The Madawaska Highlands Observatory. Wide-Field-Telescope. Preliminary Technical Specifications

Transcription

1 The Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications

2 World s Premier Monolithic Wide-field Telescope The 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 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 ( nm) allowing extremely faint magnitudes over a very wide field of view with short exposures reaching 26 th 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 x 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 550nm and superb NIR of 50% 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 x /9μ pixel pitch Etendue AΩ = 6.0m²deg² Will reach 26 th magnitude in 45 minutes with the wl filter ( nm), and 27 th 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 optical surface - real time temperature tracking 10,560 x 10,560 CCD 16-port image sensor 94% 550 nm and 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 12 second downloads - 10 e- read 2 second download ugriz, wideband and narrow band filters with < 10 seconds filter change time Exceptionally dark night sky 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

3 Band Field u g r i z L wl Boxes are 25 µm x 25 µm - inner box is 1 pixel 9 µm mm deg ( ) 9 µm/ µm/ x 2 matrix pixel area Airy Radius: µm Wavelength nm 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 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

4 2.5 Spot Diagram With 80% Energy Encircled Diameter u g r i z L wl 80% Encircle Diametre in Arcsec Field of View in Degrees Figure 2 Spot curve showing for 1.56 radius, 5 degrees 2 FOV, over the ugriz, L ( nm) and wl ( nm) bands. Figure 3 Field Curvature and distortion for g band. Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications June

5 80% encircle diametre in microns Spot diagram with 80% energy encircled diameter u g r i z L Relative Illumination Vignetting Field of View in degrees Figure 4 Spot diagram in microns, 1 pixel = 9 μm Field in Degrees Figure 5 Vignetting showing a 6% drop-off at 1.6. QE (%) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% STA1600 QE STA1600DD STA1600A HfO2-MgF Wavelength (nm) Figure 6 Quantum efficiency. Magnitude r' s/n=3 (wl) s/n=10 s/n=500 s/n=3 s/n=20 s/n=50 s/n= ,000 10, ,000 1,000,000 Exposure (s) Figure 7 Limiting magnitude in r with wl ( nm) STA1600A Noise vs. Download time rms read noise (e-) Download time (s) Figure 8 Download times vs. read noise. Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications June

6 Survey Coverage Based On 8hrs 1.25" FWHM 100,000 s/n=3 r' s/n=5 r' s/n=1 0 r' s/n=2 0 r' s/n=3 L Square Degrees 10,000 1, Limiting Magnitude Figure 9 Sky coverage with various s/n in the r and the L ( nm) Average science hours per month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month 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

7 Quartz Window CCD Filter L1 SiO mm L2 SiO 2 L3 SiO 2 L4 CaF 2 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

8 The 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 = magnitude in <30 minutes for a magnitude 17 star (r, s/n=3, Zθ =0º, FWHM=1.25 ) and 1σ= magnitude in 30 minutes for 20 th 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

9 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

10 SITE 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 ~21.90 mag/arcsec ² (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 10,580 x 10,580 ~ 112 mega-pixel prime focus camera (STC STA-1600A) mm x 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, nm back illuminated CCD (thinned) with enhanced UV 125 mm Bonn Shutter. Minimum exposure 300 μs, 1% accuracy at 1 s exposure, OPTICS 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 SiO 2 L1-3 and L4 CaF 2, 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 ( nm) + wl ( 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 SiO 2 /Ta 2 O 5 coatings, >95% nm, 75% nm 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 degrees 2 5,000 degrees² per night (8 hours, m r =22.0, s/n=3, FWHM=1.25 ) OPTICAL TUBE ASSEMBLY 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 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 m r =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 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 Specifications SOFTWARE/COMPUTERS 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

11 Night Sky Brightness Boston Québec City Montréal NYC Philadelphia Dark Zone Dark Zone Ottawa Rochester Buffalo Toronto Detroit Figure 17 Night Sky brightness map showing the site with a bulls eye (east is top, north is left) Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications June

12 450 m Plateau Madawaska Highlands Figure 18 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 19 The facility is located in a micro-climate in southern Ontario (i.e. Southern Canada) with 800 mm of annual precipitation ( CE). We are expecting about 750 hours of science time. Madawaska Highlands Observatory Corp. Figure mm x 95 mm CCD Imaging chip worlds largest. Figure 21 Corporate logo. Madawaska Highlands Observatory Corp. Ottawa, Canada Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications June

13 Figure 22 The northern Milky Way at the site of the Observatory. This exceptional image, is a short 10 minute exposure. Madawaska Highlands Observatory Wide-Field-Telescope Preliminary Technical Specifications June