Results of a ground-based optical monitoring campaign on 3C 390.3 in 1994-1995 are presented. The broadband fluxes (B, V, R, and I), the spectrophotometric optical continuum flux F_{lambda}_(5177{AA}), and the integrated emission-line fluxes of H{alpha}, H{beta}, H{gamma}, He I 5876, and He II {lambda}4686 all show a nearly monotonic increase with episodes of milder short-term variations superposed. The amplitude of the continuum variations increases with decreasing wavelength (4400-9000{AA}). The optical continuum variations follow the variations in the ultraviolet and X-ray with time delays, measured from the centroids of the cross-correlation functions, typically around 5 days, but with uncertainties also typically around 5 days; zero time delay between the high-energy and low-energy continuum variations cannot be ruled out. The strong optical emission lines H{alpha}, H{beta}, H{gamma}, and He I {lambda}5876 respond to the high-energy continuum variations with time delays typically about 20 days, with uncertainties of about 8 days. There is some evidence that He II {lambda}4686 responds somewhat more rapidly, with a time delay of around 10 days, but again, the uncertainties are quite large (~8 days). The mean and rms spectra of the H{alpha} and H{beta} line profiles provide indications for the existence of at least three distinct components located at +/-4000 and 0km/s relative to the line peak. The emission-line profile variations are largest near line center.
We present a catalogue of 261 new infrared selected members of the 3C 129 galaxy cluster. The cluster, located at z=0.02, forms part of the Perseus-Pisces filament and is obscured at optical wavelengths due to its location in the zone of avoidance. We identified these galaxies using the J- and K-band imaging data provided by the UKIDSS Galactic Plane Survey within an area with a radius of 1.1{deg} centred on the X-ray emission of the cluster at (l, b) = (160.52{deg}, 0.27{deg}). A total of 26 of the identified galaxy members have known redshifts 24 of which are from our 2016 Westerbork HI survey and two are from optical spectroscopy. An analysis of the galaxy density at the core of the 3C 129 cluster shows it to be less dense than the Coma and Norma clusters, but comparable to the galaxy density in the core of the Perseus cluster. From an assessment of the spatial and velocity distributions of the 3C 129 cluster galaxies that have redshifts, we derived a velocity of cz=5227+/-171km/s and=1097+/-252km/s for the main cluster, with a substructure in the cluster outskirts at cz=6923+/-71km/s with {sigma}=422+/-100km/s. The presence of this substructure is consistent with previous claims based on the X-ray analysis that the cluster is not yet virialised and may have undergone a recent merger.
Based on O-C curves, we present detailed period investigations of two weak-contact binaries CC Com and BV Dra. It is found that the periods of these two binaries have varied in a cyclic variation way superposed on a secular period change. The periods and amplitudes of the cyclic variations are P_3_=23.6(+/-0.4)yr and A=0.0028(+/-0.0003)d for CC Com and P_3_=23.8(+/-0.6)yr and A=0.0029(+/-0.0003)d for BV Dra.
We measured the angular separations, position angles, Delta(V), Delta(y) and Delta(I) of wide visual double stars during the period 2003-2005. At least one component of the double stars in our sample has an entry in the Hipparcos catalogue.
Observations of the globular cluster M10 were taken at the Kitt Peak National Observatory (KPNO) 0.9 m telescope on the nights of UT dates 1995 May 6 and 9 using BVI filters. All frames were taken using a 2048x2048 pixel CCD with pixels covering 0.68 arcseconds on a side, for a total field of approximately 23.2 arcminutes on a side. The data were calibrated against Stetson (2000PASP..112..925S) standard stars. Additional high-resolution images were taken at the 3.6 m Canada-France-Hawaii Telescope (CFHT) on the night of UT date 1993 April 13 in BI filters. These observations used a 1200x1200 pixel CCD with pixels covering 0.11 arcseconds on a side, for a total field 2.2 arcminutes on a side, roughly centered on the cluster core. These data were calibrated against the KPNO data.
We present for the globular cluster NGC 5927 the first multicolor CCD photometry that reaches below the cluster's main sequence turnoff. The turnoff is located approximately at V_TO_=20.1mag, (B-V)_TO_=1.18mag, (V-I)_TO_=1.30mag. There is a hint of horizontal branch morphology variations with distance from the cluster center. Using the isochrones of VandenBerg & Bell (1985ApJS...58..561V), we derive the cluster age to be about 15Gyr.
The observations were done on the nights of UT dates 1995 May 6 and 9 by using the Kitt Peak National Observatory (KPNO) 0.9 m telescope. The file contains BVI data of the globular cluster M12. All frames were taken using a 2048x2048 pixel CCD with pixels covering 0.68 arcseconds on a side, for a total field of approximately 23.2 arcminutes on a side. The data were calibrated against Stetson (2000PASP..112..925S) standard stars.
We present CCD BVI observations obtained for 1759 stars in 4'x4' regions around the unstudied southern stellar aggregates Ruprecht 103, 124, 129, 146 and 166, which are described as open clusters in several catalogues. Our analysis shows that none of these stellar groups are genuine open clusters since no clear main sequences or other meaningful features can be seen in their colour-magnitude diagrams. Star counts carried out within and outside the cluster candidate fields not only support these results but also show that the studied objects do not appear to be candidate late stages of star cluster dynamical evolution.
We present BVI photometry for poorly known southern hemisphere open clusters: NGC 2425, Haffner 10 and Czernik 29. We have calculated the density profile and established the number of stars in each cluster. The colour-magnitude diagrams of the objects show a well-defined main sequence. However, the red giant clump is present only in NGC 2425 and Haffner 10. For these two clusters we estimated the age as 2.5+/-0.5Gyr assuming metallicity of Z=0.008. The apparent distance moduli are in the ranges 13.2<(m-M)_V<13.6 and 14.3<(m-M)_V<14.7, while heliocentric distances are estimated to be 2.9<d<3.8kpc and 3.1<d<4.3kpc, respectively for NGC 2425 and Haffner 10. The angular separation of 2.4deg (150pc at mean distance) may indicate a common origin of the two clusters.
