Photometries of B, V, Rc, Ic, y, J, and Ks bands and low dispersion optical spectroscopic observations of Nova V1280 Sco, started soon after the outburst, are reported. We show that V1280 Sco is an Fe II nova and it is going through the historically slowest spectroscopic evolution. The rapid decline observed in the early phase was caused by formation of a dust shell. We estimate the abundances of CNO using the absorption lines on a spectrum at pre-maximum, and find over-abundances by [C/Fe] ~ 1.4, [N/Fe] > 2.0 and [O/Fe] ~ 1.1.
The preliminary analysis of the optical data of SN1999cw show that this object has the photometric and spectroscopic behavior of a Type Ia supernova similar to SN1991T, reaching an apparent magnitude at maximum B(max)=14.30 and a Delta m_{15}(B)=0.94.
A small fraction of subluminous B stars show short-period, multiperiodic light variations and form the new class of pulsating star known as EC 14026 variables, after the prototype. The Multi-Site Spectroscopic Telescope (MSST) is a virtual instrument and is also the name of a collaboration that aims to open up a new observational window to provide access to a mode identification for and an asteroseismological analysis of the pulsating sdB star PG 1605+072. Although the primary aim is to obtain time resolved spectroscopy it also includes the most extended photometric monitoring campaign for PG …
The K20 survey is an ESO VLT optical and near-infrared spectroscopic survey aimed at obtaining spectral information and redshifts of a complete sample of about 550 objects to K_s\leq20.0 over two independent fields with a total area of 52 arcmin^2. In this paper we discuss the scientific motivation of such a survey, we describe the photometric and spectroscopic properties of the sample, and we release the $K_s$-band photometric catalog. Extensive simulations showed that the sample is photometrically highly complete to K_s=20. The observed galaxy counts and the R-K_s color distribution are cons…
We present an analysis of spectroscopic and photometric data for cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron et al.(2001), and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey.
We present spectroscopic and photometric data for 920 galaxies selected in 68 fields of the Aquarius Cluster Catalog. Typically the 15 brightest candidate members with magnitudes in the range 16 < b_J < 21 were selected for observations, and ~ 71% turn out to be cluster members. Using the new redshift determinations we assign galaxies to groups and clusters, and by including data from the literature we calculate systemic velocities and velocity dispersions for 74 clusters, each with redshifts measured for at least 6 individual galaxies.
We present a comparison between the spectroscopic catalog of the HDF recently published by Cohen et al and the redshifts measured by our group for those objects using photometric techniques. We perform this comparison in order to characterize the errors associated to the photometric redshift technique. The spectroscopic sample includes over 140 objects in the HDF proper, representing the deepest, cleanest, most complete spectroscopic catalog ever compiled. We study each object for which our redshift and the one measured by Cohen et al disagree. In most cases the photometric evidence is strong …
We use the deepest and most complete redshift catalog currently available (the Hubble Deep Field (HDF) North supplemented by new HDF South redshift data) to minimize residuals between photometric and spectroscopic redshift estimates. The good agreement at z_spec < 1.5 shows that model libraries provide a good description of the galaxy population. At z_spec > 2.0, the systematic shift between photometric and spectroscopic redshifts decreases when the modeling of the absorption by the interstellar and intergalactic media is refined. As a result, in the entire redshift range 0 < z < 6, residuals …
We describe a new method for measuring the true redshift distribution of any set of objects studied only photometrically. The angular cross-correlation between objects in a photometric sample with objects in some spectroscopic sample as a function of the spectroscopic z, in combination with standard correlation measurements, provides sufficient information to reconstruct the true redshift distribution of the photometric sample. This technique enables the robust calibration of photometric redshifts even beyond spectroscopic limits. The spectroscopic sample need not resemble the photometric one …
We present a survey for z~3 Lyman break galaxies (LBGs) associated with damped Lyman alpha systems (DLAs) with the primary purpose of determining the DLA-LBG cross-correlation. This paper describes the acquisition and analysis of imaging and spectroscopic data of 9 quasar fields having 11 known z~3 DLAs covering an area of 465 arcmin^2. Using deep u'BVRI images, 796 LBG candidates to an apparent R_AB magnitude of 25.5 were photometrically selected from 17,343 sources detected in the field. Spectroscopic observations of 529 LBG candidates using Keck LRIS yielded 339 redshifts. We have conservat…
