Transcript Xian: A Detector for GRB Afterglows and other Optical

XIAN: A large array of telescopes in
Antarctica dedicated to transient science
with “all-sky” imaging every 5 seconds
US:
Donald G. York (Chicago), Lifan Wang (LBL), Carl Pennypacker
(SSL), Morley Blouke (Ball Aerospace), Don Lamb (Chicago), Doyal
Harper(Chicago), Dale Sandford(Chicago), Julie Thorburn (Chicago)
China:
Xiangqun Cui (NAIOT), Xu Zhou (CAS, Beijing), Jingyao Hu (CAS, Beijing),
Xiangyan Yuan (NAIOT)
Europe:
Enrico Cappellaro, (INAF, Padova),
Roger Malina (LAM, France), Stephane Basa (LAM, France)
Australia
John Storey (UNSW), J. Lawrence (UNSW), Michael Ashley
(UNSW),
XIAN Prime Science Goal
Gamma Ray Burst detection and follow up science
• 20th mag detections in 5-10 seconds (V, R)
• Detect 25-50% GRBS in sky covered
– .3 GRB/day
– > 100/day orphan afterglows/day
– 0.1/day SN « blue flashes », 2000SN/yr
Follow up for GRB physics, use as cosmological probes,
study high z host galaxy chemistry
• GLAST and SVOM space mission timeframes
– SVOM is Sino-French Space Mission for GRB
– Previously known as ECLAIRS
400, 50cm telescope array -Xian
Area for
Follow-up
Telescope(s)
SVOM
• Sino-French GRB satellite (ex ECLAIRS)
• Currently in CNES Phase A study for 2011 launch.
• Chinese: NAOC ( Beijing), IHEP (Beiking), XIOPM
(Xian)
– Jianyan Wei (PI), Shuang Nan Zhang (Co-PI),
Jingyao Hu, Qiu Yulei, Shouchen Li
• French: CEA ( J Paul PI), CESR D Barret.. J L
Atteia, ....Klotz,Casse, Daigne....
• S.Basa (LAM) co-pi visible camera, ground based
follow up
• CESR, LATT, IAP, APC
• ISF Milan, TIFR Mumbai, MIT
XIAN Science Goals
• Light curves from v short t (~5s) to 4 months
--GRBs, with coincident optical/GRB (& X-ray)
for cosmic distance scale
--Orphan afterglows (GRB opening angle)
--Type II blue flash, early time Type Ia curves
--Type II counts at low z
--GRB and host physics (circumstellar lines,
clumpy?)
• Deep optical survey (much deeper than SDSS)
• “Calibration” of gravitational wave events
(shortest bursts) LIGO,LISA and neutrino
bursts (ICE CUBE, ANTARES)
• Gravitational Lens planet searches
Xian Strawman under study
• 8000 sq. deg., 400 scopes,
each 5x5 deg
• 0.5 meter, (clear aperture) Schmidts
•
• 16 K x 16 K pixels, segments 1 K x 4 K (so, 16x4
small devices per focal plane), 10 readouts per
segment.
• Reduce sky coverage by x 2 , option under study
– provide 2 Telescope coverage of each 5x5 deg area,
– to minimize false positives
– Redundancy
• Mag. Limit: 20 R effective, but broad band
• Single filter, each year (to test trigger schemes)
The need for Xian as dedicated
ground based array for transient
science
Once the flash is detected, follow-up is currently
intermittent (less than 1%GRBS) owing to
•
--Lack of acceptable weather at a properly
equipped site
--Lack of a system to allow overriding on-going
programs
--Lack of a system into which all new
observations are reported
.
--The impossibility of getting complete light
curves.
The Need for Xian
•Light curves are not well known
--Some objects die out and recover
-- Short bursts (< 2 sec bursts) have a long tail
with the same energy in it as the short spike.
--Physics of events as Zs are determined
short bursts=merging, condensed matter stars
long bursts =collapsing stars-SNe II)
-- GRB science drives need for dedicated facility (
cf early days of SN science)
XIAN Roadmap
•
•
•
•
•
Test-beds
T2 -- Test array at APO. Under development.
T5-- Expanded array, 2+3 in SW-USA
Deployment
T3 -- Test array of 3-5, identical telescopes.
