Low Resolution Spectrograph Research Articles

The chemical abundances of the stellar populations in the Leo I and II dSph galaxies

We have obtained calcium abundances and radial velocities for 102 red giant branch (RGB) stars in the Leo I dwarf spheroidal galaxy (dSph) and 74 RGB stars in the Leo II dSph using the low-resolution spectrograph (LRIS) on the Keck I 10-m telescope. We report on the calcium abundances [Ca/H] derived from the strengths of the Can triplet absorption lines at 8498, 8542 and 8662 A in the stellar spectra using a new empirical Ca II triplet calibration to [Ca/H]. The two galaxies have different average [Ca/H] values of -1.34 ± 0.02 for Leo I and - 1.65 ± 0.02 for Leo II with intrinsic abundance dispersions of 1.2 and 1.0 dex, respectively. The typical random and total errors in derived abundances are 0.10 and 0.17 dex per star. For comparison to the existing literature, we also converted our Can measurements to [Fe/H] on the scale of Carretta and Gratton (1997) though we discuss why this may not be the best determinant of metallicity; Leo I has a mean [Fe/H] = -1.34 and Leo II has a mean [Fe/H] = -1.59. The metallicity distribution function of Leo I is approximately Gaussian in shape with an excess at the metal-rich end, while that of Leo II shows an abrupt cut-off at the metal-rich end. The lower mean metallicity of Leo II is consistent with the fact that it has a lower luminosity, hence lower the total mass than Leo I; thus, the evolution of Leo II may have been affected more by mass lost in galactic winds. Our direct and independent measurement of the metallicity distributions in these dSph will allow a more accurate star-formation histories to be derived from future analysis of their colour-magnitude diagrams(CMDs).

Spectra of bulge stars with known abundance ratios for population synthesis

Spectra in the range 4000-7000 Å were obtained for a sample of bulge stars using the GMOS-Gemini low resolution spectrograph. The sample stars were selected from a VLT-FLAMES project for the observation of 1000 bulge stars, for which abundance ratios have been derived. Our aim is to study old stellar populations in external galaxies.

The Las Campanas Infrared Survey -- V. Keck spectroscopy of a large sample of extremely red objects

We present deep Keck spectroscopy, using the Deep Imaging Multi-Object Spectrograph and the Low-Resolution Imaging Spectrometer spectrographs, of a large and representative sample of 67 extremely red objects (EROs) to H= 20.5 in three fields (SSA22, Chandra Deep Field South and NTT Deep Field) drawn from the Las Campanas Infrared Survey (LCIRS). Using the colour cut (I-H) > 3.0 (Vega magnitudes) adopted in earlier papers in this series, we verify the efficiency of this selection for locating and studying distant old sources. Spectroscopic redshifts are determined for 44 sources, of which only two are contaminating low-mass stars. When allowance is made for incompleteness, the spectroscopic redshift distribution closely matches that predicted earlier on the basis of photometric data. Our spectra are of sufficient quality that we can address the important question of the nature and homogeneity of the z > 0.8 ERO population. A dominant old stellar population is inferred for 75 per cent of our spectroscopic sample, a higher fraction than that seen in smaller, less complete samples with broader photometric selection criteria (e.g. R-K). However, only 28 per cent have spectra with no evidence of recent star formation activity, such as would be expected for a strictly passively evolving population. More than |30 per cent of our absorption-line spectra are of the ‘E+A’ type with prominent Balmer absorption consistent, on average, with mass growth of 5–15 per cent in the past gigayear. We use our spectroscopic redshifts to improve earlier estimates of the spatial clustering of this population as well as to understand the significant field-to-field variation. Our spectroscopy enables us to pinpoint a filamentary structure at z= 1.22 in the Chandra Deep Field South. Overall, our study suggests that the bulk of the ERO population is an established population of clustered massive galaxies undergoing intermittent activity consistent with continued growth over the redshift interval 0.8 < z < 1.6.

