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We present a newly discovered magnetically active binary system detected by Yunnan-Hong Kong wide field survey, with an orbital period of 0.60286 days. Two color photometry for the system was performed using the 1 m Cassegrain telescope of Yunnan Observatories with its CCD (Charge-Coupled Device) camera. In the observed light curves, there are clearly different light maxima existed in the out-of-eclipse regions. We made spectroscopic observations for the binary system using the 2.4 m telescope and YFOSC (Yunnan Faint Object Spectrograph and Camera) of Lijiang station of Yunnan Observatories, China. The radial velocity curve was derived for primary star of the binary system. The primary star exhibited strong chromospheric activity, which confirms that the distortion of the light curves results from the starspot activity on the primary star. Through analyzing the light curves and RV (Radial Velocity) curve mentioned above by means of the W-D (Wilson-Devinney) code, orbital parameters and starspot configuration of the binary system are obtained. Finally, we have discussed the properties of the binary system, and given the prospects on the future work.

The results of a spectroscopic survey of H alpha emission line stars associated with fourteen bright rimmed clouds are presented. Slit-less optical spectroscopy was carried out with the Inter University Centre for Astronomy and Astrophysics (IUCAA) 2m telescope and IUCAA Faint Object Spectrograph and Camera (IFOSC). H alpha emission line was detected from 173 objects. Among them 85 objects have a strong H alpha emission line with its equivalent width larger than 10 A. Those are classical T Tauri stars. 52 objects have a weak H alpha emission line with its equivalent width less than 10 A and do not show intrinsic near-infrared excess. Those are weak-line T Tauri stars. On the other hand, 36 objects have a weak H alpha emission line (

We present a multiwavelength characterization of the planetary nebula (PN) NGC 6905 and its [Wolf–Rayet]-type ([WR]) central star (CSPN) HD 193949. Our Nordic Optical Telescope Alhambra Faint Object Spectrograph and Camera (ALFOSC) spectra and images unveil in unprecedented detail the high-ionization structure of NGC 6905. The high-quality spectra of HD 193949 allowed us to detect more than 20 WR features including the characteristic O-bump, blue bump, and red bump, which suggests a spectral type no later than a [WO2]-subtype. Moreover we detect the Ne VII and Ne VIII broad emission lines, rendering HD 193949 yet another CSPN with Teff ≲ 150 kK exhibiting such stellar emission lines. We studied the physical properties (Te and ne) and chemical abundances of different regions within NGC 6905 including its low-ionization clumps; abundances are found to be homogeneous. We used the PoWR stellar atmosphere code to model the spectrum of HD 193949, which is afterwards used in a photoionization model performed with CLOUDY that reproduces the nebular and dust properties for a total mass in the 0.31–0.47 M⊙ range and a mass of C-rich dust of ∼2 × 10−3 M⊙. Adopting a current stellar mass of 0.6 M⊙, our model suggests an initial mass ∼1 M⊙ for HD 193949, consistent with the observations. © 2021 The Author(s)., VMAGG acknowledges support from the Programa de Becas posdoctorales of the Dirección General de Asuntos del Personal Académico of the Universidad Nacional Autónoma de México (DGAPA, UNAM, Mexico). VMAGG and JAT acknowledge funding by DGAPA UNAM PAPIIT project IA100720. JAT also acknowledges support from the Marcos Moshinsky Fundation (Mexico). GR acknowledge support from Consejo Nacional de Ciencia y Tecnología (CONACYT) for student scholarship. MAG acknowledges support of the Spanish Ministerio de Ciencia, Innovación y Universidades grant PGC2018-102184-B-I00, cofunded by FEDER funds. LS acknowledges funding by DGAPA UNAM PAPIIT project IN-101819. GR-L acknowledges support from CONACYT grant 263373 and PRODEP (Mexico). This work is based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos in La Palma, Spain, of the Instituto de Astrofisica de Canarias. This work uses public data from the IR telescope Spitzer Space Telescope through the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory at the California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). WISE is a joint project of the University of California (Los Angeles, USA) and the JPL/Caltech. The Infrared Astronomical Satellite (IRAS) was a joint project of the US, UK, and the Netherlands. This research is based on observations with AKARI, a JAXA project with the participation of ESA. This work has make extensive use of the NASA’s Astrophysics Data System., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

We report the results of the STRong lensing Insights from the Dark Energy Survey (STRIDES) follow-up campaign of the late 2017/early 2018 season. We obtained spectra of 65 lensed quasar candidates either with EFOSC2 on the NTT or ESI on Keck, which confirm 10 new gravitationally lensed quasars and 10 quasar pairs with similar spectra, but which do not show a lensing galaxy in DES images. Eight lensed quasars are doubly imaged with source redshifts between 0.99 and 2.90, one is triply imaged by a group (DESJ0345-2545, $z=1.68$), and one is quadruply imaged (quad: DESJ0053-2012, $z=3.8$). Singular isothermal ellipsoid models for the doubles, based on high-resolution imaging from SAMI on SOAR or NIRC2 on Keck, give total magnifications between 3.2 and 5.6, and Einstein radii between 0.49 and 1.97 arcseconds. After spectroscopic follow-up, we extract multi-epoch $grizY$ photometry of confirmed lensed quasars and contaminant quasar+star pairs from the first 4 years of DES data using parametric multi-band modelling, and compare variability in each system's components. By measuring the reduced ${\chi}^2$ associated with fitting all epochs to the same magnitude, we find a simple cut on the less variable component that retains all confirmed lensed quasars, while removing 94 per cent of contaminant systems with stellar components. Based on our spectroscopic follow-up, this variability information can improve selection of lensed quasars and quasar pairs from 34-45 per cent to 51-70 per cent, with the majority of remaining contaminants being compact star-forming galaxies. Using mock lensed quasar lightcurves we demonstrate that selection based only on variability will over-represent the quad fraction by 10 per cent over a complete DES magnitude-limited sample (excluding microlensing differences), explained by the magnification bias and hence lower luminosity (more variable) sources in quads., Comment: 22 pages, 16 figures, submitted to MNRAS

Results of BVRI photometric studies of 131 stars in the stellar association Cyg OB7 are presented. Observational data were obtained with the 2.6-m telescope at the Byurakan Observatory during 2000, 2002, 2004, and 2011 using the ByuFOSC-2 and SCORPIO spectral cameras. Observations made in 2007 on the 182-cm telescope (Asiago, Italy) at the Padova Astronomical Observatory with the AFOSC (Asiago Faint Object Spectrograph and Camera) detector system are also used. Variations with amplitudes ranging from 0m.2 to 2m.16 are detected in 42 of the stars. Variability is observed for the first time in 31 of the 42 stars. The brightness of 32 of the stars was essentially unchanged during the time of our measurements. All of the 42 variables lie very close to the T Tau type stars on a two-color diagram.

