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We present new HST STIS NUV-MAMA and STIS CCD observations of the BL Lac object AO 0235+164 and the intervening damped Ly alpha (DLA) line at z_a = 0.524. The line profile gives N(H I) = 5 +/- 1 x 10^{21} cm^{-2} and, combined with the H I 21 cm absorption data leads to a spin temperature of T_s = 220 K +/- 60 K. Those spectra also show a strong, broad feature at the expected position of the 2175 Angstrom graphitic dust feature at z_a = 0.524. Assuming a Galactic type dust extinction curve at z_a = 0.524 gives a dust-to-gas ratio of 0.19 Galactic, but the fit, assuming the underlying, un-reddened spectrum is a single power-law, is poor in the far-UV. A dust-to-gas ratio of 0.19 Galactic is similar to the LMC, but the AO 0235+164 spectrum does not fit the LMC extinction curve, or the SMC extinction curve (which has practically no 2175 Angstrom feature). A possible interpretation includes dust similar to Galactic, but with less of the small particles that produce the far-UV extinction. The metallicity of the z_a = 0.524 absorber, estimated from the observed N(H I) and excess X-ray absorption (beyond Galactic) derived from contemporaneous and archival ASCA and ROSAT X-ray data, is Z = 0.72 +/- 0.28 Z_sun, implying in turn the dust-to-metals ratio of 0.27 Galactic. If the dust mass density is the same in the z_a = 0.524 DLA system as in our Galaxy, only 14% (+/- 6%) of the metals (by mass) are in dust compared with 51%, 36%, and 46% for the Galaxy, LMC, and SMC respectively. Such a dusty z_a = 0.524 AO 0235+164 absorption system is a good example of the kind of DLA system that will be missed due to selection effects, which in turn can bias the measurement of the co-moving density of interstellar gas (in units of the closure density), Omega_g, as a function of z., 39 pages, 8 figures, accepted for publication in ApJ

We analyze Hubble Space Telescope/Goddard High Resolution Spectrograph spectra of AB Doradus, the prototypical, ultrarapidly rotating K dwarf. We observed chromospheric (Mg II) and transition-region (C II, Si IV, C IV, and N V) lines periodically throughout the stellar rotation period and provide a low-dispersion stellar atlas of 78 emission lines. The quiescent line profiles of the chromospheric and transition-region lines show narrow cores superposed on very broad wings. The broad wings of the Mg II k and h lines and of the transition-region lines can be explained by emission from gas corotating with the star and extending out to near the Keplerian corotation radius (2.8 stellar radii). While this is not a unique solution, it is consistent with previous studies of Hα emission, which are naturally explained by large corotating prominences. We find no evidence for rotational modulation of the emission-line fluxes. The density diagnostics suggest that the transition region is formed at constant pressure, with an electron density of 2–3 × 1012 cm-3 at a temperature of 3 × 104 K. The electron pressure is about 100 times larger than that for the quiet Sun. The emission-measure distribution shows a minimum between log T = 5 and 5.5. The Mg II line exhibits three interstellar absorption components along the 15 pc line of sight. We identify the lowest velocity component with the G Cloud, but the other components are not identified with any interstellar clouds previously detected from other lines of sight.

Observations of the ultra-sharp-lined, chemically peculiar star chi Lupi taken by the Goddard High Resolution Spectrograph in echelle mode are presented. Thirty-six intervals of the spectral region between 1249 and 2688 Angstrom are covered with resolving powers in the range 75,000-93,000. Line identifications are provided, and the observed spectra are compared with synthetic spectra calculated using the SYNTHE program and associated line lists with changes to the line lists. The significance of these spectra for the chi Lupi Pathfinder Project and the closely related atomic physics effort is discussed in a companion paper.

Goddard High Resolution Spectrograph echelle-mode observations of the interstellar absorption lines of Mg II, Si IV, C IV, and N V toward μ Columbae (HD 38666) are presented. The observations have a spectral resolution of 3.5 km s-1 and signal-to-noise ratios (S/Ns) of 20–200. The μ Col sight line (l = 2373, b = -271, d = 0.40 kpc, z = -0.18 kpc) extends though the Local Bubble and the warm neutral, warm ionized, and hot ionized phases of the interstellar medium (ISM). The high-ionization column densities toward μ Col are log N(Si IV) = 12.16 ± 0.05, log N(C IV) = 12.88 ± 0.02, and logN(N V) = 11.8–12.3. Profile fits to Copernicus satellite measures of O VI absorption toward μ Col yield log N(O VI) = 13.82±0.01 and b = 38.7 km s-1. This implies N(C IV)/N(O VI) = 0.11 ± 0.01, which is typical of the values found for the hot ISM of the Galactic disk. The O VI profile is twice as broad as the C IV and N V profiles, even though these species have roughly similar average velocities. Some of the C IV, N V, and O VI absorption toward μ Col may occur at the interface of the Local Cloud and Local Bubble, although additional contributions to these ions probably also occur in more distant gas along the sight line. A substantial part of the Si IV absorption likely arises in warm photoionized gas in an H II region surrounding μ Col. The profile width differences among the high-ionization lines of C IV, N V, and O VI could be produced if the line of sight passes through a highly evolved supernova remnant. The observations for μ Col and for other stars observed at high resolution with the GHRS reveal that multiple gas types (warm and hot) contribute to the absorption by the highly ionized atoms along both nearby and distant sight lines. Disentangling the relative contributions from the different gas types requires high-resolution and high-S/N observations. The Mg II observations, combined with a solar Mg reference abundance, imply that the Mg depletion toward μ Col is -0.31 dex. As observed for other sight lines through the warm neutral medium, the gas-phase observations of Mg, when combined with results for Fe and Si, suggest that Mg and Fe are more deficient from the gas phase than one would expect if these elements are only contained in silicate dust grains.

