- ID:
- ivo://CDS.VizieR/J/other/NewA/27.25
- Title:
- BVRI photometry of Nova KT Eri 2009
- Short Name:
- J/other/NewA/27.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We obtained extensive new BVRcIc photometry of Nova KT Eri 2009 over a 539-day interval during the post-outburst quiescence, from 30 September 2011 to 22 March 2013 (days +684 to +1223 past maximum). The median magnitudes we measured are B=15.24, V=15.00, Rc=14.75 and Ic=14.49. A marked variability is present (total amplitude of {Delta}V=1.6mag). Accounting for a generally overlooked correction to blue photographic magnitudes calibrated against modern B-band data, we found that mean brightness and amplitude of variability of KT Eri in quiescence are the same before and after the 2009 nova outburst. The distance to KT Eri derived from standard relations involving the absolute magnitude at maximum vs rate of decline (MMRD), is ~6.5kpc. At such a distance, to fit the BVRcIc + JHK flux distribution of KT Eri in quiescence requires an 8200K blackbody with a radius of 3.5R_{sun}_, which is vastly larger than the radius of typical accretion disks of CVs and classical old novae (0.1R_{sun}_). The distance to KT Eri could therefore be much shorter than expected from MMRD relation. We also observed a new eclipse-like minimum to occur right on time following the 752 day period suspected to modulate the quiescence of KT Eri before the outburst. The nature of this period remains unclear. The faintness of KT Eri at infrared wavelengths (K=14.1) precludes it from being the orbital period of the accreting WD, because in such a case the Roche lobe filling companion would be a cool giant shining at K~9mag.
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- ID:
- ivo://CDS.VizieR/J/other/PZ/30.4
- Title:
- BVRI photometry of nova V445 Pup
- Short Name:
- J/other/PZ/30.4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- V445 Pup was a peculiar nova having no hydrogen spectral lines in the outburst. The spectrum contained strong emission lines of carbon, oxygen, calcium, sodium and iron. We have performed digital processing of photographic images of the V445 Pup progenitor using astronomical plate archives. The brightness of the progenitor in the B band was 14.3mag. It was found to be a periodic variable star, its most probable period being 0d.650654+/-0.000011d. The light curve shape suggests that the progenitor was a common-envelope binary having a spot on the surface and variable surface brightness. The spectral energy distribution of the progenitor between 0.44 and 2.2um was similar to that of an A0V type star.
- ID:
- ivo://CDS.VizieR/J/A+AS/129/569
- Title:
- BVRI photometry of OJ 287
- Short Name:
- J/A+AS/129/569
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of BVRI CCD photometric monitoring and fast photometry in the I band for the blazar OJ 287 in 1994-1995 are presented. The predicted outburst of the blazar had been observed, the maximum appeared in 1994 November, after that, the luminosity decreased by 1.6mag for about three months and dropped to near the level in 1994 April. Rapid variations with timescales of minutes, hours and one day were observed in our observations, with small amplitude. The amplitude of the most rapid variations (minutes) is in the range of 0.043-0.12mag . The results of the statistical analysis of the fast photometry data are as follows. In five nights out of six rapid variability appeared in the sampling interval, which ranged from 3.4 minutes to 6.5 minutes, with a rms amplitude of flux variations of 1.70%-2.3%. The rapid variability can be explained by the model of shocks within turbulent jet or of vortices and magnetic flux tubes on accretion disk.
- ID:
- ivo://CDS.VizieR/J/AN/326/3
- Title:
- BVRI photometry of 4 open clusters
- Short Name:
- J/AN/326/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry of the galactic open clusters NGC 2627, NGC 5617, Pismis 7, and Ruprecht 75 is presented. For the first cluster, BV data are given, for the others the data are BV(RI)_c. The star coordinates are relative to the corresponding cluster center. The observations were carried out from the Complejo Astronomico El Leoncito (Argentina), and from Las Campanas (Chile). Each cluster was observed on two different nights; when possible, measurements for a given star were averaged. NGC 2627 observations were carried out from CASLEO on the nights of 7-8 January 1997 and 23-24 April 2001, in the BV filters. NGC 5617 data in the BVRI filters were obtained at Las Campanas on the nights 10-11 and 11-12 April 1996, and at CASLEO on the 1-2 April 2001 night. Pismis 7 was observed from Campanas on the 13-14 and 15-16 April 1996 nights (BVRI). Ruprecht 75 data in the BVRI filters were obtained at Las Campanas on the 12-13 April 1996 night, and at CASLEO on the 20-21 April 2001 night.