We report the results of spectral and photometric observations of DQ Her. Available spectra from International Ultraviolet Explorer (IUE), Hubble Space Telescope Faint Object Spectrograph (HST - FOS) and CCD photometry of one night were used. Some profiles revealing the variations of some spectral lines at different times are presented. There is variation with time for photometric observations and the brightness of DQ Her is changed from 14 mag. to 17.7 mag with clear display of burst. The ultraviolet luminosity for emitting region is in the range of (1.9x1031 erg s −1). The mass accretion rate is in the range of (3.5x10−12 M⊙yr −1). The line flux modulations at different times can be explained in terms of the accretion curtain model for intermediate polars, Kim & Beuermann (1996).

We report optical observations of TGSS J1054+5832, a candidate high-redshift ($z=4.8\pm2$) steep-spectrum radio galaxy, in $r$ and $i$ bands using the faint object spectrograph and camera mounted on 3.6-m Devasthal Optical Telescope (DOT). The source previously detected at 150 MHz from Giant Meterwave Radio Telescope and at 1420 MHz from Very Large Array has a known counterpart in near-infrared bands with $K$-band magnitude of AB 22. The source is detected in $i$-band with AB$24.3\pm0.2$ magnitude in the DOT images presented here. The source remains undetected in the $r$-band image at a 2.5$\sigma$ depth of AB 24.4 mag over an $1.2''\times1.2''$ aperture. An upper limit to $i-K$ color is estimated to be $\sim$2.3, suggesting youthfulness of the galaxy with active star formation. These observations highlight the importance and potential of the 3.6-m DOT for detections of faint galaxies., Comment: 7 pages, 2 figures, Accepted in Jr. of Astrophysics & Astronomy (JApA)

We present SPLOT, a small scale pilot survey to test the potential of snapshot (single epoch) linear imaging polarimetry as a supplementary tool to traditional transient follow-up. Transients exist in a vast volume of observational parameter space and polarimetry has the potential to highlight sources of scientific interest and add value to near real-time transient survey streams. We observed a sample of $\sim 50$ randomly selected optical transients with the EFOSC2 and SofI instruments, on the 3.6m New Technology Telescope (NTT) to test the feasibility of the survey. Our sample contained a number of interesting individual sources: a variety of supernovae, X-ray binaries, a tidal disruption event, blazar outbursts, and, by design, numerous transients of unknown nature. We discuss the results, both for the individual sources and the survey in detail. We provide an overview on the success and limitations of SPLOT and also describe a novel calibration method for removing instrumental polarisation effects from Nasymth-mounted telescopes. We find that a SPLOT-like survey would be a benefit to the large scale future transient survey streams such as LSST. The polarimetric measurements have added scientific value to a significant number of the sources and, most importantly, has shown the potential to highlight unclassified transient sources of scientific interest for further study., Comment: Accepted in MNRAS. 20 pages, 10 figures, 3 tables. Also contains a 10 page, two part appendix with unpolarised standard star measurements used for calibration (A) and individual source information and light curves (B). Corrected more typos

Mt. Abu Faint Object Spectrograph and Camera-Pathfinder (MFOSC-P) is an instrument currently under development for PRL 1.2m Optical-Near Infrared Telescope at Mt. Abu. It is a pathfinder instrument for a bigger and more complex next generation instrument on upcoming PRL 2.5m telescope. MFOSC-P has been conceptualized as a general purpose user’s instrument with sufficient ease in its operation. It offers options for both the imaging as well spectroscopy within the same optical chain in visible waveband (4500-8500 angstroms). The optics has been designed to provide ‘seeing limited imaging’ in astronomy standard Bessell’s B, V, R and I filters. Three modes of spectroscopy with resolutions (λ/Δλ) 2000, 1000 and 500 around 6500, 5500 and 6000 angstroms are achieved with plane reflection gratings. The mechanical system of the instrument has been designed and successfully evaluated for its structural integrity using finite element analysis. Here we present the optical and opto-mechanical designs of the instrument, which have been successfully developed in house under several existing technical constraints. The results of finite element analysis of the instrument are also presented.

The Beijing Faint Object Spectrograph and Camera (BFOSC) is one of the most important instruments of the 2.16-m telescope of the Xinglong Observatory. Every year there are ~ 20 SCI-papers published based on the observational data of this telescope. In this work, we have systemically measured the total efficiency of the BFOSC of the 2.16-m reflector, based on the observations of two ESO flux standard stars. We have obtained the total efficiencies of the BFOSC instrument of different grisms with various slit widths in almost all ranges, and analysed the factors which effect the efficiency of telescope and spectrograph. For the astronomical observers, the result will be useful for them to select a suitable slit width, depending on their scientific goals and weather conditions during the observation; For the technicians, the result will help them systemically find out the real efficiency of telescope and spectrograph, and further to improve the total efficiency and observing capacity of the telescope technically., 13 pages, 11 figures, 4 tables, accepted for publication in RAA

EFOSC2 (the European Southern Observatory Faint Object Spectrograph and Camera v2) is one of the workhorse instruments on ESO's New Technology Telescope (NTT), and is one of the most popular instruments at La Silla observatory. It is mounted at a Nasmyth focus, and therefore exhibits strong, wavelength and pointing-direction dependent instrumental polarisation. In this document we describe our efforts to calibrate the broadband imaging polarimetry mode, and provide a calibration for broadband B, V, R filters to a level that satisfies most use cases (i.e. polarimetric calibration uncertainty ~0.1%). We make our calibration codes public. This calibration effort can be used to enhance the yield of future polarimetric programmes with EFOSC2, by allowing good calibration with a greatly reduced number of standard star observations. Similarly, our calibration model can be combined with archival calibration observations to post-process data taken in past years, to form a EFOSC2 legacy archive with substantial scientific potential., 10 pages, 4 figures. Accepted for publication in PASA

This study expands the coverage and improves the homogeneity of the distribution of MILES template stars in the parameter space, as well as extends the wavelength coverage of the template spectra to the far red beyond the Ca\,{\sc{ii}} triplet. To achieve this we have carried out a major observational campaign using the OMR long-slit spectrograph mounted on the NAOC 2.16\,m telescope and the YFOSC long-slit spectrograph mounted on the YNAO 2.4\,m telescope. The original sample is based on the MILES library, supplemented by 918 stars selected from PASTEL database. In total, 822 OMR and 1,324 YFOSC spectra, covering respectively the wavelength ranges $\lambda\lambda$3800--5180 and $\lambda\lambda$5150--9000, have been collected and reduced. The spectra have a mean resolution FWHM (full-width at half-maximum) of $\sim 3.3$\,{\AA} and are wavelength- and flux-calibrated to an accuracy of $\sim 20$\,km\,s$^{-1}$ and $\sim 5$\,per\,cent, respectively. The spectra are further corrected for systematic errors in the wavelength calibration to an accuracy of $\sim 4$\,km\,s$^{-1}$ by cross-correlating with the theoretical spectra. Almost all the spectra have an average signal to noise ratio (SNR) better than 100 per pixel. Combined with the MILES spectra, there are now 1,731, 1,542, 1,324 and 1,273 stars with spectra covering respectively $\lambda\lambda$3800--5180, $\lambda\lambda$3800--7500, $\lambda\lambda$5150--9000 and $\lambda\lambda$3800--9000. This paper describes our template star selection, the observation and data reduction, and presents the reduced spectra collected hitherto., Comment: 17 pages, 20 figures, MNRAS, accepted

As a facility used for astronomical research, the Lijiang 2.4-m telescope of Yunnan Astronomical Observatories, requires the ability to change one auxiliary instrument with another in as short a time as possible. This arises from the need to quickly respond to scientific programs (e.g. transient observation, time domain studies) and changes in observation conditions (e.g. seeing and weather conditions). In this paper, we describe the design, construction and test of hardware and software in the rapid instrument exchange system (RIES) for the Cassegrain focal station of this telescope, which enables instruments to be quickly changed at night without much loss of observing time. Tests in the laboratory and at the telescope show that the image quality and pointing accuracy of RIES are satisfactory. With RIES, we observed the same Landolt standard stars almost at the same time with the Princeton Instruments VersArray 1300B Camera (PICCD) and the Yunnan Faint Object Spectrograph and Camera (YFOSC), while both were mounted at the Cassegrain focus. A quasi-simultaneous comparison shows that the image quality of the optical system inside the YFOSC is comparable with that provided by the PICCD.

