Kyiv meridian axial circle with CCD camera

We describe the modifications made in the design of the Kyiv meridian axial circle (MAC) and in the observation technique after the instrument was equipped with a CCD camera with an array of 1040×1160 pixels. The observations are performed in the drift-scan mode (time-delay imaging) with an effective exposure time of 108 s for equatorial stars. The MAC photometric system reproduces the standard V system; the limiting magnitude is V = 17 ^m . The observations made with the modified MAC in 2001–2003 served as the basis for the KMAC1 catalog which contains positions, proper motions, and magnitudes B, V, R, r′, J for 100 000 stars in the sky areas with the ICRF objects. The errors of positions and V magnitudes in the catalog are 50–90 mas and 0.1 ^m , respectively, for stars with V = 15 ^m . Stars in the equatorial sky areas and radio stars are presently observed with the aim to determine their exact positions, proper motions, and magnitudes. The catalogs are available in the data base of the Centre de Données Astronomiques de Strasbourg (ftp.cdsarc.u-strasbg.fr) and on the site of the Main Astronomical Observatory (http://www.mao.kiev.ua).     

A study of the photometric system of the Kiev network telescope

We performed a series of CCD observations in BVRI bands of a celestial region in cluster M67 (NGC 2682) to study the photometric system of the Kyiv network telescope. The signal recording system consists of a CGE-1400 telescope, Celestron #94175 focal reducer, an automatic turret with a set of UBVRI filters, and a Rolera Mgi CCD camera. The operating field of the system is 10.62′ × 10.62′. CCD images are processed in the MIDAS/ROMAFOT package. The reduction coefficients of the instrumental photometric system relative to Johnson’s BVRI system are determined. The resulted value of the module of distance to cluster M67 V ? M _V = 9.63 ^m does not contradict the results of other researchers. The mean square errors for one determination of stellar magnitude for different bands are 0.02–0.12 ^m . The errors in determining equatorial coordinates in the TYCHO-2 catalog system are ± 1″.     

Photometric survey near the Main Galactic Meridian: 1. Photoelectric stellar magnitudes and colours in the UBVR system

A catalogue of photoelectric stellar magnitudes and colours in the UBVR Johnson system in 47 sky areas with galaxies near the Main Galactic Meridian is presented. The catalogue includes 1141 stars within the V magnitude interval 4^m.5–15^m.5. The rms errors are ±0.014, ±0.026, ±0.012, ±0.016 mag for stellar magnitudes V and colours (U – B),(B – V),(V – R), respectively. The catalogue contains accurate equatorial coordinates (α, δ)1950.0, too.     

Astrometric catalogue of stars in the KMAC3 equatorial zone

The catalogue of positions and stellar V magnitudes of up to 17 ^m stars in the declination zone from 2° to 5.5° has been compiled. The catalogue includes 2.05 × 10⁶ stars and is based on the observations performed in 2010–2015 on the meridian axial circle (MAC) of GAO NAN Ukraine and the Astronomical Observatory of Taras Shevchenko National University. The errors of the positions and photometry for stars of 11–14 magnitude are 0.06″–0.08″ and 0.04 ^m –0.08 ^m , respectively.     

Trigonometric parallaxes of 29 stars with large proper motions

While implementing the first stage of the Pulkovo program of research on stars with large proper motions, we determined the trigonometric parallaxes of 29 stars (12 ^m < V < 16 ^m ) based on CCD observations with a 26-inch refractor. The mean standard error was 3.7 mas. Comparison of the Pulkovo parallaxes with those obtained at the Observatory of the Yale University and the US Naval Observatory (USNO) has shown that the parallax differences (Pulkovo-Yale/USNO) lie within the limits of their measurement errors in an overwhelming majority of cases. On average, they are −0.6 ± 1.0 mas. No systematic dependences on stellar distance, magnitude, and color in this set of differences have been found. Our comparisons show that the observing and data reduction techniques used in the Pulkovo program of research on fast stars allow highly accurate trigonometric parallaxes of these objects to be obtained. All program stars are within 50 pc of the Sun; most of them belong to the immediate solar neighborhood (D < 25 pc). For two stars (J0522+3814 and J1202+3636), the trigonometric parallaxes have been determined for the first time.     

