The 1.6 m Off-Axis Solar Telescope for BBSO

1. The 1.6 m Off-Axis Solar Telescope for BBSO Philip R. Goode Big Bear Solar Observatory Center for Solar-Terrestrial Research New Jersey Institute of Technology

2. 1.6 m off-axis solar telescope Largest aperture solar telescope Largest aperture off-axis telescope Team of BBSO/UH/KASSI Active optics New dome for larger telescope Downstream instrumentation Adaptive optics IR and visible light Fabry-Perot polarimeters NST first light late in 2006 New Solar Telescope (NST) Big Bear Solar Observatory

3. Center Overview • Five senior faculty (Denker, Gary, Goode, Lanzerotti and Wang) • Searching for new tenure track faculty member supported by NSF Faculty Bridge Program • Eighteen Ph.D. researchers (seven in Newark and eleven in Big Bear) • Ten support staff (seven in Big Bear) • More than 10 Ph.D. students • Average about 30 refereed publications per year • Eight former students/postdocs have tenure track positions Big Bear Solar Observatory

4. Center Science • Big Bear Solar Observatory over the years • Observations • Instrumentation • 1.6 m off-axis solar telescope • Climate • Sun’s variable output • Earth’s global reflectance and absorption (earthshine) • Owens Valley Solar Array • FASR Next • Polar Programs and Satellites • Antarctic magnetometers • Ulysses, etc Big Bear Solar Observatory

5. Big Bear Solar Observatory BBSO was built by Caltech in 1969. The dome sits at the end of a 1000 ft. causeway on Big Bear Lake’s north shore at 6,750 foot elevation. Offices, workshops and dormitories are located on shore. Observatory was transferred to NJIT in July 1997, and the observatory is now part of the NJIT Center for Solar-Terrestrial Research.

6. Big Bear Solar Observatory The surrounding waters of Big Bear Lake reduce ground level convection, and predominate winds bring smooth air flows across the flat surface of the lake providing superb conditions for solar observing. The observatory contains a single fork equatorial mount supporting four telescopes: a 65 cm reflector plus 25, 20, & 15 cm refractors. The New Solar Telescope (NST) will replace these instruments.

7. NST Science • High Resolution, High Cadence Studies of Solar Flares • Structure and Evolution of Magnetic Fields in Flaring Active Regions • Dynamics of Kilogauss Fluxtubes • Magneto-Convection in Sunspots • Heating of Upper Atmosphere • Campaigns with Space Missions • Earthshine Big Bear Solar Observatory

8. Atmospheric Seeing Big Bear Solar Observatory

9. Adaptive Optics Big Bear Solar Observatory

10. Big Bear Solar Observatory Big Bear Solar Observatory

11. Filament eruptions are often accompanied by flares and coronal mass ejections (CMEs). H from Kanzelhohe Solar Observatory (KSO) Extreme ultraviolet Imaging Telescope (EIT) image and Large Angle and Spectrometric Coronagraph (LASCO) C2 image combined 2000 September 12 Big Bear Solar Observatory

12. Big Bear Solar Observatory New Solar Telescope NST Project • BBSO and NJIT will build the world’s largest aperture solar telescope at 1.6 meters. • The NST will be optimized for high resolution imaging of the solar surface employing active and adaptive optics technologies. • Funding from NSF, AFOSR, Korea, and NJIT. • Scientific partners are: • University of Hawaii • KASSI • Steward Observatory

13. NST –BBSO/UH/KASSI • 1.6 m clear aperture (1.7m blank) – being figured by Steward Mirror Lab • Active optics (36 actuators in PM mirror cell) to control thermally induced variations & airknifes, backside cooling • Primary: f/# 2.4, 4.4 m telescope length, <20 nm surface quality, <10 Å μ–roughness, and blank of Zerodur with CTE of (0.0±1.0)  10-7 per °C • Observable wavelengths: 0.39–1.6 μm with AO and >0.39 μm without AO • FOV: 180” in optical labs or 1/2° in prime focus • Real–time telescope alignment • Polarization and calibration optics immediately before M3 • Diffraction limit: 0.06” @ 0.5 μm and 0.2” @ 1.56 μm Big Bear Solar Observatory

14. The Primary Mirror • One significant cost driver would be expected to be the polishing of the primary mirror. • However, it will be polished in partnership with the University of Arizona Mirror Lab, as part of their 20/20 project (see www.optics2001.com/telescope.htm). • Lab is funded to polish a fast, off-axis 1.7 m mirror (as a proof-of-concept for figuring seven 8.4 m mirrors for twin 21 m telescopes). • The end-product of the proof-of-concept will be the primary mirror for the NST. Big Bear Solar Observatory