We present the first orbit-resolved ultraviolet spectroscopic observations of the two polar systems EU UMa and ST LMi obtained with the Hubble Space Telescope Faint Object Spectrograph (HST FOS) and International Ultraviolet Explorer (IUE) during their intermediate- and low-luminosity states in the period between 1982 and 2003. Different line profiles of the two systems showing variations of line fluxes at different orbital phases are presented. This paper focuses on the C IV emission line at 1550 A produced in the accretion stream, presenting calculations of spectral line fluxes, ultraviolet luminosities, and accretion rates for the two systems. Our analysis of the spectroscopic data reveals changes with orbital phase of the emission line profiles that correspond to the light curve variations of both EU UMa and ST LMi in the optical and infrared bands. The variations of line fluxes are attributed to variations of both density and temperature as a result of a changing rate of mass transfer from the secondary star to the white dwarf. The ultraviolet luminosity and accretion rate of EU UMa are smaller than the ultraviolet luminosity and accretion rate of ST LMi.

Blazars, a type of Active Galactic Nuclei, present a particular orientation of their jets close to the line ofsight. Their radiation is thus relativistically beamed, giving rise to extreme behaviors, specially strong variability on very short time-scales (i.e., microvariability). Here we present simultaneous photometric and polarimetric observations of two relatively nearby blazars, 1ES 1959+650 and HB89 2201+044, that were obtained using the Calar Alto Faint Object Spectrograph mounted at the 2.2 m telescope in Calar Alto, Spain. An outstanding characteristic of these two blazars is the presence of well resolved host galaxies. This particular feature allows us to produce a study of their intrinsic polarization, a measurement of the polarization state of the galactic nucleus unaffected by the host galaxy. To carry out this work, we computed photometric fluxes from which we calculated the degree and orientation of the blazars polarization. Then, we analyzed the depolarizing effect introduced by the host galaxy with the main goal to recover the intrinsic polarization of the galactic nucleus, carefully taking into consideration the spurious polarimetric variability introduced by changes in seeing along the observing nights. We find that the two blazars do not present intra-night photo-polarimetric variability, although we do detect a significant inter-night variability. Comparing polarimetric values before and after accounting for the host galaxies, we observe a significant difference in the polarization degree of about 1 % in the case of 1ES 1959+650, and 0.3 % in the case of HB89 2201+044, thus evidencing the non-negligible impact introduced by the host galaxies. We note that this host galaxy effect depends on the weaveband, and varies with changing seeing conditions, so it should be particularly considered when studying frequency-dependent polarization in blazars., 11 pages, 8 figures

We present an analysis of the blank sky spectra observed with the Faint Object Spectrograph on board the Hubble Space Telescope. We study the diffuse sky emission from ultraviolet to optical wavelengths, which is composed of the zodiacal light (ZL), diffuse Galactic light (DGL), and residual emission. The observations were performed toward 54 fields distributed widely over the sky, with the spectral coverage from 0.2 to 0.7 um. In order to avoid contaminating light from the earthshine, we use the data collected only in orbital nighttime. The observed intensity is decomposed into the ZL, DGL, and residual emission, in eight photometric bands spanning our spectral coverage. We found that the derived ZL reflectance spectrum is flat in the optical, which indicates major contribution of C-type asteroids to the interplanetary dust (IPD). In addition, the ZL reflectance spectrum has an absorption feature at ~0.3 um. The shape of the DGL spectrum is consistent with those found in earlier measurements and model predictions. While the residual emission contains a contribution from the extragalactic background light, we found that the spectral shape of the residual looks similar to the ZL spectrum. Moreover, its optical intensity is much higher than that measured from beyond the IPD cloud by Pioneer10/11, and also than that of the integrated galaxy light. These findings may indicate the presence of an isotropic ZL component, which is missed in the conventional ZL models., This paper is dedicated to the memory of Dr. Kimiaki Kawara; accepted for publication in PASJ

We report 192 previously unpublished optical linear polarization measurements of quasars obtained in April 2003, April 2007, and October 2007 with the European Southern Observatory Faint Object Spectrograph and Camera (EFOSC2) instrument attached to the 3.6m telescope at the La Silla Observatory. Each quasar was observed once. Among the 192 quasars, 89 have a polarization degree $p \geq 0.6\%$, 18 have $p \geq 2\%$, and two have $p \geq 10\%$., Comment: Accepted for publication in A&A

We present preliminary results from a pencil-beam spectroscopic survey of low-luminosity quasars at z ≈ 2.2 - 2.5 . Our goal is to compare these sources with low redshift analogues of similar luminosity. High s/n and moderate resolution spectra were obtained for 15 sources using the faint object spectrograph Osiris on the 10m Gran Telescopio Canarias. The new data make possible an almost unprecedented comparison between sources with the same (moderate) luminosity at widely different cosmic epochs. Preliminary analysis of our spectra confirms the presence of a relatively evolved population of quasars radiating at modest L / L Edd . A notable difference between the low and high z quasars may involve the presence of lower metallicity quasars at high redshift.

We present a study of the properties of star-forming regions within a sample of 7 Wolf-Rayet (WR) galaxies. We analyze their morphologies, colours, star-formation rate (SFR), metallicities, and stellar populations combining broad-band and narrow-band photometry with low-resolution optical spectroscopy. The $UBVRI$ observations were made through the 2m HCT (Himalayan Chandra Telescope) and 1m ARIES telescope. The spectroscopic data were obtained using the Hanle Faint Object Spectrograph Camera (HFOSC) mounted on the 2m HCT. The observed galaxies are NGC 1140, IRAS 07164+5301, NGC 3738, UM 311, NGC 6764, NGC 4861 and NGC 3003. The optical spectra have been used to search for the faint WR features, to confirm that the ionization of the gas is consequence of the massive stars, and to quantify the oxygen abundance of each galaxy using several and independent empirical calibrations. We detected the broad features originated by WR stars in NGC 1140 and NGC 4861 and used them to derive their population of massive stars. Using our H$\alpha$ images we have identified tens of regions within these galaxies, for which we derived the SFR. For all regions we found that the most recent star-formation event is 3 - 6 Myr old. We used the optical broad-band colours in combination with Starburst99 models to estimate the internal reddening and the age of the dominant underlying stellar population within all these regions. Knots in NGC 3738, NGC 6764 and NGC 3003 generally show the presence of an important old (400 - 1000 Myr) stellar population. However, the optical colours are not able to detect stars older than 20 - 50 Myr in the knots of the other four galaxies. This fact suggests both the intensity of the starbursts and that the star-formation activity has been ongoing for at least some few tens of million years in these objects., Comment: 22 Pages, 14 Figures, accepted for publication in MNRAS

