J/MNRAS/490/3508 The Southern Stellar Stream Sp. Survey (S5) (Li+, 2019)
The Southern Stellar Stream Spectroscopic Survey (S5): overview, target
selection, data reduction, validation, and early science.
Li T.S., Koposov S.E., Zucker D.B., Lewis G.F., Kuehn K., Simpson J.D.,
Ji A.P., Shipp N., Mao Y.-Y., Geha M., Pace A.B., Mackey A.D., Allam S.,
Tucker D.L., Da Costa G.S., Erkal D., Simon J.D., Mould J.R., Martell S.L.,
Wan Z., De Silva G.M., Bechtol K., Balbinot E., Belokurov V.,
Bland-Hawthorn J., Casey A.R., Cullinane L., Drlica-Wagner A., Sharma S.,
Vivas A.K., Wechsler R.H., Yanny B., (the S5 Collaboration)
<Mon. Not. R. Astron. Soc., 490, 3508-3531 (2019)>
=2019MNRAS.490.3508L 2019MNRAS.490.3508L (SIMBAD/NED BibCode)
ADC_Keywords: Spectra, optical; Surveys; Radial velocities; Abundances, [Fe/H];
Photometry, infrared; Stars, distances; Redshifts; QSOs
Keywords: globular clusters: general - galaxy: halo -
galaxy: kinematics and dynamics - galaxies: dwarf
Abstract:
We introduce the Southern Stellar Stream Spectroscopy Survey (S5),
an on-going program to map the kinematics and chemistry of stellar
streams in the southern hemisphere. The initial focus of S5 has been
spectroscopic observations of recently identified streams within the
footprint of the dark energy survey (DES), with the eventual goal of
surveying streams across the entire southern sky. Stellar streams are
composed of material that has been tidally striped from dwarf galaxies
and globular clusters and hence are excellent dynamical probes of the
gravitational potential of the Milky Way, as well as providing a
detailed snapshot of its accretion history. Observing with the 3.9m
Anglo-Australian Telescope's 2-degree-Field fibre positioner and
AAOmega spectrograph, and combining the precise photometry of DES DR1
with the superb proper motions from Gaia DR2, allows us to conduct an
efficient spectroscopic survey to map these stellar streams. So far
S5 has mapped nine DES streams and three streams outside of DES; the
former are the first spectroscopic observations of these recently
discovered streams. In addition to the stream survey, we use spare
fibres to undertake a Milky Way halo survey and a low-redshift galaxy
survey. This paper presents an overview of the S5 program,
describing the scientific motivation for the survey, target selection,
observation strategy, data reduction, and survey validation. Finally,
we describe early science results on stellar streams and Milky Way
halo stars drawn from the survey.
Description:
The Southern Stellar Stream Spectroscopy Survey (S5) uses the
Two-degree Field (2dF) fibre positioner coupled with the dual-arm
AAOmega spectrograph on the 3.9m Anglo-Australian Telescope (AAT)
located at the Siding Spring Observatory in Australia; 2dF provides
392 science fibres that can be distributed across a field of view
(FOV) of ∼3deg2. S5 is an ongoing survey, with 25 nights observed
in 2018 August-October and 12h observed in 2019 as of June, and more
nights in 2019.
The First Public Data Release of the Southern Stellar Stream
Spectroscopic Survey was on April 24, 2021. S5 DR1 is added in this
catalog and contains data derived from all observations taken between
2018-2019 (see http://s5collab.github.io/).
