Transcript Current astrometric surveys

HST and Astrometry
in the 2010 Decade
William van Altena
Yale University, New Haven, CT USA
With thanks to:
Jay Anderson
Rolly Bedin
Dave Monet
Norbert Zacharias
Terry Girard
Dana Casetti
Elliott Horch
Imants Platais
Todd Henry
HST Cal. WS: July 21-23, 2010
Fritz Benedict
Barbara McArthur
Art Bradley
René Méndez
Andrea Ghez
1
Astrometry in the 21st century
• Analyze data contained in large multipurpose surveys
– SDSS, 2MASS, PanSTARRS, LSST, etc.
• Extract relevant data from astrometric surveys
– UCAC, SPM, NPM
• PI projects on medium to large multipurpose telescopes
– HST, 4-m telescopes, 8-10-m large telescopes
• Small PI projects on dedicated astrometric telescopes
– USNO 1.5-m astrometric reflector
– UCAC 0.25-m astrograph
– SPM 0.50-m astrograph, etc.
• Educational use of small ground-based telescopes
• Instrumentation development
HST Cal. WS: July 21-23, 2010
2
Ground vs Space Astrometry
• Where ground-based Astrometry will remain important
– Ground-based parallax errors can be as low as 0.25 mas, almost as accurate
as HST FGS which are about 0.20 mas.
• Beware of relying on very large “root n”
• N > 100: systematic errors may dominate
– Targets fainter than magnitude 16 can be reached, much fainter than FGS
astrometry.
– Binary stars will be done primarily by speckle interferometry from the ground.
– Strong role for ground-based astrometry until Gaia results are available.
• After Gaia proper motions and positions will be determined from the ground using a
Gaia reference frame.
• Where space-based Astrometry will remain important
– Crowded regions such as the centers of globular clusters
– Projects requiring high-precision individual observations
HST Cal. WS: July 21-23, 2010
3
HST Astrometry
• Surveys
– Deep fields (1995 HDF, 1998 HDFS, 2003
HUDF)
• Crowded regions
– Globular Clusters (pm membership, absolute pms
& orbits)
– Magellanic Clouds (absolute pms & orbits)
• Parallaxes
– Special objects (Planetary nebulae, novae, neutron
stars, …)
– Cepheid Pop I and II P-L relations
• Binaries
– Masses and orbits (close binaries)
– Extra-Solar planets (perturbation astrometry of
nearby stars)
HST Cal. WS: July 21-23, 2010
4
Ground-based surveys current and future
• Current astrometric
surveys
– UCAC
– NPM
– SPM
• Schmidt plate scans
– USNO-A2, USNO-B
– SuperCosmos
• Planned astrometric
surveys
– URAT
• Current multipurpose
surveys
–
–
–
–
–
SDSS and derivatives
2MASS
Dennis
SkyMapper
PanSTARRS
• Planned multipurpose
surveys
– LSST
HST Cal. WS: July 21-23, 2010
5
Current Astrometric Surveys
•
•
•
UCAC3: U.S. Naval Observatory CCD Astrograph Catalog
– A compiled, all-sky star catalog of 100 million stars
– Magnitude range 9 < R < 16
– Positional errors: 15 to 20 mas for 10 < R < 14
– Proper motions from early epoch SPM data (-90 to -10 deg Dec) and Schmidt plate
data
– Zacharias, et al. 2009
SPM4: Yale/San Juan Southern Proper Motion Catalog 4: (2009)
NPMx: Lick Northern Proper Motion Catalog: first epoch positions: (2010)
to be used as first-epoch positions for the UCAC4.
– 103,319,647 stars and galaxies south of -20 degrees declination - SPM.
– 160,000,000 stars and galaxies north of -30 degrees declination - NPM.