Observations of the narrow-lined O-type star 10 Lacertae taken with the Goddard High Resolution Spectrograph in 1992 November are presented. The spectra cover the wavelength range 1181–1777 A with a resolution of 15 km s-1 and signal-to-noise ratio greater than 100:1. Absorption lines arising in the interstellar medium, the photosphere, and the stellar wind are identified and discussed.

We present HST/FOS spectra of the two bright images (A and B) of the gravitationally lensed QSO 0957+561 in the wavelength range 2200-3300 A. We find that the absorption system (Z(sub abs)) = 1.3911) near z(sub em) is a weak, damped Ly alpha system with strong Ly alpha absorption lines seen in both images. However, the H(I) column densities are different, with the line of sight to image A intersecting a larger column density. The continuum shapes of the two spectra differ in the sense that the flux level of image A increases more slowly toward shorter wavelengths than that of image B. We explain this as the result of differential reddening by dust grains in the damped Ly alpha absorber. A direct outcome of this explanation is a determination of the dust-to-gas ratio, k, in the damped Ly alpha system. We derive k = 0.55 + 0.18 for a simple 1/lambda extinction law and k = 0.31 + 0.10 for the Galactic extinction curve. For gravitationally lensed systems with damped Ly alpha absorbers, our method is a powerful tool for determining the values and dispersion of k, and the shapes of extinction curves, especially in the FUV and EUV regions. We compare our results with previous work.

Twelve ruminally, duodenally, and ileallycannulated Hereford heifers (average initial BW 313 f 20 kg) were used in a replicated experiment to evaluate dairy food processing wash water solids (WWS) as a protein source. Heifers were fed 2.8 kg of chopped (7.6 cm) hay and one of three supplements (1.5 kg/d, DM basis). Supplements were formulated to be similar in energy and contained 1.0 (control), 23.2 (WWS), and 21.6% (soybean meal, SBM) CP on an OM basis. Total N and nonammonia N entering the duodenum (gld) were greater (P c .lo) for heifers fed WWS and SBM supplements than for controls. Bacterial N flow (g/d) at the duodenum was less (P < .lo) for controls (43.9) than for WS- (63.9) and SBM- (69.9) supplemented heifers. Feed escape N (g/d) was greater (P e .lo) for WWS-fed heifers than for those fed SBM (32.1 vs 20.7 gld, respectively). Total tract N digestion (g/d) was greatest (P < .lo) for SBM, intermediate for WWS, and least for control heifers. Microbial protein synthesis (g/kg of OM intake) was enhanced (P < .lo) by WWS and SBM supplementation, but efficiency of synthesis @/kg of OM fermented) did not differ among treatments. Essential amino acid (AA) disappearance in the small intestine (g/d) was less (P < .lo) for control than for the other two treatments. Nonessential AA disappearance was greatest (P < .lo) for the WWS and least (P c .lo) for the control treatment. Based on our short-term feeding data, WWS can be used as a protein source for ruminants, but N availability of WWS seems less than that of soybean meal.

Imaging and spectroscopy with HST show that LBQS 0103-2753 (V = 17.8, z = 0.848) is a binary quasar with a separation of 0.3 arcsec or 2.3 kpc. This is by far the smallest separation binary quasar reported to date. The two components have very different spectra, including the presence of strong broad absorption lines (BALs) in component A only. The emission-line redshifts, based on the broad high ionization C IV lines, are z_A = 0.834 and z_B = 0.858; their difference is 3900 km/s in velocity units. The broad C IV lines, however, are probably not a good indicator of systemic redshift; and LBQS 0103-2753 A and B could have a much smaller systemic redshift difference, like the other known binary quasars. If the systemic redshift difference is small, then LBQS 0103-2753 would most likely be a galaxy merger that has led to a binary supermassive black hole. There is now one known 0.3 arcsec binary among roughly 500 QSOs that have been observed in a way that would reveal such a close binary. This suggests that QSO activity is substantially more likely for black hole binaries at spacings ~2 kpc than at ~15 to 60 kpc. Between 1987 and 1998, the observed Mg II BAL disappeared., 12 pages LATEX with 3 EPS figures; uses aaspp4.sty. Accepted for publication in The Astrophysical Journal Letters, volume 550 (2001 March 20)

