Search

Start Over Subject photometry
4941. Photometric Classification Catalogue of SDSS DR7
ID:
ivo://CDS.VizieR/J/MNRAS/419/80
Title:
Photometric Classification Catalogue of SDSS DR7
Short Name:
J/MNRAS/419/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a catalogue of about six million unresolved photometric detections in the Sloan Digital Sky Survey (SDSS) Seventh Data Release, classifying them into stars, galaxies and quasars. We use a machine learning classifier trained on a subset of spectroscopically confirmed objects from 14th to 22nd magnitude in the SDSS i band. Our catalogue consists of 2430625 quasars, 3544036 stars and 63586 unresolved galaxies from 14th to 24th magnitude in the SDSS i-band. Our algorithm recovers 99.96 per cent of spectroscopically confirmed quasars and 99.51 per cent of stars to i~21.3 in the colour window that we study. The level of contamination due to data artefacts for objects beyond i=21.3 is highly uncertain and all mention of completeness and contamination in the paper are valid only for objects brighter than this magnitude. However, a comparison of the predicted number of quasars with the theoretical number counts shows reasonable agreement.
4942. Photometric classification of QSO from RCS-2
ID:
ivo://CDS.VizieR/J/A+A/584/A44
Title:
Photometric classification of QSO from RCS-2
Short Name:
J/A+A/584/A44
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new quasar candidate catalogs from the Red-Sequence Cluster Survey 2 (RCS-2), identified solely from photometric information using a Random Forest algorithm. The algorithm is trained using a well-defined SDSS spectroscopic sample of quasars and stars. The algorithm identifies putative quasars from broadband magnitudes (g, r, i, z) and colors. Exploiting NUV GALEX measurements for a subset of the objects, we refine the classifier by adding new information. An additional subset of the data with WISE W1 and W2 bands is also studied. Upon analyzing 542,897 RCS-2 point sources, the algorithm identified 21,501 quasar candidates, with a training-set-derived precision of 89.5% and recall of 88.4%. These performance metrics improve for the GALEX subset; 6530 quasar candidates are identified from 16898 sources, with a precision and recall respectively of 97.0% and 97.5%. Algorithm performance is further improved when WISE data are included, with precision and recall increasing to 99.3% and 99.1% respectively for 21834 quasar candidates from 242902 sources. After merging these samples and removing duplicates, we obtain 38257 candidates.
4943. Photometric data for ASASSN-15ed
ID:
ivo://CDS.VizieR/J/MNRAS/453/3649
Title:
Photometric data for ASASSN-15ed
Short Name:
J/MNRAS/453/3649
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of the spectroscopic and photometric monitoring campaign of ASASSN-15ed. The transient was discovered quite young by the All Sky Automated Survey for SuperNovae (ASAS-SN) survey. Amateur astronomers allowed us to sample the photometric SN evolution around maximum light, which we estimate to have occurred on JD=2457087.4+/-0.6 in the r band. Its apparent r-band magnitude at maximum was r=16.91+/-0.10, providing an absolute magnitude M_r_~-20.04+/-0.20, which is slightly more luminous than the typical magnitudes estimated for Type Ibn SNe. The post-peak evolution was well monitored, and the decline rate (being in most bands around 0.1 mag/d during the first 25 d after maximum) is marginally slower than the average decline rates of SNe Ibn during the same time interval. The object was initially classified as a Type Ibn SN because early-time spectra were characterized by a blue continuum with superimposed narrow P-Cygni lines of HeI, suggesting the presence of a slowly moving (1200-1500 km/s), He-rich circumstellar medium. Later on, broad P-Cygni HeI lines became prominent. The inferred velocities, as measured from the minimum of the broad absorption components, were between 6000 and 7000 km/s. As we attribute these broad features to the SN ejecta, this is the first time we have observed the transition of a Type Ibn SN to a Type Ib SN.