– roughly complete to V=17.5 (all are contained in 2MASS)
– precision of SPM4 positions: 30 to 150 mas
– precision of SPM4 absolute proper motions: 2 to 10 mas/yr
– van Altena, et al. 2009; Girard, et al. 2010
HST Cal. WS: July 21-23, 2010
6
Future Astrometric Survey
• URAT: USNO Robotic Astrometric Telescope
– Magnitude range 9 < R < 16
– Positional errors: 15 to 20 mas for 10 < R < 14
– Proper motions from early epoch SPM data (-90 to -10 deg Dec) and
Schmidt plate data
– Zacharias, et al. 2009
20-cm astrograph
UCAC
51-cm double astrograph
SPM
HST Cal. WS: July 21-23, 2010
110 megapixel CCD "superchip"
URAT
7
Schmidt Plate Scanners
STScI Guide Star Measuring Machine
USNO PMM Measuring Machine
ROE SuperCOSMOS scanner
HST Cal. WS: July 21-23, 2010
8
Schmidt Plate Scans
• GSC 2.3 release of GSC II
– 945,592,683 objects measured
on STScI PDS machines
– GSC 2.3 is a current catalog
release extracted from the
Guide Star Catalog II database
– Positions on ICRF ACT/Tycho
– Bucciarelli, et al. 2008
•
– 526,280,881 stars measured on
PMM
– Average J2000 position on red and
blue POSS plates
– ACT/Tycho system
– Monet, et al. 1998
•
USNO-B
•
– 1 billion stars
– Average J2000 positions and proper
motions from 3 colors at 2 epochs
– Monet, et al. 2003
XPM: 2MASS - USNO-A2.0
– 280 million stars - whole sky
– Positions and proper motions
– Mag range 12 < B < 19 mag
– Federov, et al. 2009
• SuperCOSMOS
– 1.9 billion objects
– Average J2000 positions and
proper motions from 3 colors
at 2 epochs
– Positions on Tycho2 and ACT
– http://surveys.roe.ac.uk/ssa/
USNO-A2
HST Cal. WS: July 21-23, 2010
9
Multipurpose Surveys
• General characteristics:
–
–
–
–
Not primarily astrometric, but huge amounts of useful data.
New surveys should get around 10-mas per visit; lots of visits and colors.
Surveys need much more input on astrometric needs.
Don’t need Gaia-class accuracy for nearby stars, etc.
• Some priorities:
– Develop algorithms for finding these needles in very big haystacks.
– Understand astrometric accuracy:
• Regime of low signal-to-noise ratios, short exposures, fast optics, etc.
• Morphology and statistics of “reference galaxies”.
• Contribute to design and mission of LSST.
– Work on IR version of large etendue telescope+camera.
HST Cal. WS: July 21-23, 2010
10
•
•
•
•
•
Multipurpose Surveys
2MASS - A large-area, deep
photometric survey
SDSS based proper motions
SDSS-USNO-B
– Covers about 3000 square
degrees
– Sigma pm about 3.5 mas/yr.
– Munn, et al. AJ 127, 3034, 2004 &
AJ 136, 895, 2008
SDSS-Flagstaff 1.3-m telescope
– Covers about 3000 square degrees
– Proper motion accuracy about 2030 mas/yr with a 5-year baseline.
– Munn, et al. AAS 215, 45202,
2009
SDSS-SDSS proper motions
– 300 square degree Southern
Equatorial Stripe
•
Pan-STARRS 1.8-m Sky Survey
– Pan-STARRS will survey the
whole sky to 24th magnitude
every few days
•
•
SkyMapper - ANU 1.35-m survey
– analogous to the Sloan Digital Sky
Survey; 20,000 sq. deg. South of
equator.
LSST - Large Synoptic Survey
Telescope 8.4-m primary, 6.7-m
effective aperture
– Ten-year imaging survey over 20,000
square degrees south of +15 deg.
– Each pointing will be imaged 1000
times with fifteen second exposures
in
– total point-source depth of r~27.5.
– Gaia parallax accuracy at r = 20.5
mag and to go 4 mag fainter than
Gaia
HST Cal. WS: July 21-23, 2010
11
Deep Astrometric Standards (DAS)
• Large telescopes need deep and
precise reference frames for
astrometric calibrations.
• Absolute astrometry at the 5 - 10
mas level and absolute proper
motions good to 2 mas/yr in four
10 deg2 Galactic fields, to a depth
of V=25.