Ultraviolet spectra of IP Peg and DW UMa observed with Hubble Space Telescope Space Telescope Imaging Spectrograph & Faint Object Spectrograph (HST STIS FOS) and International Ultraviolet Explorer (IUE) satellites were analyzed during the period between 1989–1994 and 1985–2004. Different profiles of two systems showing variations of line fluxes at different orbital phases are presented. Both IP Peg and DW UMa are characterized by emission lines in high, intermediate and low states. DW UMa is characterized by absorption lines in an unusual low state. This paper focuses on the C IV emission line at 1550 A produced in an accretion disk for two systems ( Saito et al., 2005 , Knigge et al., 2000 ), by calculating spectral line fluxes. Our results show that there are significant variations of line fluxes with time for two systems. The variations of line fluxes are attributed to the variations of both density and temperature as a result of a changing rate of mass transfer from the secondary star to the white dwarf ( Saito et al., 2005 , Knigge et al., 2000 ). These results from the IUE and HST observations support a white dwarf model atmospheres of IP Peg and DW UMa producing sufficient UV flux for orbital modulations.

We present time-series imaging polarimetry observations of a very nearby superluminous supernova 2018hti at z = 0.063, to probe its explosion mechanism and shed light on the energy source powering superluminous supernovae (SLSNe). We obtain linear polarimetry using the Alhambra Faint Object Spectrograph and Camera on board the 2.5 m Nordic Optical Telescope. Our observations show polarization at the ~1.9% level before and after the supernova reached light-curve maximum. However, this level of polarization is consistent with the line-of-sight interstellar polarization; hence, the polarization from the supernovae itself was not detected at a level of >3σ. This suggests that the explosion of SN 2018hti is almost spherical, similar to previous polarimetry studies of other SLSNe.

We present the optical imaging polarimetric observations of comet C/2009 P1(Garradd) at three different phase angles e.g., 28.2$^\circ$, 28.1$^\circ$ and 21.6$^\circ$. The observations were carried out using IUCAA Faint Object Spectrograph and Camera mounted on Cassegrain focus of the 2-m Telescope of IGO, IUCAA, Pune in R$_{comet}$, R photometric bands, on 21 and 22 March 2012 and ARIES Imaging Polarimeter mounted on Cassegrain focus of the 1.04-m Sampurnanand Telescope of ARIES, Nainital in R photometric band, on 23 May 2012. We show the presence of a jet activity in the rotational gradient treated image of comet Garradd at phase angle 28.1$^\circ$. These jets are mainly oriented towards the Sun and extended up to $\sim$ 5100 km from the cometary photocenter. The antisolar extension of jet seems to be fainter, which is extended up to $\sim$ 1800 km. It is found that the comet Garradd shows negative polarization at phase angle 21.6$^\circ$. The degree of polarization derived for Garradd is in good agreement with other comets at nearly similar phase angles e.g., comets 67P/Churyumov-Gerasimenko, 22P/Kopff, 1P/Halley, C/1990 K1 (Levy), 4P/Faye, and C/1995 O1 (Hale-Bopp) at phase angle $\sim$ 28$^\circ$, and 47P/Ashbrook-Jackson at phase angle $\sim$ 21.6$^\circ$, respectively. It is also found that the degree of polarization of dusty coma of comet Garradd at phase angle $\sim$ 28$^\circ$ is high but, not as high as in the case of comet Hale-Bopp., Comment: (Accepted in MNRAS on September 26, 2013) 8 pages, 3 figures, 3 tables

By comparing several integral field units (IFU), we focus on the image slicer and prove that the field matching of image slicer can be equal to radius matching in the off-axis telecentric light path. We prove that the single slice is still on the same spherical surface after rotation by using matrix, so spherical mirrors array come from one spherical surface has been demonstrated in theory. Based on the above conclusion, we have succeeded in modification 2.16-meter telescope and BFOSC (Bologna Faint Object Spectrograph and Camera) into integral field spectrograph. At the end, we propose a modification method that a slit imaging spectrograph can be turned into integral field spectrograph by inserting an appropriate image slicer.

BVRI photometric observations of Geosynchronous Earth Orbit (GEO) objects were conducted with the 1.5 m Cassini Telescope located in Loiano, Italy. The observatory is operated by the INAF (National Institute for Astrophysics) Astronomical Observatory of Bologna, Italy. The Ritchey–Chretien optical system is equipped with the BFOSC (Bologna Faint Object Spectrograph and Camera), a multipurpose instrument for imaging and spectroscopy, with an EEV CCD (1340 × 1300 pixel). This paper deals with the results of the photometric observations of several targets from the SSN (Space Surveillance Network) catalog that were acquired in May and December 2013. In particular: • 1 piece of debris from Ekran: SSN 29014 • 1 piece of debris from LES 8: SSN 13753 • 5 SL-12 rocket bodies: SSN 38104, 17125, 20926, 17705 and 27444 • 2 IUS rocket bodies: SSN 19913, 21641 • 3 operational GEO satellite: SSN 34810, 27509, 28912 • 1 non-operational GEO satellites: SSN 02653 Observations of Landolt standard fields were performed for calibration purposes. In addition, long exposures with sidereal tracking with no filter have been taken where the object image is trailed to study the brightness variability over timescales of a second. This paper describes the results of the code developed in order to detect the primary frequencies of the object’s brightness variation.

The Xinglong 2.16-m reflector is the first 2-meter class astronomical telescope in China. It was jointly designed and built by the Nanjing Astronomical Instruments Factory (NAIF), Beijing Astronomical Observatory (now National Astronomical Observatories, Chinese Academy of Sciences, NAOC) and Institute of Automation, Chinese Academy of Sciences in 1989. It is Ritchey-Chr\'{e}tien (R-C) reflector on an English equatorial mount and the effective aperture is 2.16 meters. It had been the largest optical telescope in China for $\sim18$ years until the Guoshoujing Telescope (also called Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST) and the Lijiang 2.4-m telescope were built. At present, there are three main instruments on the Cassegrain focus available: the Beijing Faint Object Spectrograph and Camera (BFOSC) for direct imaging and low resolution ($R\sim500-2000$) spectroscopy, the spectrograph made by Optomechanics Research Inc. (OMR) for low resolution spectroscopy (the spectral resolutions are similar to those of BFOSC) and the fiber-fed High Resolution Spectrograph (HRS, $R\sim30000-65000$). The telescope is widely open to astronomers all over China as well as international astronomical observers. Each year there are more than 40 ongoing observing projects, including 6-8 key projects. Recently, some new techniques and instruments (e.g., astro-frequency comb calibration system, polarimeter and adaptive optics) have been or will be tested on the telescope to extend its observing abilities., Comment: 16 figures, 5 tables; accepted for publication in PASP

We observed the open clusters NGC 1664 (43 exposures) and M35 (42 exposures) by the Yunnan Faint Object Spectrograph and Camera in the 2.4 m telescope at Yunnan Astronomical Observatory on 2011 January 3, and processed them by a method recently proposed by us. The result shows that there is a geometric distortion effect in the field of view and the maximum distortion is ~ 0.25'' (i.e. 1 pixel). After correcting the geometric distortion, the precision of stellar positional measurement is significantly improved. The best precision in each direction is 6 mas for well-exposed stars.

