Download Report

The Madawaska Highlands Observatory
Wide-Field-Telescope
Technical Specifications
World’s Premier Monolithic Wide-field Telescope
T
he Madawaska Highlands Observatory Wide-Field-Telescope (WFT), with its genesis in October of 2007, is set
to become the most powerful telescope on Canadian soil. It will be situated in the Madawaska Highlands of
Ontario; this area has the darkest night skies in southern Canada. The facility will be a state-of-the-art world-class
facility capable of making significant discoveries and important contributions to astronomy and astrophysics.
The observatory will be equipped with the latest advanced technologies and innovations. Such as world’s widest
field-of-view prime focus telescope, active optics, carbon fibre sandwich core optical tube assembly, ultra-light
vented cellular ribbed open backed mirrors, the world’s largest monolithic CCD image sensor, ¾ sphere Calotte dome
and an innovative mount/drive system with fully programmable advanced control electronics.
The telescope will have a useful spectral range of 350 - 1100 nm with the u’, g’, r’, i’, z’ + L + wL filters with a
range of filters also available. The exceptionally dark sky with the highly corrected FOV allows an exceptionally wide
luminance filter of 500 nm (400-900 nm) allowing extremely faint magnitudes over a very wide field of view with
short exposures reaching 26th magnitude in less than one hour. The observatory will be fully automated and designed
to be a high throughput instrument with superb wide field imaging. Careful attention is being paid to achieving the
optimum local seeing with an advanced carbon fibre composite core Calotte dome with rapid ambient temperature
tracking with filtered venting. The observatory will be energy self-sufficient operating on solar power.
With its fast 1 metre f/2.4 optical system it will employ a 10,580 x 10,580 array, 112 megapixel sensor, the largest
monolithic CCD sensor in the world. The camera is mounted prime focus has 9μ-0.76 arcsec/pixel pitch with 95.22
x 95.22 mm imaging surface yielding an image plane of 2.23° X 2.23° with a total field of view of 5 degrees². The
specifications are also superb, cry-cooled to -100°C with 1e-/pix/hr of dark noise, <5 e- of read noise with readout
time under 12 seconds and 10 e- read noise with a 2 second readout, 16 bit sampling, 80,000e- full well capacity and
94% quantum efficiency @ 550nm and superb NIR of 50% QE @ 1000 nm. The FOV is fully corrector over 135 mm or
3.2° image circle, with 80% of the energy focused into a 8μ circle, less than the 9μ pixel (0.76 arcsec) pitch and 13μ
(1.1 arcsec) 1.4 pixels at the edge 1.6° from the central axis.
Key Technical Highlights
— Five degrees2 - gapless and seamless field-of-view - 2.23° x 2.23° - 0.76”/9μ pixel pitch
— Etendue AΩ = 6.0m²deg²
— Will reach 26th magnitude in 45 minutes with the wL filter (400 - 900 nm), and 27th magnitude in 5 hours
— Active optics - with 1μ resolution - 6 degrees of freedom with focus
— Cryo-Tiger -100 °C cooling
— Carbon fiber - Optical Tube Assembly 200 Kg
— Open back cellular mirror - 0.25” optical surface - real time temperature tracking
— 10,560 x 10,560 CCD 16-port image sensor
— 94% QE @ 550 nm and 50% @ 1,000 nm back side illuminated sensor
— ¾ sphere calotte carbon fiber dome
— Highly corrected field-of-view - on axis 8 μm and edge (1.6°) 13 μm 80% encircle energy
— 5 e- read noise @ 12 second downloads - 10 e- read noise @ 2 second download
— ugriz, wideband and narrow band filters with < 10 seconds filter change time
— Exceptionally dark night sky 21.90 mag/arcsec² (SQM, v)
— Easy to reach, within a few hours drive to 30+ Institutions in Canada and the northeast USA
Note: These specifications are preliminary and are subject to change.