LBQS 0103$-$2753 is a binary quasar with a separation of only 0.3 arcsec. The projected spacing of 2.3 kpc at the distance of the source (z = 0.848) is much smaller than that of any other known binary QSO. The binary nature is demonstrated by the very different spectra of the two components and the low probability of a chance pairing. LBQS 0103$-$2753 presumably is a galaxy merger with a small physical separation between the two supermassive black holes. Such objects may provide important constraints on the evolution of binary black holes and the fueling of AGN., Comment: 6 pages LATEX with 2 EPS figures; uses epsfig, aipproc. Proceedings of the 20th Texas Symposium on Relativistic Astrophysics, ed. J. C. Wheeler and H. Martel, American Institute of Physics, in press (2001)

We use new UV and optical spectra and an archival HST-WFPC2 image to study the z_a~z_e absorber in the z_e = 0.20 QSO PKS 2135-147. The UV spectra, obtained with HST-FOS, show strong z_a~z_e absorption lines of C IV, N V, O VI, Ly-alpha and Ly-beta. The z_a~z_e line profiles are resolved, with deconvolved FWHM of 270 to 450 km/s. Lower limits on the total column densities are of order 10^15 cm-2 for all ions. If the absorber is photoionized by the QSO and the derived relative columns in C IV and H I are roughly correct, then the metallicity must be at least solar. The location of the z_a~z_e absorber remains uncertain. Two ~L_* galaxies in a small cluster centered on PKS 2135-147 lie within 36h^{-1} kpc projected distance and have redshifts consistent with causing or contributing to the z_a~z_e lines. The extensive halo of the QSO's host galaxy could also contribute. Calculations show that the QSO is bright enough to photoionize gas up to O VI in the low-density halos of the host and nearby cluster galaxies. Nonetheless, there is indirect evidence for absorption much nearer the QSO, namely (1) the derived high (albeit uncertain) metallicity, (2) the relatively strong N V absorption lines, which might be caused by a higher nitrogen abundance in the metal-rich gas, and (3) strong, lobe-dominated steep-spectrum radio emission, which is known to correlate with a much higher incidence of (probably intrinsic) z_a~z_e lines. We propose that the CIV/NV/OVI line ratios can be used as a general diagnostic of intrinsic versus intervening absorption, as long as the line saturation effects are understood., Comment: 14 pages (LaTeX) plus 4 figures (*.eps.tar.gz), in press with ApJ

During the Science Verification phase of the Hubble Space Telescope mission, it was determined that the Faint Object Spectrograph's (FOS) Red detector displayed significant image motions which correlated with orbital changes in the geomagnetic field. The Blue detector exhibited similar but less pronounced motions. The cause of this motion was determined to be inadequate magnetic shielding of the instrument's Digicon detectors. The results of these motions were decreases in onboard target acquisition accuracy, spectral resolution, and photometric accuracy. The Space Telescope Science Institute and the FOS Investigation Definition Team, set about correcting this Geomagnetically-induced Image Motion Problem (GIMP) through a real-time on-board correction scheme. This correction required modifications to almost all aspects of the HST ground system as well as additional NSSC1 flight software and the use of an existing software 'hook' in the FOS microprocessor firmware. This paper presents a detailed description of the problem, the proposed solution, and results of on-orbit testing of the correction mechanism.

Observations of the sky background obtained with the Faint Object Spectrograph during 1991 - 1992 are discussed. Sky light can be an important contributor to the observed count rate in several of the instrument configurations especially when large apertures are used. In general, the sky background is consistent with the pre-launch expectations and showed the expected effects of zodiacal light and diffuse galactic light. In addition to these sources, there is, particularly during the daytime, a highly variable airglow component which includes a number of emission lines. The sky background will have an impact on the reduction and possibly the interpretation of some spectra.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present the results of an investigation of the in-orbit performance of the Digicon detectors in the Faint Object Spectrograph (FOS), conducted as part of the commissioning phase of the Hubble Space Telescope. This paper includes orbital results on detector background noise, sensor image stability, and photometric stability along with several typical FOS observations. This information should be of general interest to designers of future spacecraft detectors and to astronomers observing with the FOS instrument.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Goddard High Resolution Spectrograph observations of the nucleus of the bright, nearby Seyfert galaxy NGC 4151 are presented and briefly described.

