to calibrate many airglow instruments. In the course of the project detailed maps, based on satellite data, have been made of the galactic and zodiacal light background at a number of wavelengths, and a substantial source of contaminating emission has been discovered in the satellite data; the contamination appears to result from interaction of the spacecraft and the atmosphere at altitudes below 170 km.     

Machine Learning for Improving Stellar Image-based Alignment in Wide-field Telescopes

Stellar images will deteriorate dramatically when the sensitive elements of wide-field survey telescopes are misaligned during an observation,and active alignme...     

Wide-field imaging and polarimetry for the biggest and brightest in the 20-GHz southern sky

We present the wide-field imaging and polarimetry at  ν= 20 GHz  of seven most extended, bright  ( S _total≥ 0.50 Jy)  , high-frequency selected radio sources in the southern sky with declinations  δ < −30°  . Accompanying the data are brief reviews of the literature for each source. The results presented here aid in the statistical completeness of the Australia Telescope 20-GHz Survey: the Bright Source Sample. The data are of crucial interest for future cosmic microwave background missions as a collection of information about candidate calibrator sources. We were able to obtain data for seven of the nine sources identified by our selection criteria. We report that Pictor A is thus far the best extragalactic calibrator candidate for the Low Frequency Instrument of the Planck European Space Agency mission due to its high level of integrated polarized flux density  (∼0.50 ± 0.06 Jy)  on a scale of 10 arcmin. Six out of the seven sources have a clearly detected compact radio core in our images, with either a null detection or less than 2 per cent detection of polarized emission from the nuclei. Most sources with detected jets have magnetic field alignments running in a longitudinal configuration, however, PKS 1333−33 exhibits transverse fields and an orthogonal change in field geometry from nucleus to jets.     

Ground-layer Adaptive Optics for the 2.5 m Wide-field and High-resolution Solar Telescope

The 2.5 m wide-field and high-resolution solar telescope(WeHoST) is currently under developing for solar observations. WeHoST aims to achieve high-resolution observations over a super-wide field of view(FOV) of5′ × 5′, and a desired resolution of 0.3″. To meet the scientific requirements of WeHoST, the ground-layer adaptive optics(GLAO) with a specially designed wave front sensing system is as the primary consideration. We introduce the GLAO configuration, particularly the wave front sensing sch...     

Kamenetsk—A new impact structure in the Ukrainian Shield

The Kamenetsk impact structure is a deeply eroded simple crater that formed in crystalline rocks of the Ukrainian Shield. This study presents structural, lithologic, and shock metamorphic evidence for an impact origin of the Kamenetsk structure, which was previously described as a paleovolcano. The Kamenetsk structure is an oval depression that is 1.0–1.2 km in diameter and 130 m deep. The structure is deeply eroded, and only the lower part of the sequence of lithic breccia has been preserved in the deepest part of the crater to recent time, while the predominant part of impact rocks and postimpact sediments was eroded. Manifestations of shock metamorphism of minerals, especially planar deformation features in quartz and feldspars, were determined by petrographic investigations of lithic breccia that allowed us to determine the impact origin of the Kamenetsk structure. The erosion of the crater and surrounding target to a minimal depth of 220 m preceded the deposition of the postimpact sediments. The time of the formation of the Kamenetsk structure is bracketed within a wide interval from 2.0 to 2.1 Ga, the age of the crystalline target rocks, to the Late Miocene age of the sediments overlaying the crater. The deep erosion of the structure suggests it is probably Paleozoic in age.     

Observations of the X-ray burster MX 0836-42 by the INTEGRAL and RXTE orbiting observatories

We present the results of our study of the emission from the transient burster MX 0836-42 using its observations by the INTEGRAL and RXTE X-ray and gamma-ray observatories in the period 2003–2004. The source’s broadband X-ray spectrum in the energy range 3–120 keV has been obtained and investigated for the first time. We have detected 39 X-ray bursts from this source. Their analysis shows that the maximum 3–20-keV flux varies significantly from burst to burst, F ～ (0.5–1.5) × 10^?8 erg cm^?2 s^?1. Using the flux at the maximum of the brightest detected burst, we determined an upper limit for the distance to the source, D ? 8 kpc.     

Observations of the transient X-ray pulsar KS 1947+300 by the INTEGRAL and RXTE observatories

We analyze the observations of the X-ray pulsar KS 1947+300 performed by the INTEGRAL and RXTE observatories over a wide (3–100 keV) X-ray energy range. The shape of the pulse profile was found to depend on the luminosity of the source. Based on the model of a magnetized neutron star, we study the characteristics of the pulsar using the change in its spin-up rate. We estimated the magnetic field strength of the pulsar and the distance to the binary.     

Total current of the auroral electrojet estimated from the IMS Alaska meridian chain of magnetic observatories

Based on magnetic data from the IMS Alaska meridian chain of observatories, the total current of the westward auroral electrojet flowing across the meridian is estimated by using two independent methods. The first one is a simple integration of the north-south component of magnetic perturbations along the meridian, providing the quantity F in units of nT·km. The other is to use the forward method, providing the total current I in units of A. It is shown that F and I have nearly identical time variations. Thus, by normalizing the two quantities and taking the numerical value of F in units of nT·km, it is possible to estimate the total electrojet current flowing across a magnetic meridian, with an accuracy of 90%, by using the latitudinal profile of the H component, namely I (A) = 2.0 F (nT·km).     

Influence of the geomagnetic field on the IACT detection technique for possible sites of CTA observatories

We investigate the influence of the geomagnetic field (GF) on the Imaging Air Cherenkov Telescope technique for two northern (Tenerife and San Pedro Martir) and three southern (Salta, Leoncito and Namibia (the H.E.S.S.-site)) site candidates for Cherenkov Telescope Array (CTA) observatories. We use the CORSIKA and sim_telarray programs for Monte Carlo simulations of gamma ray showers, hadronic background and the telescope response. We focus here on gamma ray measurements in the low energy, sub-100 GeV, range. Therefore, we only consider the performance of arrays of several large telescopes. Neglecting the GF effect, we find (in agreement with previous studies) that such arrays have lower energy thresholds, and larger collection areas below 30 GeV, when located at higher altitudes. We point out, however, that in the considered ranges of altitudes and magnetic field intensities, 1800–3600 m a.s.l. and 0–40 μT, respectively, the GF effect has a similar magnitude to this altitude effect. We provide the trigger-level performance parameters of the observatory affected by the GF effect, in particular the collection areas, detection rates and the energy thresholds for all five locations, which information may be useful in the selection of sites for CTA. We also find simple scaling of these parameters with the magnetic field strength, which can be used to assess the magnitude of the GF effect for other sites; in this work we use them to estimate the performance parameters for five sites: South Africa-Beaufort West, USA-Yavapai Ranch, Namibia-Calapanzi, Chile-La Silla and India-Hanle. We roughly investigate the impact of the geophysical conditions on gamma/hadron separation procedures involving image shape and direction cuts. We note that the change of altitude has an opposite effect at the trigger and analysis levels, i.e. gains in triggering efficiency at higher altitudes are partially balanced by losses in the separation efficiency. In turn, a stronger GF spoils both the shape and the direction discrimination of gamma rays, thus its effects at the trigger and analysis levels add up resulting in a significant reduction of the observatory performance. Overall, our results indicate that the local GF strength at a site can be equally important as its altitude for the low-energy performance of CTA.     

Solar physics at the Main Astronomical Observatory of the Ukrainian Academy of Sciences

A brief review of the research highlights at the Main Astronomical Observatory since 1968.