Madawaska Highlands Observatory — Wide-Field-Telescope —Preliminary Technical Specifications — June 2015
Band →
Field
↓
u’
g’
r’
i’
z’
L
wL
0.000
0.000
17.157
0.400
Boxes are 25 µm x 25 µm - inner box is 1 pixel 9 µm
33.123
0.770
47.511
1.100
67.651
1.555
mm
deg (°)
9 µm/0.76”
18 µm/1.52”
2 x 2 matrix
pixel area
Airy Radius: µm→
374.0
362.0
391.0
340.0
398.0
1.067
481.0
410.0
552.0
445.0
516.0
1.209
622.0
550.0
694.0
586.0
658.0
1.621
Wavelength nm
770.0
694.0
847.0
732.0
808.0
2.046
895.0
840.0
950.0
867.5
922.5
2.476
400.0
500.0
600.0
700.0
1.474
400.0
500.0
600.0
700.0
900.0
1.771
Figure 1 — Spot diagram showing 80% encircled energy over various radii and in various bands. The large square is 25μm and the inner square
showing a single 9μm pixel with an image scale of 0.76”/pixel and a with 2 x 2 pixel matrix 1.52 “ X 1.52”. The superb correction over the 2.3° x
2.3° [5 degrees²] CCD imager FOV where 80% of the energy is concentrated in less one pixel (8μ) over most of the FOV, even in the corners at
1.6° from the centre the 80% encircle energy is only 1.4 pixels (13μ).
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Spot Diagram With 80% Energy Encircled Diameter
2.5
80% Encircle Diametre in Arcsec
u
g
r
i
z
L
wL
1.00
1.20
2.0
1.5
1.0
0.5
0.0
0.00
0.20
0.40
0.60
0.80
Field of View in Degrees
1.40
1.60
Figure 2 — Spot curve showing for 1.56° radius, 5 degrees2 FOV, over the ugriz, L (400-700
nm) and wL (400-900 nm) bands.
Figure 3 — Field Curvature and distortion for g’ band.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Spot diagram with 80% energy encircled diameter
Vignetting
30.0
g
r
i
z
1.0
L
0.9
25.0
Relative Illumination
80% encircle diametre in microns
u
20.0
15.0
10.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
5.0
0.1
0.0
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.0
0.0000
1.6
0.1556 0.3112
0.4668 0.6224
Figure 4 — Spot diagram in microns, 1 pixel = 9 μm.
30
1.4004 1.5560
s/n=3 (wL)
s/n=3
28
90%
s/n=10
26
80%
s/n=20
s/n=50
24
Magnitude r'
70%
60%
50%
STA1600DD
STA1600A HfO2-MgF2
40%
s/n=200
22
18
16
20%
14
10%
12
0%
300
400
500
600
700
800
900
1000
Wavelength (nm)
Figure 6 — Quantum efficiency.
1100
s/n=500
20
30%
10
1
10
100
1,000
Exposure (s)
10,000
100,000
1,000,000
Figure 7 — Limiting magnitude in r’ with wL (400 - 900 nm).
STA1600A Noise vs. Download time
100
rms read noise (e-)
QE (%)
1.0892 1.2448
Figure 5 — Vignetting showing a 6% drop-off at 1.6°.
STA1600 QE
100%
0.7780 0.9336
Field in Degrees
Field of View in degrees
10
1
0 .1 0
1 .0 0
1 0 .0 0
1 0 0 .0 0
Download time (s)
Figure 8 — Download times vs. read noise.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Survey Coverage Based On 8hrs 1.25" FWHM
s/n=3 r'
Square Degrees
100,000
s/n=5 r'
s/n=1 0 r'
s/n=2 0 r'
s/n=3 L
10,000
1,000
100
10
18
19
20
21
22
23
24
25
26
Limiting Magnitude
Figure 9 — Sky coverage with various s/n in the r’ and the L (400 - 700 nm).
95
Average science hours per month
101
77
81
81
Aug
Sep
88
74
75
Nov
Dec
66
56
51
42
Jan
Feb
Mar
Apr
May
Jun
Month
Jul
Oct
Figure 10 — Average available science time on a monthly language, with a yearly total of 900
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Quartz
Window
CCD
Filter
L1
SiO2
345 mm
L2
SiO2
L3
SiO2
L4
CaF2
M1, D = 1016 mm
Figure 11 — Optical Design: 4 lenses, one aspheric surface, total corrector length 2417 mm.
Figure 12 — Off axis integrate ghost images on detector. (Test for both image and pupil ghost).
Figure 13 — On axis integrated ghost images on detector.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
T
he site has the darkest night skies in southern Canada with a measured sky brightness of ~21.90 mag/arcsec²
(40° half angle with the Unihedron Sky Quality Monitor in the v) and expected nominal seeing of 1.25 arcsec
FWHM. Because of its excellent dark site, innovative materials, careful attention to the seeing parameters, large field
of view and advanced design; this telescope is expected to outperform much larger established instruments. The
limiting magnitude is expected to reach 26 (wL, s/n=3, Zθ =0°, FWHM=1.25”) in 75 minutes and magnitude 27 in 5
hours. Photometrically it is expecting 1σ = 0.001 magnitude in <30 minutes for a magnitude 17 star (r’, s/n=3, Zθ =0º,
FWHM=1.25”) and 1σ= 0.005 magnitude in 30 minutes for 20th mag star.