Proper motions and CCD photometry of stars in the region of the open cluster NGC 6866

We present the results of our comprehensive study of the Galactic open star cluster NGC 6866. The positions of stars in the investigated region have been obtained with the “Fantasy” automatic measuring machine from 10 plates of the normal astrograph at the Pulkovo Astronomical Observatory. The size of the investigated field is 40′ × 40′, the limiting magnitude is B ∼ 16_· ^m 6, and the maximum epoch difference is 79 yr. For 1202 field stars, we have determined the relative proper motions with an rms error of 2.5 mas yr⁻¹. Out of them, 423 stars may be considered cluster members with a probability P > 70% according to the astrometric criterion. Photometric diagrams have been used as an additional criterion. We have performed two-color BV CCD photometry of stars with the Pulkovo ZA-320M mirror astrograph. The U magnitudes from the literature have also been used to construct the two-color diagrams. A total of 267 stars have turned out to be members of NGC 6866 according to the two criteria. We present refined physical parameters of the cluster and its age estimate (5.6 × 10⁸ yr). The cluster membership of red and blue giants, variable, double, and multiple stars is considered. We have found an almost complete coincidence of the positions of one of the stars in the region (a cluster nonmember) and a soft X-ray source in the ROSAT catalog. The “Fantasy” automatic measuring machine is described in the Appendix.     

The Eddington Mission

The Eddington mission was given full approval by the European Space Agency on the 23rd May 2002, with launch scheduled for 2007/8. Its science objectives are stellar evolution and asteroseismology, and planet finding. In its current design it consists of 4 × 60 cm folded Schmidt telescopes, each with 6^o × 6^o field of view and its own CCD array camera. Eddington will spend 2 years primarily devoted to asteroseismology with 1–3 months on different target fields monitoring up to 50,000 stars per field, and 3 years continuously on a single field monitoring upwards of 100,000 stars for planet searching. The asteroseismic goal is to be able to detect oscillations frequencies of stars with a precision 0.1–0.3 μHz, to probe their interior structure and the study the physical processes that govern their evolution. This revised version was published online in August 2006 with corrections to the Cover Date.     

Photometric survey near the main Galactic meridian: 2.2. Finding charts and photoelectric UBVR stellar magnitudes in 26 fields

Finding charts and photoelectric magnitudes of stars in the UBVR system in 26 fields of the MEGA programme are presented. This part of the photometric survey near the Main Galactic Meridian includes the fields with right ascentions 8^h < α < 16^h30^m and declinations −2° < δ < 58°. Together with the finding charts of 2.5° × 2.5° the equatorial coordinates of the stars are given for epoch and equinox 1950. Photometric properties of the night sky at the Mount Terskol observatory near Mount Elbrus are derived from the photoelectric observations.     

Determining the orientation parameters of the ICRS/UCAC2 system using the Kharkov catalog of absolute stellar proper motions

The absolute proper motions of about 275 million stars from the Kharkov XPM catalog have been obtained by comparing their positions in the 2MASS and USNO-A2.0 catalogs with an epoch difference of about 45 yr for northern-hemisphere stars and about 17 yr for southern-hemisphere stars. The zero point of the system of absolute proper motions has been determined using 1.45 million galaxies. The equatorial components of the residual rotation vector of the ICRS/UCAC2 coordinate system relative to the system of extragalactic sources have been determined by comparing the XPM and UCAC2 stellar proper motions: ω _x,y,z = (−0.06, 0.17, −0.84) ± (0.15, 0.14, 0.14) mas yr⁻¹. These parameters have been calculated using about 1 million faintest UCAC2 stars with magnitudes R _UCAC2 > 16 ^m and J > 14 ^m . 7, for which the color and magnitude equation effects are negligible.     

