The X-Ray Telescope aboard Solar-B: An Overview Taro Sakao (ISAS/JAXA) and The XRT Team

XRT Sciences Photosphere-Corona connection Formation and heating of the corona incl. energy transport, storage, and dissipation Outer-corona investigation extending to CME and solar wind investigations Imaging observation of the soft X-ray/XUV corona with advanced imaging/temperature-diagnostic capabilities Vast varieties of active, or even non-active, phenomena in the corona:

Investigation of Photosphere-Corona Connection with XRT Photospheric Magnetic Activity Reservoir ? Energy Storage Increase Spatial Scale Transient Brightenings ? Large-Scale Coronal Phenomena ? Eruptive flares CMEs... StorageRelease Immediate Response Trigger ? Time scale: minutes Spatial scale: ~1 arcsec Time scale: days Spatial scale: ~AR ? Coronal Behavior SOTXRT / EIS

Coronal Activity Assoc. with Evolution of an Active Region (from Morita & McIntosh 2005) Mar 13Mar 14Mar 15Mar 16 Mar 17Mar 18Mar 19Mar 20 NOAA (Emerged in a Coronal Hole region) Growing phase Large-flare-productive phase

Typical Flare Evolution in the Growing Phase Two sets of dome-shaped loops Tiny transient sigmoid EIT 195 Å Flares at “dome intersection”

Sigmoid along the inversion line Flare kernel brightening Post-flare loops Typical Flare Evolution in the Large-Flare- Productive Phase

Emergence with “two bipoles” Growing phase with occasional small flares Large-flare-productive phase Flares at “dome intersection” Well-developed sigmoid structure Emerging bipoles into a coronal hole (Morita and McIntosh 2005)

Emergence with “two bipoles” Growing phase with occasional small flares Large-flare-productive phase Flares at “dome intersection” Well-developed sigmoid structure Emerging bipoles into a coronal hole (Morita and McIntosh 2005) Investigate Temperature structure of the corona (both hot & cool loops) Pre-flare evolution leading to energy release Long-term evolution of coronal magnetic structure accompanying flare energy release, particularly for entire active regions together with photospheric magnetic evolution

XRT Advanced Features over Yohkoh SXT Imaging/temerature-diagnositic capabilities for low-temperature (< 1MK) plasmas – Observe entire SXR/XUV phenomena in the corona With back-thinned CCD together with optimum focal plane filters Highest-ever achieved angular resolution as GI imager, with wide FOV (covering the whole Sun) – 1 arcsec pixel size – Cadence as high as, or even better than, SXT High-cadence ( ≦ 1 s) observation with small FOV available Adjustable Focus Position Adds variety in observations: – Highest angular-resolution (1 arcsec) for SOT/EIS FOV – Full-sun observation with 2–3 arcsec

XRT Advanced Features over Yohkoh SXT Imaging/temerature-diagnositic capabilities for low-temperature (< 1MK) plasmas – Observe entire SXR/XUV phenomena in the corona With back-thinned CCD together with optimum focal plane filters Highest-ever achieved angular resolution as GI imager, with wide FOV (covering the whole Sun) – 1 arcsec pixel size – Cadence as high as, or even better than, SXT High-cadence ( ≦ 1 s) observation with small FOV available Adjustable Focus Position Adds variety in observations: – Highest angular-resolution (1 arcsec) for SOT/EIS FOV – Full-sun observation with 2–3 arcsec Temperature Diagnostics with XRT Optimized filter layout Adjacent filter pairs for temperature diagnostics SXT-like filters in one FW while TRACE-like in the other Low temperature ( ≦ 1 MK) diagnostics High-temperature plasmas

XRT Advanced Features over Yohkoh SXT Imaging/temerature-diagnositic capabilities for low-temperature (< 1MK) plasmas – Observe entire SXR/XUV phenomena in the corona With back-thinned CCD together with optimum focal plane filters Highest-ever achieved angular resolution as GI imager, with wide FOV (covering the whole Sun) – 1 arcsec pixel size – Cadence as high as, or even better than, SXT High-cadence ( ≦ 1 s) observation with small FOV available Adjustable Focus Position Adds variety in observations: – Highest angular-resolution (1 arcsec) for SOT/EIS FOV – Full-sun observation with 2–3 arcsec