We present theoretical predictions for photometric and spectroscopic signatures of rings around transiting extrasolar planets. On the basis of a general formulation for the transiting signature in the stellar light curve and the velocity anomaly due to the Rossiter effect, we compute the expected signals analytically for a face-on ring system, and numerically for more general configurations. We study the detectability of a ring around a transiting planet located at a=3AU for a variety of obliquity and azimuthal angles, and find that it is possible to detect the ring signature both photometrica…
We investigate, using simulated galaxy catalogues, the completeness of searches for massive clusters of galaxies in redshift surveys or imaging surveys with photometric redshift estimates, i.e. what fraction of clusters (M>10^14/h Msun) are found in such surveys. We demonstrate that the matched filter method provides an efficient and reliable means of identifying massive clusters even when the redshift estimates are crude. In true redshift surveys the method works extremely well. We demonstrate that it is possible to construct catalogues with high completeness, low contamination and both varyi…
We present a sample of 9 nearby F-type stars with detailed spectroscopic analyses to investigate the Basel Stellar Library (BaSeL) in two photometric systems simultaneously, UBV Johnson and uvby Stromgren. The sample corresponds to potential targets of the central seismology programme of the COROT space experiment, which have been recently observed at Observatoire de Haute-Provence (OHP, France). The atmospheric parameters Teff, [Fe/H], and log g obtained from the BaSeL models are compared with spectroscopic determinations as well as with results of other photometric calibrations. Moreover, ne…
We investigate the radial dependence of the spectroscopic properties, in particular the Mg2, <Fe> and H beta spectroscopic indices, in a sample of galaxies spanning a wide range of absolute luminosity in the Coma cluster. After allowing for the magnitude dependence of these indices, we find a significant gradient in Mg2, in the sense that galaxies in the core of the cluster have stronger Mg2. We find only weak gradients in <Fe> and H beta. Using the model grids presented in an earlier paper in this series, we attribute the Mg2 gradient to changes in metal abundance. One possible mechanism to c…
We present the analysis of simultaneous multicolour $uvyI_{\rm C}$ photometry and low-resolution spectroscopy for the rapidly rotating $β$ Cephei star SY Equ. From the photometric time series, we confirm the dominant pulsation frequency, $f_1$ = 6.029 d$^{-1}$, and we find an evidence for two additional modes. In spectroscopy, the highest peak occurs at $f_{\rm a}$ = 0.197 d$^{-1}$ or its alias 0.803 d$^{-1}$. It can be interpreted either in terms of a binary motion or as the $g$-mode pulsation. In addition, we reveal the pulsation mode with frequency of about 6.029 d$^{-1}$, i.e. the same whi…
The cross-correlation between the ROSAT all-sky survey (~150000 sources) and the Tycho mission (~1000000 stars) catalogs has selected about 14000 stellar X-ray sources (RasTyc sample, Guillout et al. 1999). About 200-300 stars have been spectroscopically observed at high resolution both in the Halpha and LiI lambda-6708 regions with Elodie and Aurelie spectrographs of the OHP (Observatoire de l'Haute Provence, France). The aim was to classify the RasTyc star sample in terms of age and chromospheric activity level and to detect eventual binary systems. Photometric and spectroscopic follow-up ob…
We present high angular resolution observations with the Keck Interferometer, high dispersion spectroscopic observations with Keck/NIRSPEC, and near-IR photometric observations from PAIRITEL of a sample of 11 solar-type T Tauri stars in 9 systems. We use these observations to probe the circumstellar material within 1 AU of these young stars, measuring the circumstellar-to-stellar flux ratios and angular size scales of the 2.2 micron emission. Our sample spans a range of stellar luminosities and mass accretion rates, allowing investigation of potential correlations between inner disk properties…
We present the results of a long-term program of monitoring of the famous SN 1995N, observed both in photometry (UBVRIJHK bands) and optical spectroscopy. The observations span a period of about 9 years. These new data, together with others available in literature, extend from the X-ray wavelengths to the radio, and allow to estimate the total energy radiated by the supernova over a decade after its explosion.