Photometric study of the FUor star V 1735 Cyg (Elias 1-12)

Results from optical photometric observations of the PMS star V 1735 Cyg are reported. The star is located in the IC 5146 dark cloud complex—a region of active star formation. On the basis of observed outburst and spectral properties, V 1735 Cyg was classified as a FUor object. We present data from BVRI CCD photometric observations of the star, collected from March 2003 to January 2009. Plates from the Rozhen Schmidt telescope archive were scanned for a brightness estimation of the star. A sequence of sixteen comparison stars in the field of V 1735 Cyg was calibrated in BVRI bands. The data from photographic observations made from 1986 to 1992 show a strong light variability (ΔV=1_⋅^m2). In contrast, the recent photometric data obtained from 2003 to 2009 show only small amplitude variations (ΔI=0_⋅^m3). The analysis of existing photometric data shows a very slow decrease in star brightness—1_⋅^m8 (R) for a 44 year period. The possibilities for future photometric investigations of V 1735 Cyg using the photographical plate archives is discussed briefly.     

Instability of LBV stars against radial oscillations

Hydrodynamic calculations of nonlinear radial oscillations of LBV stars with effective temperatures 1.5 × 10⁴ K ⩽ T _eff ⩽ 3 × 10⁴ K and luminosities 1.2 × 10⁶ L _⊙ ⩽ L ⩽ 1.9 × 10⁶ L _⊙ have been performed. Models for the evolutionary sequences of Population I stars (X = 0.7, Z = 0.02) with initial masses 70M _⊙ ⩽ M _ZAMS ⩽ 90M _⊙ at the initial helium burning stage have been used as the initial conditions. The radial oscillations develop on a dynamical time scale and are nonlinear traveling waves propagating from the core boundary to the stellar surface. The amplitude of the velocity variations for the outer layers is several hundred km s⁻¹, while the bolometric magnitude variations are within ΔM _bol ⩽ 0_· ^m 2. The onset of oscillations is not related to the κ-mechanism and is attributable to the instability of a self-gravitating envelope gas whose adiabatic index is close to its critical value of Γ₁ = 4/3 due to the dominant contribution of radiation in the internal energy and pressure. The interval of magnitude variation periods (6 days ≤ II ≤ 31 days) encompasses all currently available estimates of the microvariability periods for LBV stars, suggesting that this type of nonstationarity is pulsational in origin.     

Investigation of the motions of fast stars based on observations with the Pulkovo normal astrograph

Astrometric CCD observations of 1123 stars with large proper motions (μ > 300 mas yr⁻¹) from the LSPM (I/298) catalog in the declination zone +30°–+70° have been carried out with the Pulkovo normal astrograph since 2006. The observational program includes mostly stars that previously have not entered into high-accuracy projects to determine the proper motions. Our studies are aimed at determining new proper motions of fast stars in the HCRF/UCAC3 system and searching for stars with invisible companions in the immediate Galactic neighborhoods of the Sun. Having analyzed about 10 000 CCD frames, we have obtained the equatorial coordinates of 414 program stars in the HCRF/UCAC3 system at an accuracy level of 10–50 mas and determined their new proper motions. To derive the proper motions, we have used the data from several star catalogs and surveys (M2000, CMC14, 2MASS, SDSS) as early epochs. The epoch differences range from 5 to 13 years (on average, about 10 years); the mean accuracy of the derived proper motions is 4–5 mas yr⁻¹. For 70 stars, we have revealed significant differences between the derived proper motions and those from the LSPM and I/306A catalogs (these proper motions characterize the mean motion of the photocenter in 50 years or more). Apart from systematic errors, these differences can result from the existence of invisible components of the program stars.     

<Emphasis Type="Italic">UVR</Emphasis> CCD photometry of stars in five sky areas with matched IR/radio sources

Five sky areas about the radio sources ICRS 1254+571, ICRS 1345+125, ICRS 1641+399, ICRS 1732+389, and ICRS 1807+698 were observed with the aim to identify reliably the extragalactic radio sources in these areas with bright infrared objects and objects in the optical range. The test CCD observations were made in the U, V, and R bands of the Johnson system with the 2-meter telescope of the Terskol Peak Observatory (North Caucasus, Russian Federation). The U, V, and B magnitudes and the equatorial coordinates α and δ in the USNO-A2.0 catalog system were determined for objects down to V ≈ 23^m in 8.5′ × 8.5′ areas, and these objects were identified with stars and infrared objects in the 2MASS catalog. The CCD image processing realized within the MIDAS/ROMAFOT program package on the basis of a new method for flat-field elimination is briefly described.     