The ~200 kg Optical Tube Assembly (OTA) will be built with an advanced carbon fibre sandwich core yielding a light,
ultra stiff structure. It will be dimensionally stable thanks to its low temperature expansion coefficient. The forced air
vented 60 kg ultra-light f/2.34 primary mirror will be made of Borofloat® with an open back cellular rib structure and
thin optical surface (~0.25”), thus enabling extremely rapid tracking of ambient temperature which will eliminate
mirror seeing issues, internal thermal stresses and permit the optic to operate at the diffraction limit. The OTA
will employ active optics, thus maintaining collimation (optical geometrical alignment) by compensating for gravity
induced dimensional distortions, and enable a precision focus to 1μ; it is capable of fast lateral x, y movements (20
Hz) and can be employed in improving the seeing. Extensive baffling will be used to minimize stray light and enhance
contrast and flap doors will be used on the mirror to prevent dust accumulation.
Having a low mass OTA will permit to use of a one tyne fork equatorial mount. The mount will feature an advanced
technology dual-harmonic drive system for high pointing/tracking accuracy, zero backlash and high stiffness. The
high performance control electronics and high torque servo motors can slew at 4 degrees/second, can point to
within 5 arcsec rms (Zθ+70°) and track to better than 0.05 arcsec, thanks to the focal plane guide sensor, the
periodic error will be <2 arcsec peak-to-peak with a 20 minutes period. In addition the mount is fully programmable.
The observatory will operate in an autonomous queuing mode; observations are scripted in advance, this will permit
maximum use of the sky conditions. With its ultra wide-field of view of almost five degrees it can serve as a powerful
survey tool able to image over five thousand square degrees per night to magnitude 22 (r’, s/n=3, FWHM=1.25”).
Figure 14 — 3D model of optical tube assembly.
Figure 15 — Open back cellular mirror.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
The ¾ sphere Calotte dome is made of carbon fibre composite sandwich core, elevated off the ground by some 4
metres of free space for smooth air flow and to minimize ground air turbulence. It is designed with rapid ambient
temperature tracking, resulting in the best possible local seeing. A significant amount of computing power ~200
TFLOPS will be available on site for special projects. A 200 Mbps internet link will be available for communications
and file downloads, thus astronomers can access their data immediately.
Figure 16 — ¾ sphere carbon fibre Calotte dome, pier and struts. This type of dome has superb airflow and other properties
that make it an excellent choice for the best possible science. The ~4 metre elevation allows rapid cooling and minimizes
ground air turbulence. It also permits a smooth air flow around the entire structure, thereby minimize local seeing issues.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Specifications
SITE
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Located in the Madawaska Highlands of Southern Ontario
450 metres altitude on a peak.
200 Mbps communications link to outside world for immediate data access – 15 s image download
90 minutes from Ottawa and 3.5 hours drive from the GTA and Montréal
Ground 12” top-soil with granite base with ~40 acres of available relatively flat land
NIGHT SKY
•
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~21.90 mag/arcsec² (v). Visual limiting magnitude ~7.1
Expected seeing 1.25 arcsec FWHM mean
Excellent horizons (<2º), -45 degrees declination southern horizon available without artificial light
CAMERA
•
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10,580 x 10,580 ~ 112 mega-pixel prime focus camera (STC STA-1600A)
95.22 mm x 95.22 mm active area with 100% fill factor
0.76 arc-sec pixels (9μ pixel width)
14/1.4 seconds full array with <4e-/12e- readout noise, 16-ports and Gbit fiber interface
94% QE in the r’, 50% QE at 1000 nm
100 °C cryo-cooled, dark current 1e-/pix/hr, no dark frames required
16 bit quantization. Full well >80,000 ℮350-1100nm back illuminated CCD (thinned) with enhanced UV
125 mm Bonn Shutter. Minimum exposure 300 μS, 1% accuracy at 1 s exposure,
OPTICS
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1 metre clear aperture f/2.34, A= 0.79 m², rear vented with nine 120 mm low vibration fans
4 lens corrector/flattener, f/2.4 final f ratio, fused silica on SiO2 L1-3 and L4 CaF2, L1=342 mm diameter, 2417 mm corrector length, one aspheric surface
Highly corrected 135 mm FOV, with 80% encircle energy: on axis <8 µm, edge field < 13 µm
< 6% vignetting on edge of chip, worst case hosting 8 e-9 on filter and worst case integrated ghost image 1 e-6
5 deg², 2.23° x 2.23° FOV (Prime focus), AΩ = 6.0m²deg² étendue.
