Transcript 070709_Max_SciReqs.ppt

Science Requirements Impacting
AO Architecture
Claire Max
Architecture Meeting
July 9 2007
Science Cases Considered
• Most strongly determinant of NGAO system design
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Galactic Center: general relativity measurements
High-redshift field galaxies
Planets around low-mass stars
Black hole mass measurements in nearby AGNs
Distant galaxies lensed by galaxies
• Other science cases
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Asteroid size and shape
Asteroid companions
Debris disks and protostellar objects
Moons of the giant planets
QSO host galaxies
• Special case: NGS observations of Uranus and Neptune
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Summary of AO Architecture Requirements
from Science Cases (all)
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AO Requirements Roll-Up for First
Five Science Cases
Science Case
Observing
wavelengths
HO WFE
TT Error
50% Enclosed
Energy Diam
Contrast
Sensitivity
Photometric
accuracy
Astrometric
accuracy
Radial velocity
accuracy
Background
Polarimetric
accuracy
Overheads
between
targets
Minimum sky
coverage
Planets around
low-mass stars
0.9 – 2.4 m
Š170 nm
from sky
coverage
na
J>[email protected]",
J>[email protected]"
H=25 (5-sigma)
in 20 minutes at
1arc sec sep'n
5% relative to
primary star
< 1 mas relative
to primary
na
na
na
At most 10 min
> 30%
Galactic Center
K band; maybe H
and J bands
Š170 nm at Gal.
Ctr. (low
elevation target)
flows down from
astrometry
requirement
flows down from
radial velocity
requirement
na
not the limiting
issue (crowding
is key)
5%
Š 0.1 mas using
many GC stars
Š10 km/sec
na (confusion
limited)
? (may be impt
for SagA*)
na (long
exposures)
Must give
desired WFE at
GC
Nearby AGNs
0.8 - 2.4 m;
emphasis on 0.8 0.9 m (Ca
triplet)
Š170 nm
Š 15 mas
Š 25 mas
na
not the limiting
issue
not the limiting
issue
na
Š20 km/sec
na (galaxy bkgnd
is more impt)
? (may be
useful)
na (long
exposures)
> 30%
Š 20 km/sec
Requirement:
Gaussian sigma
<30% above
for spatial
(sky plus
resolutions of 50 telescope); Goal:
mas
<20%
na
na (long
exposures)
> 50% with
enclosed energy
radius within 0.1
arc sec at H or K
Requirement:
<30% above
(sky plus
telescope); Goal:
<20%
na
na (long
exposures)
•30% with 50%
encircled energy
diam = 0.07 arc
sec at K band
Gravitational
Lensing
High z Galaxies
JHK
JHK bands;
emphasis on K
Spec: flows down Spec: flows down
from sky
from sky
coverage and
coverage and
50% enclosed
50% enclosed
energy. Imaging: energy. Imaging:
50 mas spatial
50 mas spatial
resolution
resolution
required
required
derived from 30%
na (170 nm OK
sky coverage and
but not a primary
enclosed energy
requirement)
diameter
Š 100 mas
•50% within
0.07 arc sec
na
SNR •10 for a z
= 1 – 2 galaxy in
0.1 mag relative,
an integration
0.3 mag
time Š 3 hours for
absolute
a Gaussian width
20 km/sec
na
na
SNR •10 for a z
= 2.6 galaxy in
an integration
time Š 3 hours for
5% for
a spectral
subcomponents
resolution R =
of galaxy
3500 with a
spatial resolution
of 70 mas
na
Š30 km/sec
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Instrument requirements,
first six science cases
Science Case
NIR imager
Narrow Field
Diffraction Limited
NIR IFU
Narrow field
R~4000
Diffraction Ltd
Vis imager
Narrow field
Diffraction Limited
Vis IFU
Narrow field
Diffraction Limited
Asteroid
companions
J&H, 3”
diameter
J&H, 3”
diameter
I band, 3”
diameter
I band and
longer, 3”
diameter, R~100
desired
Planets around
low-mass stars
yzJH, 5 arc sec,
1 or more
coronagraphs ,
possible dualchannel mode,
need IR ADC
Lower spectral
resolution
desirable
(R~100)
Galactic Center
10 arc sec
Nearby AGNs
zJHK, >10 arc
sec diam
Gravitational
Lensing
High z Galaxies
zJHK, > 4" diam
(goal: 5")
JHK to 2.4
microns, 3”
diameter
zJHK, > 4" diam
(goal: 5")
Other requirements
Static errors
(AO+tel+NCP+la
ser+etc.) < 30 nm
If radial velocity
accuracy of 10
more than one
km/sec can't be
IFU head within
achieved at
10"x10"
R~4000,
consider higher R
1 arc sec
zJHK
NIR dIFU R~4000
emphasis on 0.8 I band, 10-20 arc
0.9 m (Ca
sec
triplet), a few arc
sec R~4000
maybe
I band, > 4" diam
(goal: 5")
Simultaneous sky
background
zJHK, > 4" diam measurements
(goal: 5")
with same field of
view as science
field
0.8 microns and
longer
Simultaneous sky
background
measurements
within a radius of
3” with same field
of view as
science field
JHK to 2.4
0.8 microns and microns, •1x3"
longer
for sky bkgnd
meast
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Other comments
• If we want to do NGS observations of Neptune and
Uranus, WFS needs to be able to accept large objects
– Neptune of order 1 arc sec
– Uranus of order 4 arc sec
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