• Basic reference frame is UCAC2
catalog, significantly improved by
additional observations, and new
VLBI positions of radio-loud and
optically visible QSOs.
Platais, et al. 2006
(PASP 118, 107, 2006)
Careful of LSST 15-sec exposures!
HST Cal. WS: July 21-23, 2010
12
Science in the Halo of the Galaxy
• Dwarf galaxies and Globular Clusters
– The formation of the GC system: accreted from early/recent
mergers of satellites and/or formed in situ?
– Orbits help to understand formation scenarios of the Galaxy and
origins of GCs
– Ground-based surveys & some HST provide absolute proper
motions and orbits
• Casetti, et al. (2010)
• Rees & Cudworth (2010)
• Bellini & Bedin (2010)
HST Cal. WS: July 21-23, 2010
13
Science in the Halo of the Galaxy
• Magellanic Clouds
– Ground-based pms imply
systems probably bound to
Galaxy
• Vieira, et al. (2010)
– HST-based pms imply systems
probably unbound
• Kallivayalil, et al. (2006,
2010)
• Reference systems of galaxies
& QSOs now provide the link
to absolute
– Gaia will be the link to
absolute in the future
HST Cal. WS: July 21-23, 2010
14
Finding Merger Remnants from Surveys
• Velocity dispersion in a remnant stream
predicted Sigma v ~ ± 5 km/s (Helmi &
White, 1999; Kathryn Johnston, 2006)
• 300-500 remnant streams predicted by H&W
within the local 1 kpc3
• Sigv = k*Sigpm*D
– 5 km/sec = 4.74* Sigpm *1000pc
– Sigpm = 1 mas/yr
• Proper motions with sigpm = 0.5 mas/yr can
now be determined with medium-sized
telescopes in a 3-4 years to mag 21.
• Detection/non-detection of streams could
place limits on the validity of the lambdaCDM models of cosmology
HST Cal. WS: July 21-23, 2010
15
Measuring the orbit of Sgr stream
Casetti, et al. 2010
Sgr core
SA 71
SA 94
SA 116
SA 93
SA 117
HST Cal. WS: July 21-23, 2010
16
Proper Motions in the
Hubble Deep Field North
Kilic, von Hippel, Winget &
Méndez, Ap J accepted.
HST Cal. WS: July 21-23, 2010
17
Globular Cluster Proper Motion Membership
• HST imaging cameras
enable us to determine
precise relative proper
motions.
• This enables us to
separate the cluster
members from the field
stars and therefore
“clean” the CMDs. In
some cases it is possible
to study the internal
dynamics of the clusters.
• Proper motion precision
of 0.25 mas/year for a 3
year baseline.
• This corresponds to
≈10 km/s at 10 kpc.
Anderson & King, 2003, “The Rotation of 47 Tuc,” AJ, 126, 772
HST Cal. WS: July 21-23, 2010
18
The First Full CMD of a Globular Cluster
• Richer et al. 2005 observed
NGC6397 with 126 orbits
– Discoveries
• End of WD cooling
seq
• Blue hook at bottom!
• End of MS?
– Limitation: field stars
– Solution: proper motion
membership
• Slides courtesy of Jay
Anderson
HST Cal. WS: July 21-23, 2010
19
19
Proper-Motion Cleaning
HST Cal. WS: July 21-23, 2010
20.0
20.3
20.2
20.1
PI-Rich, UCLA
20
Where are the stars centered?
HST Cal. WS: July 21-23, 2010
21
Open Cluster Membership
• Low field density, so a
ground-based project for
Wide-Field Imagers
• Proper motion precision
now available with time
baseline of 3-4 years:
– igmapm ~ ± 0.5
mas/yr, or
– igmav ~ ± 2.6 km/s @
1kpc
• Very clean separation
of members from
field stars for
clusters with D < 1-2
kpc
HST Cal. WS: July 21-23, 2010
22
The Stellar Census and Dark Matter
• Ground-based programs
– USNO Flagstaff (Dahn, et al.