Antarctica. Compelling stand alone science.
• Xian -- Large array of small telescopes. Antarctica
• Big Telescope (BT)--Dedicated, on site , 2.5m
NIR robotic telescope for spectroscopy,photometry
Close view of Xian
Slide 19
Triggers for Transients
--Short frame comparisons for triggers (little
changes in sky, CCD artifacts, etc. over 5-10 sec)
--Mask known stars and asteroids (masking
depends on brightness)
--Use SDSS (T2, T5 in the North) or Mt Stromlo
Survey (T3, Xian in the South) for quiescent
sources until we have our own from averaging
one season’s worth of data.
--Co-add in, e.g., 100s, 3000s, 10 hr, 100hr., 1000
hr., images to look for triggers for longer time
scales (orphan afterglows, SN Ia or AGNs).Full
reductions for these.
Data (per telescope)
--52 megabtyes/sec for the triggers
--2 Terabytes per night, short term
storage
--4 Terabytes long term storage (will
increase as storage becomes cheaper)
VARIABLES
OF
INTEREST
*No. per
Sq. degree
Per year
365 per year,
all-sky,
==> F = 0.01
source
t(sec)
F*
Vlim
GRB(>2s)
2-200
0.02
g-rays
GRB a. glow
200-105
0.01
20-23
Orphan
104-105
>2
23
Blue flash-r
600
0.0005
18 ( z=0.03)
Blue flash-b
60
0.0005
21.6
Type Ia SNe
106
2.2
23 (z=0.3)
Type II SNe
106
0.1
23 (z=0.1)
Strong Grav.
Lens (QSO)
105.6
0.01
22
AGN
106
20
21
AM CVn
600
0.001
19
Cataclysmic
Variables
1800
0.05
17.5
Planet eclipse
3600
0.01
13 (rocky
Planets)
Figures of merit
System
FOV
Dq
t(sec)
h*
Vlim
SDSS-SNe
4
1.5
~106
0.2
22
Deep Lens
4
0.5
1300
0.16
24
ROTSE III
3.5
4
1800
1.7
17.5
T2
20
2
30
2
20.4
T3
60
2
10
6
20
Xian
4000
2
10
1200
20
Tombo
10000
4
60
4000
17
P
10000
60
60
5000
12
*[h] = sq.deg.- yr, the no. of sq. deg. constantly covered for timescales, t, in a year
KS-Technical Desiderata-1
• Maximum coverage at Dome C/A
--Circumpolar sky is large, excellent
observing efficiency, cold
• No moving parts: natural focus, one filter,
no telescope motion, no(?) CCD Dewars
• Trade off CCD block size design (t min) with
acceptable yield on amplifiers
• Single pixel triggers, drift scan
• Magnitude limit in selected time
• Low power because fuel is expensive
For better image quality, adopt two correcting Schmidt
plates (achromatic Schmidt)
Fig.3 Layout of the achromatic Schmidt telescope
Spot diagram
for Antarctica
The above simulation shows the focal length changed 0.02mm from 20°C to
–50.8 °C; the best image plane changed 3microns.
The image quality only slightly changed in geo diameter (encircled energy 100%).
Design of the telescopes
FOV 5x5 degrees, 20 sq. degrees
0.5 meter Schmidt
1 arcsec per pixel (9 micron pixel)
80% encircled energy in 1 pixel
3860A to 9000A
26% obscuration
f/3.28
Focus independent of temperature
CCD layout (16,000 x 8,000 pixels)--x and y
scales differ
4 m odules across, 16,000 pixels across
10, 100x4000 TDI array s per m odule
8 m odules
8k pixels
dy 0+/-100 
dx 2000+/-2000 
CCD Design
QE > 50% (red favored?)