This is the second paper in a series studying the photometric and spectroscopic properties of galaxies of different luminosities in the Coma cluster. The sample selection, spectroscopic observations and completeness functions are presented here. To study the spectral properties of galaxies as a function of their local environment, two fields were selected for spectroscopic observations to cover both the core (Coma1) and outskirts (ie. south-west of the core and centered on NGC4839)- (Coma3) of the cluster. Medium resolution spectroscopy (6-9 Å) was carried out for a total of 490 galaxies in bo…
Results of a blind test of photometric redshift predictions against spectroscopic galaxy redshifts obtained in the Hubble Deep Field with the Keck Telescope are presented. The best photometric redshift schemes predict spectroscopic redshifts with a redshift accuracy of |Delta-z|<0.1 for more than 68 percent of sources and with |Delta-z|<0.3 for 100 percent, when single-feature spectroscopic redshifts are removed from consideration. This test shows that photometric redshift schemes work well at least when the photometric data are of high quality and when the sources are at moderate redshifts.
We present CCD UBVI photometry and high-resolution spectroscopy of the intermediate age open cluster NGC 3960. The colour - magnitude diagrams (CMDs) derived from the photometric data and interpreted with the synthetic CMD method allow us to estimate the cluster parameters. We derive: age = 0.9 or 0.6 Gyr (depending on whether or not overshooting from convective regions is included in the adopted stellar models), distance (m-M)0 = 11.6 +/- 0.1, reddening E(B-V) = 0.29 +/- 0.02, differential reddening Delta E(B-V) = 0.05 and approximate metallicity between solar and half of solar. We obtained h…
In a large coordinated attempt to further our understanding of the $p$-mode pulsating sdB star PG1605+072, the Multi-Site Spectroscopic Telescope (MSST) collaboration has obtained simultaneous time-resolved spectroscopic and photometric observations. The photometry was extended by additional WET data which increased the time base. This contribution outlines the analysis of the MSST photometric light curve, including the four-colour BUSCA data from which chromatic amplitudes have been derived, as well as supplementary FUV spectra and light curves from two different epochs. These results have th…
Given multiband photometric data from the SDSS DR6, we estimate galaxy redshifts. We employ a Random Forest trained on color features and spectroscopic redshifts from 80,000 randomly chosen primary galaxies yielding a mapping from color to redshift such that the difference between the estimate and the spectroscopic redshift is small. Our methodology results in tight RMS scatter in the estimates limited by photometric errors. Additionally, this approach yields an error distribution that is nearly Gaussian with parameter estimates giving reliable confidence intervals unique to each galaxy photom…
We present the first optical photometric study of the active galaxy SBS 0748+499. First, we present B, V, R and I photometric data: total magnitudes and B-V, B-R, B-I colors; surface brightness, color and geometric profiles, with emphasis on the morphology and its relation to the global photometric properties of this galaxy. Then, from our surface photometry study we derive the bulge-to-disk luminosity ratio B/D in the four bands. We find that the host galaxy shows a bar (a ~ 8 kpc) and a low-brightness spiral structure. The morphological classification for the host galaxy of this AGN is SBab.…
The line profile variability and photometric variability of the O9.5 Vp star HD93521 are examined in order to establish the properties of the non-radial pulsations in this star. Fourier techniques are used to characterize the modulations of the He I 5876, 6678 and H-alpha lines in several spectroscopic time series and to search for variations in a photometric time series. Our spectroscopic data confirm the existence of two periods of 1.75 and 2.89 hr. The line profiles, especially those affected by emission wings, exhibit also modulations on longer time scales, but these are epoch-dependent an…
This paper is aimed at giving an overview of the global properties of the rich cluster of galaxies ABCG 209. This is achieved by complementing the already available data with new medium resolution spectroscopy and NIR photometry which allow us to i) analyse in detail the cluster dynamics, distinguishing among galaxies belonging to different substructures and deriving their individual velocity distributions, using a total sample of 148 galaxies in the cluster region, of which 134 belonging to the cluster; ii) derive the cluster NIR luminosity function; iii) study the Kormendy relation and the p…