Luminosity Functions of the Galaxy Cluster MS 1054−0321 atz = 0.83 based on ACS Photometry

We present new measurements of the galaxy luminosity function (LF) and its dependence on local galaxy density, color, morphology, and clustocentric radius for the massive z = 0.83 cluster MS 1054-0321. Our analyses are based on imaging performed with the Advanced Camera for Surveys (ACS) on board the Hubble Space Telescope (HST) in the F606W, F775W, and F850LP passbands and extensive spectroscopic data obtained with the Keck Low-Resolution Imaging Spectrograph. Our main results are based on a spectroscopically selected sample of 143 cluster members with morphological classifications derived from the ACS observations. Our three primary findings are (1) the faint-end slope of the LF is steepest in the bluest filter, (2) the LF in the inner part of the cluster (or highest density regions) has a flatter faint-end slope, and (3) the fraction of early-type galaxies is higher at the bright end of the LF, and gradually decreases toward fainter magnitudes. These characteristics are consistent with those in local galaxy clusters, indicating that, at least in massive clusters, the common characteristics of cluster LFs are established at z = 0.83. These results provide additional support for the hypothesis that the formation of galaxies in MS 1054-0321 began at redshifts considerably greater than unity. We also find a 2 σ deficit of intrinsically faint, red galaxies (i775 - z850 ≥ 0.5, Mi > -19) in this cluster. Although the significance is marginal, this trend may suggest that faint, red galaxies (which are common in z 30 Mpc-2, coinciding with the environment where the galaxy star formation rate and the morphology-density relation start to appear. A physical process that begins to become effective at around the virial radius or Σ ~ 30 Mpc-2 may thus be responsible for the evolution of color and luminosity of cluster galaxies.

Redshift Accuracy Requirements for Future Supernova and Number Count Surveys

We investigate the required redshift accuracy of type Ia supernova and cluster number-count surveys in order for the redshift uncertainties not to contribute appreciably to the dark energy parameter error budget. For the SNAP supernova experiment, we find that, without the assistance of ground-based measurements, individual supernova redshifts would need to be determined to about 0.002 or better, which is a challenging but feasible requirement for a low-resolution spectrograph. However, we find that accurate redshifts for z < 0.1 supernovae, obtained with ground-based experiments, are sufficient to immunize the results against even relatively large redshift errors at high z. For the future cluster number-count surveys such as the South Pole Telescope, Planck or DUET, we find that the purely statistical error in photometric redshift is less important, and that the irreducible, systematic bias in redshift drives the requirements. The redshift bias will have to be kept below 0.001-0.005 per redshift bin (which is determined by the filter set), depending on the sky coverage and details of the definition of the minimal mass of the survey. Furthermore, we find that X-ray surveys have a more stringent required redshift accuracy than Sunyaev-Zeldovich (SZ) effect surveys since they use a shorter lever armmore » in redshift; conversely, SZ surveys benefit from their high redshift reach only so long as some redshift information is available for distant (zgtrsim1) clusters.« less

Spectroscopy of KISS Emission-Line Galaxy Candidates. II. Hobby-Eberly Telescope Observations

The KPNO International Spectroscopic Survey (KISS) is an ongoing wide-field objective-prism survey for extragalactic emission-line objects. Over 2200 emission-line galaxy (ELG) candidates have been cataloged to date. To study the characteristics of the survey objects, spectroscopic follow-up observations are being carried out at several telescopes. Here we present the results of the spectroscopic observations for 258 KISS ELG candidates that have been obtained using the Marcario Low Resolution Spectrograph on the 9.2 m Hobby-Eberly Telescope (HET). We present the following data derived from the HET spectra: redshifts, reddening estimates, line equivalent widths, emission-line ratios, and galaxy activity types (e.g., AGN or star-forming). The long-slit redshifts are compared to those determined from the KISS objective-prism spectra and show good agreement. Earlier spectroscopic follow-up observations have typically verified the presence of emission lines for over 90% of the KISS ELG candidates. However, in the sample observed with the HET, only 78% of candidates are confirmed to be extragalactic emission-line sources. This is because the HET sample contains a large fraction of the faintest KISS objects, which typically have low spectral quality. A small number of objects at higher redshift (z ~ 0.3), detected by KISS from their [O III] emission rather than from Hα emission, are identified based on their spectra.