Read noise < 2 electrons, rms (on chip,
variable gain)
Integration time 5-10s, drift scan
Pixel size 9-10 microns
Well capacity <0.99995 electrons
Dark current < 0.1 electrons per sec
Serial registers per unit: up to 13
1 unit: 1000x4000 pixels
64 units per focal plane
16K x 16K pixels
Power dissipation per focal plane 16W
KS-Technical Desiderata-2
• Minimize computing goals, evolve as
technology evolves
-- t(short) to t(short) comparisons
-- Send triggers to separate pipeline for
evaluation, pull out that track of triggered
object to get long timescale information
-- Co add and compare for longer time scales
-- Discard most frames after co-add’s are
done (consider look-back requirements)
KS-Technical Desiderata-3
• Follow-up maximal number of selected
classes of bursts with on-site,
conventional, well equipped telescope,
sized to science:
• 2.5m class, rapid response (IRAIT .8m)
• --spectra, IR, optical (for redshifts to 10)
--photometry (optical, IR)
--polarimetry
--autoalert, fast tracking
• This is called BT (Big Telescope).
T2,T3, T5
• Test of engineering and of science goals
• 10-100 sq. deg. (2-5 telescopes, underfill focal
plane with CCDs if need be.)
• Self-reliant science goals (does not depend on
KS):
--Minimum set of orphan afterglows
--Minimum set of blue bursts, SN II
--Confirmation of SN II /SN Ia rate at low z
(z~0.3).
--Deep co-added survey (SDSS imaging
equivalent)
T2,T3, T5 -Engineering
--software for triggers (identify sources of
false positives)
--test triggering schemes (different filters
each year)
--recognition of triggers early enough to
get correct follow-up (spectra photometry)
--Dewarless CCDs, focus by design
Examples of false positives
--variable detector artifacts
--solar system, atmospheric events
--saturated stars
--stars that make “dipoles” because of variable
PSFs when comparing frames
-- radiation hits (cosmic rays or gamma rays from
equipment near the CCDs)
--ghosts from Schmidt systems (which move as
strip scans) (need AR coatings)
--true variable sources (CVs, etc.)
--slow moving asteroids (put half of telescopes at
different sites and use triangulation of asteroids
in co-pointed fields.)
--Earth orbiting satellites
Conclusions
The 16Kx 16K CCDs are feasible to build. Low power
electronics is a major development.
The minimum-moving-parts goal is attainable on paper
Previous experience to build on, but a large step is needed.
Fast algorithms will be a major challenge
T2, T3, T5 are logical first steps
Xian is feasible and should be built
Xian will impact the study of cosmology, supernova physics,
variable stars, gravitational waves and neutrino astronomy
SVOM
• Sino-French GRB satellite
• Currently in CNES Phase A study for 2011
launch.
• Chinese: NAOC ( Beijing), IHEP (Beiking),
XIOPM (Xian)
– Jianyan Wei (PI), Shuang Nan Zhang
(Co-PI)
• French: CEA ( J Paul PI),
• S.Basa (LAM) co-pi visible camera, ground
based follow up
• CESR, LATT, IAP, APC
• ISF Milan, TIFR Mumbai, MIT
SVOM High Energy Instruments
FOV Energy Range
CXG
SXC
GRM
2 sr
2 sr
6.2 sr
Pos
4-300 kev 10 arcmin
1-12 kev
30 arcsec
.02 -5 Mev NA
Expected GRB rate: 100/yr
SVOM
• Trigger on 200GRB’s per year
• X, Gamma, Visible on satellite
• Location in <10 sec to <10 arc min
– 50% of the cases <1 arc min for ground follow up
• Allow for 75% cases red shift and
spectroscopy follow up
• On board visible cameras under study
– WAC V 40 degx 40 deg 15 mag in 10 sec
– VIRT K 10arc min x 10 20 mag in 300 sec
– Observe « prompt » emission before and after GRB
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Requirements for SVOM
Ground Based Follow up
Telescope
Provide link to 8m class telescopes
Visible to NIR for high z GRB
Positions to 1 arc sec within 5 min
Lightcurve
Photometric redshifts
Transient sorting for 8m follow up
Current Strawman: 1.5 m class, R I J
H
Acknowledgements
While our designs developed independently,
many of the ideas here were also arrived at, in
connection with the TOMBO* project, by Y.
Ohno, T. Ebisuzaki, K. Sunouchi, R. Susukita, C.
Otani, H. M. Shimizu, A. Yoshida, No. Kawai,
M. Matsuoka, M. Euno, T. Wada, M. Yamauchi
and N. Takeyama, Riken Review No. 47, July
2002. We acknowledge discussions with C.
Akerlof.
*TOMBO stands for Tombo Observing for Microlensing
and Bursting Objects.