More S5 observations were taken in 2020 and the survey is continuing
in 2021 with more streams observed. S5 DR2 will include all data from
2018-2021.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
s5dr1.dat 799 31777 First Public Data Release of the Southern Stellar
Stream Spectroscopic Survey (S5 DR1)
table2.dat 79 115 S5 fields observed with the Anglo-Australian
Telescope (AAT) as of 2019 June
tableb1.dat 51 674 A list of 674 QSOs identified by S5 with
robust redshift measurements
--------------------------------------------------------------------------------
See also:
II/358 : SkyMapper Southern Sky Survey. DR1.1 (Wolf+, 2018)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/357 : The Dark Energy Survey (DES): Data Release 1 (Abbott+, 2018)
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
II/371 : The Dark Energy Survey (DES): Data Release 2 (Abbott+, 2021)
J/AJ/128/245 : M giant stars in the Sagittarius dwarf gal. (Majewski+, 2004)
J/AJ/136/2070 : SEGUE stellar param. pipeline. III. (Allende Prieto+, 2008)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/736/146 : Radial velocities of stars in Bootes I (Koposov+, 2011)
J/ApJ/762/27 : Most metal-poor stars. III. [Fe/H]≤-3.0 stars (Yong+, 2013)
J/A+A/550/A103 : Model 1D (LHD) & 3D (CO5BOLD) spectra (Allende Prieto+, 2013)
J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013)
J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)
J/ApJ/809/59 : Ophiuchus stellar stream with PS1 data (Sesar+, 2015)
J/ApJ/819/1 : Wide-field photometry of the GC Palomar 5 (Ibata+, 2016)
J/MNRAS/474/4112 : Cand. RR Lyr star streams in inner Galaxy (Mateu+, 2018)
J/ApJ/857/145 : MagLiteS Carina II and Carina III spectroscopy (Li+, 2018)
J/A+A/616/A10 : Open clusters GaiaDR2 HR diagrams (Gaia Collaboration, 2018)
J/MNRAS/478/4513 : GALAH Survey DR2 (Buder+, 2018)
J/ApJ/866/22 : Spectroscopic analysis of Tuc III stream (Li+, 2018)
J/ApJ/870/83 : Abund. in the ultra-faint dwarf gal. GruI & TriII (Ji+, 2019)
J/A+A/622/A60 : Gaia DR2 misclassified RR Lyrae list (Clementini+, 2019)
J/MNRAS/482/4570 : Gaia DR2 white dwarf candidates (Gentile Fusillo+, 2019)
J/A+A/623/A110 : Gaia DR2. Variable stars in CMD (Gaia Collaboration+, 2019)
J/ApJ/875/77 : Proper motions of MW satellites with Gaia & DES (Pace+, 2019)
J/ApJ/885/3 : Membership in 12 stellar streams from DES (Shipp+, 2019)
http://s5collab.github.io/ : The Southern Stellar Stream Sp. Survey home page
http://zenodo.org/record/4695135#.Y0m86OzMI_Y : S5 DR1 on Zenodo
Byte-by-byte Description of file: s5dr1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.3 km/s vel1 [-2000/1999] Radial velocity
statistic from rvspecfit 1st
percentile of the RV posterior
distribution (1)
11- 19 F9.3 km/s vel99 [-1990/2000] Radial velocity
statistic from rvspecfit 99th
percentile of the RV posterior
distribution (1)
21- 29 F9.3 km/s vel50 [-1998/2000] Radial velocity
statistic from rvspecfit 50th
percentile of the RV posterior
distribution (1)
31- 39 F9.3 km/s vel16 [-2000/2000] Radial velocity
statistic from rvspecfit 16th
percentile of the RV posterior
distribution (1)
41- 49 F9.3 km/s vel84 [-1996/2000] Radial velocity
statistic from rvspecfit 84th
percentile of the RV posterior
distribution (1)
51- 57 F7.3 km/s vel_std [0.027/228] Standard deviation of the
distribution
59- 64 F6.3 km/s vel_skew [-7.3/5.7] Vel skewness
66- 72 F7.3 km/s vel_kurt [-1.9/120] Vel kurtosis
74- 80 F7.4 [-] feh1 [-4.9/1.1] Metallicity statistic from
rvspecfit, 1st percentile of the
distribution
82- 88 F7.4 [-] feh99 [-4.3/1.9] Metallicity statistic from
rvspecfit, 99th percentile of the
