J/AJ/155/104 MEGaSaURA. I. The sample and the spectra (Rigby+, 2018)
The Magellan Evolution of Galaxies Spectroscopic and Ultraviolet Reference Atlas
(MEGaSaURA).
I. The sample and the spectra.
Rigby J.R., Bayliss M.B., Sharon K., Gladders M.D., Chisholm J., Dahle H.,
Johnson T., Paterno-Mahler R., Wuyts E., Kelson D.D.
<Astron. J., 155, 104 (2018)>
=2018AJ....155..104R 2018AJ....155..104R
ADC_Keywords: Galaxies; Gravitational lensing; Spectra, optical; Ultraviolet;
Atlases
Keywords: atlases ; galaxies: evolution ; galaxies: high-redshift ;
gravitational lensing: strong
Abstract:
We introduce Project MEGaSaURA: the Magellan Evolution of Galaxies
Spectroscopic and Ultraviolet Reference Atlas. MEGaSaURA comprises
medium-resolution, rest-frame ultraviolet spectroscopy of N=15 bright
gravitationally lensed galaxies at redshifts of 1.68<z<3.6, obtained
with the MagE spectrograph on the Magellan telescopes. The spectra
cover the observed-frame wavelength range 3200<λo<8280Å;
the average spectral resolving power is R=3300. The median spectrum
has a signal-to- noise ratio (S/N)=21 per resolution element at
5000Å. As such, the MEGaSaURA spectra have superior S/N and
wavelength coverage compared to what COS/HST provides for starburst
galaxies in the local universe. This paper describes the sample, the
observations, and the data reduction. We compare the measured
redshifts for the stars, the ionized gas as traced by nebular lines,
and the neutral gas as traced by absorption lines; we find the
expected bulk outflow of the neutral gas, and no systemic offset
between the redshifts measured from nebular lines and the redshifts
measured from the stellar continuum.
Description:
Observations spanning 2010 December to 2015 November were obtained
with The Magellan Echellette (MagE) spectrograph on the twin 6.5m
Magellan telescopes at the Las Campanas Observatory in Chile. The
majority of observations were conducted with MagE mounted on the Clay
telescope; some observations were made after 2015 October, when MagE
was moved to the Baade telescope.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 147 20 The MEGaSaURA sample
table2.dat 153 16 Oxygen abundances for the MEGaSaURA sample
table3.dat 77 197 Observation log
table4.dat 166 20 Redshifts for the MEGaSaURA sample
spectra/* . 20 *Calibrated final spectra from the MEGaSaURA
survey, taken with the MagE instrument on
Magellan for the MEGaSaURA sample; in ASCII
individual files
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Note on spectra/*: MW reddening correction of E(B-V) from table 1, Rv=3.1,
CCM has been applied.
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
J/A+AS/103/97 : Grids of stellar models V. (Meynet+ 1994)
J/ApJS/193/8 : Spectroscopy of 26 lensing cluster cores (Bayliss+, 2011)
J/ApJ/794/156 : MgII/FeII absorption profile for 0.3<z<1.4 gal. (Rubin+, 2014)
J/ApJ/814/L6 : CIII] emission in near & far star-forming gal. (Rigby+, 2015)
J/ApJ/853/87 : MEGaSaURA. II. Stacked spectra (Rigby+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Gal Galaxy name
23- 32 A10 --- Name Arc name within galaxy
34- 35 I2 h RAh Hour of Right Ascension (J2000) (1)
37- 38 I2 min RAm Minute of Right Ascension (J2000) (1)
40- 45 F6.3 s RAs Second of Right Ascension (J2000) (1)
47- 47 A1 --- DE- Sign of the Declination (J2000) (1)
48- 49 I2 deg DEd Degree of Declination (J2000) (1)
51- 52 I2 arcmin DEm Arcminute of Declination (J2000) (1)
54- 58 F5.2 arcsec DEs Arcsecond of Declination (J2000) (1)
60- 64 F5.2 h Texp [1/14] Total MagE/Magellan on-source
integration time
66- 69 I4 --- R [2500/4760] MagE spectral resolution (2)
71- 73 I3 --- e_R [70/230] Uncertainty in R
75- 81 F7.5 mag E(B-V) [0.02/0.09] Reddening due to the Milky Way
Galaxy, Green+ (2015ApJ...810...25G 2015ApJ...810...25G);
values from Note in spectrum files (3)
83-107 A25 --- Disc Discovery paper(s) for the arc (4)
109-147 A39 --- Refs Additional references, in bibcodes
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Note (1): Right ascension and declination (J2000) for the center of the MagE
slit. Astrometry for most targets is from HST images; the exceptions are
SGAS∼J142954.9+120239 and SGAS∼J145836.1-002358 where the astrometry is
from the Nordic Optical Telescope (NOT) images corrected to the USNO
system, and SGAS∼J003341.5+024217 where the astrometry is from
IMACS/Magellan images corrected to the USNO system.
Note (2): MagE spectral resolution, defined as R~=lambda/(FWHM), where
FWHM is the full width at half maximum, measured as the median (± the
median absolute deviation) of measurements of isolated night-sky
emission lines in each combined spectrum.