The authors discuss results of an analysis of background dark data obtained with the Digicon detector in the faint object spectrograph on board the Hubble Space Telescope. Time sequenced data are presented which show the background recorded by the detector as it orbits the Earth at an altitude of 600 km. The authors propose that Cerenkov radiation produced by cosmic ray particle interactions with the MgF2 faceplate comprises the major source of this detector noise. Cerenkov light will be emitted whenever a high-energy particle traverses the detector faceplate and can result in large portions of the detector array being illuminated simultaneously. The effects of Cerenkov radiation have been modeled in image tubes by means of a Monte Carlo simulation. This model produces images which qualitatively resemble observed dark data. Moreover, the model closely reproduces the observed average background level and calculates background count statistics which are difficult to determine directly given the rapid sampling rate that would be required. The model can provide optimal settings for the detector burst noise rejection algorithm so that the signal-to-noise ratio of astronomical data can be maximized.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Seven Angus and six Brangus steers averaging 225 and 245 kg, respectively, were assigned randomly to zeranol (36 mg) implant (I) and no implant (NI) treatments. Steers had ad libitum access to a corn silage diet plus .68 kg of a soybean meal-based supplement fed daily. Steers were bled via jugular catheters on d 0, 28, 56, and 84 at 15-min intervals for 4 h before and 4 h after feeding. Concentrations of growth hormone (GH), insulin (INS), triiodothyronine (T3), thyroxine (T4), and glucose were determined. Whole-body protein and fat contents were monitored. A breed x I interaction (for d 56 to 84 and d 0 to 84) was observed for ADG (P less than .05 and P less than .07, respectively), feed conversion (P less than .05 and P less than .07, respectively), and protein deposition (for d 0 to 29 and d 0 to 84; P less than .07 and P less than .05, respectively). These interactions were attributed to a greater response to I by Angus than by Brangus steers. A feeding x period interaction (P less than .10) was observed for mean GH concentration, and INS, T4, and T3 concentrations were higher (P less than .05) during the 4-h postfeeding period than during the 4-h prefeeding period. The implant increased (P less than .08) mean GH concentration but did not alter the frequency, duration, or amplitude of plasma GH peaks. Steers that were implanted had lower (P less than .05) plasma T3. Brangus steers had lower (P less than .05) plasma glucose, T3, and T4 concentrations than Angus steers. Results indicate that growth factors beyond those measured are responsible for the anabolic response to zeranol.

Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and gamma-ray emitting QSO (or BL Lac object) AO 0235 + 164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235 + 164 was bright (m approx. 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO following the nomenclature of Yanny et al. (1989), the companion object named A, 2 sec south of AO, is discovered not to be an elliptical galaxy as hypothesized earlier, but to be an AGN object, with a central UV-bright point-source nucleus and faint surrounding nebulosity extending to AO. The second companion object 1.3 sec east of AO discovered by Yanny et al. (1989) and named object Al, appears more like a normal spiral galaxy. We have measured the positions, luminosities, and colors of some 30 faint objects in the field around AO 0235 + 16; most are extended and may be star-forming galaxies in a loose group or cluster. Our most surprising result of the HST observations comes from FOS spectra obtained in 1995 July, discussed in Sec. 4. Because of a positioning error of the telescope and AO's faintness at that time (m approx. 20), object A was observed instead of the intended target AO. Serendipitously, we discovered A to have broad deep BALQSO-type absorptions of C IV, Si IV, N V shortward of broad emissions. A is thus ejecting high velocity, highly ionized gas into the surrounding IGM. We discuss in Sec. 5 the relationship of the objects in the central 10 sec X 1O sec region around AO, where redshifts z(sub e) = 0.94, z(sub a) = 0.524, 0.851 in AO, (sub e) = 0.524 and Z(sub BAL)=0.511 in A, are found. We hypothesize that some of the 30 faint objects in the 77 sec. x 77 sec. field may be part of a large star-forming region at z approx. 0.5, as suggested for a few objects by Yanny et al. (1989). The proximity of two highly active extragalactic objects, AO 0235+164 and its AGN companion A, is remarkable and one of the authors (EMB) suggests it may require consideration of a non-cosmological component of redshift in AO 0235+164.

We present imaging and spectroscopy of the quasar 3CR 196 (z(sub e) = 0.871), which has 21 cm and optical absorption at z(sub a) = 0.437. We observed the region of Ly alpha absorption in 3CR 196 at z(sub a) = 0.437 with the Faint Object Spectrograph on the Hubble Space Telescope. This region of the spectrum is complicated because of the presence of a Lyman limit and strong lines from a z(sub a) approx. z(sub e) system. We conclude that there is Ly alpha absorption with an H I column density greater than 2.7 x 10(exp 19) cm(exp -2) and most probably 1.5 x 10(exp 20) cm(exp -2). Based on the existence of the high H I column density along both the optical and radio lines of sight, separated by more than 15 kpc, we conclude that the Ly alpha absorption must arise in a system comparable in size to the gaseous disks of spiral galaxies. A barred spiral galaxy, previously reported as a diffuse object in the recent work of Boisse and Boulade, can be seen near the quasar in an image taken at 0.1 resolution with the Wide Field Planetary Camera 2 on the HST. If this galaxy is at the absorption redshift, the luminosity is approximately L(sub *) and any H I disk should extend in front of the optical quasar and radio lobes of 3CR 196, giving rise to both the Ly alpha and 21 cm absorption. In the z(sub a) approx. z(sub e) system we detect Lyman lines and the Lyman limit, as well as high ion absorption lines of C III, N V, S VI, and O VI. This absorption probably only partially covers the emission-line region. The ionization parameter is approximately 0.1. Conditions in this region may be similar to those in broad absorption line QSOs.

