Instrument Performance Spefication

13 July 2001

SECCHI Consortium Meeting

Cosner’s House, Abington

Dan Moses

Instrument Performance Specification

• The IPS demonstrates the flow down of the instrument specifications (and resulting requirements) from the SECCHI science objectives.

• The SECCHI instrument specifications can be described relative to those of the SOHO LASCO/EIT.– The current CME paradigm is derived from SOHO.

– LASCO/EIT is the current state of the art in CME observations and forms the technological basis for SECCHI.

STEREO SECCHI Science Objectives

• There are three listings of the Science Objectives:

– The June 2001 STEREO Pre-Confirmation Review Level 1 Science Objectives presentation (Joseph M. Davila/Lika Guhathakurta).

– The February 2001 STEREO De-scope Plan Science Requirements Presentation (Joseph M. Davila/Lika Guhathakurta).

– The August 2000 SECCHI Phase A Concept Study Report (SECCHI Consortium).

June 4, 2001June 4, 2001

Haydee Maldonado - STEREO Project ManagerHaydee Maldonado - STEREO Project Manager

Solar Terrestrial Relations Observatory (STEREO) Pre-Confirmation Review Delta

STEREO Level 1 Science

Joseph M. Davila/Lika Guhathakurta

Science Objective

• CME initiation• 3D CME propagation• Energetic particle

acceleration• Ambient solar wind

structure

Organizational Approach

• Consider observational opportunities unique to STEREO - Stereo viewing by remote sensing suite: two views of the same source from different positions - Multipoint in-situ observations: two observations from different positions within a single event

• Coronagraph stereo viewing requirement divides mission into 3 roughly equal phases

Stereo Imaging with Two Coronagraphs

• No overlap in FOV at intermediate separation angles

• Overlapping FOV exists at small angles, and large separation angles

AB

EARTH

Corona seen by coronagraph B

Corona seen by coronagraph A

Polar View

0

50

100

150

200

250

300

0 200 400 600 800 1000

Time After Launch (days)

Cu

mu

lati

ve

To

tal

of

Ste

reo

CM

Es

Earth Directed

Stereo Imaged

Multipoint In-Situ

Mission Phases

Mission Observational Capabilities

•STEREO-A at quadrature with STEREO-B

•Multipoint observation of Earth directed CMEs

•Multipoint observation of Earth directed CMEs

In-Situ

•Stereo view of plane of sky CMEs and their propagation

Stereo Science

Remote SensingPhase

•View of Earth directed CMEs

LWS Precursor Science

•Halo and limb CMEs and their propagation

Multipoint Science

Level 1 Science Statement

Must have 80% of the in-situ and 80% of the remote sensing instruments operating on each spacecraft for the first 150 days after reaching heliocentric orbit

And 80% of the in-situ and 80% of the remote sensing instruments operating on one spacecraft for the remainder of the 2 year mission

•Heliocentric orbit is reached approximately 90 days after launch•150 day period will allow the observation of up to 100 events at solar

Level –1 STEREO Science Requirements From: “Prioritized STEREO mission science objectives”,

J. Davila (STEREO Program Scientist) February 2001.

Objective COR1 COR2 EUVI HI SWAVESSW Plasma

& Mag Field

HighEnergy

Particles

OtherMissions

1

Understand the3D propagationof CMEs ininterplanetaryspace

X X x x X x

2

Understand theorigin of CMEsin the 3Dcorona

x X x X x

3

Discover themechanismsand sites ofsolar energeticparticleacceleration

x X x x

4

Understand theinteraction ofCMEs withEarth

X X x x x

Instrument Performance RequirementsNote: Improvements in the supporting photospheric magnetic field measurements (higher sensitivity, higher spatial

resolution and vector measurements) would increase the level of success in Objectives III &IV.

SECCHI ScientificObjective

STEREO L-1Science

Required Improvement over SOHO EIT/LASCO Physical Property to be Observed

I. Determine the 3Dstructure of coronalloops, coronal streamers,and large-scale coronalstructure.

2, 3 i. Stereo observations and reconstruction techniques.

ii. K corona observations at <2Rsolar.

>Density distribution of coronal structuresfrom multiple viewpoints

II. Determine the 3Dproperties of CMEs

1, 2 i. Stereo observations and reconstruction techniques.

ii. K corona observations at <2Rsolar.

iii. K corona observations from 30Rsola to >120Rsolar.

iv. Cadence in low corona to match spatial scales.

>Density distribution of CMEs, frommultiple viewpoints and as a function oftime

III. Establish the timingof physical propertiesinvolved in CMEinitiation.

2, 3 i. Stereo observations and reconstruction techniques.

ii. K corona observations at <2Rsolar.

iii. Image cadence and timing accuracy to matchobserved spatial scales.

>Identify evolution during CME initiationof Transition Region Structures, Coronalstructures (e.g. coronal streamers), EUVwaves, Coronal dimming, andGlobal interactions.>Identify absolute timing of the above.

IV. Determine the criticalforces controllingpropagation of CMEs inthe corona andinterplanetary medium(IPM).

1, 3, 4 i. Stereo observations and reconstruction techniques.

ii. K corona observations at <2Rsolar.

iii. Improved image cadence and timing accuracy.

iv. K corona observations from 30Rsola to >215Rsolar.

v. Advanced modeling of the IPM.