Further Multiwavelength Observations of the SSA 22 Lyα‐Emitting Blob

We present new follow-up observations of the submillimeter luminous Lyα-emitting object in the SSA 22 z = 3.09 galaxy overdensity, referred to as blob 1 by Steidel and coworkers. In particular, we discuss high-resolution Hubble Space Telescope (HST) optical imaging, Owens Valley Radio Observatory (OVRO) spectral imaging, Keck spectroscopy, Very Large Array (VLA) 20 cm radio continuum imaging, and Chandra X-ray observations. We also present a more complete analysis of the existing James Clerk Maxwell Telescope (JCMT) submillimeter data. We detect several optical continuum components that may be associated with the core of the submillimeter-emitting region. A radio source at the position of one of the HST components [α = 22h17m2594, δ = +00°12'389] identifies it as the likely counterpart to the submillimeter source. We also tentatively detect the CO(4-3) molecular line centered on the radio position. We use the CO(4-3) intensity to estimate a limit on the gas mass for the system. The optical morphology of sources within the Lyα cloud appears to be filamentary, while the optical source identified with the radio source has a dense knot that may be an active galactic nucleus (AGN) or compact starburst. We obtain a Keck Low-Resolution Imaging Spectrograph (LRIS) spectrum of this object, despite its faintness (R = 26.8). The spectrum reveals weak Lyα emission but no other obvious features, suggesting that the source is not an energetic AGN (or that it is extremely obscured). We use nondetections in deep Chandra X-ray images to constrain the nature of the blob. Although conclusive evidence regarding the nature of the object remains hard to obtain at this redshift, the evidence presented here is at least consistent with a dust-obscured AGN surrounded by a starburst situated at the heart of this giant Lyα cloud.

Effective suppression of fluorescence light in Raman measurements using ultrafast time gated charge coupled device camera

A high level of fluorescence background signal rejection was achieved for solid and powder samples by using a combination of simple low-resolution spectrograph and ultrafast gated charge coupled device (CCD) camera. The unique timing characteristics of the CCD camera match exceptionally well to characteristics of a Ti:sapphire oscillator allowing fast gated light detection at a repetition rate of up to 110 MHz, making this approach superior in terms of the duty cycle in comparison with other time-resolved Raman techniques. The achieved temporal resolution was about 150 ps under 785 nm Ti: sapphire laser excitation. At an average excitation power up to 300 mW there was no noticeable sample damage observed. Hence, the demonstrated approach extends the capabilities of Raman spectroscopy regarding the investigation of samples with a short fluorescence lifetime. The combination of a spectrometer and a gated CCD camera allows simultaneous study of spectral and temporal characteristics of emitted light. This capability opens an exciting possibility to build a universal instrument for solving multitask problems in applied laser spectroscopy.