The in-orbit performance of the Goddard High Resolution Spectrograph onboard the Hubble Space Telescope (HST) is presented. This report covers the pre-COSTAR period, when instrument performance was limited by the effects of spherical aberration of the telescope's primary mirror. The digicon detectors provide a linear response to count rates spanning over six orders of magnitude, ranging from the normal background flux of 0.01 counts diode -1 s-1 to values larger than 104 counts diode-1 s-1. Scattered light from the first-order gratings is small and can be removed by standard background subtraction techniques. Scattered light in the echelle mode is more complex in origin, but it also can be accurately removed. Data have been obtained over a wavelength range from below 1100 A to 3300 A, at spectral resolutions as high as R = lambda/delta-lambda = 90,000. The wavelength scale is influenced by spectrograph temperature, outgassing of the optical bench, and interaction of the magnetic field within the detector with the earth's magnetic field. Models of these effects lead to a default wavelength scale with an accuracy better than 1 diode, corresponding to 3 km s-1 in the echelle mode. With care, the wavelength scale can be determined to an accuracy of 0.2 diodes. Calibration of the instrument sensitivity functions is tied into the HST flux calibration through observations of spectrophotometric standard stars. The measurements of vignetting and the echelle blaze function provide relative photometric precision to about 5% or better. The effects of fixed-pattern noise have been investigated, and techniques have been devised for recognizing and removing it from the data. The ultimate signal-to-noise ratio achievable with the spectrograph is essentially limited only by counting statistics, and values approaching 1000:1 have been obtained.

We discuss measurements of Ne VIII lambda 774 absorption and the time variability of other lines in the z(sub a) approximately equal z(sub e) absorption system of the z(sub e) = 2.15 QSO UM 675 (0150-203). The C IV lambda 1549 and N V 1240 doublets at z(sub a) = 2.1340 (shifted approximately 1500 km/s from z(sub e) strengthened by a factor of approximately 3 between observations by Sargent, Boksenberg and Steidel (1981 November) and our earliest measurements (1990 November and December). We have no information on changes in other z(sub a) approximately equal z(sub e) absorption lines. Continued monitoring since 1990 November shows no clear changes in any of the absorptions between approximately 1100 and 1640 A rest. The short timescale of the variability (less than or approximately equal to 2.9 yr rest) strongly suggests that the clouds are dense, compact, close to the QSO, and photoionized by the QSO continuum. If the line variability is caused by changes in the ionization, the timescale requires densities greater than approximately 4000/cu cm. Photoionization calculations place the absorbing clouds within approximately 200 pc of the continuum source. The full range of line ionizations (from Ne VIII lambda 774 to C III lambda 977) in optically thin gas (no Lyman limit) implies that the absorbing regions span a factor of more than approximately 10 in distance or approximately 100 in density. Across these regions, the total hydrogen (H I + H II) column ranges from a few times 10(exp 18)/sq cm in the low-ionization gas to approximately 10(exp 20)/sq cm where the Ne VIII doublet forms. The metallicity is roughly solar or higher, with nitrogen possibly more enhanced by factors of a few. The clouds might contribute significant line emission if they nearly envelop the QSO. The presence of highly ionized Ne VIII lambda 774 absorption near the QSO supports recent studies that link z(sub a) approximately equal to z(sub e) systems with X-ray 'wamr absorbers. We show that the Ne VIII absorbing gas would itself produce measurable warm absorption -- characterized by bound-free O VII or O VIII edegs near 0.8 keV -- if the column densities were N(sub H) greater than or approximately equal to 10(exp 21)/sq cm (for solar abundances).

The Goddard High Resolution Spectrograph (GHRS), currently in Earth orbit on the Hubble Space Telescope (HST), operates in the wavelength range 1150-3200 A with spectral resolutions (lambda/delta lambda) of approximately 2 x 10(exp 3), 2 x 10(exp 4), and 1 x 10(exp 3). The instrument and its development from inception, its current status, the approach to operations, representative results in the major areas of the scientific goals, and prospects for the future are described.

The observations of the quasar 3C 273 taken with the Goddard High Resolution Spectrograph in 1991 February are presented here. We have included both the reduced raw data, and smoothed and deconvolved spectra. Also, a list of observed absorption lines is presented. The data comprise 11 spectra, including one low resolution and 10 medium resolution observations. The wavelength region covered ranged from about 1150 to 2820 A, but was not all inclusive. The procedures used to obtain and reduce the data, including corrections for fixed pattern noise, compensation for the effects of spherical aberration in the HST primary mirror, and objective detection of weak absorption lines, are described. We also have included a short discussion on the detection of galactic Ni II and Virgo cluster metal lines.

To investigate the far-UV spectral properties of a QSO and to look for evidence of He I 584 A emission and absorption the Faint Object Spectrograph aboard the HST was used to observed UM 675. Light is detected down to 520 A in the object in the rest frame and limits are set to He I emission, the He I Gunn-Peterson effect at z = 2.148, and Ly-alpha absorption at z roughly 0.5.