4944. Photometric data for SN 2009ip
ID:
ivo://CDS.VizieR/J/ApJ/787/163
Title:
Photometric data for SN 2009ip
Short Name:
J/ApJ/787/163
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present time series photometric and spectroscopic data for the transient SN 2009ip from the start of its outburst in 2012 September until 2013 November. These data were collected primarily with the new robotic capabilities of the Las Cumbres Observatory Global Telescope Network, a specialized facility for time domain astrophysics, and includes supporting high-resolution spectroscopy from the Southern Astrophysical Research Telescope, Kitt Peak National Observatory, and Gemini Observatory. Based on our nightly photometric monitoring, we interpret the strength and timing of fluctuations in the light curve as interactions between fast-moving ejecta and an inhomogeneous circumstellar material (CSM) produced by past eruptions of this massive luminous blue variable (LBV) star. Our time series of spectroscopy in 2012 reveals that, as the continuum and narrow H{alpha} flux from CSM interactions declines, the broad component of H{alpha} persists with supernova (SN)-like velocities that are not typically seen in LBVs or SN impostor events. At late times, we find that SN 2009ip continues to decline slowly, at <~0.01 mag/day, with small fluctuations in slope similar to Type IIn supernovae (SNe IIn) or SN impostors but no further LBV-like activity. The late-time spectrum features broad calcium lines similar to both late-time SNe and SN impostors. In general, we find that the photometric and spectroscopic evolution of SN 2009ip is more similar to SNe IIn than either continued eruptions of an LBV star or SN impostors but we cannot rule out a nonterminal explosion. In this context, we discuss the implications for episodic mass loss during the late stages of massive star evolution.
4945. Photometric Data for the Bright Stars
ID:
ivo://CDS.VizieR/II/128
Title:
Photometric Data for the Bright Stars
Short Name:
II/128
Date:
21 Oct 2021
Publisher:
CDS
Description:
References are given to the photometric data available for 9008 stars in the Bright Star Catalog.
4946. Photometric data of HD 209458b
ID:
ivo://CDS.VizieR/J/ApJ/790/53
Title:
Photometric data of HD 209458b
Short Name:
J/ApJ/790/53
Date:
21 Oct 2021
Publisher:
CDS
Description:
The hot Jupiter HD 209458b is particularly amenable to detailed study as it is among the brightest transiting exoplanet systems currently known (V-mag = 7.65; K-mag = 6.308) and has a large planet-to-star contrast ratio. HD 209458b is predicted to be in synchronous rotation about its host star with a hot spot that is shifted eastward of the substellar point by superrotating equatorial winds. Here we present the first full-orbit observations of HD 209458b, in which its 4.5 {mu}m emission was recorded with Spitzer/IRAC. Our study revises the previous 4.5 {mu}m measurement of HD 209458b's secondary eclipse emission downward by ~35% to 0.1391%_-0.0069%_^+0.0072^%, changing our interpretation of the properties of its dayside atmosphere. We find that the hot spot on the planet's dayside is shifted eastward of the substellar point by 40.{deg}9+/-6.{deg}0, in agreement with circulation models predicting equatorial superrotation. HD 209458b's dayside (T_bright_= 1499+/-15 K) and nightside (T_bright_= 972+/-44 K) emission indicate a day-to-night brightness temperature contrast smaller than that observed for more highly irradiated exoplanets, suggesting that the day-to-night temperature contrast may be partially a function of the incident stellar radiation. The observed phase curve shape deviates modestly from global circulation model predictions potentially due to disequilibrium chemistry or deficiencies in the current hot CH_4_ line lists used in these models. Observations of the phase curve at additional wavelengths are needed in order to determine the possible presence and spatial extent of a dayside temperature inversion, as well as to improve our overall understanding of this planet's atmospheric circulation.