XRT Advanced Features over Yohkoh SXT Imaging/temerature-diagnositic capabilities for low-temperature (< 1MK) plasmas – Observe entire SXR/XUV phenomena in the corona With back-thinned CCD together with optimum focal plane filters Highest-ever achieved angular resolution as GI imager, with wide FOV (covering the whole Sun) – 1 arcsec pixel size – Cadence as high as, or even better than, SXT High-cadence ( ≦ 1 s) observation with small FOV available Adjustable Focus Position Adds variety in observations: – Highest angular-resolution (1 arcsec) for SOT/EIS FOV – Full-sun observation with 2–3 arcsec Telescope performance to be presented by Ed Deluca-san et al. in the next talk

Improved on-board observation control by the MDP/XRT system – Automatic Exposure Control (AEC) – Automatic Region Selection (ARS) – Image-based Flare Detection (FLD; new feature) – Table-based Observation Sequence Control e.g., Exposure tracking and stabilization for AEC Implementation of pre-flare data buffer memory inside MDP – Potentially powerful tool for detailed observation of the pre-flare corona – Investigation of pre-flare energy storage and release processes XRT Advanced Features over Yohkoh SXT

LASCO/C2 XRT FOV for Limb Observation Yohkoh SXT 2.1 R SUN 2.3 R SUN Wide-FOV Observation of Outer Corona with Diagnostic Capability on Temperature Structure

LASCO/C2 XRT FOV for Limb Observation Yohkoh SXT Wide-FOV Observation of Outer Corona with Diagnostic Capability on Temperature Structure Frequent observation opportunity for the outer corona Temperature structure of the corona up to 2 Rsun (c.f. Foley et al & Wheatland et al with Yohkoh data) Tracking transient ejections (CMEs, filaments) in the corona 2.1 R SUN 2.3 R SUN

Cadence (sec) Flare Core Active Region Global Corona / Heliospheric (Hardware limit by Telescope) (w/o filter motion) (w/ adjacent filter motion) Non-flare Flare Full-Sun Yohkoh SXT Full-Sun Coverage 2” pxl size, or Q~75 (3 bit/pxl) XRT FOV vs Cadence Observing FOV Size (arcsec) (orbit-ave.) Cover SOT FOV

Observing FOV Size (arcsec) Cadence (sec) (Hardware limit by Telescope) (w/o filter motion) (w/ adjacent filter motion) Non-flare Flare Full-Sun Coverage XRT Yohkoh SXT Observation with Pre-Flare Buffer Flare Core Active Region FOV vs Cadence (orbit-ave.) ~x 3 Global Corona / Heliospheric Cover SOT FOV 2” pxl size, or Q~75 (3 bit/pxl)

Observing FOV Size (arcsec) Cadence (sec) (Hardware limit by Telescope) (w/o filter motion) (w/ adjacent filter motion) Non-flare Flare Full-Sun Coverage XRT Yohkoh SXT Flare Core Active Region FOV vs Cadence (orbit-ave.) Global Corona / Heliospheric Outer corona investigation Cover SOT FOV 2” pxl size, or Q~75 (3 bit/pxl) Flare core with high spatial/temporal resolution High-cadence observation on magnetic configuraiton and temperature evolution

Basic Features of the XRT X-ray Optics OpticsOptimized Wolter-I-like grazing incidence optics Focal length2708 mm Mirror micro-roughness 6 Å expected (mirror characterization analysis in progress) Aperture size> 340 mm Spatial resolution68 % of encircled energy in 2 arcsec (at keV) Wavelength range 6 – 200 Å Effective area> 1.0 cm 2 at keV Visible Light Optics Focal length2708 mm Wavelength 4305 Å (G-band) Focal Plane CCD Camera CCD deviceE2V (former Marconi) 2048×2048 back-illuminated (13.5  m pixel size) Field of view34×34 arcmin (capable of covering the whole Sun) Image readout500 kpixel/s