We present ultraviolet spectra of 62 cataclysmic variables observed with Hubble Space Telescope Space Telescope Imaging Spectrograph & Faint Object Spectrograph (HST STIS FOS) to diagnose cataclysmic variables with enhanced NV/C IV line flux ratios. We concentrated on calculating the line flux ratios of the above mentioned sample. We found that a number of cataclysmic variables reveal enhanced NV/C IV line flux ratios in agreement with the previous studies ( de Martino and Gansicke, 2009 , Gansicke et al., 2003 ). Also we found that two new systems (U SCO, V1974 CYG) reveal enhanced NV/C IV line flux ratios. Such anomalous line flux ratios confirmed that these CVs went through a phase of thermal timescale mass transfer (TTSMT) and now accrete CNO processed material from a companion stripped of its external layers ( Gansicke et al., 2003 , Gansicke, 2004 , de Martino and Gansicke, 2009 ).

In this Letter, the Evans and Koratkar Atlas of Hubble Space Telescope Faint Object Spectrograph Spectra of Active Galactic Nuclei and Quasars is used to study the redward asymmetry in CIV broad emission lines (BELs). It is concluded that there is a highly significant correlation between the spectral index from 10 GHz to 1350 $��$ and the amount of excess luminosity in the red wing of the CIV BEL ($>99.9999%$ significance level for the full sample and the radio loud subsample independently, but no correlation is found for the radio quiet subsample). This is interpreted as a correlation between radio core dominance and the strength of the CIV redward asymmetry. The data implies that within the quasar environment there is BEL gas with moderately blueshifted emission associated with the purely radio quiet quasar phenomenon (the accretion disk) and the radio jet emission mechanism is associated with a redward BEL component that is most prominent for lines of sight along the jet axis. Thus, radio quiet quasars have CIV BELs that tend to show blueshifted excess and radio loud quasars show either a red or blue excess with the tendency for a dominant red excess increasing as the line of sight approaches the jet axis., To appear in ApJ

We have studied the SED of the quasar LBQS 0102-2713. The available multiwavelength data are one optical spectrum between 3200 and 7400 A, 7 HST FOS spectra between 1700 and 2300 A, one GALEX NUV flux density and a K_S magnitude obtained from NED, and 3 public ROSAT PSPC pointed observations in the 0.1$-$2.4 keV energy band. The alpha_ox values obtained are -2.3 and -2.2, respectively, comparable to BAL quasars. The ROSAT photon index is 6.0+-1.3. The 2500 A luminosity density is about a factor of 10 higher compared to the mean of the most luminous SDSS quasars. We argue that the object might be indicative for a new class of quasars with an unusual combination in their UV-, X-ray, and N_H properties., Comment: 16 pages, 8 figures, accepted by ApJ

The study of kiloparsec-scale dual active galactic nuclei (AGN) will provide important clues to understand the co-evolution between the host galaxies and their central supermassive black holes undergoing a merging process. We present long-slit spectroscopy of the J0038$+$4128, a kiloparsec-scale dual AGN candidate discovered by Huang et al. recently, using the Yunnan Faint Object Spectrograph and Camera (YFOSC) mounted on Li-Jiang 2.4-m telescope at Yunnan observatories. From the long-slit spectra, we find that the average relative line-of-sight (LOS) velocity between the two nuclei (J0038$+$4128N and J0038$+$4128S) is about 150 km s$^{-1}$. The LOS velocities of the emission lines from the gas ionized by the nuclei activities and of the absorption lines from stars governed by the host galaxies for different regions of the J0038$+$4128 exhibit the same trend. The same velocities trend indicates that the gaseous disks are co-rotating with the stellar disks in this ongoing merge system. We also find several knots/giant HII regions scattered around the two nuclei with strong star formation revealed by the observed line ratios from the spectra. Those regions are also detected clearly in HST $F336W/U$-band and HST $F555W/V$-band images., Comment: 12 pages, 5 figures, 3 tables, Research in Astronomy and Astrophysics accepted

Aims. We searched for photometric variability in a sample of hot, hydrogen-deficient planetary nebula nuclei (PNNi) with “PG 1159” or “O VI” spectral type, most of them embedded in a bipolar or elliptical planetary nebula envelope (PNe). These characteristics may indicate the presence of a hidden close companion and an evolution affected by episodes of interaction between them. Methods. We obtained time-series photometry from a sample of 11 candidates using the Nordic Optical Telescope (NOT) with the Andalucia Faint Object Spectrograph and Camera (ALFOSC), modified with our own control software to be able to observe in a high-speed multi-windowing mode. The data were reduced on-line with the real time photometry (RTP) code, which allowed us to detect periodic variable stars with small amplitudes from CCD data in real time. We studied the properties of the observed modulation frequencies to investigate their nature. Results. We report the first detection of low-amplitude pulsations in the PNNi VV 47, NGC 6852, and Jn 1. In addition, we investigated the photometric variability of NGC 246. Time-series analysis shows that the power spectra of VV 47, NGC 6852, and NGC 246 are variable on time scales of hours. Power spectra from consecutive nights of VV 47 and NGC 6852 show significant peaks in different frequency regions. The same type of variability is present in NGC 246 in 2 observing runs separated by 3 days. Changes are also found in the power spectra of VV 47 and NGC 246 during the same night. The VV 47 power spectra are peculiar since they present modulation frequencies in a wide range from 175 to 7600 μ Hz. This is different from the previously known pulsating PNNi where no frequencies are found above ~3000 μ Hz. The high-frequency modulation observed in VV 47 may be due to g -modes triggered by the ϵ -mechanism, observed for the first time.

