ROSA ROSA A high-cadence synchronized multi-camera solar imaging system Dr. Mihalis Mathioudakis Dr. Mihalis Mathioudakis Physics and Astronomy, Queen’s University Belfast ROSA : Rapid Oscillations in the Solar Atmosphere

History (SECIS – RDI) Science examples Improving image quality Post-observing correction (Speckle, PDS) The proposed instrument – Tests Observing modes Associated instruments SummaryOutline

SECIS (Solar Eclipse Coronal Imaging System) (RAL Ken Phillips, QUB) Fast mode impulsively generated wave in a loop (6 s) Williams, Phillips et al. MNRAS 2001 Williams, Mathioudakis et al. MNRAS 2002 RDI (Rapid Dual Imager) Oscillation induced along a flare ribbon (40 – 70 s) (BBSO - NSO, Sac Peak) McAteer et al. ApJ 2005 High frequency oscillations in the lower atmosphere (15 – 30s) Andic, Jess, Mathioudakis in preparation SECIS - RDI

EIT/Loop image Williams, Mathioudakis et al. MNRAS 2002

Intensity variations along the loop Williams, Mathioudakis et al. MNRAS 2002

NOAA 9591 – C9.6 in Hα NOAA 9591 – C9.6 in Hα 200 arcsecs McAteer et al. ApJ 2005 RDI at Big Bear Solar Observatory

C9.6 flare – Period of 52sec McAteer et al. ApJ 2005

Ha blue wing 50 arcsec n Oscillatory power 15 – 30 sec (60 – 30mHz) n RDI at DST Sac Peak Andic, Jess, Mathioudakis in preparation RDI was funded by a Royal Society Instrument Grant

Multi-wavelength Multi-wavelength McAteer et al. ApJ (2003)

Krijger, Rutten et al A&A (2001) The need for synchronised imaging The need for synchronised imaging

Krijger, Rutten et al. A&A 2002

The need for high cadence The need for high cadence Allred et al. ApJ (2005)

G-Band G-Band Image credit : SST - MPS

Atmospheric turbulence Fried’s r 0 – diameter of refractive index fluctuations r 0 = (( λ cosz) / 550)) 0.6 m r 0 = 11 cm ( λ = 550nm, z = 0) Spatial resolution of a ground based telescope limited to that of a telescope with diameter r 0 The largest telescopes have the same image quality as an 11cm telescope (if no image correction is applied) Choose an observing site with a large r 0 Time scale of atmospheric fluctuations : t = r 0 / v Wind speed v = 11 mph, t = 20 msec, (moves by its own diameter) Act quickly – Exposure times of a few msec at most! Image quality – The problem Image quality – The problem

Speckle pattern Speckle pattern Remember : Seeing is equivalent to many small telescopes observing the same object but affected differently by atmospheric turbulence

Speckle reconstruction Speckle reconstruction Image of a source in an ideal telescope in the absence of atmosphere is shaped by diffraction The Imaging Equation i (x) = o (x) ٭ p (x) (1) i - observed intensity/image of the source o - actual/true image of the source p - PSF describing instrument and seeing x - angular position Following the FT of (1) I (u) = O (u) P (u) P (u) – is the Optical Transfer Function (OTF) u – spatial frequency

Speckle reconstruction Speckle reconstruction

G-band Andic, Jess, Mathioudakis in preparation

Improving image quality For Speckle to work you need Very short exposures. Freeze the seeing for each exposure (<20ms) Very high cadence. A sequence of images (50-100) over timescales that solar features remain unchanged (< 10 s). Bad seeing requires more images Great demand on camera read out speeds Signal to noise can be very low in narrow band images

National Solar Observatory (NSO/NSF) Sacramento Peak n Altitude : 2800m n Very good seeing for short periods (morning) n Dunn Solar Telescope 0.76m 41m above ground + 67m underground n ASP/DLSP/SPINOR (vector magnetograms) IBIS, HSG, UBF, High Order AO n PPARC approved solar facility n 20 days per year for UK led proposals

iXon X 1002 CCD Andor/Texas Instruments Max Frames per sec : 32 (full CCD) 200 (125 x 125) 1.8TB/day/CCD (8 hours observing) Fast local disks (15K RPM) LTO2/3 tape autoloaders Camera - Computing

ROSA – Hardware tests

Ha center before and after reconstruction

Doppler velocities – Narrow band filters Doppler velocities – Narrow band filters Construction of blue ( λ – Δ λ) and red ( λ + Δ λ) wing images. The intensity difference between the images provides a Doppler shift. In a symmetric profile there is no difference in intensity.

Image credit : IBIS group

Fe I velocity map Image credit : IBIS group

Magnetic Fields Zeeman effect – Polarization Magnetic Fields Zeeman effect – Polarization n Longitudinal case B  to the line of sight n Transverse case B  to the line of sight n Splitting proportional to the magnetic field n Components are polarized

Magnetic Fields Δλ = 4.67 x g λ 2 B // where B // is the line of sight component of B UBF (Universal Birefringent Filter) and a Wollaston prism Images of opposite circular polarization

Summary Summary ROSA has been funded £450K (SRIF3 and PPARC) Hardware tests completed (lab & telescope) Software tests (November 2006) Delivery in late 2008 at DST/NSO Common user instrument Time through TAC The DST is a PPARC approved facility Strong interest from the UK community 20 days per year for UK proposals (any instrument) The solar microscope Advanced Technology Solar Telescope (ATST)

Photospheric photon mean free path and pressure scale height 0.1’’ = 70 km Magnetoconvection coupled with atmospheric dynamics Small scale structures Umbra dots – Spicules – Bright points Flux Tubes – Buidling blocks of the magnetic photosphere Flux Tubes and Wave Generation Flux Tubes & Coronal Loops – How are they linked ? Physical processes take place in very small scales (10-20 km) Implications on stellar activity The need for high resolution

Advanced Technology Solar Telescope ATST Advanced Technology Solar Telescope ATST Aperture : 4m FoV : 5’ 0.35 – 35 µm 0.5 µm 1.6 µm First light in 2012 Haleakala, Hawai Altitude : 3,080m Broad-band imager - Visible & NIR spectropolarimeters - Visible tunable filter - NIR tunable filter - IR spectrograph - Vis/NIR high dispersion spectrograph Design challenges : Energy removal, AO, scattered light, detectors