2008)
• Special objects with parallax
precision of 0.25 mas
– RECONS at CTIO (Henry)
– Parallaxes with wide-field imagers
on the ground.
• ±1 mas positional astrometry can
yield 0.5 mas parallax precision.
• Determine stellar density to 2% in
Solar Nbhd.
• Brown dwarfs, L & T dwarfs
– Detect to MI ≤ 21 at 150 pc
Courtesy of Todd Henry
HST Cal. WS: July 21-23, 2010
23
HST FGS parallaxes
• HST FGS
– Stars brighter than 16th mag
• Parallax precision to 0.2 mas
– Pop I Cepheid P-L calibration 2007
– Planetary nebulae - 2009
– Pop II Cepheid P-L calibration
- HST orbits approved.
• Benedict, et al. 2007, 2009
Pop I Cepheid P-L calibration
HST Cal. WS: July 21-23, 2010
24
HST FGS parallaxes of Planetary Nebulae
Benedict, et al. 2009
HST Cal. WS: July 21-23, 2010
25
• Binary stars.
Binaries:
Orbits and masses.
– Gravitation --> orbit.
N
• Semi-major axis from
•
– ground-based speckle
interferometry
– HST FGS scans
• separations down to
10-15 mas with FGS.
r
Need SIZE of orbit which
means we need the parallax.
– Gaia and SIM will do the
job here.
HST Cal. WS: July 21-23, 2010
26
The  And System
McArthur, et al. 2010
4 years, from 11 pc
50 y of Solar System from 10 pc
HST Cal Workshop 27
Adaptive Optics
• Adaptive optics: correct for
atmospheric turbulence in Infrared
• Can see through the 20 magnitudes
of visual extinction
– Very small areas of the sky, say 1”
– Need a fairly bright reference star
to monitor the atmosphere, so
limited unless laser reference is
used
• Mass of Black Hole at the Galactic
center from orbital motions of the
stars
HST Cal. WS: July 21-23, 2010
28
Space Satellite accuracy projections
Mission
Positional
accuracy
Parallax
accuracy
Proper
motion
accuracy
Gaia
V < 15
V = 20
6 uas
205 uas
21 uas
275 uas
11 uas
145 uas/yr
SIM
V < 20
3 uas
4 uas
2.5 uas/yr
Gaia and SIM will determine the parallaxes
that with orbits from HST FGS, while groundbased Speckle Interferometry will define the
Mass-Luminosity relation.
HST Cal. WS: July 21-23, 2010
29
Kinematics: The Future
SIM (18 mag)
Distances
1%
10%
SIM
2.5 kpc 25 kpc
Gaia
0.4 kpc 4 kpc
Hipparcos 0.01 kpc 0.1 kpc
Proper Motions:
SIM ~ 2.5 uas/yr
Gaia ~ 11 uas/yr
Hipparcos ~ 1 mas/yr
Gaia (15 mag)
Gaia and SIM will define
the kinematical structure of
the Galaxy.
HST Cal. WS: July 21-23, 2010
30
Local Group members
• Beyond the merging
satellite galaxies
– Note that all of the
proper motions are
predicted to be large in
the context of SIM and
Gaia accuracies
– 3D velocities of the LG
members will provide
mass estimates of the
LG and dark matter
Gaia
SIM
HST Cal. WS: July 21-23, 2010
31
Summary
• The potential for Astrometry to contribute to
science is greater than at any time in history!
• A desperate need exists to train young scientists
in Astrometry to make the most of this exciting
future.
• There is a trend, especially in the US, for
diminishing support for Astrometry.
• We need to convince universities, observatories
and astronomical institutes to support the
education of Astrometrists (and to hire them!!)