In an effort to determine the orbital period of the star DI Cru, we made photometric and spectroscopic observations of this object between 1996 and 2002. The star is highly variable on short (few hours) as well as on long (few months) time-scales. The optical spectrum is rich in strong emission lines of high ionization species. Temporal Variance Spectrum - TVS - analysis shows that the He II 4686A line has P Cyg-like variable absorption, while NV 4603/19A lines have a strong and broad variable component due to the continuum fluorescence from a source (stellar atmosphere/optically thick wind) o…
We present new high and low resolution spectroscopic and photometric data of nine members of the young association CMa R1. All the stars have circumstellar dust at some distance as could be expected from their association with reflection nebulosity. Four stars (HD 52721, HD 53367, LkHalpha 220 and LkHalpha 218) show Halpha emission and we argue that they are Herbig Be stars with discs. Our photometric and spectroscopic observations on these stars reveal new characteristics of their variability. We present first interpretations of the variability of HD 52721, HD 53367 and the two LkHalpha stars…
We present uvby-beta CCD photometry of the field of the open cluster NGC 1893. Our photometry is deep enough to cover the complete main sequence B spectral type. We identify ~50 very likely members of the cluster down to spectral type B9-A0, some of which have much higher reddenings than the average. We derive a color excess E(b-y) = 0.33+-0.03 and a dereddened distance modulus V_0 - M_V = 13.9+-0.2. From the beta index, we identify several candidates as emission-line stars, for which we have obtained spectroscopy. Three of them display spectra corresponding to spectral type F, but showing H-a…
From SDSS commissioning photometric and spectroscopic data, we investigate the utility of photometric redshift techniques to the task of estimating QSO redshifts. We consider empirical methods (e.g. nearest-neighbor searches and polynomial fitting), standard spectral template fitting and hybrid approaches (i.e. training spectral templates from spectroscopic and photometric observations of QSOs). We find that in all cases, due to the presence of strong emission-lines within the QSO spectra, the nearest-neighbor and template fitting methods are superior to the polynomial fitting approach. Applyi…
We present an analysis of spectroscopic and photometric observations of cool DQ white dwarfs based on improved model atmosphere calculations. In particular, we revise the atmospheric parameters of the trigonometric parallax sample of Bergeron, Leggett, & Ruiz, and discuss the astrophysical implications on the temperature scale and mean mass, as well as the chemical evolution of these stars. We also analyze 40 new DQ stars discovered in the first data release of the Sloan Digital Sky Survey. Our analysis confirms that effective temperatures derived from model atmospheres including carbon are si…
Using the Gemini Near-InfraRed Spectrograph (GNIRS), we have completed a near-infrared spectroscopic survey for K-bright galaxies at z~2.3, selected from the MUSYC survey. We derived spectroscopic redshifts from emission lines or from continuum features and shapes for all 36 observed galaxies. The continuum redshifts are driven by the Balmer/4000 Angstrom break, and have an uncertainty in dz/(1+z) of <0.019. We use this unique sample to determine, for the first time, how accurately redshifts and other properties of massive high-redshift galaxies can be determined from broadband photometric dat…
We present medium-resolution spectroscopy of a sample of stars in the second Galactic quadrant selected from the literature because their colours suggest that they are moderately-reddened early-type stars at very large distances. From the derived spectral types and observed colours, we calculate distances to all these objects. For a sizable fraction of our sample, we find distances well in excess of what is expected for Perseus Arm objects, even allowing for rather generous errors. In the interval l=150degr-180degr, there is a large number of objects with distances in excess of 4 kpc, which ar…
We describe a new RR Lyrae identification technique based on out-of-phase single-epoch photometric and spectroscopic observations contained in SDSS Data Release 6 (DR-6). This technique detects variability by exploiting the large disparity between the g-r color and the strength of the hydrogen Balmer lines when the two observations are made at random phases. Comparison with a large sample of known variables in the SDSS equatorial stripe (Stripe 82) shows that the discovery efficiency for our technique is ~85%. Analysis of stars with multiple spectroscopic observations suggests a similar effici…
