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We present photoionisation modelling of the intrinsic absorber in the bright quasar HS 1603+3820. We construct spectral energy distribution using optical/UV/X-ray observations as an input to photoionisation calculations. Spectra from Keck telescope show extremely high ratio of CIV to HI, for the first absorber in system A, named A1. This value, together with high column density of CIV ion, puts strong constraints on photoionisation model. We use photoionisation modeling to derive hydrogen number density at the cloud illuminated surface. Estimating bolometric luminosity of HS 1603+3820, from typical formula for quasars, we calculate the distance to A1. The derived location is as close as 0.1 pc, and situates an absorber even closer to the nucleus than the possible location of the Broad Line Region in this object, Comment: 15 pages, 9 figures, submitted to New Astronomy

We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope. From this, we derive a luminosity of M_v = -2.5, a half-light radius of 34 pc and a systemic velocity of -40$ km/s. Our MMT data also provides evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighboring fields. We resolve the velocity dispersion of Segue 2 as 3.4 km/s and the possible stream as about 7 km/s. This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites -- survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts z > 10 and are good candidates for fossils of the reionization epoch., Comment: MNRAS, Submitted

We report optical B-band observations with the Large Binocular Telescope LBT of the isolated neutron star RBS1774. The stacked image with total exposure 2.5h reveals a candidate optical counterpart at mB = 26.96 +- 0.20 at position RA(2000) = 21:43:03.4, DEC(2000)} = +06:54:17:5, within the joint Chandra and XMM-Newton error circles. We analyse archival XMM-Newton observations and derive revised spectral and positional parameters. The predicted optical flux from the extrapolated X-ray spectrum is likely twice as high as reported before. The measured optical flux exceeds the extrapolated X-ray spectral flux by a factor ~40 (15 - 60 at 1sigma confidence). We interpret our detection and the spectral energy distribution as further evidence of a temperature structure over the neutron star's surface and present a pure thermal model reflecting both the SED and the pulsed fraction of the light curve., Comment: 7 pages, 7 figures, submitted to A&A

We present deep imaging of the star-forming dwarf galaxy IC2574 in the M81 group taken with the Large Binocular Telescope in order to study in detail the recent star-formation history of this galaxy and to constrain the stellar feedback on its HI gas. We identify the star-forming areas in the galaxy by removing a smooth disk component from the optical images. We construct pixel-by-pixel maps of stellar age and stellar mass surface density in these regions by comparing their observed colors with simple stellar populations synthesized with STARBURST99. We find that an older burst occurred about 100 Myr ago within the inner 4 kpc and that a younger burst happened in the last 10 Myr mostly at galactocentric radii between 4 and 8 kpc. We analyze the stellar populations residing in the known HI holes of IC2574. Our results indicate that, even at the remarkable photometric depth of the LBT data, there is no clear one-to-one association between the observed HI holes and the most recent bursts of star formation in IC2574. The stellar populations formed during the younger burst are usually located at the periphery of the HI holes and are seen to be younger than the holes dynamical age. The kinetic energy of the holes expansion is found to be on average 10% of the total stellar energy released by the stellar winds and supernova explosions of the young stellar populations within the holes. With the help of control apertures distributed across the galaxy we estimate that the kinetic energy stored in the HI gas in the form of its local velocity dispersion is about 35% of the total stellar energy., Comment: 16 pages, 14 figures, accepted for publication in ApJ

We report the discovery of the progenitor of the recent type IIn SN 2008S in the nearby galaxy NGC 6946. Surprisingly, it was not found in deep, pre-explosion optical images of its host galaxy taken with the Large Binocular Telescope, but only through examination of archival Spitzer mid-IR data. A source coincident with the SN 2008S position is clearly detected in the 4.5, 5.8, and 8.0 micron IRAC bands, showing no evident variability in the three years prior to the explosion, yet is undetected at 3.6 and 24 micron. The distinct presence of ~440 K dust, along with stringent LBT limits on the optical fluxes, suggests that the progenitor of SN 2008S was engulfed in a shroud of its own dust. The inferred luminosity of 3.5x10^4 Lsun implies a modest mass of ~10 Msun. We conclude that objects like SN 2008S are not exclusively associated with the deaths or outbursts of very massive eta Carinae-like objects. This conclusion holds based solely on the optical flux limits even if our identification of the progenitor with the mid-IR source is incorrect., Comment: ApJ letters, in press; corrected a typo