HST Cal. WS: July 21-23, 2010
32
HST Cal. WS: July 21-23, 2010
33
UCAC3: U.S. Naval Observatory
CCD Astrograph Catalog
•
•
•
•
•
•
•
UCAC3 is a compiled, all-sky star catalog of 100
million stars
8-inch USNO astrograph: south from CTIO, north
from USNO Flagstaff
Magnitude range 9 < R < 16
Wavelength range 670 to 750 nm
Positional errors: 15 to 20 mas for 10 < R < 14
Photometric data: SuperCosmos and 2MASS
Proper motions:
– bright stars are based on about 140 catalogs,
including Hipparcos and Tycho, as well as all
catalogs used for the Tycho-2 proper motion
construction
– faint stars are based on a re-reduction of early epoch
SPM data (-90 to -10 deg Dec) plus Schmidt plate
data from the SuperCosmos project
•
Zacharias, et al 2009
HST Cal. WS: July 21-23, 2010
34
URAT: USNO Robotic
Astrometric Telescope
•
•
•
•
•
•
URAT successor to the UCAC
Same lens as the UCAC, but four
110 megapixel CCD "superchips"
(shown right) in a mosaic to cover 28
square degrees/exposure.
Magnitude range 9 R < 17.5
Wavelength range 670 to 750 nm
All sky coverage to start in
Flagstaff and then move to CTIO
First light expected in 2010 in
Washington
HST Cal. WS: July 21-23, 2010
35
SPM4: Yale/San Juan
Southern Proper Motion Catalog
•
47-year collaboration between the National
University of San Juan, Argentina and the
Yale Southern Observatory
– 103,319,647 stars and galaxies south of -20
degrees declination.
– roughly complete to V=17.5 (all are
contained in 2MASS)
– precision of its positions: 30 to 150 mas
– precision of absolute proper motions: 2 to 10
mas/yr
– blue and visual passband photometry +
2MASS J,H,K
HST Cal. WS: July 21-23, 2010
36
SPM4: Yale/San Juan
Southern Proper Motion Catalog
•
47-year collaboration between the
National University of San Juan,
Argentina and the Yale Southern
Observatory
– 103,319,647 stars and galaxies
south of -20 degrees declination.
– roughly complete to V=17.5 (all
are contained in 2MASS)
– precision of its positions: 30 to
150 mas
– precision of absolute proper
motions: 2 to 10 mas/yr
– blue and visual passband
photometry + 2MASS J,H,K
•
SPM density of observations
SPM4:  < -200; 102.9 million
absolute proper motions
Girard, et al. 2009
85,155 LEDA reference galaxies
HST Cal. WS: July 21-23, 2010
37
Schmidt Plate Scans - USNO
• USNO-A2
– 526,280,881 stars measured on
PMM
– Average J2000 position on red
and blue POSS plates
– ACT/Tycho system
– Monet, et al. 1998
• USNO-B
– 1 billion stars
– Average J2000 positions and
proper motions from 3 colors
at 2 epochs
– Monet, et al. 2003
USNO PMM Measuring Machine at Flagstaff
HST Cal. WS: July 21-23, 2010
38
Schmidt Plate Scans - STScI & Cosmos
• GSC 2.3 release of GSC II
– 945,592,683 objects measured
on STScI PDS machines
– GSC 2.3 is a current catalog
release extracted from the
Guide Star Catalog II database
– Positions on ICRF ACT/Tycho
– Bucciarelli, et al. 2008
Guide Star Automatic Measuring MAchine
• SuperCOSMOS
– 1.9 billion objects
– Average J2000 positions and
proper motions from 3 colors
at 2 epochs
– Positions on Tycho2 and ACT
– http://surveys.roe.ac.uk/ssa/
SuperCOSMOS scanner
HST Cal. WS: July 21-23, 2010
39
XPM: 2MASS - USNO-A2.0
•
•
•
•
•
•
280 million stars - whole sky
Mag range 12 < B < 19 mag
Zero-point of the absolute pms uses
about 1.45 million galaxies from
2MASS, about 1 mas/yr
Systematic errors still exist that are
a function of magnitude.
Scatter of formal proper motions
for the DR5 quasars versus RA and
Dec.
