- ID:
- ivo://CDS.VizieR/J/MNRAS/454/3094
- Title:
- Optical transit light curves of WASP-57
- Short Name:
- J/MNRAS/454/3094
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 transit light curves from professional facilities which confirm and refine this finding, and high-resolution imaging which show no evidence for nearby companions. We use these data to determine a new and precise orbital ephemeris, and measure the physical properties of the system. Our revised orbital period is 4.5 s shorter than found from the discovery data alone, which explains the early occurrence of the transits. We also find both the star and planet to be larger and less massive than previously thought. The measured mass and radius of the planet are now consistent with theoretical models of gas giants containing no heavy-element core, as expected for the subsolar metallicity of the host star. Two transits were observed simultaneously in four passbands. We use the resulting light curves to measure the planet's radius as a function of wavelength, finding that our data are sufficient in principle but not in practise to constrain its atmospheric properties. We conclude with a discussion of the current and future status of transmission photometry studies for probing the atmospheres of gas-giant transiting planets.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/725
- Title:
- Optical-UV-IR survey of North Celestial Cap
- Short Name:
- J/MNRAS/443/725
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe the final product of the North Celestial Cap Survey (NCCS) - the optical-UV-IR merged catalogue for the region within 10{deg} of the North Celestial Pole. The North Celestial Cap (NCC) region at {delta}>=80{deg} is poorly covered by modern CCD-based surveys. The optical part of the survey was observed in V, R and I with the Wide-field Infrared Survey Explorer (WISE) Observatory telescopes and was merged with GALEX UV and WISE IR data, producing the catalogue. More than four million objects were observed in at least one optical band. The final catalogue contains ~1.6 million sources observed in all three optical bands, of which some 1.4 million have WISE counterparts and ~300000 have GALEX counterparts. The astrometric accuracy of the optical NCCS data, derived from a comparison with the UCAC3 catalogue, is better than 0.2-arcsec and the photometry, when compared with Sloan Digital Sky Survey, is good to ~0.15mag for sources brighter than V=20.3, R=21.0 and I=19.2mag. The Sloan Digital Sky Survey point-extended source separation is reproduced with >92 per cent efficiency.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/403
- Title:
- Optical Variabilities in 3C 120
- Short Name:
- J/PAZh/35/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on our UBVRI observations and X-ray data from the RXTE satellite we have investigated the variabilities of the Seyfert Galaxy 3C 120 over the period 1996-2008.
- ID:
- ivo://CDS.VizieR/J/PAZh/21/652
- Title:
- Optical variability in NGC 7469
- Short Name:
- J/PAZh/21/652
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of three-color UBV observations of rapid variability in the nucleus of the Seyfert galaxy NGC 7469 carried out in 1990-1994 are presented. The observations have been carried out during 15 different nights using the 60- and 125-cm telescopes with time resolution of 6-8min (50 hours monitoring) with the aperture of 27.5". The mean errors of one measurement are 1.8, 1.2 and 1.4% for U, B and V. The data set length during one night is from 2 up to 5h. The different nights show the variations at different level: from weak, when the standard deviation during the night exceeds the error of one measurement only by 10-20%, up to strong ones, when the standard deviation exceeds the error of the measurement by factor two.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/24
- Title:
- Optical variability of AGN from the HSC SSP survey
- Short Name:
- J/ApJ/894/24
- Date:
- 03 Dec 2021 00:44:13
- Publisher:
- CDS
- Description:
- We study variability of active galactic nuclei (AGNs) by using the deep optical multiband photometry data obtained from the Hyper Suprime-Cam Subaru Strategic Program (HSC SSP) survey in the COSMOS field. The images analyzed here were taken with 8, 10, 13, and 15 epochs over three years in the g, r, i, and z bands, respectively. We identified 491 robust variable AGN candidates, down to i=25mag and with redshift up to 4.26. Ninety percent of the variability-selected AGNs are individually identified with the X-ray sources detected in the Chandra COSMOS Legacy survey. We investigate their properties in variability by using structure function analysis and find that the structure function for low-luminosity AGNs (L_bol_<~10^45^erg/s) shows a positive correlation with luminosity, which is the opposite trend for the luminous quasars. This trend is likely to be caused by a larger contribution of the host galaxy light for lower-luminosity AGNs. Using the model templates of galaxy spectra, we evaluate the amount of host galaxy contribution to the structure function analysis and find that dominance of the young stellar population is needed to explain the observed luminosity dependence. This suggests that low-luminosity AGNs at 0.8<~z<~1.8 are predominantly hosted in star-forming galaxies. The X-ray stacking analysis reveals the significant emission from the individually X-ray undetected AGNs in our variability-selected sample. The stacked samples show very large hardness ratios in their stacked X-ray spectrum, which suggests that these optically variable sources have large soft X-ray absorption by dust-free gas.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2866