>Measure the evolution of 3D density andinferred magnetic fields in the corona andIPM;>Measure the speed, acceleration anddeceleration of CMEs;>Observe tracers of the interaction ofCME with corona and IPM;>Observe formation of shock associatedwith the CME;>Observe sweep-up of ambient material

Challenges Compared to SOHO • Range of Field of View

– Requires 4 separate instruments in Visible regime

– Requires improved polarization measurement

• Image Cadence– Requires higher image throughput

• CCD Camera Readout Rate

• Image Processing Rate (Software and CPU Challenge)

• Telemetry Interface

• Ground System Challenge

• 3 Dimensional Analysis– Two instrument suites

– Absolute timing requirement

– Other requirements not yet specified???

• STEREO Spacecraft Accommodation– Pointing control

– Jitter compensation

– Telemetry interface

Concept Study Report Traceability Matrix

Scientific Objective Derived MeasurementQuantities

Measurement Accuracy

EUVI COR1 COR2 HI1 HI2I What is the 3D structure of coronalloops, helmet streamers

Coronal Brightness 10% 10% 10%

Polarized Brightness 5% 5%Cadence 1 hour 1 hour 1 hourTime Accuracy 1 sec 1 sec 1 secPositional Accuracy 0.8 arc

sec3 arc sec 6 arc sec

II What are the 3D properties of CMEs? Coronal Brightness 10% 10% 10% 10% 10%Polarized Brightness 5% 5%Cadence 3 min 10 min 20 min 60 min 120 minTime Accuracy 1 sec 1 sec 5 sec 10 sec 20 secPositional Accuracy 0.8 arc

sec3 arc sec 6 arc sec 20 arc

sec60 arc

secIII What is the timing of physicalproperties involved in CME initiation?

Coronal Brightness 10% 10% 10%

Polarized Brightness 5% 5%Velocity 5 km/s 5 km/s 10 km/sCadence 1 min 1 min 5 minTime Accuracy 1 sec 1 sec 5 secPositional Accuracy 0.8 arc

sec3 arc sec 6 arc sec

IV What are the critical forces controllingpropagation of CMEs in the corona andinterplanetary medium?

Coronal Brightness 10% 10% 10% 10% 10%

Polarized Brightness 5% 5%Cadence 1 min 1 min 5 min 60 min 120 minTime Accuracy 0.5 sec 0.5 sec 1 sec 5 sec 10 secPositional Accuracy 0.8 arc

sec3 arc sec 6 arc sec 20 arc

sec60 arc

secVelocity 5 km/s 5 km/s 10 km/s 25 km/s 50 km/s

Updated Instrument Parameter Table

COR1 COR2 HI EUVI

Instrument Type Internally OccultedLyot Coronagraph

Externally OccultedLyot Coronagraph

Externally OccultedCoronagraph

EUV Narrow-BandpassCassegrain Telescope

Observable K-Corona and CMEs K-Corona, F-Coronaand CMEs

K-Corona, F-Corona andCMEs

Emission Line (EUV) Corona &Upper Chromosphere

Field of View 1.25 - 4 Rsun 2 - 15 Rsun 12 to >215 RsunHI-1: 12-84 RsunHI-2: 66-318 Rsun

0 to 1.7 Rsun

Spatial Scale 7.5” pixels 14” pixel HI-1: 35.2” pixelsHI-2: 120” pixels

1.6” pixels

Baseline Image Size 1024 x 1024 2048 x 2048 1024 x 1024 2048 x 2048

Bandpass 650-750 nm 650-750 nm HI-1: 650-750 nmHI-2: 450-850 nm

He II 30.4 nmFe IX 17.1 nmFe XII 19. 5 nmFe XV 28.4 nm

Exposure Times 1 sec3 required for pB

3 sec3 required for pB

HI-1: 12 secHI-2: 60 secExposures>40 required

Fe IX: 3 secFe XII: 5 secFe XIV: 7 secHe II: 10 sec

Maximum Cadence 15 sec 22 sec HI-1: 1 minHI-2: 8 min

7 sec at full resolution in Fe IX(11 sec @ 0.5MHz Readout)

Synoptic Cadence 8 min 20 min HI-1: 1 hourHI-2: 2 hours

20 min full resolution and2.5 min half resolution

Absolute PointingRequired

7 arcsec occulterpositioning

30 arcsec occulterpositioning

20 arcmin 3 arcminFOV overlap

Pointing StabilityRequired

1.9 arcsec over pBsequence (7 sec)

3.75 arcsec over pBsequence (17 sec)

0.5 arcmin over HI-2sequence (1 hr)

0.9 arcsec over 1 exposure

Stray Light/Disk LightRejection

10-6 Bsun 10-11 Bsun HI-1 10-13 HI-2 10-14 Bsun 10-12 ratio of visible/EUV

CCD & CameraElectronics

EEV 42-40, 2k x 2k, 13.5 µm pixels, backside illuminated, AR coated (except EUVI), >100k e- full well,Common electronics, 1 MHz readout rate, 14 bit/pixel digitization