Keck spectroscopy of Cosmic Lens All-Sky Survey gravitational lenses

We present the optical spectra of four newly discovered gravitational lenses from the Cosmic Lens All-Sky Survey (CLASS). These observations were carried out using the Low-Resolution Imaging Spectrograph on the W. M. Keck-I Telescope as part of a programme to study galaxy-scale gravitational lenses. From our spectra, we found the redshift of the background source in CLASS B0128+437 (z s = 3.1240 ± 0.0042) and the lensing galaxy redshifts in CLASS B0445+123 (z 1 = 0.5583 ± 0.0003) and CLASS B0850+054 (z 1 = 0.5883 ± 0.0006). Intriguingly, we also discovered that CLASS B0631+519 may have two lensing galaxies (z 1,1 = 0.0896 ± 0.0001, z 1,2 = 0.6196 ± 0.0004). We also found a single unidentified emission line from the lensing galaxy in CLASS B0128+437 and the lensed source in CLASS B0850+054. We find the lensing galaxies in CLASS B0445+123 and CLASS B0631+519 (1, 2) to be early-type galaxies with Einstein radii of 2.8-3.0 h -1 kpc. The deflector in CLASS B0850+054 is a late-type galaxy with an Einstein radius of 1.6 h -1 kpc.

QSOs Associated with M82

The starburst/AGN galaxy M82 was studied by Dahlem, Weaver, and Heckman using X-ray data from ROSAT and ASCA as part of their X-ray survey of edge-on starburst galaxies. They found 17 unresolved hard X-ray sources around M82, in addition to its strong nuclear source, and other X-rays within the main body of M82. We have measured optical point sources at these positions and have obtained redshifts of six candidates at the Keck I 10 m telescope, using the low-resolution imaging spectrograph (LRIS). All six are highly compact optical and X-ray objects with redshifts ranging from 0.111 to 1.086. They all show emission lines. The three with the highest redshifts are clearly QSOs. The others with lower redshifts may be either QSOs or compact emission-line galaxies. In addition to these six, there are nine QSOs lying very close to M82 which were discovered many years ago. There is no difference between optical spectra of these latter QSOs, only two of which are known to be X-ray sources, and the X-ray-emitting QSOs. The redshifts of all 15 range between 0.111 and 2.05. The large number of QSOs and their apparent association with ejected matter from M82 suggest that they are physically associated with the galaxy and have large intrinsic redshift components. If this is correct, the absolute magnitudes lie in the range -8 < Mv < -10. Also, we speculate that the luminous variable X-ray source which has been detected by Chandra in the main body of M82 some 9'' from the center is another QSO in the process of ejection from the nucleus, and we propose some observational tests of this hypothesis.

Properties of the hermean regolith: iii. disk-resolved vis–NIR reflectance spectra and implications for the abundance of iron

Disk-resolved reflectance spectra of the surface of Mercury (longitudes 240–300°), obtained in the visual (vis) and near-infrared (NIR) spectral region, are presented and analyzed. The observations were made at the 2.6-m Nordic Optical Telescope with the ALFOSC low-resolution spectrograph on 20 and 22 June 1999 in the wavelength range 520–970 nm with a footprint size of 700 km on the mid-disk of Mercury. A method which enables more accurate correction for telluric line absorptions and atmospheric extinction than that applied on previously published vis–NIR spectra of Mercury is introduced. The resulting reflectance spectra are remarkably linear, lack significant absorption features, and have optical slopes comparable to remotely sensed lunar pure anorthosites. The relation between spectral slope and photometric geometry found by Warell (2002, Icarus 156, 313–317) is confirmed and is explained as caused by strongly backscattering particles with embedded submicroscopic metallic iron in a mature regolith. With the theoretical maturation model of Hapke (2001, J. Geophys. Res. 106 (E5), 10039–10073) an abundance of 0.05–0.3 wt% submicroscopic metallic iron in the regolith for silicate grain sizes in the range 10–80 μm is determined, implying a ferrous iron content in mafic minerals intrinsically lower than that of the lunar highlands. A binary crustal composition model with anorthite linearly mixed with pyroxene provides better spectral fits than a pure anorthitic composition. Comparison with mature lunar pure anorthosite spectra yields a confident upper limit to the FeO content of 3 wt% under the assumption that the surfaces are similarly matured, but this figure probably represents a considerable overestimate. The average mercurian regolith does not seem to be substantially more weathered than the most mature lunar highland soils in terms of abundance of submicroscopic metallic iron, indicating that a steady-state maturation level has been reached. However, the strong relation between optical spectral slope and photometric geometry may imply that the majority of regolith particles are more fine-grained than their lunar counterparts and that the regolith is admixed with complex agglutinate weathering products which are more abundant and more transparent than those of the lunar highlands. This is consistent with more energetic impacts and a higher rate of impact melt production in an iron-poor regolith. An observed relation between the spectral slope and latitude provides evidence that the Ostwald ripening process may be operating at equatorial latitudes on Mercury.

