SEGUE Meeting

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SEGUE Meeting AM Talks towards a task
list pipeline changes/updates Target Selection
updates
SDSS Collaboration Meeting Oct 2, 2004 Pittsburgh
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Over-arching Question Can the
SEGUE imaging and spectroscopy meet the basic
science goals, as laid out in the SEGUE white
paper and various SEGUE proposals?
Reminder Key project SEGUE science drivers 1.
Map Halo structure trace streams such as the
Sagittarius and Monoceros-- Canis Major streams
around the Galaxy. Constrain Dark Matter
potential/shape. 2. Disk(s) Structure Study
the thin/thick disk transition, and the
transition to the halo/spheroid in number counts
(model parameters scale lengths, falloffs w/
radius, metalicities, kinematics and formation
history.
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Fibers per plate Pair WD 25 CWD
10 BHB 125 F TO 150 G 375 K III
125 Low Fe150 K V 125 Ms 50 AGB
10 SKY 96 QA 15 RED/SP
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Saturday Oct 2, 2004 AM (Room Allen 318)
900 Intro 910 J. Bochanski SDSSWhite
Dwarf/M-Dwarf pairs, red Star update 930 J. A.
Smith Photometry Update, WD/MD stars 945
C. Rockosi Radial Velocities for
SEGUE 1015-1045 Break 1045 C. Allende-P.
Metalicity, Gravity determination 1115 R.
Wilhelm Metalicity, Gravity determination
hot stars 1145 T. Beers Atmospheric
Parameter determination in stars 1230-130
Lunch 130-330 Open discussion spectroscopic
pipeline, SEGUE science 400-530 SEGUE target
selection category by category
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Observing strategy Imaging 3900 sq deg, mostly
at low b Spectra 240,000 stellar spectra (520
plate-equivalents) of stars of a range of colors.
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-44 -41 -38
-35 -32 -29
-26 -23 -20
-17 -14
-11
Strip 1100S (l50 deg) CMDs (g-r,g)
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SEGUE Level 0 Deliverables Medium latitude
frames (b gt 10 deg) processed through PHOTO,
initial calibration with PT patches to
roughly SDSS-I accuracy (i.e. g-r errors of 2).
Flat file format ok (tsObj catalogs). turn
around in time for Target Selection one month or
one year time scales, can use SDSS-I
imaging Target Selection Pipeline for SEGUE TS,
with documentation, including usual TS items
skies, guide stars, redden standards, plPlugMapT
input files. Spectro plates processed through
existing SDSS-I 2D1D pipelines with improved
Radial Velocities from ELODIE template fits (or
equivalent) for all stars with S/Ngt5. First-pass
estimation of stellar atmos params Teff, Fe/H,
log g for stars with g lt 18.5. 'Value added
Catalog' format. Matches to existing Proper
motion data when available. Design, observation,
processing of 'calibration/standard' plates with
stars of known Fe/H, RV, log g, etc.
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Enhanced Goals Imaging processing Ability to
process imaging in regions of high stellar
density (b lt 10 deg), producing accurate
catalogs stellar magnitudes and positions in
these regions. Calibration Use crossing scans
or other techniques to improve photometry from
2 RMS to 1 with fewer outliers. Spectroscopy
Incorporate parameter (i.e. Fe/H)
estimation into pipeline processing. Database
Insert Imaging catalogs and spectra w/
all parameters (i.e. PPM matches, Rvs), into
indexed database (i.e. CAS-style) in addition to
DAS style flat field access.
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To Do List Great interest has been expressed by
current and new partners in SEGUE and the other
SDSS-II science projects. Note that we are
currently effort limited, and need to organize a
team to handle development and operations as well
as science analysis aspects of SEGUE, and we hope
and expect to draw resources from many of you.
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Development tasks (broad categories target
selection, imaging, spectro, data processing,
Q/A, calibration/standards, science analysis,
database and distribution and, of course,
documentation) Target Selection
tasks Refine, verify SEGUE Target Selection
algorithm in each of the 10 Stellar Categories (F
turnoff, G dwarf, K giant, BHB/A, Low
Metalicities) There are at least projects for 10
people here! Weight low-metal stars to
bright mags lt 18, improve K-giant efficiency from
current 20 Are we selecting the right stars
enough stars in each category to do the science
(trace halo streams or disk structure, explore
metalicity history of the Milky Way or Chemical
gradients in the Galaxy. Are we selecting
enough stars in each category to have sufficient
statistics to do the science? More F stars to
trace streams? Web link to target selection
color/mag cuts and links to early SEGUE
plates. (A more formal web page is coming)
http//www-sdss.fnal.gov/yanny/seguets/
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Imaging Plan, obtain and reduce SEGUE
imaging stripe data. Analyze photometric
accuracy as f(stellar density). Update imaging
pipeline to work at high density i.e.
stars-only 'DAOPHOT' mode Analyze photometric
accuracy as f(dust/variable sky). Update imaging
pipeline to work in variable sky
background conditions (i.e. b
0. Spectroscopy Plan, obtain and process SEGUE
plate pairs. Analyze RV accuracy as f(S/N),
stellar color/type. Update RV templates as
needed to reach goals. Do we have enough sky
fibers? New ELODIE templates to
insert zeropoints, N best fit (now 12)
Develop algorithms for Fe/H, Teff, log g of
stars as f(S/N), stellar type. Expanded Lick
indicies, continuum-subtracted spectra in blue,
smoothing, unskysubtracted-sky spectra
availability Incorporate algorithms into
pipeline processing.
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Quality Assurance During observing 2004-2008,
monitor imaging and spectra data as they occur.