– Proper motion accuracy: 3-4
mas/yr
– North pm accuracy: 3 mas/yr
– South pm accuracy: 7 mas/yr
Federov, et al. 2009
HST Cal. WS: July 21-23, 2010
40
Large-area, deep photometric surveys
Carried out on small aperture telescopes for extragalactic studies, but very
useful for astrometry: 2MASS (1.3 m), SDSS (2.5 m), INT-WFS (2.5 m) also
finding lists for many other surveys, e.g. SPM4.
2MASS (Cutri et al. 2003)
HST Cal. WS: July 21-23, 2010
41
SDSS 2.5-m at Apache Point
• SDSS-I/II contains 25% of sky
and includes more than 350
million objects
• The 300 square degree
Southern Equatorial Stripe was
scanned more than 20 times in
SDSS-I and more than 40 times
in the SDSS-II supernova
survey.
• SDSS DR7: The final data set
also includes spectra of 930,000
galaxies, 120,000 quasars, and
460,000 stars.
SDSS photometry: streams in the halo.
HST Cal. WS: July 21-23, 2010
K. Johnston,
J. Bullock
42
SDSS-Based Proper Motions
• SDSS-USNO-B
– Serious local systematic errors corrected using QSOs.
– Covers about 3000 square degrees, i.e. the DR1 release of SDSS.
– Typical proper-motion errors between SDSS-SDSS and USNO-B are
reduced by 20-30%; the systematic differences are much smaller.
• Sigma pm about 3.5 mas/yr.
• Munn, et al. AJ 127, 3034, 2004 & AJ 136, 895, 2008
• SDSS-Flagstaff 1.3-m telescope
– Covers about 3000 square degrees to date to r = 21 mag.
– Proper motion accuracy about 20-30 mas/yr with a 5-year baseline.
– Munn, et al. AAS 215, 45202, 2009
• SDSS-SDSS proper motions
– 300 square degree Southern Equatorial Stripe was scanned more than
20 times in SDSS-I and more than 40 times in the SDSS-II supernova
survey.
HST Cal. WS: July 21-23, 2010
43
Pan-STARRS 1.8-m Sky Survey
• Pan-STARRS will survey the whole
sky to 24th magnitude every few days
• Primary purpose is to detect
potentially hazardous objects and to
study the minor bodies in the Solar
System.
• Wide-field, repetitive nature of the
Pan-STARRS observations makes
them ideal for determination of proper
motions.
– Comparison with existing catalogs
– Pan-STARRS repeat observations for
high proper-motion objects
• PS1, first of 4 planned telescopes had
first light on May 13, 2010.
http://pan-starrs.ifa.hawaii.edu/
HST Cal. WS: July 21-23, 2010
44
SkyMapper - ANU 1.35-m survey telescope
•
•
•
•
•
1.35-m survey telescope
under construction by the
Australian National Univ.
Designed to carry out the
Stromlo Southern Sky Survey
(S3), a multi-color, multiepoch survey of the southern
sky analogous to the Sloan
Digital Sky Survey.
20,000 sq. deg. South of
equator.
SDSS uvgriz bandpasses to
mag 21.
Astrometry to 50 mas.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
http://msowww.anu.edu.au/skymapper/
HST Cal. WS: July 21-23, 2010
45
Large Synoptic Survey Telescope
8.4-m primary, 6.7-m effective aperture
•
•
•
•
•
•
•
First light planned for 2015
Ten-year imaging survey over 20,000 square degrees south of +15 deg.
Each pointing will be imaged 1000 times with fifteen second exposures in
six broad bands from 0.35 to 1.1 microns, to a total point-source depth of
r~27.5.
Proper motions from observations in Chile over a 10-yr period.
Designed to have Gaia parallax accuracy at r = 20.5 mag and to go 4 mag
fainter than Gaia
Required accuracy:
– Parallax accuracy of 1 mas at r = 22.4;
– Parallax accuracy of 6 mas for red stars with 10 sigma y-band
detections;
– Proper motion accuracy of 0.2 mas/yr at r = 20.5.
Projected accuracy at r = 24.2 mag
– Parallax accuracy: 3 mas
– Proper motion accuracy 1 mas/yr at r = 15.
http://www.lsst.org/lsst
HST Cal. WS: July 21-23, 2010
46