Spectroscopy of Low Surface Brightness Galaxies with the Hobby-Eberly Telescope

We have obtained low resolution spectra of nineteen red and blue low surface brightness galaxies, using the Marcario Low Resolution Spectrograph on the 9.2m Hobby-Eberly Telescope. These galaxies form a very heterogeneous class, whose spectra qualitatively resemble those of high surface brightness galaxies covering the full range of spectra seen in galaxies of Hubble types from E to Irr. We use a combination of emission line (EW(Halpha), NII/Halpha) and absorption line (Mgb, Hbeta, ) based diagnostics to investigate the star-formation and chemical enrichment histories of these galaxies. These are diverse, with some galaxies having low metallicity and very young mean stellar ages, and other galaxies showing old, super-solar metallicity stellar populations. In contrast with some previous studies which found a strong trend of decreasing metallicity with decreasing central surface brightness, we find a population of galaxies with low surface brightness and near-solar metallicity. Correlations between several of the gas phase and stellar population age and metallicity indicators are used to place contraints on plausible evolutionary scenarios for LSB galaxies. The redshift range spanned by these galaxies is broad, with radial velocities from 3400 km/s to more than 65000 km/s. A subset of the sample galaxies have published HI redshifts and gas masses based on observations with the Arecibo 305m single-dish radio telescope, which place these galaxies far off of the mean Tully-Fisher relation. Our new optical redshifts do not agree with the published HI redshifts for these galaxies. Most of the discrepancies can be explained by beam confusion in the Arecibo observations, causing erroneous HI detections for some of the galaxies.

Suspected Wolf-Rayet Galaxies UM 456 and UM 594

First results of an on-going search for Wolf-Rayet galaxies, based on new observations obtained with the Hobby Eberly Telescope ? (HET) and the Marcario Low Resolution Spectrograph ?? (LORES), are presented. UM 456 and UM 594 have been found to be normal HII galaxies. New determinations of radial velocities have been given: UM 456 { Vr = 1702 48 km s 1 UM 594 { Vr = 6540 45 km s 1 . Independent estimates of distances,

Keck spectroscopy and imaging of faint galaxies identified as microjansky radio sources

We investigate the nature of the faintest radio sources detected in three Very Large Array surveys, to F(8.5 GHz)∼8 μJy. Using the Keck low-resolution imaging spectrograph in BRI and the near-infrared camera in K′ (2.1 μm), we image 51 radio sources, and identify probable optical counterparts for 50. With low-resolution imaging spectroscopy, we successfully acquire new redshifts for 17 sources. Combining these with nine prior redshifts, we can then analyse a sample of 26 sources with spectroscopic redshifts. Based on this sample of 26, we find the largest contribution, about 60 per cent (15), to be from disc galaxies with high radio-to-optical ratios, indicating ongoing or very recent starbursts, at redshifts of z=0–1. Most of these have large optical luminosities (MB≃−22±1), although two are sub-L*(MB>−20). About 20 per cent (five) of the sample have relatively low ratios of radio-to-optical flux, consistent with normal, non-interacting galaxies, all at z<0.4. Four are quasi-stellar objects (QSOs), of which one appears to be interacting and shows strong Mg ii absorption. Two others are very radio-luminous giant ellipticals and presumably contain active galactic nuclei. All of the 14 non-QSO galaxies with spectra show Hβ and [O ii] λ3727 emission lines, with luminosities corresponding to star formation rates (SFRs) of the order of ∼10 M⊙ yr−1. These SFRs are about an order of magnitude lower than estimated from the radio luminosities. This result may be explained if the galaxies are observed ∼107–108 yr after a starburst and/or their regions of current star formation are heavily obscured by dust. Three of the galaxies show strong Hδ absorption and can be classed as post-starburst or ‘e(a)’ galaxies. The Keck spectra are of high enough resolution to provide approximate emission linewidths and rotation curves, as well as [O iii]/Hβ ratios (‘excitation’). Most of the galaxies (12/14) have high-amplitude kinematics (100–400 km s−1), implying large dynamical masses, and moderate excitation (∼0.51±0.12), consistent with their morphological appearance as non-AGN, L⩾L* spirals, of probable near-solar metallicity. The two with low optical luminosities appear to be low-mass galaxies with much higher excitations (∼2.8), and may be more similar to local H ii galaxies than to normal spirals.