Within one month timescale for imaging (turn
around for Target Selection), check tracking,
photometric accuracy, S/N depth of images. Color
magnitude diagrams. Search for 'special regions
to scan' i.e. if a new 'great stream
appears'. Spot check spectra of each type vs. S/N
estimates and science requirements. Calibration/S
tandards (IM) target and process 'PT' patches
along SEGUE stripes for initial 2 rms
calibration (in time for Target Selection).
scan crossing scans as needed to allow
photometric ties of SEGUE 'constant l' stripes to
each other and to SDSS imaging. process
crossing scan and other available photometric
calib info. (SP) Obtain samples of stars with
known Rvs, Metals, log g, spectral types to
calibrate algorithms for parameter
estimation. i.e. plates on Globular and Open
Clusters of known RV, Fe/H. Match to USNO-B2.0
or other catalogs of known info proper
motions.
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Databases/Data distribution/Documentation Suppo
rt initial catalogs and value-added information
as 'Flat Files' in SDSS 'DAS' format, with web
sites Design/Modify 'indexed-database' design
to include new parameters/information (data
model changes). Publish (in some form), TS
algorithm, selection function, goals and science
background. Science Analysis Stellar
Atmosphere modeling and parameter estimation is
still a bit of a 'black art', we need your
experts and expertise. SEGUE has potential to
revolutionize this field!! Think Big! Work
on the key project or some of the other '57'
science projects with initial sample (20,000
SEGUE stars already available in Aug/Sep 04) with
intent to determine feasibility of the
science.
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Papers Metals in Sag stream Metals in
Mono/Canis Major Stream Spectra of everything
selection function, stellar spectral atlas SDSS
DR2/DR3 selection function, target selection
algorithm Metalicity Distribution in the MW (DR2
and beyond) The Lowest Metal Stars Techinques
for measures stellar atmosphere parameters in
large sample of R2000 SDSS spectra. SEGUE
Target Selection and early results.
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We are 'new' to the rich field of stellar
kinematic and population analysis, with
implications for dark matter and galaxy history
studies on the Galaxy easiest to observe. We
need your help! Meeting Oct 2 There are many
opportunities to contribute, including student
projects.
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Dual turnoffs, indicates stream(s?) at 10 and 20
kpc from the sun.
Thick Disk Fs
Thin disk M stars
Halo or stream(s)?
Color-Magnitude (g-r,g) diagram for Strip 1260N
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SEGUE as of September 30, 2004 Black completed
stripe or plate pair
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WD A/BHB F Turnoff G III V Low Metals K III K
V M V AGB Cool Wds
SEGUE currently has 10 categories, (we have
openings for G dwarf specialists)
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-250 -200 -150 -100 -50 0 50
km/s
G dwarf Radial Velocity histograms, by Magnitude
(dist)
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SEGUE spectroscopic sample Radial Velocities of
populations of similar stars, Metalicity, Teff,
log g determinations Kinematic, Chemical
population studies of the Milky Way and halo
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N25
White Dwarf
Issues ?
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N10
Issues Proper Motion gt 30mas/yr
Cool White Dwarf Candidate
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N125
BHB Star, probe outer halo, streams to 150 kpc
Issues Are we getting essentially 'all' of
these?
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-400 -300 -200 -100 0
100 km/s
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N150
Issues Do we need more faint Fs per plate for
streams? What about P1 cut?
F turnoff star, trace streams, halo, low Fe/H
to 20kpc
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-400 -300 -200 -100 0
100 km/s
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N375
Issues Giants vs. Dwarfs? Color band ok?
G dwarf, largest SEGUE sample, probe disk/inner
halo 1.5kpc to 8 kpc distances, Stream Giants
also here
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-400 -300 -200 -100 0
100 km/s
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N125
K Giants
Issues Color cuts ok, selection efficiency still
low?
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K Giant Narrower lines, features less
deep. K dwarf Stronger features, broader l
ines.
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N125
Issues Faint cutoff? USNO Match? Disk Science
ok?
K dwarf , kinematics from match to USNO-B,
RV photometric parallax probe disks from 0.5
2 kpc
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N150
Issues Wish to weight much more towards bright
glt18.5
Low metalicity candidate, Fe/H -2.6, g15.8,
g-r0.47 Pop III exploration, gradients in
inner/outer halo
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N50
M dwarfs
Issues sub-dwarf alg, brown dwarf alg, PPM cut
modify? How faint?
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N10
Issues Efficiency, use only on Sag/Mon? color
cuts?
AGB candidate, Giants in Sagittarius/Monoceros
streams? g 16.5,g-r 1.12, u-g 3.1, RV
-72km/s d(AGB) 18 kpc
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Globular Cluster Plates 1960-1962 (M15/M2) Open
Cluster Plates M67, Hyades? RV standards, go
down stellar locus
Issues Exposure times for GC plates? When
will be ready to tackle Open Clusters? Peregrine'
s cross scan on open clusters for this
Fall? Redo Hyades, M67?
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SEGUE is doing well with the grant of Fall season
observing during the last full year of
SDSS-I. This 2004 data is available to all SDSS
participants for analysis and papers.
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WD A/BHB F Turnoff G III V Low Metals K III K
V M V AGB Cool Wds
Spectroscopic targets selected to probe variety
of distances from the sun from lt 1 kpc to gt 100
kpc, basically through a 'standard candle' color
cut to select stars representative of each
distance.
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Cool White Dwarf Candidate
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1100S Binned 6x3deg
Photo in crowded fields as we pass thru b
0 plane, will be improved in SEGUE outyears.
-43 -37 -31
-25
l 50 deg at 4 b's. Possible stream
present, but need to model spheroid.
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SEGUE footprint as of Sep 30, 2004 Black
completed stripe/plate 29/400 plates 7 done.
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K Giants