Twelve ruminally, duodenally, and ileally cannulated (average initial BW 313 +/- 20 kg) and 27 intact Hereford heifers (average initial BW 256 +/- 17 kg) were used in two experiments to evaluate dairy food wash water solids (WWS) as a protein source in medium-quality hay diets. Heifers received a basal diet of orchardgrass hay (7.4% CP) and were assigned to one of three supplement treatments: control (C; .9% CP), WWS (18.8% CP)-, and soybean meal (SBM; 19.1% CP)-based supplements (fed at 1.5 kg of DM/d). Supplements were formulated to have similar ME concentrations. Ruminal ammonia concentrations were greater (P less than .10) for WWS- and SBM-supplemented heifers than for C heifers at most sampling times. Moreover, WWS and SBM increased (P less than .10) total VFA (mM) and acetate (mol/100 mol) and lowered propionate (mol/100 mol) at several sampling times. Ruminal fluid volume (liters) was unchanged (P greater than .10) by treatment; however, fluid dilution and flow rate (liters/h) were less (P less than .10) in C heifers than in heifers fed SBM or WWS supplements. Wash water solids and SBM supplementation increased (P less than .10) OM, NDF, and ADF digestibilities compared with C heifers. Feeding WWS and SBM supplements increased BW at 84 d (P less than .10) compared with C-supplemented heifers. Forage intake at 54 and 84 d by heifers supplemented with SBM or WWS was greater (P less than .10) than by C heifers. Control-supplemented heifers had the least, WWS intermediate, and SBM the greatest ADG at 84 d (P less than .10; .14 vs .35 vs .48 kg/d, respectively). These data indicate that WWS may be used as a protein source without serious adverse effects in heifers consuming medium-quality hay for 84 d.

Two experiments were conducted with sheep fed orchardgrass hay plus one of four supplements to evaluate use of a cheese processing wash water solid (WWS) material as a protein supplement. In both trials, lambs were fed either a cornstarch control (0% WWS-N) or a protein supplement containing 25, 50 or 75% N from WWS (25, 50 or 75% WWS-N, respectively). The majority of the remaining protein was supplied by soybean meal (SBM). Trial 1 was a replicated 4 x 4 extra-period Latin square. Protein supplementation increased total tract NDF and N digestibilities (P less than .10) 13% and 29%, respectively, compared with the cornstarch control. Total tract N digestibility was depressed (P less than .10) when 75% WWS-N (71.5%) vs 25 or 50% WWS-N (75.9 and 75.9%, respectively) was fed. Total VFA were depressed (P less than .10) 6 and 9 h postfeeding in sheep fed 75% WWS-N compared with the control (78.3 and 74.6 mM vs 98.8 and 94.6 mM for 6 and 9 h, respectively). Two hours postfeeding, lambs fed control had lower (P less than .10) ruminal pH compared with lambs fed 25, 50 and 75% WWS-N (6.2 vs 6.4, 6.5 and 6.5, respectively). Ruminal ammonia concentrations were 5 to 10 mg/dl lower (P less than .10) at all times in control lambs. In Trial 2, a metabolism study, feeding 75% WWS-N resulted in lower N digestibility (P less than .10) than did feeding 25% and 50% WWS-N (47.2 vs 56.4 and 55.2%, respectively). Data suggest that up to 50% of the SBM-N in a protein supplement for wethers may be replaced by WWS-N without adversely altering nutrient digestibility, ruminal fermentation or N metabolism.

To evaluate effects of previous forage systems on feedlot performance, yearling Hereford steers (average initial weight of 249 kg) were grazed on tall fescue (TF), smooth bromegrass-red clover (BG-RC) or orchardgrass-red clover (OG-RC) pastures before finishing. Serial slaughter was utilized during the first 2 yr of this study to determine changes in carcass characteristics throughout finishing, while steers were slaughtered at approximately 29% body fat during the third year. Steers grazing TF entered the feedlot at lighter weights and maintained lighter weights throughout finishing (P less than .05) even though dry matter intakes and feed conversions were similar (P greater than .05) among treatments. Steers that previously grazed TF had less (P less than .05) body fat, body protein, fat thickness and marbling, smaller (P less than .05) ribeye areas and lower (P less than .05) USDA yield and quality grades than than those that grazed BG-RC and OG-RC. However, linear contrasts indicated that steers grazing TF were compensating in ribeye area, marbling and quality grade as days in feedlot increased. This was confirmed in the third-year study, since carcass characteristics were similar among all steers. During the third year, linear and quadratic contrasts indicated that steers that grazed TF partially compensated in body protein. As days in feedlot increased, live and hot carcass weights, body fat, fat thickness, kidney, pelvic and heart fat, marbling, and USDA yield and quality grades increased (P less than .05), while ribeye area and body protein plateaued. Although carcass characteristics were similar among treatments, steers backgrounded on TF entered the feedlot at lighter weights, and partially compensated in weight after 134 d of finishing.