Imaging and Spectroscopy of the Multiphase Halo of NGC 4631

We have performed narrowband imaging of NGC 4631 in the [O III] 5007 and Hα lines, and long-slit spectroscopy using the Low-Resolution Imaging Spectrograph at the W. M. Keck Observatory. Hα and [O III] λ5007 are detected far from the disk, with the highest [O III]/Hα ratios coincident with the soft X-ray emission. Spectroscopy reveals that the ionization is higher than that of the Milky Way diffuse ionized gas (DIG), with an average ratio [O III]/Hβ ~ 1, rising to 6 in one region. We use the Balmer decrement to probe extinction in the halo. Extinction appears as high as 5 kpc above the disk. Distinct smaller scale variations of [O III], Hβ, and [S II] indicate that we are viewing multiple zones with distinct ionization conditions along the line of sight, in some cases separated by dust. This suggests that the gas has multiple phases and that the ionization may be much higher in some zones. A model using photoionized clouds reproduces the average trends in the line ratios. The inferred densities and pressures are high for halo gas but consistent with observations of other phases that may be colocated with this gas. A combination of high- and low-ionization gas is best for explaining the majority of the fluctuations. The high-ionization phase could be in shocks, but the velocity resolution is not adequate to prove or reject this possibility. Gas at 6 × 105 K discovered by ROSAT by Wang and colleagues in 1995 could be a source of radiatively cooling gas. We present a new model of optical line emission from cooling clouds and compare it to the data. We show that it can produce part or all of the observed [O III] and fluctuations, may generate part or all of the EDIG gas itself, and may contribute to the photoionization of the upper halo. Our most important conclusions are that the halo is complex and multicomponent and that average line-of-sight line ratios alone cannot be used to determine the ionization conditions.

The Absorbers toward CSO 118: Superclustering at [CLC][ITAL]z[/ITAL][/CLC] ∼ 3, or an Intrinsic Absorption Complex?

We present two low-resolution (R ~ 1300) high signal-to-noise ratio spectra (Wr, lim ≈ 50 mA) of the quasar CSO 118 (zem = 2.97) taken with the Hobby-Eberly Telescope Marcario Low-Resolution Spectrograph. We detect eight absorbers selected by the C IV λλ1548, 1550 absorption doublet in the redshift range 2.23 zabs 2.97, seven of which are zabs 2.68. In the redshift range covered by the seven zabs 2.68 systems, one expects to find two absorbers. We discuss possible explanations for such an excess of absorbers in a small velocity range. Only superclustering at high redshift and absorption due to intrinsic gas are feasibly allowed.

