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"Tokarz, Susan"
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Hectospec, the MMT’s 300 Optical Fiber‐Fed Spectrograph
by
Goddard, Richard
,
Fabricant, Daniel
,
Bergner, Henry
in
Astronomical objects
,
Astronomy
,
Calibration
2005
The Hectospec is a 300 optical fiber fed spectrograph commissioned at the MMT in the spring of 2004. In the configuration pioneered by the Autofib instrument at the Anglo‐Australian Telescope, Hectospec’s fiber probes are arranged in a radial “fisherman on the pond” geometry and held in position with small magnets. A pair of high‐speed, six‐axis robots move the 300 fiber buttons between observing configurations within ∼300 s, and to an accuracy of ∼25 μm. The optical fibers run for 26 m between the MMT’s focal surface and the bench spectrograph, operating at
\\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 $R\\sim 1000{\\mbox{--}} 2000$ \\end{document}
. Hectochelle, another high‐dispersion bench spectrograph offering
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, is also available. The system throughput, including all losses in the telescope optics, fibers, and spectrograph, peaks at ∼10% at the grating blaze in 1
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FWHM seeing. Correcting for aperture losses at the 1
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5 diameter fiber entrance aperture, the system throughput peaks at ∼17%, close to our prediction of 20%. Hectospec has proven to be a workhorse instrument at the MMT. Together, Hectospec and Hectochelle have been scheduled for
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of the available nights since its commissioning. Hectospec has returned approximately 60,000 reduced spectra for 16 scientific programs during its first year of operation.
Journal Article
Hectochelle: A Multiobject Optical Echelle Spectrograph for the MMT
by
Goddard, Richard
,
Meibom, Soeren
,
Dupree, Andrea
in
Astronomy
,
Earth, ocean, space
,
Exact sciences and technology
2011
The Hectochelle is an optical band, fiber-fed, multiobject echelle spectrograph deployed at the MMT Observatory on Mount Hopkins, Arizona. The optical fibers that feed the Hectochelle are positioned by the Hectospec robot positioner on the MMT f/5 focal surface, and the Hectochelle shares an optical fiber feed system with the Hectospec, a moderate-dispersion spectrograph that is collocated with the Hectochelle. Hectochelle can record up to 240 spectra simultaneously at a resolution of 38,000. Spectra cover a single diffractive order that is approximately 150 Å wide. The total potential operating passband of the Hectochelle extends from 3800 Å to 9000 Å. Operated in conjunction with the MMT f/5 secondary, the MMT wide-field corrector, and the atmospheric dispersion compensator, the patrol field is 1° in diameter and the individual fiber slits are 1.5′′ in diameter. The throughput of the combined telescope, fiber feed, and spectrograph is measured to be 6.1% at 5275 Å, exclusive of atmospheric extinction. A 20 minute observation of a
V = 15
V
=
15
F-type star yields a signal-to-noise ratio of 35 per resolution element. Hectochelle had first light 2003 December 4 and continues to be operated at the MMT today.
Journal Article
Center for Astrophysics Optical Infrared Science Archive. I. FAST Spectrograph
by
Brown, Warren R
,
Chilingarian, Igor V
,
Fabricant, Daniel
in
Archives & records
,
Astrophysics
,
Observatories
2020
We announce the public release of 141,531 moderate-dispersion optical spectra of 72,247 objects acquired over the past 25 years with the FAST Spectrograph on the Fred L. Whipple Observatory 1.5-meter Tillinghast telescope. We describe the data acquisition and processing so that scientists can understand the spectra. We highlight some of the largest FAST survey programs, and make recommendations for use. The spectra have been placed in a Virtual Observatory accessible archive and are ready for download.
