- ID:
- ivo://CDS.VizieR/J/A+AS/128/315
- Title:
- BVRI photometry of blazars
- Short Name:
- J/A+AS/128/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of both BVRI CCD photometric monitoring and fast photometry for 8 blazars and variable quasars are presented. There is intraday variability for 6 blazars and very short timescales (minutes to two hours) variability for 5 objects. Implications for relativistic beaming are briefly discussed.
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- ID:
- ivo://CDS.VizieR/J/A+AS/136/455
- Title:
- BVRI photometry of 3 BL Lac objects
- Short Name:
- J/A+AS/136/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of optical photometric (BVRI) monitoring of three BL Lac objects over a time interval of about four years are presented. The sources are three classical radio-selected BL Lac objects, BL Lac, OJ 287 and PKS 0735+178. During our observation OJ 287 was in the stage of a large periodic outburst which consisted of at least two peaks. Almost all the observations obtained over consecutive nights detected intranight variations. In 1995 and 1996 BL Lac kept in faint states, with fewer and smaller rapid flares and fluctuations. On the contrary, in late 1997 BL Lac was at the stage of a large outburst, accompanied with much more large amplitude rapid flares and fluctuations. PKS 0735+178 was almost at its faint end from 1994 to early 1998. Over this time interval, the intraday variations and microvariations in PKS 0735+178 were rare and the amplitude was very small, except a rapid darkening of ~0.4mag on 24 January 1995. Previous work by Webb et al. (1988AJ.....95..374W), Wagner et al. (1996AJ....111.2187W) and Pian et al. (1997ApJ...486..784P) also showed the same behaviour of variability as BL Lac and PKS 0735+178 in BL Lac, S5 0716+714, PKS 2155-304, respectively. We propose that the motion of orientation of the relativistic jet in a BL Lac object be responsible for these variability behaviours.
- ID:
- ivo://CDS.VizieR/J/A+AS/132/83
- Title:
- BVRI photometry of 7 BL Lac objects
- Short Name:
- J/A+AS/132/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Seven BL Lac objects have been photometrically observed in an effort to study the difference of optical intraday variability between the radio-selected BL Lac objects (RBLs) and X-ray-selected BL Lac objects (XBLs). The objects we observed are selected arbitrarily. They are four RBLs, PKS 0735+178, PKS 0754+101, OJ 287 and BL Lac, and three XBLs, H 0323+022, H 0548-322 and H 2154-304. During the observation all of them exhibited microvariation, and H 0323+022 and H 0548-322 sometimes showed brightness oscillation. PKS 0735+178 and BL Lac were in their faint states and not very active. It seems that RBLs do not show microvariability more frequently than XBLs.
- ID:
- ivo://CDS.VizieR/J/AJ/134/778
- Title:
- BVRI photometry of candidate subdwarfs
- Short Name:
- J/AJ/134/778
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical (BVRI) photometric measurements of a sample of 564 candidate cool subdwarfs in the nearby halo are presented. The stars generally span the color range 0.4<(B-V)<1.8; hence, the sample is composed of early F- through early M-type stars on the subdwarf sequence. The sample is selected from the revised NLTT catalog of Gould and Salim and Salim and Gould via a reduced proper motion diagram. The photometry is precise and accurate; in particular, for stars with 9<V<13.5 the photometry is accurate to 0.013, 0.015, 0.012, and 0.013mag in V, B-V, V-R, and V-I, respectively. For stars with 13.5<V<16 the photometry is accurate to 0.022, 0.018, 0.013, and 0.018mag in the same bands.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/297
- Title:
- BVRI photometry of Central Field of {omega} Cen
- Short Name:
- J/A+AS/115/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is a four colour photometric study of stars in the central part of the globular cluster {omega} Centauri. The observations were made at Siding Spring Observatory in April 1992 with the 1m ANU telesecope; a 1024x1024CCD has been used. The photometry was reduced to the BVRI system using standards by Landolt
- ID:
- ivo://CDS.VizieR/J/A+AS/144/481
- Title:
- BVRI photometry of five X-ray selected BL Lacs
- Short Name:
- J/A+AS/144/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical data obtained with the 1.05 m telescope of the Torino Astronomical Observatory for five X-ray selected BL Lacertae objects. The data are in the Johnson's B, V, and Cousins' R bands. As the observing periods include the pointings of the Satellite per Astronomia X ``Beppo'' (BeppoSAX), our optical information will be comparable with the X-ray observations for a better understanding of the properties of these objects. The present data also provide optical information on sources that have been rarely observed in the optical band. Variability on short time scales (a few days) was found only for 1ES 1959+650.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/425
- Title:
- BVRI photometry of 6 galaxies
- Short Name:
- J/A+AS/142/425
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of the brightest stars in six nearby spiral and irregular galaxies with corrected radial velocities from 340 to 460km/s. Three of them are resolved into stars for the first time. Based on luminosity of the brightest blue stars we estimate the following distances to the galaxies: 5.0Mpc for NGC 784, 9.2Mpc for NGC 2683, 8.9Mpc for NGC 2903, 4.1Mpc for NGC 5204, 6.8Mpc for NGC 5474, and 8.7Mpc for NGC 5585.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A33
- Title:
- BVRI photometry of high-mass X-ray binaries
- Short Name:
- J/A+A/574/A33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric observations of the field around the optical counterparts of high-mass X-ray binaries. Our aim is to study the long-term photometric variability in correlation with their X-ray activity and derive a set of secondary standard stars that can be used for time series analysis. We find that the donors in Be/X-ray binaries exhibit larger amplitude changes in the magnitudes and colours than those hosting a supergiant companion. The amplitude of variability increases with wavelength in Be/X-ray binaries and remains fairly constant in supergiant systems. When time scales of years are considered, a good correlation between the X-ray and optical variability is observed. The X-rays cease when optical brightness decreases. These results reflect the fact that the circumstellar disk in Be/X-ray binaries is the main source of both optical and X-ray variability. We also derive the colour excess, E(B-V), selecting data at times when the contribution of the circumstellar disk was supposed to be at minimum, and we revisit the distance estimates.
- ID:
- ivo://CDS.VizieR/J/A+A/333/952
- Title:
- BVRI photometry of HR 1105
- Short Name:
- J/A+A/333/952
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- BVRI photometry of the extrinsic S star HR 1105 shows a stable periodic light variability with a period of 24.76 days superimposed upon long term changes presumably related to the orbital period. The variations are in phase for all four magnitudes with the amplitude of this variability being about the same for B and V, but smaller for R and even smaller for I. As the primary is a M3 III star, these brightness changes are mostly likely due to the pulsation of the primary star.
- ID:
- ivo://CDS.VizieR/J/AJ/134/2286
- Title:
- BVRI photometry of isolated spirals
- Short Name:
- J/AJ/134/2286
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A release of multicolor broadband (BVRI) photometry for a subsample of 44 isolated spirals drawn from the Catalogue of Isolated Galaxies is presented. Total magnitudes and colors at various circular apertures, as well as some global structural/morphological parameters, are estimated. Morphology is reevaluated through optical and sharp-filtered R-band images, (B-I) color index maps, and archived near-IR JHK images from the Two Micron All Sky Survey. The CAS structural parameters (concentration, asymmetry, and clumpiness) were calculated from the images in each of the bands.