Using the Multimission Archives at Space Telescope (MAST), we have extracted spectra and determined continuum light curves for 175 Seyfert Galaxies that have been observed with the International Ultraviolet Explorer (IUE) and the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST). To obtain the light curves as a function of Julian Date, we used fix bins in the object's rest frame, and measured small regions (between 30 and 60 Angstroms) of each spectrum's continuum flux in the range 1150 Angstroms to 3200 Angstroms. We provide access to the UV light curves and other basic information about the observations in tabular and graphical form via the Internet at this http URL

We report a study of the spectra and structure of the accretion disk of the dwarf nova V2051 Ophiuchi while the star was in an unusual faint brightness state during 1996. The differences between the UV resonant lines and continuum disk surface brightness distributions indicate a vertically extended disk with the emission from these lines arising from the upper atmospheric layers. Distinct emission along the stream trajectory suggests the occurrence of gas stream overflow. Spatially resolved spectra show that the lines are in emission at all disk radii. The Balmer decrement becomes shallower with increasing radius. The FWHMs of the emission lines show differences with respect to that expected for a gas in Keplerian rotation, and the line intensities drop with a radial dependency of I ∝ R-1.78. The uneclipsed light contributes about 5%-10% of the total flux, and its spectrum is dominated by a Balmer jump and strong lines in emission. Broad absorption bands, possibly due to Fe II, are present in the spectra of the disk side farther away from the secondary star, suggesting it arises from absorption by a extended gas region above the disk; the differences between the spectra of the hemisphere farther from and nearer to the secondary star are interpreted in terms of chromospheric emission from a disk with a nonnegligible opening angle (limb-brightening effect). Stellar atmosphere model fits to the extracted white dwarf spectrum lead to a temperature TWD = 9500 K and a distance d = 67 pc if the inner disk is opaque or d = 92 pc if the inner disk is optically thin.

We investigate the variety in quasar UV spectra (??1020-1600), with emphasis on the weak emission lines in the Ly? forest region, using principal component analysis (PCA). We use 50 smooth continuum-fitted quasar spectra (0.14 < z < 1.04) taken by the Hubble Space Telescope (HST) Faint Object Spectrograph. The first, second, and third principal component spectra (PCS) account for 63.4%, 14.5%, and 6.2% of the variance, respectively, and the first seven PCS account for 96.1% of the total variance. Three weak emission lines in the Ly? forest are identified as Fe II ?1070.95, Fe II + Fe III ?1123.17, and C III* ?1175.88. Using the first two standardized PCS coefficients, we introduce five classifications. By actively using PCS, we can generate artificial quasar spectra that are useful in testing the detection of quasars, DLAs, and the continuum calibration. We show that the power-law-extrapolated continuum is inadequate to perform precise measurements of the mean flux in the Ly? forest because of the weak emission lines and the extended tails of Ly? and Ly?/O VI emission lines. We show that we miss 5.3% of the flux on average, and there are cases where we would miss 14% of the flux. These corrections are essential in the study of the intergalactic medium at high redshift in order to achieve precise measurements of physical properties, cosmological parameters, and the reionization epoch.

The ultraviolet (UV) spectra of 16 blazars ( ~1) from the archives of the Hubble Space Telescope Faint Object Spectrograph have been analyzed in order to study in a systematic way the properties oftheir broad UV emission lines. We find that the luminosities of the most prominent and intense lines, Ly_alpha and C IV lambda1549, are similar to those of normal radio-loud quasars at comparable redshifts. However, the equivalent widths of blazar lines are significantly smaller than those of radio-loud quasars. Therefore, while the intrinsic broad line region luminosity of blazars appears to be indistinguishable from that of radio-loud quasars, their continuum must be comparatively higher, most probably due to relativistic beaming. We have combined the UV luminosities of the de-beamed continuum with the emitting gas velocity to derive estimates of the masses of the central supermassive black holes. The size of the broad line region was computed in two ways: 1) via an empirical relationship between UV continuum luminosity and broad line region size, and 2) through the external photon density required by blazar models to reproduce the inverse Compton components observed at gamma-rays. The second method yields significantly different results from the first method, suggesting that it provides only a very rough estimate or a lower limit on the size of the broad line region. We find that the average mass of the central black holes in blazars is ~2.8e8 Msun, with a large dispersion, comparable to those computed for other radio-loud active galactic nuclei., Comment: published in MNRAS (small changes with respect to preprint previously submitted)

We investigate the ionization mechanisms in the Seyfert galaxy Markarian 78, chosen because its narrow-line region (NLR) is dominated by a strong jet-gas interaction. Our principal aim is to ascertain whether or not shock-related ionization is important. We use Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) optical and UV spectra from four slits, as well as HST Faint Object Spectrograph optical spectra from 10 apertures. Ultimately, several lines of evidence argue against the importance of shocks but in favor of central source photoionization, even for gas that is clearly accelerated by the jet flow. Following earlier work, we compare emission-line ratios with four classes of ionization model: photoionization of optically thick gas (standard and dusty U sequences), photoionization of optically thick and thin gas (Am/i sequence), and fast shocks. Traditional excitation measures are well matched by all three models, with -3.0 < log U < -2.0, -0.5 < log Am/i < +1.0, and 300 km s-1 < Vshock < 500 km s-1. However, several other line ratios provide clear discrimination, with significantly poorer fits for standard and dusty U models and even poorer for shock models. Importantly, our data span a sufficient range of conditions that they show trends in the ratio-ratio plots, and these trends clearly favor central source photoionization models, particularly the Am/i models. To achieve essentially perfect agreement, we make two slight modifications to the Am/i models of Binette et al.: we lower the ionization of the optically thin component (Mrk 78 has somewhat lower than normal excitation), and we increase the nitrogen abundance toward the nucleus. We suspect that this latter effect has introduced ambiguities in previous work. The UV lines are less helpful than anticipated, partly because of their weakness and partly because high ionization parameter photoionization can mimic shocks. An exception is N V, which, in the absence of abundance effects, can provide unambiguous discrimination. We extend the above analysis to include comparison of line profiles. We first show that even slight differences in velocity between pre- and postshock gas (shock scenario) and optically thin and thick gas (Am/i scenario) predict significant profile differences between [O III] λ5007 and other emission lines. The marked absence of such differences argues strongly against the two-component shock models and also demands, for an Am/i model, that optically thin and thick gas have similar velocity distributions. The possible presence, however, of a weak broad low-ionization component may indicate a minor shock contribution. Further evidence against shock ionization is the absence of correlations between line ratios and kinematic parameters (e.g., FWHM or Vpeak); that is, the calmest and the most turbulent gas both have similar ionization. Conversely, a global decrease in excitation away from the nucleus qualitatively supports central source photoionization. Quantitatively, however, Mrk 78 exhibits the so-called Q problem seen in many other active galactic nuclei, although we speculate that a detailed extension of Am/i-type models may resolve the problem without requiring in situ sources of ionization. Finally, we use NLR excitation and far-infrared luminosity to provide two independent estimates of the nuclear ionizing luminosity. Both these estimates match the simple picture of central source photoionization, yielding the observed emission-line luminosity and a plausible (~20%–100%) NLR covering factor. We conclude that despite the NLR in Mrk 78 being strongly disturbed by radio-emitting ejecta, there is little or no evidence for shock-related ionization. There is, however, strong evidence for central source photoionization, including both optically thick and thin gaseous components. In Paper III we make further use of the STIS data to derive the dynamics of the emission-line region and the nature of the jet flow.