HectoMAP and Horizon Run 4: Dense Structures and Voids in the Real and Simulated Universe
by
Hwang, Ho Seong
,
Fabricant, Daniel G
,
Geller, Margaret J
in
Astronomical models
,
Cold dark matter
,
Computer simulation
2016
HectoMAP is a dense redshift survey of red galaxies covering a 53 \\(deg^{2}\\) strip of the northern sky. HectoMAP is 97\\% complete for galaxies with \\(r<20.5\\), \\((g-r)>1.0\\), and \\((r-i)>0.5\\). The survey enables tests of the physical properties of large-scale structure at intermediate redshift against cosmological models. We use the Horizon Run 4, one of the densest and largest cosmological simulations based on the standard \\(\\Lambda\\) Cold Dark Matter (\\(\\Lambda\\)CDM) model, to compare the physical properties of observed large-scale structures with simulated ones in a volume-limited sample covering 8\\(\\times10^6\\) \\(h^{-3}\\) Mpc\\(^3\\) in the redshift range \\(0.22
The Updated Zwicky Catalog (UZC)1, 2, 3
by
Geller, Margaret J.
,
Elwell, Barbara
,
Peters, James
in
Astronomical magnitude
,
Astronomical objects
,
Cataloging
1999
The Zwicky Catalog of galaxies (ZC), with
\\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 $m_{\\mathrm{Zw}\\,}\\leq 15.5$ \\end{document}
, has been the basis for the Center for Astrophysics (CfA) redshift surveys. To date, analyses of the ZC and redshift surveys based on it have relied on heterogeneous sets of galaxy coordinates and redshifts. Here we correct some of the inadequacies of previous catalogs by providing (1) coordinates with ≲2
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errors for all of the 19,369 catalog galaxies, (2) homogeneously estimated redshifts for the majority (98%) of the data taken at the CfA (14,632 spectra), and (3) an estimate of the remaining “blunder” rate for both the CfA redshifts and for those compiled from the literature. For the reanalyzed CfA data we include a calibrated, uniformly determined error and an indication of the presence of emission lines in each spectrum. We provide redshifts for 7257 galaxies in the CfA2 redshift survey not previously published; for another 5625 CfA redshifts we list the remeasured or uniformly rereduced value. Among our new measurements, 1807 are members of UZC “multiplets” associated with the original Zwicky catalog position in the coordinate range where the catalog is 98% complete. These multiplets provide new candidates for examination of tidal interactions among galaxies. All of the new redshifts correspond to UZC galaxies with properties recorded in the CfA redshift compilation known as ZCAT. About 1000 of our new measurements were motivated either by inadequate signal‐to‐noise in the original spectrum or by an ambiguous identification of the galaxy associated with a ZCAT redshift. The redshift catalog we include here is ∼96% complete to
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and ∼98% complete (12,925 galaxies out of a total of 13,150) for the right ascension ranges
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and
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and declination range
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. This more complete region includes all of the CfA2 survey as analyzed to date. The Great Wall structure persists throughout the northern survey region.
Journal Article
Discovery of Gas Accretion Onto Stars in 13 Myr old h and chi Persei
2007
We report the discovery of accretion disks associated with ~ 13 Myr-old intermediate/low-mass stars in h and chi Persei. Optical spectroscopy of ~ 5000 stars in these clusters and a surrounding halo population reveal 32 A-K stars with H(alpha) emission. Matching these stars with 2MASS and optical photometry yields 25 stars with the highest probability of cluster membership and EW(H(alpha)) > 5 angstroms. Sixteen of these sources have EW(H(alpha)) > 10 angstroms. The population of accreting sources is strongly spectral type dependent: H(alpha) emission characteristic of accretion, especially strong accretion (EW(H(alpha)) > 10 angstroms), is much more prevalent around stars later than G0. Strong H(alpha) emission from accretion is typically associated with redder Ks-[8] colors. The existence of accreting pre-main sequence stars in h and chi Persei implies that circumstellar gas in some systems, especially those with primaries later than G5 spectral type, can last longer than 10-15 Myr.