distribution
90- 96 F7.4 [-] feh50 [-4.4/1.5] Metallicity statistic from
rvspecfit, 50th percentile of the
distribution (2)
98- 104 F7.4 [-] feh16 [-4.5/1.4] Metallicity statistic from
rvspecfit, 16th percentile of the
distribution
106- 112 F7.4 [-] feh84 [-4.4/1.9] Metallicity statistic from
rvspecfit, 84th percentile of the
distribution
114- 122 E9.4 [-] feh_std [1.9e-5/2.2] Metallicity standard
deviation
124- 130 F7.4 [-] feh_skew [-9.2/8.7] feh skewness
132- 138 F7.4 [-] feh_kurt [-2/95] feh kurtosis
140- 147 F8.5 [cm/s2] logg1 [-1.5/6.4] Log of surface gravity
from rvspecfit, 1st percentile
149- 156 F8.5 [cm/s2] logg99 [-0.9/7.6] Log of surface gravity
from rvspecfit, 99th percentile
158- 165 F8.5 [cm/s2] logg50 [-1.3/7.3] Log of surface gravity
from rvspecfit, 50th percentile
167- 174 F8.5 [cm/s2] logg16 [-1.4/7] Log of surface gravity from
rvspecfit, 16th percentile
176- 183 F8.5 [cm/s2] logg84 [-1/7.3] Log of surface gravity from
rvspecfit, 84th percentile
185- 191 F7.5 [cm/s2] logg_std [0.0001/3.1] logg standard deviation
193- 201 F9.5 [cm/s2] logg_skew [-15.4/12.3] logg skewness
203- 211 F9.5 [cm/s2] logg_kurt [-2/336] logg kurtosis
213- 220 F8.3 K teff1 [1655/9893] Effective temperature
from rvspecfit, 1st percentile
222- 230 F9.3 K teff99 [2070/18973] Effective temperature
from rvspecfit, 99th percentile
232- 240 F9.3 K teff50 [1781/12514] Effective temperature
from rvspecfit, 50th percentile
242- 250 F9.3 K teff16 [1774/11514] Effective temperature
from rvspecfit, 16th percentile
252- 260 F9.3 K teff84 [1790/14340] Effective temperature
from rvspecfit, 84th percentile
262- 269 F8.3 K teff_std [0.07/3238] teff standard deviation
271- 276 F6.3 K teff_skew [-7.4/11.2] teff skewness
278- 284 F7.3 K teff_kurt [-2/161] teff kurtosis
286- 293 F8.2 km/s velcalib [-1999/1999] Radial velocity
calibrated to have no zeropoint
offset (vel_calib) (3)
295- 300 F6.2 km/s velcalib_std [0.6/294] Calibrated radial velocity
uncertainty using repeated
observations (velcalibstd)
302- 311 E10.5 --- fehcalib_std [2.5e-5/2.8] Calibrated [Fe/H]
uncertainty using repeated
observations (fehcalibstd)
313- 319 F7.3 --- rchi2_1700d [0.8/481] Reduced chi square from the
best fit template model from
rvspecfit (redchisq_1700d)
321- 330 F10.3 --- chi2_1700d [1579/956425] Chi square from the
best fit template model from
rvspecfit (chisq_1700d)
332- 337 F6.4 --- absdev_1700d [0.006/0.5] Median absolute deviation
from the best fit template model from
rvspecfit (4)
339- 349 F11.7 deg RAdeg Right ascension in decimal degrees
(J2000) (ra)
351- 361 F11.7 deg DEdeg [-77/13.2] Declination in decimal
degrees (J2000) (dec)
363- 381 A19 --- Name Object name used for AAT observation
(5)
383- 401 A19 --- Field Name of the stream fields
as in Table2 (6)
403- 452 A50 --- FileName Filename of the reduced AAT spectra
from each field - files not released
in DR1 (fileinfo)
454- 464 F11.5 --- MJD [58141.4/58579.8] UT Modified Julian
Date of the observation (utmjd)
466- 471 F6.2 --- sn_1700d [3/228] Median Signal-to-Noise ratio
of the 1700d spectra (7)
473- 482 F10.6 deg MoonDist [12/179] Moon distance (moon_dist)
484- 489 F6.3 --- MoonPhase [0.04/100] Moon phase
(0-100% fraction of surface
illumination; 0%=new moon -
100%=full moon) (moon_phase)
491- 499 F9.5 deg MoonAlt [-78/61] Moon altitude (moon_alt)
501 I1 --- Flag [0] QSO flag based on WISE
photometry; always 0 = not a QSO
(see Section 4.4) (qsoflagwise)
503- 504 I2 --- P [-1/9] Initial target selection
priorities (priority) (8)
506 I1 --- Prim [0/1] For some object, multiple
observations were taken (primary) (9)