A performance study of several CCD cameras of the Chinese Joint Laboratory of Optical Astronomy (CJLOA) is presented. The main results are: 1) We propose a modified classical method to analyse the linearity of CCD cameras. This method is more sensitive and accurate as well as more intuitive, especially in measuring around the 0.1%-0.2% range of nonlinearity. 2) To illustrate the advantage of the method, the linearity performance of the CCD cameras at CJLOA has been measured and analysed. 3) For the CCD systems tested, there is no unique formula to represent the correlation over the entire CCD frame between the deviation from linearity and the pixel value, i.e., different pixel has different correction even though their pixel values are the same. 4) For the BFOSC (BAO Faint Object Spectrograph Camera) Loral CCD camera and the Tek CCD camera at the 1.56-m reflector, blooming (bleeding) happens long before saturation, and we suspect whether it could have resulted from the charge transfer efficiency (CTE) not being high enough.

We present an analysis of optical HST/STIS and HST/FOS spectroscopy of 6 blue stragglers found in the globular clusters M3, NGC6752 and NGC6397. These stars are a subsample of a set of ~50 blue stragglers and stars above the main sequence turn-off in four globular clusters which will be presented in an forthcoming paper. All but the 6 stars presented here can be well fitted with non-LTE model atmospheres. The 6 misfits, on the other hand, possess Balmer jumps which are too large for the effective temperatures implied by their Paschen continua. We find that our data for these stars are consistent with models only if we account for extra absorption of stellar Balmer photons by an ionized circumstellar disk. Column densities of HI and CaII are derived as are the the disks' thicknesses. This is the first time that a circumstellar disk is detected around blue stragglers. The presence of magnetically-locked disks attached to the stars has been suggested as a mechanism to lose the large angular momentum imparted by the collision event at the birth of these stars. The disks implied by our study might not be massive enough to constitute such an angular momentum sink, but they could be the leftovers of once larger disks., Comment: Accepted by ApJ Letters 10 pages, 2 figures

We present a detailed study of the Seyfert 2 galaxy Markarian 78, using continuum and emission-line images and multiaperture spectra from the Hubble Space Telescope (HST) and a deep 3.6 cm VLA image. Our overall aim is to study the interaction between the radio source and the emission-line gas, since ground-based data already indicate the presence of a strong bipolar jet-driven flow. First, in the wider context, Mrk 78 is probably a post-merger system, with a nuclear dust lane, approximate r1/4 continuum profile, and highly extended asymmetric gas distribution. The [O III] and radio images both show complex structures with many similarities but also important differences. A careful comparison shows convincing morphological evidence for jet-gas interaction: (1) the western inner radio jet terminates and flares at the position of a bright [O III] knot; (2) the weaker eastern radio jet changes direction as it encounters a large [O III] knot; (3) most [O III] features appear limb brightened on the upstream side, and flared on the downstream side; and (4) in the outer regions the radio components tend to lie between or adjacent to [O III] knots, indicating the radio and line emitting phases do not easily interpenetrate. In addition to evidence of jet-gas interaction, two features indicate the importance of a central ionizing radiation field: an inner fanlike structure to the east, with a straight kinematically quiet northern edge; and an approximately fanlike extended narrow-line region to the west, lying well outside the radio source. The [O III] line profiles from 10 Faint Object Spectrograph apertures provide further kinematic insight into the jet-gas interaction. (1) On the eastern side, where the radio source is deflected, the [O III] profile contains a highly redshifted component (~700 km s-1) that is also narrow (FWHM ≤ 200 km s-1), indicating significant coherent gas acceleration with almost no induced turbulence. (2) At this location, the [O III] profile is also double, suggesting lateral expansion away from a jet axis, as it burrows into the cloud complex. (3) In contrast, the bright western inner knot, which seems to disrupt the inner radio jet, has essentially undisturbed kinematics. (4) Across the outer complex western region, gas velocities are higher in the region center, decrease at the leading edge and may be highest where radio flows "blow out" of the region. Overall, morphology and kinematics suggest the western side is best described as an initially disrupted jet that then fills, accelerates, and leaks out of a complex incomplete "bubble" of ionized gas. The eastern side is best described as a large centrally illuminated fanlike gas structure that is penetrated, accelerated, and ultimately deflects the radio source. We use these different regions to construct a plausible evolutionary sequence: Initially, a dense (molecular?) cloud enters the jet flow and disrupts it (inner western knot); as time passes, the jet begins to penetrate, accelerate, and ablate the cloud (eastern knot complex); continued jet influence further disperses the cloud fragments, sweeping out channels and gaps (western lobe region). This process may repeat itself many times over the lifetime of the jet. In companion papers, we study the ionization mechanisms and jet properties in more detail using recently acquired Space Telescope Imaging Spectrograph spectra, taking a more complete account of the energetics of the radio source and the ionized gas.

We present consistent emission-line measurements for active galactic nuclei (AGNs), useful for reliable statistical studies of emission line properties. This paper joins a series including similar measurements of 993 spectra from the Large Bright Quasar Survey and 174 spectra of AGNs obtained from the Faint Object Spectrograph (FOS) on the Hubble Space Telescope (HST) prior to the installation of COSTAR. This time we concentrate on 220 spectra obtained with the FOS after the installation of COSTAR, completing the emission line analysis of all FOS archival spectra. We use the same automated technique as in previous papers, which accounts for Galactic extinction, models blended optical and UV iron emission, includes Galactic and intrinsic absorption lines, and models emission lines using multiple Gaussians. We present UV and optical emission line parameters (equivalent widths, fluxes, FWHM, and line positions) for a large number (28) of emission lines including upper limits for undetected lines. Further scientific analyses will be presented in subsequent papers.

We have recalibrated all nonpolarimetric, pre-COSTAR, archival Hubble Space Telescope Faint Object Spectrograph UV and optical spectrophotometry of active galaxies and quasars in order to extract uniformly calibrated spectrophotometric data for further detailed scientific investigations. The raw archival spectra have been recalibrated using the latest algorithms and calibration data. Spectral data contaminated by intermittent noisy diodes and cosmic-ray events have been identified manually and eliminated. Wherever possible we have combined multiple observations of the same source to produce a single spectrum per object with the highest possible signal-to-noise ratio and covering the widest wavelength range, scaling the individual data sets to the same photometric scale where necessary. Detailed quality assurance has been performed to ensure that the merged object spectra are of the highest quality consistent with the limitations of the individual data sets and calibrations. The recalibrated, merged object spectra are available in electronic form. We use this data set to present statistics of the photometric accuracy in the wavelength overlap regions for observations spanning multiple gratings.

The Space Telescope Imaging Spectrograph (STIS) was used to obtain the ultraviolet spectrum of AL Comae 5.5 yr past its 1995 April superoutburst. The spectrum can be fitted by a model of a log g = 8 ± 0.5 white dwarf with a temperature of 16,300 ± 1000 K. Surprisingly, the flux distribution is exactly the same as the Faint Object Spectrograph data obtained 4.5 yr earlier, but the UV fluxes are a factor of 2 lower than the previous measurement, while the optical fluxes remained the same. The implication could be that the temperature of the UV component has remained very similar, but the size of the emitting area has decreased by ~30%. Alternatively, there could be multiple components contributing in the UV, with corresponding changes in temperature and size that produce a similar flux distribution at the two epochs.