4947. Photometric data of V582 Lyr and V1016 Oph
ID:
ivo://CDS.VizieR/J/AJ/158/193
Title:
Photometric data of V582 Lyr and V1016 Oph
Short Name:
J/AJ/158/193
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new CCD photometric light curves about two eclipsing binaries of V582 Lyr and V1016 Oph. Our observations were carried out by the SARA 91.4 cm telescope of America in 2016 and the 60 cm telescope of Chile in 2018. V582 Lyr's spectra type was classified as K5, and its radial velocity was determined using the LAMOST spectral survey. There are absorptions in the observed H{alpha} line and excess emissions in the subtracted H{alpha} line, which show weak chromospheric activity. We obtained the updated ephemeris information for V582 Lr and V1016 Oph, and found that their orbital periods are both decreasing. We concluded that the decreased rate is -0.474 (+/-0.011)x10^-7^ days/yr for V582 Lyr and 3.460 (+/-0.014)x10^-7^ days/yr for V1016 Oph. For V582 Lyr, the period variation was interpreted as a mass transfer from the secondary component to the primary one, and the corresponding rate is dM_2_/dt=-1.10 (+/-0.03)x10^-7^ M_{sun}_/yr. For V1016 Oph, we explain it by transferring from the primary component to the secondary one, and the corresponding rate is dM_1_/dt=-2.69 (+/-0.04)x10^-7^ M_{sun}_/yr. The photometric solution of V1016 Oph was obtained by analyzing the CCD photometry with the Wilson-Devinney program. We also obtained the orbital parameters of V1016 Oph by simultaneously analyzing our BVRI light curves and radial-velocity curve from the LAMOST low-resolution spectral survey. Finally, our orbital solution shows that they are contact eclipsing binaries with contact factors of 3.35 (+/-0.08)% for V582 Lyr and 41.0 (+/-0.1)% for V1016 Oph.
4948. Photometric decomposition of barred galaxies
ID:
ivo://CDS.VizieR/J/AJ/133/2846
Title:
Photometric decomposition of barred galaxies
Short Name:
J/AJ/133/2846
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a nonparametric method for decomposition of the light of disk galaxies into disk, bulge, and bar components. We have developed and tested the method on a sample of 68 disk galaxies for which we have acquired I-band photometry. The separation of disk and bar light relies on the single assumption that the bar is a straight feature with a different ellipticity and position angle from that of the projected disk. Here we present the basic method, but we recognize that it can be significantly refined.
4949. Photometric distances of exoplanets
ID:
ivo://CDS.VizieR/J/MNRAS/444/711
Title:
Photometric distances of exoplanets
Short Name:
J/MNRAS/444/711
Date:
21 Oct 2021
Publisher:
CDS
Description:
Colour-magnitude diagrams form a traditional way of presenting luminous objects in the Universe and compare them to each other. Here, we estimate the photometric distance of 44 transiting exoplanetary systems. Parallaxes for seven systems confirm our methodology. Combining those measurements with fluxes obtained while planets were occulted by their host stars, we compose colour-magnitude diagrams in the near and mid-infrared. When possible, planets are plotted alongside very low mass stars and field brown dwarfs, who often share similar sizes and equilibrium temperatures. They offer a natural, empirical, comparison sample. We also include directly imaged exoplanets and the expected loci of pure blackbodies. Irradiated planets do not match blackbodies; their emission spectra are not featureless. For a given luminosity, hot Jupiters' daysides show a larger variety in colour than brown dwarfs do and display an increasing diversity in colour with decreasing intrinsic luminosity. The presence of an extra absorbent within the 4.5{mu}m band would reconcile outlying hot Jupiters with ultra-cool dwarfs' atmospheres. Measuring the emission of gas giants cooler than 1000K would disentangle whether planets' atmospheres behave more similarly to brown dwarfs' atmospheres than to blackbodies, whether they are akin to the young directly imaged planets, or if irradiated gas giants form their own sequence.
4950. Photometric follow-up observations of GJ 436b
ID:
ivo://CDS.VizieR/J/ApJ/694/1559
Title:
Photometric follow-up observations of GJ 436b
Short Name:
J/ApJ/694/1559
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents multiband photometric follow-up observations of the Neptune-mass transiting planet GJ 436b, consisting of five new ground-based transit light curves obtained in 2007 May. Together with one already published light curve, we have at hand a total of six light curves, spanning 29 days. The analysis of the data yields an orbital period P=2.64386+/-0.00003 days, midtransit time T_c_[HJD]=2454235.8355+/-0.0001, planet mass M_p_=23.1+/-0.9M_{earth}_=0.073+/-0.003M_Jup_, planet radius R_p_=4.2+/-0.2R_{earth}_=0.37+/-0.01R_Jup_, and stellar radius R_s_=0.45+/-0.02R_{sun}_. Our typical precision for the midtransit timing for each transit is about 30s. We searched the data for a possible signature of a second planet in the system through transit timing variations (TTV) and variation of the impact parameter. The analysis could not rule out a small, of the order of a minute, TTV and a long-term modulation of the impact parameter, of the order of +0.2yr^-1^.