We present deep, wide-field g and r photometry of the transition type dwarf galaxy Leo T, obtained with the blue arm of the Large Binocular Telescope. The data confirm the presence of both very young (<1 Gyr) as well as much older (>5 Gyr) stars. We study the structural properties of the old and young stellar populations by preferentially selecting either population based on their color and magnitude. The young population is significantly more concentrated than the old population, with half-light radii of 104+-8 and 148+-16 pc respectively, and their centers are slightly offset. Approximately 10% of the total stellar mass is estimated to be represented by the young stellar population. Comparison of the color-magnitude diagram (CMD) with theoretical isochrones as well as numerical CMD-fitting suggest that star formation began over 10 Gyr ago and continued in recent times until at least a few hundred Myr ago. The CMD-fitting results are indicative of two distinct star formation bursts, with a quiescent period around 3 Gyr ago, albeit at low significance. The results are consistent with no metallicity evolution and [Fe/H] ~ -1.5 over the entire age of the system. Finally, the data show little if any sign of tidal distortion of Leo T., Comment: 8 pages, 9 figures, some small textual changes, accepted for publication in the Astrophysical Journal

Using the 8.4m Large Binocular Telescope, we observed six GRB afterglows from 2.8 hours to 30.8 days after the burst triggers to systematically probe the late time behaviors of afterglows including jet breaks, flares, and supernova bumps. We detected five afterglows with Sloan r' magnitudes ranging from 23.0-26.3 mag. The depth of our observations allows us to extend the temporal baseline for measuring jet breaks by another decade in time scale. We detected two jet breaks and a third candidate, all of which are not detectable without deep, late time optical observations. In the other three cases, we do not detect the jet breaks either because of contamination from the host galaxy light, the presence of a supernova bump, or the intrinsic faintness of the optical afterglow. This suggests that the basic picture that GRBs are collimated is still valid and that the apparent lack of Swift jet breaks is due to poorly sampled afterglow light curves, particularly at late times., Comment: Accepted by ApJ Letters, 14 pages, 2 figures

We present the analysis of multi-wavelength observations of bright quasar HS1603+3820: the optical data taken with the MMT and Keck telescopes, and X-ray data obtained with the Chandra X-ray Observatory. The optical spectra contain a very large number of absorption lines from numerous heavy elements. We derived X-ray properties of HS1603. The quasar has the optical-to-X-ray slope index alpha_ox of 1.70, which is on the high end of the typical range for radio quiet QSOs. We found 49 individual heavy element absorption clouds, which can be grouped into eleven distinct systems. We determined column densities and redshifts of the individual components. Absorbers from the associated system which is likely spatially closest to the QSO show large CIV to HI column density ratio, reaching ca.20., Comment: Accepted for publication in A&A, 17 pages, 11 figures, 5 tables

In a variability survey of M81 using the Large Binocular Telescope we have discovered a peculiar eclipsing binary (MV ~ -7.1) in the field of the dwarf galaxy Holmberg IX. It has a period of 272 days and the light curve is well-fit by an overcontact model in which both stars are overflowing their Roche lobes. It is composed by two yellow supergiants (V-I ~ 1 mag, T_eff = 4800 K), rather than the far more common red or blue supergiants. Such systems must be rare. While we failed to find any similar systems in the literature, we did, however note a second example. The SMC F0 supergiant R47 is a bright (MV ~ -7.5) periodic variable whose All Sky Automated Survey (ASAS) light curve is well-fit as a contact binary with a 181 day period. We propose that these systems are the progenitors of supernovae like SN 2004et and SN 2006ov, which appeared to have yellow progenitors. The binary interactions (mass transfer, mass loss) limit the size of the supergiant to give it a higher surface temperature than an isolated star at the same core evolutionary stage. We also discuss the possibility of this variable being a long-period Cepheid., Comment: ApJ Letters, accepted, 15 pages, 4 figures, 1 table, and 1 photometry file

