- 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.
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Search Results
- 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.
- 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.
- 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.
- 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.
- 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^.
- ID:
- ivo://CDS.VizieR/J/ApJS/187/275
- Title:
- Photometric histories of recurrent novae
- Short Name:
- J/ApJS/187/275
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I collect virtually all photometry of the 10 known galactic recurrent novae (RNe) and their 37 known eruptions. This consists of my modern measures of nearly all archival plates (providing the only data for half of 37 known eruptions), my own 10000 CCD magnitudes from 1987 to present (providing virtually all of the magnitudes in quiescence for seven RNe), over 140000 visual magnitude estimates recorded by amateur astronomers (who discovered half the known eruptions), and the small scattering of magnitudes from all the literature. From this, I produce various uniform products: (1) BVRIJHK comparison star magnitudes and BV comparison star sequences to cover the entire range of eruption; (2) complete light curves for all eruptions; (3) best-fit B and V light curve templates; (4) orbital periods for all but one RN; (5) exhaustive searches for all missed eruptions; (6) measured discovery efficiencies since 1890; (7) true recurrence time scales; (8) predicted next eruption dates; (9) variations on time scales of minutes, hours, days, months, years, decades, and century; (10) uniform distances and extinctions to all RNe; (11) BV colors at peak and UBVRIJHK colors at minimum, all with extinction corrections; and (12) the spectral energy distributions over UBVRIJHK. Highlights of this work include the discoveries of one new RN, six previously unknown eruptions, and the orbital periods for half the RNe. The goal of this work is to provide uniform demographics for answering questions like the "What is the death rate of RNe in our Galaxy?" and "Are the white dwarfs gaining or losing mass over each eruption cycle?." An important use of this work is for the question of whether RNe can be the progenitors of Type Ia supernovae.
- ID:
- ivo://CDS.VizieR/J/A+A/522/A88
- Title:
- Photometric identification of BHB stars
- Short Name:
- J/A+A/522/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the performance of some common machine learning techniques in identifying Blue Horizontal Branch (BHB) stars from photometric data. To train the machine learning algorithms, we use previously published spectroscopic identifications of BHB stars from Sloan Digital Sky Survey (SDSS) data. We investigate the performance of three different techniques, namely k nearest neighbour classification, kernel density estimation for discriminant analysis and a support vector machine (SVM). We discuss the performance of the methods in terms of both completeness (what fraction of input BHB stars are successfully returned as BHB stars) and contamination (what fraction of contaminating sources end up in the output BHB sample). We discuss the prospect of trading off these values, achieving lower contamination at the expense of lower completeness, by adjusting probability thresholds for the classification. We also discuss the role of prior probabilities in the classification performance, and we assess via simulations the reliability of the dataset used for training. Overall it seems that no-prior gives the best completeness, but adopting a prior lowers the contamination. We find that the support vector machine generally delivers the lowest contamination for a given level of completeness, and so is our method of choice. Finally, we classify a large sample of SDSS Data Release 7 (DR7) photometry using the SVM trained on the spectroscopic sample. We identify 27,074 probable BHB stars out of a sample of 294,652 stars. We derive photometric parallaxes and demonstrate that our results are reasonable by comparing to known distances for a selection of globular clusters. We attach our classifications, including probabilities, as an electronic table, so that they can be used either directly as a BHB star catalogue, or as priors to a spectroscopic or other classification method. We also provide our final models so that they can be directly applied to new data.
- ID:
- ivo://CDS.VizieR/J/A+A/501/461
- Title:
- Photometric masses of early-type lens galaxies
- Short Name:
- J/A+A/501/461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The largest spectroscopically selected sample of strong gravitational lens systems presented and analyzed to date is that of the Sloan Lens ACS (SLACS) survey. For the 57 massive early-type lens galaxies in the sample, photometric and spectroscopic measurements are available from the Sloan Digital Sky Survey (SDSS). By using the SDSS multicolor photometry and lens modeling, we study stellar-mass properties and the luminous and dark matter composition of the early-type lens galaxies in the sample.
- ID:
- ivo://CDS.VizieR/II/18
- Title:
- Photometric Measurements, Eggen (102,65,62) System
- Short Name:
- II/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of photometric measures in Eggen's (102, 65, 62) system has been compiled at the Institut d'Astronomie de l'Universite de Lausanne. A catalog of individual observations and of weighted means are included, with an explanation of the coded numbering system.
