1. SWTTail Season Conjunctions 1 UCB, Dec 15 2007 THEMIS SCIENCE WORKING TEAM MEETING Tail 1 Conjunctions Sabine Frey University of California - Berkeley

2. SWTTail Season Conjunctions 2 UCB, Dec 15 2007 Overview Tail Season Schedule Conjunction Criteria Orbit Evolution Conjunctions Tail1 2008/2009 - In Space - Geographic Overview

3. SWTTail Season Conjunctions 3 UCB, Dec 15 2007 Tail Season Schedule 1 2007-11-06 } alignments P1,P2 2007-12-04 } 1 st tweaks P1,P2 9 × 12h Dawn conjunctions 2008-01-09 } 2 nd tweaks P1,P2 12 × 12h Midnight conj. 2008-02-26 } 3 rd tweaks P1,P2 9 × 12h Dusk conjunctions 2008-04-02 Center Epoch, WD of season 2008-02-02 WD-60d WD-24d WD+24d WD-88d WD+60d First Tail Season Winter 2007/2008

4. SWTTail Season Conjunctions 4 UCB, Dec 15 2007 Tail Season Schedule 2 Midnight Dusk Dawn Tail season Dawn Flanks Dusk Flanks Day side Conjunction Intervals: 00:30-12:30 UTC Dawn: 2007-Dec-08 2008-Jan-09 9 Orbits Midnight: 2008-Jan-09 2008-Feb-29 12 Orbits Dusk: 2008-Feb-29 2008-Apr-02 9 Orbits WD-60d WD WD+60d THEMIS Orbits First Year

5. SWTTail Season Conjunctions 5 UCB, Dec 15 2007 Conjunction Criteria Tail Season 1-Midnight P1 P2 P3 P5 P4 -30 -20 -10 Ecliptic X-GSE [Re] Neutral Sheet (NS) Equatorial plane P1 Orbit Plane Magnetic Axis, 22 Diurnal Range Z-GSE [Re] Distance to Neutral Sheet +5 Re +2 Re -2 Re -5Re Z-GSM X-GSM Center Epoch of Tail Season (WD) Observation geometry Inter probe separation dY GSM Pn < ±2 RE Probe to neutral sheet dZ3,4/NS < ± 2 RE dZ1,2/NS < ± 5 RE GBO midnight/noon ± 6 h C1 C2 C3

6. SWTTail Season Conjunctions 6 UCB, Dec 15 2007 Orbit Evolution Inclination Apogee

7. SWTTail Season Conjunctions 7 UCB, Dec 15 2007 Conjunctions Tail1 2007/2008 1 WD+24d WD+60d WD WD+24d WD WD-24d WD-24d WD-60d Mar 08 Feb. 08 Dec 07 Dusk Midnight Dawn WD+60d WD WD-60d Time C1,3 Y GSM X GSM C2,3 dZ X GSM

8. SWTTail Season Conjunctions 8 UCB, Dec 15 2007 Conjunctions Tail1 2007/2008 2 P5 P3 P4 Geographic Longitude of Apogee Passes of Inner Probes

9. SWTTail Season Conjunctions 9 UCB, Dec 15 2007 Back-up Slides

10. SWTTail Season Conjunctions 10 UCB, Dec 15 2007 Neutral Sheet Model Neutral Sheet (NS) model Hammond, 1994 Hinge point at inner probe orbits Distance to NS |dz| < 2 Re for inner probes |dz| < 5 Re for outer probes Compared with Tsyganenko Model T96 d Hinge Point Zone Neutral Sheet Model Verification March December