We have produced an archive of the ultraviolet low-dispersion spectra for the full set of white dwarf stars observed with the International Ultraviolet Explorer (IUE) satellite over the course of its 18 yr mission. This archive contains the spectra of 322 individual degenerate stars which have been processed to optimize the signal-to-noise for each star. In particular, all spectra have been corrected for residual temporal and thermal effects and placed on the Hubble Space Telescope Faint Object Spectrograph absolute flux scale using procedures described by Massa & Fitzpatrick. Wherever possible, multiple observations of individual stars have been co-added to further enhance signal-to-noise and have been combined into a single spectrum

This paper presents the first detailed analysis of acetylene absorption features observed longward of 190.0 nm in a jovian spectrum by the Faint Object Spectrograph on board the Hubble Space Telescope. The presence of two features located near 207.0 nm can only be explained by a substantial abundance of acetylene in the upper troposphere. Using a Rayleigh–Raman radiative transfer model, it was determined that the acetylene vertical profile is characterized by a decrease in the mole fraction with increasing pressure in the upper stratosphere, a minimum around 14 to 29 mbar, followed by an increase to about 1.5 × 10 −7 in the upper troposphere. Longward of 220 nm, the relatively high contrast of Raman features to the continuum precludes the existence of an optically significant amount of clouds from 150 to 500 mbar unless they are highly reflective. Instead, the reflectivity at these long wavelengths is determined by stratospheric, not tropospheric, scatterers and absorbers. Analysis of the data also suggests that ammonia is extremely undersaturated at pressures below 700 mbar. However, no firm conclusions can be reached because of the uncertainties surrounding its cross section longward of 217.0 nm, which are due to vibrationally excited states.

The spectroscopy of microlensed sources towards the Galactic bulge provides a unique opportunity to study (i) the kinematics of the Galactic bulge, particularly its far-side, (ii) the effects of extinction on the microlensed sources, and (iii) the contributions of the bulge and the disk lenses to the microlensing optical depth. We present the results from such a spectroscopic study of 17 microlensed sources carried out using the ESO Faint Object Spectrograph (EFOSC) at the 3.6 m European Southern Observatory (ESO) telescope. The spectra of the unlensed sources and Kurucz model spectra were used as templates to derive the radial velocities and the extinctions of the microlensed sources. It is shown that there is an extinction shift between the microlensed population and the non-microlensed population but there is no apparent correlation between the extinction and the radial velocity. This extinction offset, in our best model, would imply that 65% of the events are caused by self-lensing within the bulge. The sample needs to be increased to about 100 sources to get a clear picture of the kinematics of the bulge., Comment: 39 pages, 14 figures, Replaced with the version to be published in ApJ

The narrow absorption lines (NALs) that are seen in the rest-frame ultraviolet near the systemic redshift of active galactic nuclei (AGNs) are not always intrinsic to the near-nuclear region but may originate in the host galaxy or in neighboring galaxies intervening along the line of sight. A variety of criteria have been sought—and several identified—as evidence of an intrinsic origin. We have measured both emission and absorption lines in a Hubble Space Telescope Faint Object Spectrograph sample of objects with both C IV and N V NALs within ±5000 km s-1 of the systemic redshift. We find a strong (>99.5% confidence) linear correlation between the N V/C IV ratio in broad emission lines and that in NALs. A control sample of AGNs with NALs separated by larger velocities shows no such correlation. Our finding thus identifies an additional test for the intrinsic nature of NALs in any given object. The correlation shows that the chemical-enrichment histories and/or ionization parameters of the NAL clouds are closely related to those of clouds that produce the broad emission lines.

UV/optical emission lines offer some of the most detailed information obtainable about the intrinsic properties of quasars. Studies of the density, ionization and metal abundance of gas near the accreting black hole are probed through an intriguing but poorly understood complex of correlations between emission lines and overall quasar spectral energy distributions that has long suffered from a lack of large, consistently measured samples. As part of a broader effort to expand and systematize the data upon which these studies are built, we present measurements of the UV/optical emission line parameters in a sample of 158 active galactic nuclei observed with the Faint Object Spectrograph on the Hubble Space Telescope (HST), prior to the installation of COSTAR. We use an automated technique that accounts for galactic reddening, includes iron emission blends, galactic and intrinsic absorption lines, and performs multicomponent fits to the emission line profiles. We present measured line parameters (equivalent width and FWHM) for a large number (28) of different UV/optical lines, including upper limits for undetected lines. We also study the relations between the emission line equivalent widths and luminosity (the Baldwin effect), as well as redshift (evolution). We compare results from this HST FOS sample with our previous measurements of 993 QSOs in the Large Bright Quasar Survey using the same analysis technique and sum the samples to achieve better coverage of the luminosity-redshift plane. We confirm a significant Baldwin effect for UV iron emission from Green et al. and find that evolution dominates the effect for iron and for Si IV emission. The values of the Baldwin effect slopes for all UV emission lines and the dependence of the slopes on the sample's luminosity range point to a change of the SED as the cause of the Baldwin effect in the FOS sample.

We analyzed the absorption line spectra of all quasars observed with the high resolution gratings of the Faint Object Spectrograph on board the Hubble Space Telescope. We examined 788 spectra for 334 quasars, and present line lists and identifications of absorption lines in the spectra of 271 of them. Analysis of the statistics of the Ly-alpha and metal absorption systems are presented in companion papers (Dobrzycki et al. 2001; Scott et al. 2001; Morita et al. 2001). The data and several analysis products are available electronically and on the authors' web site.

Cool gas should be present in galaxy clusters due to stripping of galactic gas, infall onto the cluster, and from cooling flows. We searched for this gas through resonance absorption line observations from low-ionization metal line gas toward six background quasars. Both cooling flow and non-cooling flow clusters were observed, with lines of sight from the inner to outer parts of the cluster (0.2, 10 pages, 2 figures, uses emulateapj.sty; submitted to ApJ

We present a new optical spectroscopic survey of 1777 'star-forming' ('SF') and 366 'non-star-forming' ('non-SF') galaxies at redshifts z < 1 (2143 in total), 22 AGN and 423 stars, observed by instruments such as DEIMOS, VIMOS and GMOS, in 3 fields containing 5 quasi-stellar objects (QSOs) with HST UV spectroscopy. We also present a new spectroscopic survey of 165 'strong' (10^14 < NHI < 10^17 cm^-2), and 489 'weak' (10^13 < NHI < 10^14 cm^-2) intervening HI absorption line systems at z < 1 (654 in total), observed in the spectra of 8 QSOs by COS and FOS on the HST. Combining these new data with previously published galaxy catalogs such as VVDS and GDDS, we have gathered a sample of 654 HI absorption systems and 17509 galaxies at transverse scales < 50 Mpc. We present observational results on the HI-galaxy and galaxy-galaxy correlations at transverse scales r < 10 Mpc, and the HI-HI auto-correlation at transverse scales r < 2 Mpc. The two-point correlation functions are measured both along and transverse to the line-of-sight. We constrain the HI-galaxy statistical connection, as a function of both HI column density and galaxy star-forming activity. Our results are consistent with the following conclusions: (1) the bulk of HI systems on Mpc scales have little velocity dispersion (, Comment: 63 pages, 26 figures, 20 tables; To be accepted by MNRAS (reviewed); Comments still welcome