Scanning results of images of the 60th declination zone of the FON project. Measurement reduction methods and characterization of the output catalog

A Microtek ScanMaker 9800XL TMA was used to scan 102 plates of 60° declination zone of the northern sky. The images were obtained within the scope of the FON project using the double wide-angle astrograph of the Main Astronomical Observatory (National Academy of Sciences of Ukraine). The procedure is described of processing these scans and compilation of the catalog of equatorial coordinates and brightness. Mean square errors of positions and B-magnitudes of 1 108 603 stars of the output catalog (in the range from 56 to 64° in declination and from 0 to 24 ^h in right ascension) largely depend on the position on the plate, multiplicity of overlapping, and stellar magnitude. The standard deviations are 0.10–0.32″ for coordinates and 0.04–16 ^m for stellar magnitudes. The average values of mean square deviations of data of the obtained catalog from data of PPMX and UCAC catalogs are 0.23″ and 0.18 ^m .     

Two new LBV candidates in the M 33 galaxy

We present two new luminous blue variable (LBV) candidate stars discovered in the M33 galaxy. We identified these stars as massive star candidates at the final stages of evolution, presumably with a notable interstellar extinction. The candidates were selected from the Massey et al. catalog based on the following criteria: emission in H _α , V<18^./m 5 and 0_.^m 35 < (B - V) < 1_.^m 2. The spectra of both stars reveal a broad and strong H _α emission with extended wings (770 and 1000 kms⁻¹). Based on the spectra we estimated the main parameters of the stars. Object N45901 has a bolometric luminosity log(L/L_⊙) = 6.0–6.2 with the value of interstellar extinction A _V = 2.3 ± 0.1. The temperature of the star’s photosphere is estimated as T⋆ ∼ 13000–15000 K, its probable mass on the Zero Age Main Sequence is M∼ 60–80 M_⊙. The infrared excess in N 45901 corresponds to the emission of warm dust with the temperature Twarm ∼ 1000 K, and amounts to 0.1%of the bolometric luminosity. A comparison of stellar magnitude estimates from different catalogs points to the probable variability of the object N45901. Bolometric luminosity of the second object, N125093, is log(L/L_⊙) = 6.3 − 6.6, the value of interstellar extinction is A _V = 2.75 ± 0.15. We estimate its photosphere’s temperature as T⋆∼ 13000–16000K, the initial mass as M ∼ 90–120 M_⊙. The infrared excess in N125093 amounts to 5–6% of the bolometric luminosity. Its spectral energy distribution reveals two thermal components with the temperatures T_warm ∼ 1000K and T_cold ∼ 480 K. The [Ca II] λλ7291, 7323 lines, observed in LBV-like stars Var A and N93351 in M33 are also present in the spectrum of N 125093. These lines indicate relatively recent gas eruptions and dust activity linked with them. High bolometric luminosity of these stars and broad H α emissions allow classifying the studied objects as LBV candidates.     

PLATO: PLAnetary Transits and Oscillations of stars

The PLAnetary Transits and Oscillations of stars Mission (PLATO), presented to ESA in the framework of its “Cosmic Vision” programme, will detect and characterize exoplanets by means of their transit signature in front of a very large sample of bright stars, and measure the seismic oscillations of the parent stars orbited by these planets in order to understand the properties of the exoplanetary systems. PLATO is the next-generation planet finder, building on the accomplishments of CoRoT and Kepler: i) it will observe significantly more stars, ii) its targets will be 2 to 3 magnitudes brighter (hence the precision of the measurements will be correspondingly greater as will be those of post-detection investigations, e.g. spectroscopy, asteroseismology, and eventually imaging), iii) it will be capable of observing significantly smaller exoplanets. The space-based observations will be complemented by ground- and space-based follow-up observations. These goals will be achieved by a long-term (4 years), high-precision, high-time-resolution, high-duty-cycle monitoring in visible photometry of a sample of more than 100,000 relatively bright (m _V  ≤ 12) stars and another 400,000 down to m _V  = 14. Two different mission concepts are proposed for PLATO: i) a “staring” concept with 100 small, very wide-field telescopes, assembled on a single platform and all looking at the same 26° diameter field, and ii) a “spinning” concept with three moderate-size telescopes covering more than 1400 degree². See for The PLATO Consortium.     