Two split-plot designed experiments were conducted to determine the effects of breed (Angus, A, or Brangus, B) and diet (fescue hay, FH; corn silage, CS; or concentrate) on composition and rate of growth, diet digestibility and plasma hormones of steers. In Exp. 1, 10 steers (five of each breed) were fed a CS-based diet followed by a FH-based diet for two consecutive 60-d periods. Both breeds had lower (P less than .01) DM intake and digestibility when fed FH than when fed CS diets. The B steers had higher (P less than .01) plasma insulin concentrations than A steers when fed the CS diet. In Exp. 2, during two consecutive years, 10 steers previously fed CS- and FH-based diets were finished with a corn silage-whole shelled corn-based diet. During yr 1, A steers had higher (P less than .01) DM intake and plasma triiodothyronine (T3) and thyroxine (T4) concentrations (P less than .05) than B steers did. Although final weights were similar (P greater than .10), A steers had heavier (P less than .05) carcass weights than B steers did. During yr 2, A steers had higher (P less than .07) DM and starch digestibilities and higher (P less than .01) plasma T4 concentrations than B steers did. The greater (P less than .01) energetic efficiency of A steers was attributed to the greater rates of fat deposition during yr 2. Regardless of type of diet fed, A steers were more efficient at depositing energy. Higher circulating T4 concentrations of A than B steers may explain some of the physiological differences between these breeds.

The Faint Object Spectrograph (FOS) designed for use with The Space Telescope (ST), is currently preparing for instrument assembly, integration, alignment, and calibration. Nearly all optical and detector elements have been completed and calibrated, and selection of flight detectors and all but a few optical elements has been made. Calibration results for the flight detectors and optics are presented, and plans for forthcoming system calibration are briefly described.

A Fairchild CCD211 (190X244 pixels) charge coupled device was thinned for photon and photoelectron rear-illumination experiments. Image smear due to injection of charge into the interline transfer registers was measured, and leakage current changes as a result of photoelectron irradiation were recorded. As expected, damage rates were less than 10-4 of those measured for front side irradiation. Similar damage data were taken at UCSD on the Texas Instrument 100X160 thinned array. Nearly identical damage rates were measured for the two arrays.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The operation and performance of a Digicon-based autoguider system recently developed will be discussed. The photosensor is a twelve-channel, photon-counting Digicon specifically developed by SAI for this application. The design and implementation of the system will be discussed with an emphasis on the objective of developing a general purpose auto-guider system for a wide range of applications. Data will be presented on the Digicon performance, i.e., quantum efficiency, background count rate, and pulse counting performance. In addition, overall system guiding accuracy, dynamic range, and sensitivity will be detailed.© (1984) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We are developing an intensified charge-coupled device (ICCD) detector system, based on the incorporation of a thinned backside-illuminated CCD as the anode of a Hubble Space Telescope design Digicon tube, for particular application to astronomical observations with stringent requirements for accuracy, rapid temporal response, low background, and high two-dimensional resolution. In this paper, images are presented which demonstrate the capability this system provides in achieving sub-CCD-cell resolution, representing a substantial increase in this attribute. These results also indicate that the amount of this increase is at present constrained by the limited extent of the spreading of photoelectron-generated charge evident in the particular thinned CCD used here, and that further increases in resolution remain possible with the use of thicker chips. In connection with this, the potential benefits of magnetic deflection substepping in ensuring excellent uniformity of elemental response in the overall sensor system are shown dramatically in this study. Additionally, we present preliminary results from the fabrication and testing of mesh photocathodes suitable for inclusion in such a system, which may be applied to extend wavelength coverage into the extreme ultraviolet, and from the successful processing and operation of a sealed CCD-Digicon tube.

The Digicon, chosen by NASA as the detector for the High Resolution Spectrograph (HRS) and the Faint Object Spectrograph (FOS) is a 512 parallel output channel vacuum photodetector. There are two HRS Digicons with spectral sensitivity ranges from 1050 A to 1800 A and 1150 A to 3000 A respectively, and two FOS Digicons, which have spectral ranges extending to 7000 A. The significant requirements for these devices are 0.01 counts per second background count rate per diode, state-of-the-art Digicon pulse height resolution (typical 15%) and a high degree of imaging precision and stability. The results of a manufacturing and test program to develop the Digicons coupled with extensive prior work has shown that these requirements can be met. The Digicon because of its inherent ruggedness is particularly well suited to space applications.

A new version of an intensified charge-coupled device (ICCD) system, which is based on the incorporation of a CsI mesh photocathode and a thinned backside-illuminated CCD into a Space Telescope design Digicon tube, is being developed for future use in space-based observations in the Extreme Ultraviolet waveband. In this paper, a report is presented of the results of computer simulations involving the effects of the non-uniform electrostatic field near the mesh photocathode on imaging properties (especially, the spread function and modulation transfer function) of the detector system. The results are of importance in the design of the front end of the tube and the selection of optimum tube operating conditions. The overall resolution characteristics of the tube, including the effects of the mesh, the electron optics of the region between the mesh photocathode and the CCD target, and the structure of the CCD itself, are estimated.