Note (3): The value of 0.032 for SGAS J152745.1+065219 faint tail in Table 1 was
very likely a misprint. After verification on http://argonaut.skymaps.info/
(Green+ 2015ApJ...810...25G 2015ApJ...810...25G), we changed this value for 0.0503, the value
given in Note (2) of the s1527-fnttail_megasaura.txt file.
Note added by CDS.
Note (4): Discovery paper(s) for the arc in ADS bibcodes. We list multiple
discovery papers where the arc was independently found by multiple
searches. Acronyms include --
SGAS1 = SDSS Giant Arcs Survey 1, Gladders et al. in prep.;
SGAS2 = SDSS Giant Arcs Survey 2, Dahle et al. in prep..
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Gal Source name of Galaxy
23- 23 A1 --- l_[NII]/Ha Limit flag on
25- 29 F5.2 [-] [NII]/Ha [-1.4/-0.6]? Measured log([NII]6583/Hα)
ratio
31- 34 F4.2 [-] e_[NII]/Ha [0.04/0.07]? Uncertainty on [NII]/Ha
36- 36 A1 --- l_[O/H] Limit flag on [O/H]
38- 41 F4.2 [-] [O/H] [7.9/8.6]? Inferred oxygen abundance
43- 46 F4.2 [-] e_[O/H] [0.03/0.3]? Lower or symmetric uncertainty
on [O/H]
48- 51 F4.2 [-] E_[O/H] [0.3/0.4]? Upper uncertainty on [O/H]
53- 98 A46 --- Method Method
100-133 A34 --- Notes Notes
135-153 A19 --- Ref Reference (1)
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Note (1): The measurement for SGAS J000451.7-010321 is from unpublished
FIRE/Magellan spectra, obtained UT 2010-10-14 and UT 2013-09-13, with a
total integration time of 4.18hr.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Gal Galaxy name
23- 32 A10 --- Name Arc name within galaxy
34- 43 A10 "Y/M/D" Obs.date Universal Date, YYYY-MM-DD (1)
45- 52 A8 "h:m:s" Obs.time Universal Time (1)
54- 57 I4 s Texp [900/4500] integration time, seconds (1)
59- 63 F5.3 --- Airmass [1/1.9] Airmass, sec(z) (1)
65- 68 F4.2 arcsec Width [0.7/2] Slit width, arcseconds
70- 72 I3 deg PosA [30/302] Position angle of slit,
degrees east of north
74- 77 I4 deg ParA [117/326] parallactic of slit,
degrees east of north (1)
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Note (1): Times, airmasses, and parallactic angles are given for the start
of each exposure.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- Gal Galaxy name
23- 32 A10 --- Name Arc name within galaxy
34- 39 F6.4 --- z-star [1.6/3.5]? stellar redshift
41- 46 F6.4 --- e_z-star [0.0003/0.001]? uncertainty in z-star
48- 55 F8.6 --- z-neb [1.6/3.7]? nebular redshift
57- 64 F8.6 --- e_z-neb [7e-06/0.0008]? uncertainty in z-neb
66- 73 F8.6 --- z-ism [1.6/3.7] ISM redshift
75- 80 F6.4 --- e_z-ism [0.0001/0.02] uncertainty in z-ism
82-156 A75 --- Notes Notes (1)
158-166 A9 --- File Abbreviated source name used in file names;
column added by CDS
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Note (1): Notes including References --
Bayliss14 = Bayliss et al. (2014ApJ...790..144B 2014ApJ...790..144B);
Quider+09 = Quider et al. (2009MNRAS.398.1263Q 2009MNRAS.398.1263Q);
Quider10 = Quider et al. (2010MNRAS.402.1467Q 2010MNRAS.402.1467Q);
Rigby14 = Rigby et al. (2014ApJ...790...44R 2014ApJ...790...44R);
Rigby15 = Rigby et al. (2015, J/ApJ/814/L6).
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Byte-by-byte Description of file: spectra/*
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Bytes Format Units Label Explanations
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1- 9 F9.4 0.1nm lambda [3200/8280] Observed-frame vacuum barycentric
wavelength, in Angstroms
11- 25 E15.5 mW/m2/Hz Fnu [-1.4/5.2e-20]? Flux density,
in units of erg/s/cm^2/Hz (1)
27- 40 E14.4 mW/m2/Hz e_Fnu [3.4e-30/13097]? Uncertainty in fnu (1)
42- 55 E14.4 mW/m2/Hz Fcont [2.4e-30/2.8e-28]? Hand-fit continuum flux
density (1)
57- 70 E14.4 mW/m2/Hz e_Fcont [5.5e-34/3.1e-28]? Uncertainty in Fcont (1)
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Note (1): Quantities Fnu, e_Fnu, Fcont, and e_Fcont are all f_nu, not f_lambda
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History:
From electronic version of the journal
References:
Rigby et al. Paper I. 2018AJ....155..104R 2018AJ....155..104R This catalog
Rigby et al. Paper II. 2018ApJ...853...87R 2018ApJ...853...87R Cat. J/ApJ/853/87
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Oct-2018