We report the first significant detection of an X-ray cluster associated with a powerful (L(bol) ~1e47 erg/sec) radio-loud quasar at high redshift (z=1.06). Diffuse X-ray emission is detected out to ~120 kpc from the CSS quasar 3C 186. A strong Fe-line emission at the z(rest)=1.06 confirms its thermal nature. We find that the CSS radio source is highly overpressured with respect to the thermal cluster medium by ~2-3 orders of magnitude. This provides direct observational evidence that the radio source is not thermally confined as posited in the ``frustrated'' scenario for CSS sources. Instead, the radio source may be young and at an early stage of its evolution. This source provides the first detection of the AGN in outburst in the center of a cooling flow cluster. Powerful radio sources are thought to be triggered by the cooling flows. The evidence for the AGN activity and intermittent outbursts comes from the X-ray morphology of low redshift clusters, which usually do not harbour quasars. 3C186 is a young active radio source which can supply the energy into the cluster and potentially prevent its cooling. We discuss energetics related to the quasar activity and the cluster cooling flow, and possible feedback between the evolving radio source and the cluster., Comment: 5 pages, 3 figures, to appear in Proc. "The X-ray Universe 2005", San Lorenzo de El Escorial, Spain, September 2005

A Chandra ACIS-S observation of PKS 2152-699 reveals thermal emission from a diffuse region around the core and a hotspot located 10" northeast from the core. This is the first detection of thermal X-ray radiation on kiloparsec scales from an extragalactic radio source. Two other hotspots located 47" north-northeast and 26" southwest from the core were also detected. Using a Raymond-Smith model, the first hotspot can be characterized with a thermal plasma temperature of 2.6$\times10^6$ K and an electron number density of 0.17 cm$^{-3}$. These values correspond to a cooling time of about 1.6$\times10^7$ yr. In addition, an emission line from the hotspot, possibly Fe xxv, was detected at rest wavelength 10.04\AA. The thermal X-ray emission from the first hotspot is offset from the radio emission but is coincident with optical filaments detected with broadband filters of HST/WFPC2. The best explanation for the X-ray, radio, and optical emission is that of a `jet-cloud' interaction. The diffuse emission around the nucleus of PKS 2152-699 can be modeled as a thermal plasma with a temperature of 1.2$\times10^7$ K and a luminosity of 1.8$\times10^{41}$ erg s$^{-1}$. This emission appears to be asymmetric with a small extension toward Hotspot A, similar to a jet. An optical hotspot (EELR) is seen less than an arcsecond away from this extension in the direction of the core. This indicates that the extension may be caused by the jet interacting with an inner ISM cloud, but entrainment of hot gas is unavoidable. Future observations are discussed., Comment: To appear in the Astrophysical Journal 21 pages, 5 Postscript figures, 1 table, AASTeX v. 5.2

We present a measurement of the mean intensity of the hydrogen-ionizing background radiation field at low redshift using 906 Ly-alpha absorption lines in 151 quasar spectra from the archives of the Faint Object Spectrograph on the Hubble Space Telescope. Using a maximum likelihood technique and the best estimates possible for each QSO's Lyman limit flux and systemic redshift, we find J(\nu_{0})= 7.6^{+9.4}_{-3.0} x 10^{-23} ergs s^{-1} cm^{-2} Hz^{-1} sr^{-1} at 0.03 < z < 1.67. This is in good agreement with the mean intensity expected from models of the background which incorporate only the known quasar population. When the sample is divided into two subsamples, consisting of lines with z < 1 and z > 1, the values of J(\nu_{0}) found are 6.5^{+38.}_{-1.6} x 10^{-23} ergs s^{-1} cm^{-2} Hz^{-1} sr^{-1}, and 1.0^{+3.8}_{-0.2} x 10^{-22} ergs s^{-1} cm^{-2} Hz^{-1} sr^{-1}, respectively, indicating that the mean intensity of the background is evolving over the redshift range of this data set. Relaxing the assumption that the spectral shapes of the sample spectra and the background are identical, the best fit HI photoionization rates are found to be 6.7 x 10^{-13} s^{-1} for all redshifts, and 1.9 x 10^{-13} s^{-1} and 1.3 x 10^{-12} s^{-1} for z < 1 and z > 1, respectively., Comment: 8 Latex pages, 3 encapsulated Postscript figures, uses newpasp.sty, to appear in "Extragalactic Gas at Low Redshfit", ASP Conf. Series, J. S. Mulchaey and J. T. Stocke (eds.)