15. Big Bear Solar Observatory

16. Big Bear Solar Observatory

17. Polishing the SM • SM is Zerodur from Schott (plano-plano) • Space Optics Research Lab is figuring 0.5 m mirror on axis • Will cut into two concave elliptical SMs (140 and 145 mm) • <20 nm surface quality and foci downstream at f1=300 0.5 mm (if measured from on-axis mirror optical center) and f2=6482 10 mm • Delivery Summer 2005 Big Bear Solar Observatory

18. Dome Replacement The fiberglass panels have a structural foam core which serves to stiffen the shell and insulate the dome. Big Bear Solar Observatory

19. SOAR Dome MFG Ratech will replace the dome (Fall 2005) with a larger 34 ft., 5/8 sphere with a retractable shutter similar to the SOAR dome shown here. The dome structure consists of a steel frame with a shell of fiberglass panels. Modifications to the telescope pier and observing floor will follow. Big Bear Solar Observatory

20. The NST Big Bear Solar Observatory

21. Big Bear Solar Observatory New Solar Telescope Telescope Design The NST is an off-axis section of 5.3 meter, f#0.73 Gregorian telescope. The result is an f#2.4, 1.6 meter system. The design offers an unobstructed pupil allowing superior adaptive optics performance and low scattered light. The prime focus, where most of the solar radiation must be absorbed, is accessible without obstructing the light path. A small (3.5 mm) field stop (UH) at prime focus limits the radiation loads transmitted to the downstream optics.

22. Heat Stop (UH) Big Bear Solar Observatory

23. The primary mirror is supported by 36 axial and 6 tangential actuators. These force based servos will compensate for gravity and thermally induced errors in the mirror figure. A wavefront sensing system is being developed to control the active optics components collaboration is with our partners to determine the best solution. Active Optical System Big Bear Solar Observatory

24. -0.69x10-6 K-1 0.28x10-6 mbar-1 Primary Mirror (M1) Thermal Control • Function: Mitigate mirror seeing seeing Big Bear Solar Observatory

25. Nathan Dalrymple: Diffraction-Limited Error Budget Blue contours: rms wavefront error (nm) l = 500 nm Acceptable operating range, assuming no AO correction. AO correction will extend the “green” range. Big Bear Solar Observatory

26. Thermal Modeling (Dalrymple Code) Big Bear Solar Observatory

27. Big Bear Solar Observatory New Solar Telescope Telescope Design Active Optical Systems The secondary mirror will be mounted on an agile hexapod. The M850 system by PI has been purchased and tested. Software is being developed at NJIT and BBSO to control the hexapod and primary mirror actuators. The active optics development is the most complex piece of the NST effort and will stretch though the commissioning of the telescope requiring a large percentage of in-house resources.

28. Big Bear Solar Observatory New Solar Telescope Telescope Design Contract has been let for the construction of the Optical Support Structure and Mirror Cell to DFM Gross specs: 10 Ton weight Precise equatorial drive system Blind tracking at solar, stellar and lunar rates No failure to 4 g’s BBSO provides: PM actuators Heat stop & beam dump M2 cell and hexapod Solar offset guider Wave-front sensing system (KASSI) Coudé instrumentation

29. Telescope Control System Big Bear Solar Observatory

30. Big Bear Solar Observatory New Solar Telescope Telescope Design First light late 2006. Most of the NST instruments will be located in the Coudé Lab below the dome floor. Two fold mirrors, the Nasmyth mirror (M3) and Coudé mirror (M4) will send the light down the polar axis. A final fold mirror (M5) will direct the beam though the dome floor to the Coudé Lab’s vertical bench. M4 will fold out of the beam allowing light to reach instruments at the Nasmyth focus.

31. AO, IR and visible light Fabry-Perot polarmeters, and real-time image reconstruction system (first light instrumentation will be located in the Coudé Lab below the dome floor. Two fold mirrors, the Nasmyth mirror (M3) and Coudé mirror (M4) will send the light down the polar axis. A final fold mirror (M5) will direct the beam though the dome floor to the Coudé Lab’s vertical bench. M4 will fold out of the beam allowing light to reach instruments at the Nasmyth focus. Post-Focus Instrumentation Big Bear Solar Observatory

32. The End … … of the beginning … Big Bear Solar Observatory

33. Thanks! The End Big Bear Solar Observatory