A search for the tritium hyperfine line from nearby stars

A search for the tritium hyperfine line at 1516 MHz from 108 assorted astronomical objects, with emphasis on 53 nearby stars, was conducted in June 1983. All stars within 20 light-years visible from the 26-m telescope at Hat Creek Radio Observatory were examined using 256 4883-Hz channels. Twelve stars were also examined using 1024 76-Hz channels. The wideband- and narrowband-channel observations achieved sensitivities of 5–14 × 10⁻²⁴ W/m²/channel and 0.7–2 × 10⁻²⁴ W/m²/channel, respectively. No detections were made. The tritium frequency is highly attractive for SETI work because the isotope is cosmically rare and the tritium hyperfine line is centered in the SETI waterhole region of the terrestrial microwave window. In addition to beacon signals, tritium hyperfine emission may occur as a byproduct of extensive nuclear fusion energy production by extraterrestrial civilizations.     

CCD BV and 2MASS photometric study of the open cluster NGC 1513

We present CCD BV and JHK _s 2MASS photometric data for the open cluster NGC 1513. We observed 609 stars in the direction of the cluster up to a limiting magnitude of V∼19 mag. The star-count method showed that the centre of the cluster lies at α ₂₀₀₀=04 ^h 09 ^m 36 ^s , δ ₂₀₀₀=49°28^′43^″ and its angular size is r=10 arcmin. The optical and near-infrared two-colour diagrams revealed the colour excesses in the direction of the cluster as E(B−V)=0.68±0.06, E(J−H)=0.21±0.02 and E(J−K _s )=0.33±0.04 mag. These results are consistent with normal interstellar extinction values. Optical and near-infrared Zero Age Main-Sequences (ZAMS) provided an average distance modulus of (m−M)₀=10.80±0.13 mag, which can be translated into a distance of 1440±80 pc. Finally, using Padova isochrones we determined the metallicity and age of the cluster as Z=0.015±0.004 ([M/H]=−0.10±0.10 dex) and log (t/yr)=8.40±0.04, respectively.     

A research of the Orionid meteor shower by television observations in 2006–2008

The results of observations of the Orionid meteor shower are given in the period from 2006 to 2008. Observations were carried out using a highly sensitive camera FAVOR (FAst Variability Optical Registrator) a limiting magnitude of above +11.0^m (for stars) and a field of view of 18° × 20°. Over the period of the shower from October 2 to November 7, 2006–2008, there were 3713 meteors. 449 of these meteors were associated with the Orionid meteor shower. The distributions of Orionid meteors by the stellar magnitude is presented. It turned out that most of meteors (65%) of this shower have a brightness of +5.0^m-+7.0^m. On each night of observation the index of meteor activity was calculated for Orionids.     

CCD photometry inVRI bands of the galactic cluster NGC 2818

bdAbstract The open cluster NGC 2818 containing a planetary nebula has been observed inVRI bands using the CCD system at prime focus of the 2.3-metre Vainu Bappu Telescope. The study extending to starsV ∼ 21 magnitude establishes the distance modulus as(m-M) ₀ = 12.9 ±0.1 for the cluster. Based on the fitting of theoretical isochrones computed for solar metallicity, an age of 5(±1) × 10₈ years has been assigned to the cluster. Association of the planetary nebula with the cluster indicates that the progenitor mass of the planetary nebula on the main sequence is ≥2.5M_⊙ Based on observations obtained with the Vainu Bappu Telescope.