- Title:
- 2001-02 optical variability of blazar 3C 279
- Short Name:
- J/AJ/133/2866
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During 2001-2002 the optically violent variable blazar 3C 279 underwent the most intense outburst seen during the entire 14yr period that this quasar has been studied at Colgate University's Foggy Bottom Observatory. This study concentrates on ~1600 R-filter images taken during this period of activity. This data set includes 29 nights of microvariability coverage. The outburst began in 2001 March, after 3C 279 had faded to its faintest level, R=15.5, in 4yr. The source reached its brightest level, R=12.5, in the 14yr of our study in 2001 August, at which time it became unobservable due to its proximity to the Sun. On becoming observable again in 2001 mid-December, 3C 279 fluctuated between R=13.9 and 14.7, until a dramatic decrease in flux level in 2002 June-July brought the source back down to a level comparable to its preoutburst state. The source exhibited numerous week-long flares of approximately 1mag during the outburst period. Superposed on these flares were night-to-night variations of up to 0.5mag and intranight microvariability of up to 0.13mag in 3hr. We use visual inspection of the light curve, as well as numerical timescale analysis tools (the autocorrelation function, the structure function, and the power spectrum), to characterize the multiple timescales of variability ranging from 1.5yr to several hours.
- ID:
- ivo://CDS.VizieR/J/AN/340/437
- Title:
- Optical variability of blazars
- Short Name:
- J/AN/340/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The analysis of blazars' parameters from BZCAT leads to a conclusion that they do not have the same properties. The preliminary criterion to include an object in the catalog was the strong radio emission; however, two type of radio sources were selected: BL Lacertae (BLL) objects and Flat Spectrum Radio Quasars (FSRQ). As a number of properties are typical of blazars (strong radio emission, optical variability, continuum optical spectra, polarization, high luminosity, etc.), using the optical data, we investigate them to clarify which property plays the most significant role in their classification as blazars. We found that 60% of blazars have optical variability. We use a technique developed based on POSS1 and POSS2 photometry and group the variability into extreme, strong, medium, and low classes. In the optical range, 51 blazars have powerful variability (extreme variables), and 126 are high variables. In addition, 63% of blazars have detected radiation in X-ray and 28% have detected radiation in gamma rays. We give the average statistical characteristics of blazars based on our analysis and calculations.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/403
- Title:
- Optical variability of NGC 4151
- Short Name:
- J/PAZh/25/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBV observations of performed between 1972 and 1998 are presented. The aperture is 27.5".
- ID:
- ivo://CDS.VizieR/J/AJ/157/95
- Title:
- Optical variability of OJ 287 in 2016-2017
- Short Name:
- J/AJ/157/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a recent multiband optical photometric and polarimetric observational campaign of the blazar OJ 287 that was carried out during 2016 September-2017 December. We employed nine telescopes in Bulgaria, China, Georgia, Japan, Serbia, Spain, and the United States. We collected over 1800 photometric image frames in BVRI bands and over 100 polarimetric measurements over ~175 nights. In 11 nights with many quasi-simultaneous multiband (V, R, I) observations, we did not detect any genuine intraday variability in flux or color. On longer timescales, multiple flaring events were seen. Large changes in color with respect to time and in a color-magnitude diagram were seen, and while only a weak systematic variability trend was noticed in color with respect to time, the color-magnitude diagram shows a bluer-when-brighter trend. Large changes in the degree of polarization and substantial swings in the polarization angle were detected. The fractional Stokes parameters of the polarization showed a systematic trend with time in the beginning of these observations, followed by chaotic changes and then an apparently systematic variation at the end. These polarization changes coincide with the detection and duration of the source at very high energies as seen by VERITAS. The spectral index shows a systematic variation with time and V-band magnitude. We briefly discuss possible physical mechanisms that could explain the observed flux, color, polarization, and spectral variability.
- ID:
- ivo://CDS.VizieR/J/PAZh/23/277
- Title:
- Optical variability of WW Vul
- Short Name:
- J/PAZh/23/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The UBV observations of WW Vul performed between 1983 and 1993 are presented. All UBV observations of WW Vul are reduced to GAISh photometric system.
