Status of the NST

1. Status of the NST Philip R. Goode Big Bear Solar Observatory Center for Solar-Terrestrial Research New Jersey Institute of Technology

2. 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. Observatory was transferred from Caltech to NJIT in July 1997, 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.

3. 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 Spring 2007 at Nasmyth focus New Solar Telescope (NST) Big Bear Solar Observatory

4. BBSO’s Place Under the Sun • NST Science • High-resolution, high-cadence studies of solar flares • Structure/evolution of magnetic fields in flaring active regions • Dynamics of kGauss flux tubes • Magneto-convection in sunspots • Heating of the upper atmosphere • Upgraded instrumentation (2nd generation) • New (imaging) polarimeters (IR + visible) • Real-time image restoration • Adaptive optics • By 2007: Ready to solve many space weather problems • SDO, STEREO and Solar-B in space (0.5 m telescope in space) • 1.0–1.5 m telescopes in Europe (THEMIS, SST, New DOT, GREGOR) • No ATST before 2012 Big Bear Solar Observatory

5. 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. Polarization optics before M3

6. Atmospheric Seeing • Why BBSO Site? The character of the seeing at Big Bear differs markedly from the high altitude, volcanic island sites measured in the ATST site survey. • The NST primary mirror, at 14 m, will be above the 8 m height of the detector system used to take these data. Big Bear Solar Observatory

7. 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, wavefront sensing and calibration optics immediately before M3 • Diffraction limit: 0.06” @ 0.5 μm and 0.2” @ 1.56 μm Big Bear Solar Observatory

8. Primary Mirror Big Bear Solar Observatory

9. Optical testing : measuring aspheric surfaces • Interferometers use light to measure to ~1 nm surface errors, for spherical or flat surfaces • We need to measure aspheric (non-spherical) surfaces • CGH can change spherical wavefronts to aspheric, allowing the use of interferometers for measuring aspheric surfaces Aspheric surface to be measured aspherical wavefront Spherical wavefront Interferometer CGH Big Bear Solar Observatory

10. Test Tower Uses CGH Big Bear Solar Observatory

11. 35 nm rms! Hand Polishing Big Bear Solar Observatory

12. 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 2006 Big Bear Solar Observatory

13. Secondary Mirror Figuring • SM rms error is <30 nm • Hand polishing only now • Cut two SM’s out Big Bear Solar Observatory

14. BBSO - Projects Secondary Mirror for NST Big Bear Solar Observatory

15. Mechanical Design DFM Engineering Equatorial mount 36 point axial support for Primary 6 point tangential support for Primary Agile hexapod support for Secondary Nasmyth and Coudé observing stations M4 automated for beam switching M5 feeds vertical adaptive optics bench to Coudé lab Pointing and Image Control Wavefront sensing Active alignment Active correction of primary figure Tip/tilt correction at observing ports Solar guider for pointing control Adaptive optics feed to Coudé lab Mechanical Design Big Bear Solar Observatory

16. 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.

17. Big Bear Solar Observatory New Solar Telescope Telescope Design DFM: Design is nearing completion and construction will begin shortly for the construction of the Optical Support Structure, Mirror Cell and Active Optics 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 Wavefront sensing system(AOA) Nasmyth tip/tilt (KASSI) Coudé instrumentation

18. Active Optics • 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. • Real–time telescope alignment, fast tip/tilt and M1 figure control • Closed loop and open loop control (via lookup tables) will be implemented • M1: Edge of mirror attached at three points to mirror cell. 36 axial and 6 tangential actuators control M1 position, 36 axial actuators supports control figure • M2: PI–850 Hexapod purchased, control software complete • WFS: 2nd iteration optical design done, mechanical layout & components selected • Tip/Tilt: Internal to AO feed to Coudé and supplied Nasmyth instruments, CT based Big Bear Solar Observatory

19. Sophisticated dome ventilation controls 14 individually controlled vent gates Forced air circulation for low wind conditions Limited dome aperture Low thermal mass work deck Telescope structures open and dome air cooled Cooled primary mirror Forced air flows at primary and heat stop Liquid coolant systems absorb rejected light Thermal control of mirrors ( 0.5 K), incl. airknive use ATST and SOAR studies Thermal Design Big Bear Solar Observatory

20. Telescope Control System Big Bear Solar Observatory

21. Big Bear Solar Observatory New Solar Telescope Timeline Dome complete – June 2006 Design complete – July-Sept. 2006 Pier construction – Oct. 2006 Mirror tests – Sept. 2006 Components to DFM – Dec. 2006 Facility systems ready – Mar. 2007 Telescope Installation – May 2007 Full operation – Spring 2008