We present results from a spectroscopic study of ~4000 galaxies in a 6.2 square degree field in the direction of the Aquarius supercluster and a smaller typical field region in Cetus, down to R<19.5. Galaxy redshifts were measured using the Two Degree Field system on the Anglo-Australian Telescope, and form part of our wider efforts to conduct a spectro-photometric and weak gravitational lensing study of these regions. At the magnitude limit of the survey, we are capable of probing L_* galaxies out to z~0.4. We construct median spectra as a function of various survey parameters as a diagnostic…
An analysis of the candidate embedded stellar systems in the reflection nebulae vdBH-RN26, vdBH-RN38, vdBH-RN53a, GGD20, ESO95-RN18 and NGC6595 is presented. Optical spectroscopic data from CASLEO (Argentina) in conjunction with near infrared photometry from the 2MASS Point Source Catalogue were employed. The analysis is based on source surface density, colour-colour and colour-magnitude diagrams together with theoretical pre-main sequence isochrones. We take into account the field population affecting the analysis by carrying out a statistical subtraction. The fundamental parameters for the s…
The results of the redshift measurements and of the detailed surface photometry in BVR of the compact group ShCG 376 are presented. The radial velocity dispersion, the virial mass, the total luminosity, the M/L ratio, and the crossing time of the group are estimated. The group consists of eight accordant redshift spiral galaxies. Four (or possibly five) of the group members have emission-line spectra. Such morphological content and the number of emission-line galaxies are very atypical for compact galaxy groups. There are signs of interaction between some members of the group. It is suggested …
We have imaged an empty area of 34'x34' one and a half degree north of the Virgo cluster core to survey for intracluster planetary nebula candidates. We have implemented and tested a fully automatic procedure for the selection of emission line objects in wide-field images, based on the on-off technique from Ciardullo and Jacoby. Freeman et al. have spectroscopically confirmed a sample of intracluster planetary nebulae in one Virgo field. We use the photometric and morphological properties of this sample to test our selection procedure. In our newly surveyed Virgo field, 75 objects were identif…
We present new spectroscopic and photometric data for 137 early-type galaxies in nine clusters, and for a set of nearby standard galaxies. The clusters studied are Perseus (A0426), Pisces, A0262, A0347, J8, HMS0122+3305, 7S21, A2199 and A2634. Our spectroscopic data comprise radial velocities (cz), central velocity dispersions (sigma) and magnesium line strength indices (Mg). Internal errors (derived from repeat observations) are 7.6% on each measurement of sigma, and 0.010 mag on each Mg measurement. We correct the major published datasets to a standard aperture size, and define a new `standa…
We present a detailed optical spectroscopic and B,V,I,Halpha photometric study of the metal-deficient cometary blue compact dwarf (BCD) galaxy SBS 1415+437. We derive an oxygen abundance 12+log(O/H)=7.61+/-0.01 and 7.62+/-0.03 (Z =Zsun/20) in the two brightest H II regions, among the lowest in BCDs. The helium mass fractions in these regions are Y=0.246+/-0.003 and 0.243+/-0.010. Four techniques based on the equivalent widths of the hydrogen emission and absorption lines, the spectral energy distribution and the colours of the galaxy are used to put constraints on the age of the stellar popula…
We report on the detection of pulsations in the far ultraviolet (hereafter FUV) light curves of PG1219+534, PG1605+072, and PG1613+426 obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) in time-tagged mode (TTAG). Exposures of the order of a few Ksecs were sufficient to observe the main frequencies of PG1219+534 and PG1605+072 and confirm the detection of a pulsation mode at the surface of PG1613+426 as reported from ground. For the first time we derive time-resolved spectroscopic FUSE data of a sdB pulsator (PG1605+072) and comment its line profile variation diagram (hereafter lp…
We present a new spectrum extraction technique which employs optimal weights for the spectral extraction, deblends the overlapping spectra, determines the precise sky background, and takes into account correlations between errors correctly for STIS slitless observations. We obtained roughly 250 optimally extracted spectra in a deep STIS field as well as self-confirming redshift measurements for these objects, including a galaxy at $z=6.68$. In addition, we identified five isolated emission-line objects in the dispersed image that were not accounted for by objects detected in the direct image. …