We present moderate resolution data for 39 QSOs at z $\approx$ 2 obtained at the Multiple Mirror Telescope. These data are combined with spectra of comparable resolution of 60 QSOs with redshifts greater than 1.7 found in the literature to investigate the distribution of Ly-alpha forest lines in redshift and equivalent width. We find a value for $\gamma$, the parameter describing the number distribution of Ly-alpha forest lines in redshift, of $1.88\pm0.22$ for lines stronger than a rest equivalent width of 0.32 $\AA$, in good agreement with some previous studies. The Kolmogorov-Smirnov test was applied to the data and it is found that this single power law is a good fit over the relevant redshift ranges. Simulations of the Lyman alpha forest were performed to determine the completeness of the line lists and to test how well the analysis the underlying line statistics, given this level of completeness., Comment: minor corrections to text, 37 Latex pages, 11 encapsulated Postscript figures, uses emulateapj.sty, To appear in the Sept. 2000 ApJS, line lists and spectra available at http://qso.as.arizona.edu/~jscott/Spectra/index.html

A homogeneous sample of 99 moderate resolution QSO spectra at z > 1.7 were presented in Paper I, including 39 previously unpublished spectra from the Multiple Mirror Telescope. The statistics of the Lyman alpha forest were discussed. In this analysis, we demonstrate that a proximity effect is present in the data, ie. there exists a significant (5.5$\sigma$) deficit of lines at $z_{abs} \approx z_{em}$. Within 1.5 $h^{-1}$ Mpc of the QSO emission redshift, the significance does depend on QSO luminosity, in accordance with the theory that this effect is caused by enhanced ionization of hydrogen in the vicinity of the QSO from UV photons from the QSO itself. The photoionization model of Bajtlik, Duncan, and Ostriker (1988) permits an estimate of the mean intensity of the extragalactic background radiation at the Lyman limit. We compare the results of this standard analysis with those obtained using a maximum likelihood technique. The best fit value for $J(\nu_{0})$ is 7.0$^{+3.4}_{-4.4}$ x 10$^{-22}$ ergs/s/cm$^{2}$/Hz/sr, over the redshift range 1.7 < z < 3.8, using QSO redshifts based on narrow emission lines. The best fit value for the HI ionization rate is 1.9$^{+1.2}_{-1.0}$ x 10$^{-12}$ s$^{-1}$, in good agreement with models of the background which incorporate QSOs only. This large absorption line sample and these techniques for measuring the background and understanding the systematics involved allow us to place what we believe are are the firmest limits on the background at these redshifts., Comment: revised figures 13 and 14, and other minor corrections, 42 Latex pages, 23 encapsulated Postscript figures, uses emulateapj.sty, To appear in the Sept. 2000 ApJS

We present observations of the Lyman alpha forest towards B2 1225+317 taken at a resolution of 18 km/s. A clean sample of Lyman alpha forest lines is extracted after a careful profile fitting analysis and removal of absorption lines of heavy elements. The sample is analyzed for statistical properties. Eighty percent of the column densities are < 10^{14} cm^{-2}. A single power law is inconsistent with the column density distribution and a steepening/break in the distribution is indicated. The average velocity dispersion parameter is 29.4 km/s. We find 3 sigma evidence for a correlation between column density and the velocity dispersion parameter. The correlation, however, is mainly due to narrow lines and weakens to 1.2 sigma if lines with velocity dispersion parameter smaller than 20 km/s are excluded. An excess of line pairs with velocity separation $\le$ 100 km/s over the expected number is found., Comment: latex(mn.sty), 6 figures (available on request from anand@iucaa.ernet.in or khare@iopb.ernet.in), to appear in MNRAS

We report the detection, both in line and continuum emission, of a galaxy responsible for a damped Ly-alpha absorption (DLA) system at z=3.15 projected 2.3 arcsec from QSO 2233+131. The star formation rate implied by both the Ly-alpha and restframe far-UV continuum is approximately 7 M_sun / yr. The galaxy also shows no sign of an active nucleus and has blue colors, both consistent with it being observed early in its star formation history. The Ly-alpha emission is offset approximately 200 km/s from the DLA velocity, which could be explained as the rotational signature of a disk galaxy. We also report on the progress of an ongoing near-infrared narrow-band search with the Keck telescope for line emission from a population of primeval galaxies at high redshift. We have found several promising candidates which are being followed up with optical spectroscopy. Our survey is beginning to place constraints on a possible population of slightly dusty primeval galaxies at high redshift., Comment: to appear in Young Galaxies and QSO Absorbers, ASP Conf. Ser., eds. S. M. Viegas, R. Gruenwald, and R. R. de Carvalho; also available from http://astro.caltech.edu/~map/map.bibliography.html