508- 512 F5.3 --- Prob [0.5/1] Good star probability based
on random forest (goodstarpb) (10)
514 I1 --- good_star [1] A flag to select stellar spectra
with good fitting quality
(always 1=good) (11)
516- 521 F6.4 mag EBV [0.006/1.4]? E(B-V) from
Schlegel+ (1998ApJ...500..525S 1998ApJ...500..525S)
523- 541 I19 --- Gaia ? Gaia EDR3 identifier
(gaiasourceid)
543- 548 F6.3 mas plx [-5.4/9.8]? Gaia EDR3 Parallax
(parallax)
550- 554 F5.3 mas e_plx [0.01/1.3]? Parallax uncertainty
(parallax_error)
556- 562 F7.3 mas/yr pmRA [-60/131]? Gaia EDR3 Proper motion in
right ascension
564- 571 F8.3 mas/yr pmDE [-113/41]? Gaia EDR3 Proper motion in
declination (pmdec)
573- 577 F5.3 mas/yr e_pmRA [0.01/1.4]? pmRA uncertainty
(pmra_error)
579- 583 F5.3 mas/yr e_pmDE [0.009/1.3]? pmDE uncertainty
(pmdec_error)
585- 591 F7.4 mag Gmag [11.99/21.61]? Gaia EDR3 G-band
magnitude (photgmean_mag)
593- 599 F7.4 mag BPmag [12.2/20.8]? Gaia EDR3 BP-band
magnitude (photbpmean_mag)
601- 607 F7.4 mag RPmag [10.87/19.9]? Gaia EDR3 RP-band
magnitude (photrpmean_mag)
609- 615 F7.4 --- E(BP/RP) [0.86/25.5]? Gaia EDR3 BP-RP excess
factor (photbprpexcessfactor)
617- 624 F8.4 mag gmag [11.6/21.3]? DECam g-band magnitude
(decam_g) (12)
626- 633 F8.4 mag rmag [11.7/20.3]? DECam r-band magnitude
(decam_r) (12)
635- 642 F8.4 mag imag [11.3/20.2]? DECam i-band magnitude
(decam_i) (12)
644- 651 F8.4 mag zmag [10.7/20.6]? DECam z-band magnitude
(decam_z) (12)
653- 656 I4 --- r_DECam [0/1755] The source of the decam
photometry (decamphotsrc_bits) (13)
658- 669 E12.6 309.05nJy FW1 [33.5/1.9e+6]? UnWISE W1 (3.4um) band
flux density in "Vega nMgy" (flux_w1)
671- 682 E12.6 167.66nJy FW2 [93.6/2.4e+6]? UnWISE W2 (4.6um) band
flux density in "Vega nMgy" (flux_w2)
684- 695 E12.6 309.05nJy e_FW1 [4.5/1233]? FW1 uncertainty (dflux_w1)
697- 708 E12.6 167.66nJy e_FW2 [17/2856]? FW2 uncertainty (dflux_w2)
710- 716 F7.4 mag umagS [13.3/20]? Skymapper DR2 u-band
magnitude (u_skm)
718- 724 F7.4 mag gmagS [12/20.8]? Skymapper DR2 g-band
magnitude (g_skm)
726- 732 F7.4 mag rmagS [11.8/20]? Skymapper DR2 r-band
magnitude (r_skm)
734- 740 F7.4 mag imagS [11/20.1]? Skymapper DR2 i-band
magnitude (i_skm)
742- 748 F7.4 mag zmagS [10.7/19.7]? Skymapper DR2 z-band
magnitude (z_skm)
750- 758 F9.6 kpc Dist05 [0.1/54]? Starhorse distance at 5th
percentile
from Queiroz+ 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q
(starhorse_dist05)
760- 768 F9.6 kpc Dist16 [0.1/67]? Starhorse distance at 16th
percentile
from Queiroz+ 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q
(starhorse_dist16)
770- 778 F9.6 kpc Dist50 [0.1/78]? Starhorse distance at 50th
percentile
from Queiroz+ 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q
(starhorse_dist50)
780- 788 F9.6 kpc Dist84 [0.1/97]? Starhorse distance at 84th
percentile
from Queiroz+ 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q
(starhorse_dist84)
790- 799 F10.6 kpc Dist95 [0.1/120]? Starhorse distance at 95th
percentile
from Queiroz+ 2018MNRAS.476.2556Q 2018MNRAS.476.2556Q
(starhorse_dist95)
--------------------------------------------------------------------------------
Note (1): For radial velocity, we recommend the velcalib column.
Note (2): feh50 is recommended to be used as mean metallicity for each star.
Note (3): Offset is determined by cross-matching with APOGEE data.
See details in Section 4.1
Note (4): Median absolute deviation from the best fit template model from
rvspecfit, defined as Median(Data-Model)/Median(Model)
Note (5): For stellar targets, name is usually source_id from Gaia DR2, for
galaxy targets (S5-lowz), the name is usually object_id from DES DR1.