- ID:
- ivo://CDS.VizieR/J/A+A/423/935
- Title:
- BVRI photometry of OQ 530
- Short Name:
- J/A+A/423/935
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results of VLBI and optical observations are presented for the BL Lac object OQ 530 (B1418+546), whose long-term optical variability is characterised by a decreasing mean luminosity trend. EVN images at 1.6GHz and 5GHz of OQ 530 show a very bright core with a much weaker jet extending to about 35-40mas. The radio flux density from the core in June 2001 was much higher than that measured in February 1999. A similar increase was also found from nearly simultaneous optical photometry, while the total flux density of the jet remained unchanged. The structure of the jet shows several knots which move outward with an apparent superluminal motion with a beta_app_>=3.5h^-1^. The region within about 3mas from the core contains a component not well resolved in our images and emerging from it in the jet direction. That component was also detected in images taken from 1990 to 1997 and it seems to be a rather stable structural feature. Using nearly simultaneous optical and radio data, we can describe the SED of the synchrotron peak with a simple formula, approximating a power law at low frequencies and a log-parabola at the high ones, whose maximum lies in the range 3.5-5x10^13^Hz, and the extrapolation in the X-ray range give a flux comparable to that observed with BeppoSAX.
- ID:
- ivo://CDS.VizieR/J/other/BAJ/24.62
- Title:
- BVRI Photometry of 14 PMS stars
- Short Name:
- J/other/BAJ/24.6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New photometric data from CCD multicolour BVRI observations of 14 pre-main sequence stars during the period from 2013 April to 2015 September are presented. The studied objects are located in the field of 'Gulf of Mexico' in the NGC 7000/IC 5070 star-forming complex. The stars from our study exhibit different types of photometric variability in all optical passbands. Using our long-term observations and data published by other authors, we tried to define the reasons for the observed brightness variations. On the basis of our new data previously unknown periodicity in the light curve of the star LkHa 189 (2.45-days) was registered.
- ID:
- ivo://CDS.VizieR/J/other/BAJ/22.3
- Title:
- BVRI photometry of 5 PMS stars
- Short Name:
- J/other/BAJ/22.3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new data from BVRI photometric observations of five PMS stars during the period from April 2013 to July 2014. The stars are located in the field of NGC 7000/IC 5070 ("Gulf of Mexico") - a region with active star formation. The presented paper is a continuation of our long-term photometric investigations of the young stellar objects in this region. The long-term multicolor photometric observations of PMS stars are very important for their exact classification. Our results show that the studied stars exhibit different types of photometric variability in all bands. We tried to classify them using our data from the long-term photometry and data published by other authors.
- ID:
- ivo://CDS.VizieR/J/AJ/161/292
- Title:
- BVRI photometry of pre-W UMA binary V642 Virginis
- Short Name:
- J/AJ/161/292
- Date:
- 16 Mar 2022 00:08:32
- Publisher:
- CDS
- Description:
- V642Vir is a polar spotted, well-detached, UV Leo-type, low-mass, pre-WUMa (T1~4250K, ~K6V) eclipsing binary. It was observed in 2020 April, May, and June at the Dark Sky Observatory in North Carolina, USA with the 0.81m reflector of Appalachian State University. A total of 88 timings were used in our 22-year period study which included 12 Transiting Exoplanet Survey Satellite (TESS) timings. The O-C plots show a low-amplitude oscillation of residuals that points to the existence of an orbiting third body, a dwarf of minimum mass, 0.15M{sun} in an eccentric orbit (e=0.41), with an orbital period of 20.07yr. The odd light curves of V642 Virginis indicate that it has polar spots similar to UV Leo and the recently published V1023Per. Its present large polar spot region indicates that it must have a strong magnetic field and that it is synchronously rotating. The BVR_c_I_c_ simultaneous Wilson-Devinney Program solution gives a detached binary (primary and secondary components are underfilling their respective Roche Lobes, with 76% and 78% fill outs respectively). The cool spot region models near the pole of the primary component (centered at 10{deg} colatitude) and is angled toward the secondary component. Its large radius (68{deg}) and T-fact (T_spot_/T_surface_=0.69) also attest to the conclusion of the strength of the magnetic field. The small {Delta}T in the components (~318K) and mass ratio near unity (0.9542{+/-}0.0005) show that the stars are similar in spectral type (secondary ~K9V). The inclination is high, ~86.87{+/-}0.04{deg}, yet there is no time of constant light due to the two stars essentially equal radii.
- ID:
- ivo://CDS.VizieR/J/AZh/79/589
- Title:
- BVRI photometry of RC galaxies
- Short Name:
- J/AZh/79/589
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI data are presented for the majority of steep-spectrum objects in the RATAN-600 7.6cm catalog (RC) catalog with m(R)<23.5mag. Previously developed programs are applied to these data to estimate the redshifts and age of the stellar population of the host galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/450/39
- Title:
- BVRI photometry of 8 red blazars
- Short Name:
- J/A+A/450/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 2482 BVRI photometric data on eight red blazars taken from 3 Observatories in the period 2003 September - 2004 February are presented. A table is given, containing the source name, the observation time, the source magnitude, the error on the source magnitude, the photometric band, and a label indicating the Observatory where the observation was done.
