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Discussion of Synoptic Program and Use of SSR2

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  1. Discussion of Synoptic Program and Use of SSR2 SECCHI Consortium SECCHI Consortium meeting 7 March 2007 Univ. Paris XI

  2. Observational Programs • Mission Design Parameters: • Constantly increasing separation angle: 22º /yr each spacecraft • Telemetry (DSN) limited, decreasing over course of mission, minimal real-time commanding, generally weekly observing plans • Simultaneous identical observations from both spacecraft • Two telemetry buffers used simultaneously: SSR1/Synoptic and SSR2/Special Event Buffer: • Synoptic: uninterrupted observing program • Identical programs always maintained in both spacecraft • Permits stereoscopic observations: EUVI early mission, coronagraphs later mission • Based in part on evolving separation and data rate • Event: circular buffer filled at high rate, frozen/read after event • Special Observing Programs: • Two, three week ~double telemetry periods early in mission especially useful for EUVI • Special observations from On-Board CME detection capability

  3. Science

  4. SECCHI Instrument SuiteSystem Description Dan Moses SECCHI Program Scientist Naval Research Laboratory/Praxis, Inc. (202) 404-8108 moses@solar.nrl.navy.mil

  5. SECCHI Instrument Requirements • The SECCHI Instrument Requirements Are Obtained From: 1) The STEREO Science Requirements (STEREO Mission Requirements Document 460-RQMT-0001) 2) The SECCHI Science Goals (SECCHI Science Requirements & Instrument Performance Specification Document 7906-SPC-9-0-003) • The Flow Down of STEREO Requirements and the Derivation of the SECCHI Requirements Are Detailed in the SECCHI Science Requirements & Instrument Performance Specification Document

  6. STEREO Level 1 Science Objectives • Understand the Causes and Mechanisms of CME Initiation • Characterize the Propagation of CMEs Through the Heliosphere • Discover the Mechanisms and Sites of Energetic Particle Acceleration • Develop a Three-Dimensional, Time-Dependent Model of the Magnetic Topology, Density, and Velocity Structure of the Ambient Solar Wind SECCHI Requirements Flow Down

  7. Mission Science Measurement Requirements SECCHI Instrument Requirements Flow Down 1A Determine the CME Initiation Time to an Accuracy of Order 10 Minutes 1B Determine the Location of the CME Initiation to Within ±5 Degrees of Solar Latitude and Longitude 2C Determine the Evolution of the CME Mass Distribution and the Longitudinal Extent to an Accuracy of ±5 Degrees As It Propagates in the Low Corona, the Upper Corona and the Interplanetary Medium 2D Determine the CME and MHD Shock Speeds Accurate to ±10% As It Propagates in the Low Corona, the Upper Corona and the Interplanetary Medium 2E Determine the Direction of the CME and MHD Shock Propagation to Within ±5 Degrees of Latitude and Longitude As the CME Evolves in the Low Corona, the Upper Corona and the Interplanetary Medium 4J Obtain a Time Series of the Solar Wind Speed Accurate to ±10% at Two Points Separated in Solar Longitude

  8. SECCHI Science Measurement Goals 1A Determine the CME Initiation Time to an Accuracy of Order 1 Minute 1B Determine the Evolution of the CMEs, the Transition Region Structures, the Coronal Structures, EUV Waves, Coronal Dimming and Global Interactions at the Highest Cadence Rate and Matching Positional Accuracy 2A Determine the Three-Dimensional Evolution of CMEs and Associated Disturbances in Ambient Structures in the Lower Corona, the Upper Corona, and in the Interplanetary Medium at the Highest Cadence Rate and Matching Positional Accuracy 2B Determine the Evolution of the Tracers of CME Interaction With the Corona and Interplanetary Medium, the CME Shock Formation, and the Ambient Material Sweep-up at the Highest Cadence Rate and Matching Positional Accuracy 3A Determine the Candidate Sites of Energetic Particle Acceleration With a Timing Accuracy of ≤ 1 Minute 3B Determine the Evolution of the CME Front at the Highest Cadence Rate and Matching Positional Accuracy 4A Determine the Three-Dimensional Shape of Coronal Loops, Coronal Streamers, and Large-Scale Coronal Structures and Solar Wind Tracers With a Positional Accuracy of ≤1250 km in the Lower Corona From the Solar Disk to 1.5 Rsun, ≤4500 km in the Lower Corona From 1.5 Rsun to 3.0 Rsun, and ≤ 11,500 km in the Upper Corona

  9. Image Positional Accuracy Requirements Based on Velocity Accuracyand Number of Images for CME / Solar Wind Evolution Analysis

  10. SECCHI Observation Requirement Set Metric Relationship to theDerived Quantities in the STEREO Measurement Requirements

  11. SECCHI Observation Requirement Subset for EUV Emission and Visible Light Images

  12. SECCHI Observation Requirement Subset for 3D Images

  13. Image Cadence Goals to Capture CME Evolution Over Individual Coverage Regions

  14. Discussion of Synoptic Program and Use of SSR2 SECCHI Consortium SECCHI Consortium meeting 7 March 2007 Univ. Paris XI

  15. STEREO Level 1 Science Objectives • Understand the Causes and Mechanisms of CME Initiation • Characterize the Propagation of CMEs Through the Heliosphere • Discover the Mechanisms and Sites of Energetic Particle Acceleration • Develop a Three-Dimensional, Time-Dependent Model of the Magnetic Topology, Density, and Velocity Structure of the Ambient Solar Wind SECCHI Requirements Flow Down

  16. After viewing the first SECCHI Images,how to achieve these objectives? • Well observe a subset of events • Catch every event

  17. Science: Example from NRL Discussion • 3D studies – Stereoscopy • Requires “feature/tie-point” identification and minimization of error in height (Z) determination based upon knowledge of X-Y coordinates • Requires detailed timing knowledge • Optimal angles are between 3º < α < 15º, first 6 months of mission • Timing of CME related structures: one spacecraft sees limb events along with coronagraph while second spacecraft sees disk event + halo coronagraph event • Best suited for ~90º separation or ~ 2 years into mission • Science emphasis shifts as separation angle between observatories increase, can not repeat observations: requires careful planning, i.e. similar to interplanetary mission • Desire to design a mission long synoptic program that best balances the many scientific studies that can/should be performed with EUVI

  18. SECCHI/EUVI Science Objectives The EUVI plays a critical role in addressing the STEREO/SECCHI science objectives, in particular:

  19. Proposed Image Schedule: SSR1, SSR2 default • Exposure times (seconds) weighted toward achieving S/N • 171 = 4s, 195 = 6-8s, 284 = 30s, 304 = 6-8s • Compression factors based upon initial image sets • No Image binning • SECCHI SSR1 allocation ~4700 Mbit/day, desire EUVI have ~40%

  20. Special Programs (non-synoptic) • SSR2 = Circular/Event buffer, 4-8 hours of data: Variety of Options • Polar plume studies, deep exposures, all 4 passbands, synchronized on A,B • Alternating wavelength per spacecraft • 3 passbands (171A, 195A, 284A) – 30 sec, higher compression • 3 passbands (284A, 171A, 195A) – 30 sec, higher compression • Special 3 week “double” telemetry observing periods (x2), Options: • 10 second cadences single line (10 minute test just performed) • Flare studies • 1 minute cadences 4 lines • Etc…