The spectral energy distribution of the proto-galaxy candidate MS1512-cB58 at $z =2.72$ discovered by Yee et al. (1996) is presented. Photometry in seven bands ranging from $g$ to $K$$'$ (1300--6000 \AA~rest wavelength) are fitted with population synthesis models from Bruzual \& Charlot (1993). The data confirm a very young age for this galaxy, in agreement with ages estimated from preliminary \CIV~P-Cygni profile modeling. Single-burst models with ages greater than about 20 Myr can be discarded at the 99\% confidence level, and continuous star formation models with ages greater than about 35 Myr can be discarded at the 95\% confidence level. The spectral energy distribution is most consistent with a continuous star formation model of about 10--20 Myr, with reddening of $E(B-V)\sim 0.3$. No evidence for an older population of stars is seen, but the possibility of an older population with as much as 90\% of the galaxy mass cannot be ruled out. We discuss the possible ramifications of a non-standard IMF and gravitational lensing on the galaxy's age and mass., Comment: LaTeX and 3 .ps figures, accepted by ApJL

Galaxies believed to be responsible for damped Ly-alpha absorption (DLA) systems in the spectra of high-redshift quasars represent a viable population of progenitors of normal disk galaxies. They appear to contain a substantial fraction of the baryons known to exist in normal galaxies today. Here we report on the detection of an object, designated DLA 2233+131, responsible for a previously known DLA system at z(abs)=3.150 in the spectrum of a quasar 2233+131 [z(QSO)=3.295]. This is the first unambiguous detection of a DLA galaxy, in both emission line and stellar continuum. Its properties correspond closely to what may be expected from a young disk galaxy in the early stages of formation, with no sign of an active nucleus. This gives a strong support to the idea that DLA systems represent a population of young galaxies at high redshifts., Comment: to appear in Nature; self-contained TeX (6 pages) with three postscript figures; figure 3 has been B/W dithered to reduce size; entire paper, including full-resolution figures, also available from ftp://astro.caltech.edu/users/map/dla2233/ or http://astro.caltech.edu/~map/map.bibliography.html

A protogalaxy candidate at z=2.72 has been discovered serendipitously by the CNOC cluster redshift survey. The candidate is an extremely luminous (V=20.5 mag, absolute mag -26) and well resolved disk-like galaxy. The redshift is identified from a dozen strong UV absorption lines. No emission lines are found between 1000 and 2000A (rest), including Ly alpha. The photometric data fit the spectral energy distributions of a stellar population from 400 million years to an arbitrarily young age, dependent on the amount of dust extinction. However, the presence of a strong P-Cygni profile in CIV~indicates that a very substantial component of the stellar population must be younger than ~ 10 Myr. We interpret this object as an early-type galaxy observed within about 100 million years of the initial burst of star formation which created most of its stellar mass. Because of the resolved, regular, and smooth nature of the object, it is unlikely that the high luminosity is due to gravitational lensing., Comment: 31 page, Latex file with 9 encapsulated figures, requiring aasppt.sty and epsf.sty (included). Full uuencoded ps file available from: http://manaslu.astro.utoronto.ca/~carlberg/cnoc/general.html Accepted by Astronomical Journal, in press, May 1996

For the bright z = 3.02 radio-quiet quasar, HS 1946+7658, we have obtained radio to X-ray data within the past year: 5 GHz and 1415 MHz data from the Very Large Array (VLA); IR photometry at J, H, K, L prime (3.4 micrometers and N; IR spectroscopy; UBVRI photometry; optical spectrophotometry and high-resolution spectra; and an X-ray spectrum from the ROSAT Position Sensitive Proportional Counter (PSPC). The spectral energy distribution (SED) constructed from these data is compared to the mean SED for a set of low-redshift quasars, and while they appear generally similar, there are several differences. In relation to the low-redshift mean, the SED of HS 1946+7658 shows (1) only an upper limit at 10 micrometers (a rest wavelength of 2.5 micrometers, indicating that HS 1946+7658 does not have a strong near-IR excess such as hot dust would produce; (2) relatively weak Fe II and Balmer continuum emission at approximately 3000 A; and (3) a steeper turndown shortward of Ly alpha, even after correction for the Ly alpha forest absorption lines.