Filters: u', g', r', i', z' + L (400-700 nm) + wL (400-900 nm), in addition to Hα, OIII etc. Filters will available in modules with 4 filters. Filter change time <10 s
Active Optics. Prime focus hexapod for lateral motion x, y, z and rotate x, y, z and focus with 1 μm repeatability
96% reflectivity enhanced aluminum with SiO2/Ta2O5 coatings, >95% 450-650nm, 75% 300-1200nm
Limiting magnitude ~22.5 in 21 s (Zθ =0°, s/n = 3, FWHM = 1.25”, r’)
World’s largest field-of-view prime focus telescope, 5 degrees2
5,000 degrees² per night (8 hours, mr’=22.0, s/n=3, FWHM=1.25”)
OPTICAL TUBE ASSEMBLY
•
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Ultra light vented 60 kg primary Borofloat mirror, open back cellular rib structure with superb thermal tracking, active rear venting
~200 kg total mass, ¼ the mass of a classic modern telescope
Serrurier truss monolithic carbon fiber sandwich core ultra low temperature coefficient of expansion (TCE) and very high stiffness
Active optics. Focus and collimation actively controlled throughout the entire sky
Prime focus camera with on-axis guider, 4 position filter wheel <10 s change time, Bonn 125 mm high speed shutter door (0.05 s)
Extensive use of baffles throughout the OTA to minimize stray light with shutter doors on primary mirror
MOUNT
•
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Single tyne fork mount Equatorial ~200 kg mass
Advanced technology dual-harmonic drive
4 degrees/second slewing, heavy duty DC servo motors
<5 arc-sec rms expected pointing accuracy, within 70º of the zenith
<0.05” tracking accuracy mr’=14 0.1s exp guide star, 0.05 arc-sec motor/encoder resolution, focal plane guider chip
High performance control electronics for high flexibility pointing and slewing
<2 arcsec peak-peak periodic error with 20 minutes period
DOME
•
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Carbon fiber composite sandwich with ultra low TCE and low thermal mass
Fully forced air vented to match ambient temperature as quickly as possible
¾ sphere Calotte dome for lowered airflow resistance, with weather station and battery backup
Elevated by 3.5 metres of free space to minimize ground turbulence and permit smooth air flow around the dome
•
Low mass vented mount and hollow pier for reduced thermal footprint
SOFTWARE/COMPUTERS
•
•
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•
ACP control Software, Scheduler and Pinpoint
Active optics control software with full sky collimation and focus. Guided is accomplished with focal plane guide chip
PLC hardware control
Super-computer with ~200 TFLOPS peak. Redundant back-up control systems
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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Location
Dark Zone
Figure 17 — Road Map showing area of the darkest night sky in southern Canada, our location puts the emphasis on the southern part of the sky.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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Topography
Provincial Highway
County Road
Municipal Maintained Road
Municipal Seasonal Road
Private Road
Crown Road
Intermittent Stream
Permanent Stream
Contours in meters
Wetlands
Water Body
2000 ft.
500 m
Figure 18 — Topographic map showing the 100 acre site on the 450 metre plateau overlooking the Madawaska River to the east.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
Figure 19 — Night sky brightness map . The large white areas (l-r) are Detroit, Toronto, Ottawa, Montréal and Québec City. The site is located within the arrowed target.
Dark Zone
Dark Zone
Night Sky Brightness
13
Master Plan
Figure 20 — Master plan showing position of the 1m f/7 RCT Nasmyth (l) and Wide-Field-Telescope on the 450 metre plateau.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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450 m
Plateau
Madawaska
Highlands
Figure 21 — Ontario relief map indicating Madawaska Highlands and
the location of the Observatory which sits on a 450 metre plateau
overlooking the Madawaska River from a 175 metre vantage.
Figure 22 — The facility is located in a micro-climate in southern Ontario
(i.e. Southern Canada) with 800 mm of annual precipitation (1971-2000
CE). We are expecting about 750 hours of science time.
Madawaska Highlands
Observatory Corp.
Figure 2— 95 mm x 95 mm CCD Imaging chip — worlds’ largest.
Madawaska Highlands Observatory Corp.
Ottawa, Canada
www.madawaskahighlandsobservatory.com
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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Figure 21 — The northern Milky Way at the site of the Observatory.
Madawaska Highlands Observatory — Wide-Field-Telescope — Preliminary Technical Specifications — June 2015
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