Some observations prior S5 were also included and for those, names
could follow different conventions.
Note (6): The field names given in S5 DR1 were made early on and can
differ from those given in Table 2 of the paper. They have been
homogenized by the CDS.
Note (7): For DR1, we decide to only release objects with sn_1700d>3 to ensure
the high quality of this dataset.
Note (8): Priority target are:
-1 = few fields were observed prior to the official S5 observations
(2528 occurrences)
7-9 = stream targets
3-6 = halo star targets
For details, refer to Section 2.
Note (9): Primary = True ("1") if this is the observation with the highest S/N
(29,584 occurrences). For objects that only one observation was
taken, Primary is always True. This column is useful if you want to
get only one measurement per target to remove duplicates.
Note (10): Good star probability based on random forest trained on the following
parameters as features: chi-squared values of the fit, radial
velocity error, radial velocity posterior skewness and kurtosis,
effective temperature, median signal to noise in the spectrum and
median absolute deviation from the best fit template model.
See details in Section 4.5.
Note (11): A flag to select stellar spectra with good fitting quality.
good_star=0 if it meets one of the 3 following criteria:
1. goodstarpb<0.5
2. priority≤2
3. qsoflagwise≡1
See details in Section 4.5.
For DR1, we decide to only release objects with good_star=1 to
ensure the high quality of this dataset.
Note (12): DECam photometry (without reddening correction) from DES DR1,
DECaLS DR9 or NSC DR2.
If the object is in multiple catalogs, then DES is first considered,
then DECaLS and finally All-sky NOAO Source Catalog (NSC).
See r_DECam for the source of the photometry
Note (13): The source of the decam photometry. It is a 12 bit integer
"ABC DEF GHI JKL" where ABC bits describe the source of g photometry,
DEF bits the source of r photometry, etc. The value of 1 corresponds
to DES DR2, 2 to DECALS, 3 to NSC. For example, r_DECam=585
corresponds to 001 001 001 001, which means that griz photometry all
comes from DES DR2; r_DECam=83 corresponds to 000 001 010 011, which
means that the griz photometry comes from NONE, DES, DECALS, NSC.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- Field S5 field name (1)
21- 30 F10.6 deg RAdeg Centre of the field right ascension (J2000)
32- 41 F10.6 deg DEdeg [-76/12.2] Centre of the field
declination (J2000)
43- 52 A10 "Y/M/D" Date UT date of the observation (with highest S/N
if observed multiple times)
54- 61 F8.2 d MJD [58141.4/58579.7] Modified Julian Date (start)
of the observation
63- 66 I4 s Texp [600/9600] Total exposure time
68- 71 F4.1 mag Gmag [14.7/19.3] Average Gaia DR2 G-band magnitude
at S/N=5 per pixel (from red arm spectra)
73- 75 I3 --- Nt [96/367] Total number of targets
77- 79 I3 --- Ns [67/351] Number of stars (Ngoodstar) with
good measurements (2)
--------------------------------------------------------------------------------
Note (1): All fields are grouped into four categories, which are fields in
the DES footprint, fields outside the DES footprint (see Section 2.6),
calibration fields for survey validation (see Section 4), and fields
observed prior to S5 with the same instrument setup but previously
unpublished.
Note (2): i.e. good_star=1; see definition in Section 4.5.
We note that for fields in some streams such as ATLAS, Elqui, Phoenix,
etc., Ngoodstar is usually much lower than Ntargets, because these
streams are at high Galactic latitude; therefore, we used ∼100 spare
fibres to target low redshift galaxies (see Section 2.4), and all
galaxy targets are assigned good_star=0 regardless of the quality of
the spectra.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Gaia Gaia DR2 source ID
21- 30 F10.6 deg RAdeg [4.69/358.13] Right ascension (J2000)
32- 41 F10.6 deg DEdeg [-64.76/-18.59] Declination (J2000)
43- 46 F4.1 mag Gmag [15.1/20.3] Gaia DR2 G-band magnitude
48- 51 F4.2 --- z [0.04/3.4] Measured redshift
--------------------------------------------------------------------------------
Acknowledgements:
Ting Li [ting.li at astro.utoronto.ca]
History:
From electronic version of the journal for Tables 2 and B1.
S5 DR1 (s5_pdr1.fits) downloaded from: http://s5collab.github.io/
(End) Emmanuelle Perret [CDS] 13-Oct-2022