Measurements of optical emission-line flux variations based on spectra of the Seyfert galaxy NGC 5548 obtained between December 1988 and October 1989 are reported. All of the measured optical emission lines, H-alpha, H-beta, H-gamma, He I 5876, and He II 4686, exhibit the same qualitative behavior as the UV and optical continua, but with short time delays, or lags, which are different for the various lines. Cross-correlation analysis is applied to measure the lags between the various lines and the continuum. Similar lags are found with respect to the UV continuum for H-alpha and H-beta, 17 and 19 d, respectively. The lag for H-gamma is shorter (13 d), only somewhat larger than the lag measured for Ly-alpha (about 10 d). The helium lines respond to continuum variations more rapidly than the hydrogen lines, with lags of about 7 d for He II 4686 and 11 d for He I 5876.

Ultraviolet spectroscopy, optical spectroscopy, and spectrophotometry have been used to study the excess UV stars PG 0308 + 096 and PG 1026 + 002. Both objects are short-period binary systems, each containing a DA white dwarf star and a dM star. Orbital periods of approximately 0.284 day for PG 0308 + 096, and aproximately 0.597 day for PG 1026, have been found by spectroscopic analysis of the H-alpha emission line. Ly-alpha and Balmer line profile fitting were used to estimate the mass of white dwarf stars; mass estimates for the dM stars are based on their spectral types. The orbital inclinations are derived from these masses, the periods, and amplitudes of the H-alpha radial velocity curves. The equivalent width of the H-alpha emission line, in each binary system, varies with the orbital phase in such a manner as to imply that it arises, in large part at least, from the hemisphere of the M star that faces the white dwarf star.

We present measurements of the Balmer continuum/Fe II emission blend between 2160 and 4130 A in the Seyfert galaxy NGC 5548. The measurements are from spectra obtained as part of the combined space-based and ground-based monitoring program of this object in 1988-1989. An iterative scheme is used to determine and subtract the continuum emission underlying the emission blend so as to obtain a light curve sampled once every four days. The small blue bump is an important component of the emission-line cooling, constituting about one third of the line flux in this object. Its flux varies with an amplitude of approximately +/- 20 percent about the mean, similar to the amplitude of the Balmer line variations during the same period. Its light curve resembles that of Ly-alpha, with a lag of about 10 days behind the continuum variations. The bump variation amplitude is independent of the wavelength interval where it is measured, which indicates that both the Balmer continuum and Fe II emission have comparable variation amplitudes. These results suggest that the Fe II UV multiplets and the Balmer continuum are emitted in the same parts of the broad-line region as most other broad emission lines in this object.

Studying the Lyman-alpha forest allows us to trace the cosmological distribution of matter through time, and may reveal insights into important questions such as the onset of galaxy formation. An equation for determining the number of Lyman-alpha absorption lines per redshift per rest equivalent in the Lyman-alpha forest is given. For a nonevolving population of clouds gamma = 1 for q(sub 0) = 0, and gamma = 0.5 for q(sub 0) = 0.5. A detailed study of the Lyman-alpha forests of Q 1442+101 at z(sub em) = 3.54 and Q 0000-263 at z(sub em) = 4.11.

YBa2Cu3O(7-x) crystals are grown in a gold crucible by a self-flux method. The flux moves along the gold surface due to surface wetting and leaves Y123 crystals behind. The obtained crystals are clean and have a size up to two millimeters and a Tc is greater than 90 K. In an effort to recycle the used crucibles, it is found that the used gold is contaminated by copper. A CuO thin film is easily formed on the surface of the crucible that is made of the used gold. This film provides good surface wetting and a buffer layer, which reduces the reaction between gold and the Y-Ba-Cu-oxide melt.

A large, international program of ground-based optical spectroscopy and photometry of the variable Seyfert 1 galaxy NGC 5548 undertaken in support of an IUE monitoring campaign is described. This contribution presents the data base and describes the methods used to correct for systematic differences between spectra from different sources. Optical continuum and H-beta emission-line light curves are derived from the spectra. The behavior of the optical continuum is qualitatively the same as the behavior of the ultraviolet continuum. Cross-correlation of the ultraviolet and optical continuum measurements does not reveal any significant lag between them. The h-beta emission-line variations show the same basic pattern as seen in the continuum and ultraviolet emission lines, with H-beta lagging behind the continuum by about 20 days. This is significantly larger than the about 10 day lag deduced for Ly-alpha.