Spectrographs: Low-Resolution Spectrographs

Low-resolution spectrographs typically record the spectrum of astronomical objects at resolution (λ/Δλ) in the range 102–104

Optical properties of the carbon dust grains in the envelopes around asymptotic giant branch stars

ABSTRA C T We have investigated the optical properties of the carbon dust grains in the envelopes around carbon-rich asymptotic giant branch stars, paying close attention to the infrared observations of the stars and the laboratory-measured optical data of the candidate dust grain materials. We have compared the radiative transfer model results with the observed spectral energy distributions of the stars including IRAS Point Source Catalog and IRAS Low Resolution Spectrograph data. We have deduced an opacity function of amorphous carbon dust grains from model fitting with infrared carbon stars. From the opacity function, we have derived the optical constants of the AMC grains. The optical constants satisfy the Kramers‐Kronig relation and produce the opacity function that fits the observations of infrared carbon stars better than previous works in the wide wavelength range 1‐1000mm. We have used simple mixtures of the AMC and silicon carbide grains for modelling. We have compared the contributions that AMC and SiC grains make to the opacity for the cases of simple mixtures of them and spherical core‐mantle type grains consisting of a SiC core and an AMC mantle.

Observations of Faint, Hard-Band X-Ray Sources in the Field of CRSS J0030.5+2618 with the [ITAL]CHANDRA X-RAY OBSERVATORY[/ITAL][ITAL]Chandra X-Ray Observatory[/ITAL] and the Hobby-Eberly Telescope

We present results from a study of 2-8 keV X-ray sources detected by the Advanced CCD Imaging Spectrometer (ACIS) instrument on the Chandra X-ray Observatory in the field of the z=0.516 cluster CRSS J0030.5+2618. In our 63.5 arcmin^2 search area, we detect 10 sources with 2-8 keV fluxes down to approximately 4x10^{-15} erg cm^{-2} s$^{-1}; our lowest flux sources are approximately 10 times fainter than those previously available for study in this band. Our derived source density is about an order of magnitude larger than previous source counts above 2 keV, although this density may be enhanced somewhat due to the presence of the cluster. We detail our methods for source detection and characterization, and we show that the resulting source list and parameters are robust. We have used the Marcario Low Resolution Spectrograph on the Hobby-Eberly Telescope to obtain optical spectra for several of our sources; combining these spectra with archival data we find that the sources appear to be active galaxies, often with narrow permitted lines, red optical continua or hard X-ray spectra. Four of the X-ray sources are undetected to R=21.7; if they reside in L* galaxies they must have z > 0.55-0.75 and hard X-ray luminosities of L_{2-8} > 4x10^{42} erg s^{-1}. We detect all but one of our 2-8 keV sources in the 0.2-2 keV band as well. This result extends to significantly lower fluxes the constraints on any large, completely new population of X-ray sources that appears above 2-3 keV.

The Evolution of Early‐Type Galaxies in Distant Clusters. II. Internal Kinematics of 55 Galaxies in the \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $z=0.33$ \end{document} Cluster Cl 1358+62

We define a large sample of galaxies for use in a study of the fundamental plane in the intermediate redshift cluster Cl 1358+62 at z = 0.33. We have analyzed high-resolution spectra for 55 members of the cluster. The data were acquired with the Low-Resolution Imaging Spectrograph on the Keck I 10 m telescope. A new algorithm for measuring velocity dispersions is presented and used to measure the internal kinematics of the galaxies. This algorithm has been tested against the Fourier fitting method so that the data presented here can be compared with those measured previously in nearby galaxies. We have measured central velocity dispersions suitable for use in a fundamental plane analysis. The data have a high signal-to-noise ratio (S/N) and the resulting random errors on the dispersions are very low, typically less that 5%. Uncertainties due to mismatch of the stellar templates have been minimized through several tests, and the total systematic error is of order ~5%. Good seeing enabled us to measure velocity dispersion profiles and rotation curves for most of the sample, and although a large fraction of the galaxies display a high level of rotation, the gradients of the total second moment of the kinematics are all very regular and similar to those in nearby galaxies. We conclude that the data therefore can be reliably corrected for aperture size in a manner consistent with nearby galaxy samples.