Diapositiva 1

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Status of the AMICA project ready for the
Antarctic adventure
M. Dolci(1) on behalf of the AMICA and IRAIT
Teams (1) INAF Osservatorio Astronomico di
Collurania Teramo
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AMICA/IRAIT is a Project involving institutions
from Italy and Spain. It is aimed to the
installation of a 80-cm telescope at Dome C,
equipped with a NIRMIR imaging camera.
Collaborations with teams from Australia, France
and Germany are also active.
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THE IRAIT TELESCOPE
- Cassegrain optical scheme - 80 cm (75
effective) aperture - f / 21.65 total focal
ratio ( f / 3 primary focal ratio) - aluminized
mirrors
- provided with a secondary wobbling mirror for
sky chopping techniques and focussing - provided
with a movable tertiary mirror to alternatively
feed the two Nasmyth foci
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THE IRAIT TELESCOPE
Critical issues (and solutions) - motors and
drivers overheating (Peltier coolers) - optical
surfaces frosting (IR lamps) - mechanics (special
grease)
A crucial testbench was represented by
Small-IRAIT in 2007, when R. Briguglio found a
series of brilliant technical solutions !
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THE IRAIT TELESCOPE mounting on Summer Campaign
20082009
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AMICA (Antarctic Multiband Infrared CAmera)
A camera for astronomical imaging in the 2 28
?m wavelength range.
This is accomplished by using two separate
detectors.
Moderate-flux MIR detectors are normally used for
high-spatial resolution or spectroscopic
applications only
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AMICA optical system
- Focal Reduction 1 1.47
- Diffraction-limited performances
- Nyquist sampling of Airy disc at 3.42 ?m for
SWA and 8.54 ?m for LWA
- PS 0.538 arcsec/pix on SWA 1.345
arcsec/pix on LWA
- FOV 2.29 ? 2.29 arcmin2 on SWA 2.87
? 2.87 arcmin2 on LWA
- Goldcoated mirrors to avoid chromatism over
the broad wl range
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AMICA cryostat
Assembled and succesfully tested at IRLabs, in
Tucson (USA) in Nov 2008. Lab. ultimate
temperatures on NIR and MIR array 29.68 K and
5.08 K, respectively.
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AMICA cryocooler
Cryogenic temperatures are obtained with a
two-stage Sumitomo cryocooler. Vibration
dampening bellows have been provided for both the
coldhead and the compressor. Rather surprisingly,
the power consumption is below the expected
values (in lab.) ?6 kW while cooling and ?4.9 kW
steady (expected 6.5 kW).
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AMICA/IRAIT mechanical interface
- Optical axis tilt adjustment
- Vertical position adjustment
- Horizontal position adjustment
- No focussing (accomplished with IRAIT M2)
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AMICA Fast Readout and Control electronics
Successful first light with MUXs in late 2007
Pixel exposure times down to 0.7 ?sec (ADC_at_1.43
MSs)
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AMICA Fast Readout and Control electronics
Local unit (warm)
Remote unit (cold)
Cryostat (cryogenic)
Industrial Pentium 4 mobile cPCI-based Digital
prog. sequencer PMC bd Clock gen. DGT bd 3MHz
video signal sampling, 2 DCS bds 1.2 GBaud
optical link sequencerDGT
preampbias SWA bd clock SWA bd preampbias LWA
bd clock LWA bd Service bd (temperature sensors,
heaters, etc.)
NIR array board MIR array board Cryomotors Tempera
ture sensors Heaters
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AMICA Environmental Control System
Except for the cryostat and the local electronics
unit, every AMICA subsystem will be kept in a
warm and thermally controlled environment.
It is composed by two separate cabinets the
lower cabinet, that will host the cryocompressor,
and the upper cabinet, that will host all other
subsystems.
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AMICA Environmental Control System
The two cabinets will be covered by a thermally
insulating layer whose thickness has been worked
out and tested in order to have 20 C inside
when the external temperature is -60 C (winter
average temperature).
For any other external condition, a active system
composed by temperature and relative humidity
probes, heaters and fans, all controlled by a
PLC, will continuously monitor and keep the
operating conditions.
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AMICA software
CCS Chopping control, synchronization with camera
acquisitions
SCS Readout control, bias clocks, video output
preamplification
ACS General management, communication with IRAIT
CS
DCS Output real-time processing, descrambling of
data, frames piping and storing
ECS Environmental control, start-up and
shut-down, vacuum pumping, cryo maintenanace
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AMICA antarctic tests
Low temp. (- 80 C), low pressure (650 mbar) and
low RH (5 15 ) tests have been performed at
Teramo Obs. with AntarES, a small climatic
chamber designed and built to this purpose. The
main results (bias drift thermal behaviour of
boxes wind chill effect slowing down of motors
effects on vacuum seals etc.) have already been
presented during past conferences.
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AMICA antarctic tests
A test of fundamental importance has been carried
out at IRLabs. The whole cryostat was placed into
dry ice (with an additional small, continuous
flushing of liquid nitrogen) and externally
cooled at 80 C.
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AMICA antarctic tests
Final temperatures onto the two arrays were
exceptionally low 24.85 K and 4.52 K for NIR and
MIR detector, respectively ! Moreover, a vacuum
leak check has shown no leak at all (indium wire
seals).
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AMICA/IRAIT performances expected background
fluxes
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AMICA IRAYT (Inverse RAY Tracing) for
instrumental background estimation
Rays are traced back from the detector through
the whole system. This makes it possible to
quantitatively evaluate the radiative input
associated to each ray unable to escape from the
telescope within the FOV angle.
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AMICA IRAYT (Inverse RAY Tracing) for
instrumental background estimation
From a preliminary 2D model, no computed ray is
intercepted by the camera window edge, the
camera/telescope interface, the primary mirror
edges or the secondary mirror structure. Most of
rays end inside the cryostat. Less than 3 reach
the primary mirror structure.
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AMICA/IRAIT expected sensitivities N, Q bands
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AMICA/IRAIT expected sensitivities L, M bands
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AMICA/IRAIT expected sensitivities K band
Performances comparable to those of a 3-m
telescope in a temperate site.
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Observable sources
SUMMARY
TEXP 300 sec , S/N gt 10
K 18.5
L 15.5
M 12.1
N 6.4
Q 3.0
IRAS Catalog, 25 ?m Q lt 2.5 mag
140,000 point sources (1200 in LMC)
40,000 point sources (200 in LMC)
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Detection limit (5s)é point source
1 -IRAIT standard survey deeper than 2MASS by
3 magnitudes At 10-20 mm similar to IRAS!!
Epchtein 2005
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Survey example of extended sources Eta Carinae
Region
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AMICA/IRAIT, summer campaign 2009-2010
Aug/Sep 2009 shipping to Antarctica
Dec 2009 IRAIT installation completion
Jan 2010 AMICA installation, testing
Feb 2010 ?... system first light,
commissioning, OPERATION !