Yellow Supergiants in the Andromeda Galaxy (M31)
by
Drout, Maria R
,
Caldwell, Nelson
,
Meynet, Georges
in
Andromeda Galaxy
,
Color-magnitude diagram
,
Contamination
2009
The yellow supergiant content of nearby galaxies can provide a critical test of stellar evolution theory, bridging the gap between the hot, massive stars and the cool red supergiants. But, this region of the color-magnitude diagram is dominated by foreground contamination, requiring membership to somehow be determined. Fortunately, the large negative systemic velocity of M31, coupled to its high rotation rate, provides the means for separating the contaminating foreground dwarfs from the bona fide yellow supergiants within M31. Using the MMT, we obtained spectra of about 2900 stars, selected using the color and magnitude range to be yellow supergiants. Comparing the velocities to that of M31's rotation curve, we identified 54 certain, and 66 probable yellow supergiants from among the sea of foreground dwarfs. We find excellent agreement between the location of yellow supergiants in the H-R diagram and that predicted by the latest Geneva evolutionary tracks which include rotation. However, the relative number of yellow supergiants seen as a function of mass varies from that predicted by the models by a factor of more than 10, in the sense that more high mass yellow supergiants are predicted than are actually observed. Comparing the total number of yellow supergiants with masses above 20Mo with the estimated number of unevolved O stars indicates that the duration of the yellow supergiant phase is about 3000 years. This is consistent with what the 12Mo and 15Mo evolutionary tracks predict, but disagrees with the 20,000-80,000 year time scales predicted by the models for higher masses.
The Stellar Population of h and chi Persei: Cluster Properties, Membership, and the Intrinsic Colors and Temperatures of Stars
2009
(Abridged) From photometric observations of \\(\\sim\\) 47,000 stars and spectroscopy of \\(\\sim\\) 11,000 stars, we describe the first extensive study of the stellar population of the famous Double Cluster, h and \\(\\chi\\) Persei, down to subsolar masses. Both clusters have E(B-V) \\(\\sim\\) 0.52--0.55 and dM = 11.8--11.85; the halo population, while more poorly constrained, likely has identical properties. As determined from the main sequence turnoff, the luminosity of M supergiants, and pre-main sequence isochrones, ages for h Persei, \\(\\chi\\) Persei and the halo population all converge on \\(\\approx\\) 14 Myr. From these data, we establish the first spectroscopic and photometric membership lists of cluster stars down to early/mid M dwarfs. At minimum, there are \\(\\sim\\) 5,000 members within 10' of the cluster centers, while the entire h and \\(\\chi\\) Persei region has at least \\(\\sim\\) 13,000 and as many as 20,000 members. The Double Cluster contains \\(\\approx\\) 8,400 M\\(_{\\odot}\\) of stars within 10' of the cluster centers. We estimate a total mass of at least 20,000 M\\(_{\\odot}\\). We conclude our study by outlining outstanding questions regarding the properties of h and \\(\\chi\\) Persei. From comparing recent work, we compile a list of intrinsic colors and derive a new effective temperature scale for O--M dwarfs, giants, and supergiants.
The 2MASS Redshift Survey - Description and Data Release
by
Westover, Michael
,
Skrutskie, Michael
,
Schneider, Stephen
in
Bulk density
,
Galactic bulge
,
Galaxies
2011
We present the results of the 2MASS Redshift Survey (2MRS), a ten-year project to map the full three-dimensional distribution of galaxies in the nearby Universe. The 2 Micron All-Sky Survey (2MASS) was completed in 2003 and its final data products, including an extended source catalog (XSC), are available on-line. The 2MASS XSC contains nearly a million galaxies with Ks <= 13.5 mag and is essentially complete and mostly unaffected by interstellar extinction and stellar confusion down to a galactic latitude of |b|=5 deg for bright galaxies. Near-infrared wavelengths are sensitive to the old stellar populations that dominate galaxy masses, making 2MASS an excellent starting point to study the distribution of matter in the nearby Universe. We selected a sample of 44,599 2MASS galaxies with Ks <= 11.75 mag and |b|>=5 deg (>= 8 deg towards the Galactic bulge) as the input catalog for our survey. We obtained spectroscopic observations for 11,000 galaxies and used previously-obtained velocities for the remainder of the sample to generate a redshift catalog that is 97.6% complete to well-defined limits and covers 91% of the sky. This provides an unprecedented census of galaxy (baryonic mass) concentrations within 300 Mpc. Earlier versions of our survey have been used in a number of publications that have studied the bulk motion of the Local Group, mapped the density and peculiar velocity fields out to 50 Mpc, detected galaxy groups, and estimated the values of several cosmological parameters. Additionally, we present morphological types for a nearly-complete sub-sample of 20,860 galaxies with Ks < 11.25 mag and |b|>= 10 deg.
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