The high resolution spectrograph (HRS) for ultraviolet astronomy with the Space Telescope will provide a spectral resolution of approximately 120,000 over a nominal wavelength range of 110-320 nm, together with a spatial resolution of about 0.25 arc seconds. The two detectors will consist of 512-element Digicons with cesium telluride and cesium iodide photocathodes, respectively. Photoelectrons in transit between the photocathodes and the diodes within the Digicons can be deflected in two axes with 12-bit resolution. This feature facilitates a design that emphasizes reliability since (once a hermetic seal is opened in orbit), only two moving parts, a grating carrousel and a shutter, are required for regular operation of the HRS. The instrument will be controlled by a computer in the spacecraft. The scientific objectives of the HRS investigation relate to interstellar matter in our own and nearby galaxies, physical processes of stellar mass loss and mass transfer, chemical abundances, bright quasars and Seyfert galaxy nuclei, and solar system phenomena.

The Space Telescope Digicons are extremely powerful detectors, each one consisting of 512 parallel photon-counting channels. During testing, each channel of each Digicon must be characterized as to its photon-counting and noise characteristics, resulting in a tre-mendous volume of data. Furthermore, tests must be made at the component and subassembly level to screen parts not suitable for further processing. Adding to this testing task are the additional requirements that the tubes must be tested at high voltage without encapsulation, they must be kept scrupulously clean, and, in some cases, they must be tested in the vacuum ultraviolet portion of the spectrum. This paper describes the design and use of a unique, accurate and efficient test facility now in operation at EVC. Many of the tests are run by computer control, and in some cases the data are preprocessed and evaluated by the computer due to the human incomprehensibility of data consisting of thousands of numbers.© (1979) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A next logical step in the progression of state-of-the-art detector systems for use in astronomical observations is seen to be the development of an intensified charge-coupled device (ICCD) system, involving the incorporation of a thinned backside-illuminated CCD as the anode of a Space Telescope design Digicon tube. This concept extends the demonstrated fundamental photon counting accuracy, low background, sensitivity, and stability of the Digicon to the two-dimensional capabilities of CCDs. In particular, the CCD-Digicon combination enables (1) the use of magnetic deflection in order to take full advantage of the basic resolution elements in the system and to enhance the uniformity of elemental response, and (2) charge pulse centroiding to substantially increase the number of effective detector resolution elements without straining manufacturing techniques as would be required to produce such amounts of physical array cells. Results of recent investigations into the feasibility and characteristics of these techniques are presented.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Faint Object Spectrograph (FOS), one of five scientific instruments being built for the Space Telescope, has recently completed a significant milestone in its progression toward final instrument assembly, integration, and test. Seven flight Digicon phototubes have been successfully manufactured and tested and a development unit of the integrated detector assembly has successfully completed a set of difficult environmental and functional tests. This paper presents the results of these tests and details the results of the Digicon tube tests including photocathode quantum efficiency, dark count rate, uniformity, distortion, resolution, and diode array performance.

A low temperature photocathode process has been used to fabricate an intensified CCD visual photocathode image tube, by incorporating a thinned, backside-illumined CCD as the target anode of a digicon tube of Hubble Space Telescope (HST) design. The CCD digicon tube employs the HST's sodium bialkali photocathode and MgF2 substrate, thereby allowing a direct photocathode quantum efficiency comparison between photocathodes produced by the presently employed low temperature process and those of the conventional high temperature process. Attention is given to the processing chamber used, as well as the details of gas desorption and photocathode processing.

The paper presents the Faint Object Spectrograph (FOS) for the Space Telescope to provide a digitized spectra of faint astronomical objects over the 115 to 700 nm wavelength range at resolving powers of 1000 and 100. A variety of concave gratings and prisms is employed to form nearly stigmatic spectra on one of the two Digicon photon counting detectors which are optimized for two different but overlapping ranges. The scientific goals associated with quasars, active galaxies, and objects within our solar system are discussed, and the FOS optical design features, including detectors, electronics, signal processing, power supplies, and data handling are examined. The FOS structural system, mechanism, and controls are described, along with the predicted performance capabilities in the spectral and spectropolarimetry modes. Finally, system performance parameters, including spatial resolution, time resolution, noise, and efficiency are discussed.

The Digicon has been chosen as the detector for the High Resolution Spectrograph and the Faint Object Spectrograph of the Space Telescope. Both tubes are 512 channel, parallel-output devices and feature CsTe photocathodes on MgF2 faceplates. Using a computer-assisted test facility, the tubes have been characterized with respect to diode array performance, photocathode response (1100-9000 A), and imaging capability. Data are presented on diode dark current and capacitance distributions, pulse height resolution, photocathode quantum efficiency, uniformity and blemishes, dark count rate, distortion, resolution, and crosstalk.