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SECCHI Observations: Comets, Planets & Discoveries

Explore the latest findings from the SECCHI Consortium Meeting in France, including SOHO's comet discoveries and early results from HI-2, HI-1, and COR-2 observations. Discover the scientific potential and object discovery prospects for SECCHI.

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SECCHI Observations: Comets, Planets & Discoveries

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  1. 5th SECCHI Consortium MeetingOrsay, FranceSECCHI Observations of Comets and Minor PlanetsKarl Battams (NRL)

  2. Overview • SOHO Recap • Current comet status • Comet highlight • SECCHI – Early Results • HI-2, HI-1 and COR-2 • The COR-2 Kreutz comet problem... • Prospects For SECCHI Comets • Science discovery potential • New object discovery potential • Some Highlights For This Coming Year

  3. SOHO – History's Greatest Comet Discoverer! • To date, SOHO has discovered 1,273 previously unknown comets • 1,069 Kreutz • 30 Marsden • 29 Kracht • 73 Meyer • 72 Non-group (including 3 “Kracht II”; several “pairs”) • SOHO has discovered three well-populated comet groups

  4. SOHO Observations of Known Objects • Comets • Over a dozen comets (Machholz (twice), Kudo-Fujikawa, NEAT, Bradfield, McNaught, ASAS...) • Asteroids • Ceres and Vesta • Pleasant surprises • Several of Jupiter's moons!

  5. Some SOHO Comet Highlights • Nearly 1,300 new discoveries!! • Link between comet Machholz and the Marsden and Kracht groups (and two meteor showers... and an asteroid...) • Wealth of information on the dynamics and evolution of old comets • “Clusters” of comets just hours apart • Information regarding pre-perihelion fragmentation of comets • CME striking the tail of comet NEAT • Information on solar wind, comet dust tails and CME-comet interactions

  6. SECCHI – Early Results:HI-2 Observations • Stars • Apparent limiting magnitude: ~m11 • Too many stars! • Comets and Minor Planets: • Comet C/2006 M4 (SWAN) (m9.6) • Tail of comet C/2006 P1 (McNaught) • And later, all of it! • Asteroid 15 Eunomia (m10.1)

  7. SECCHI – Early Results:HI-2 Observations • Other Objects: • M31 (Andromeda) • M16, M17, M22, M25, M28... • Milky Way • LMC, SMC • Many more!

  8. SECCHI – Early Results:HI-1 Observations • Stars: • Apparent limiting magnitude: almost m14? • m12 stars certainly visible Image courtesy of A.Watson, SOHO comet hunter (Australia) using “Starry Night” software

  9. SECCHI – Early Results:HI-1 Observations • Minor Planets: • (15) Eunomia • (10) Hygiea • (532) Herculina • (8) Flora • (1) Ceres • (29) Amphitrite • (349) Dembowska • (6) Hebe • (14) Irene • (95) Arethusa (m13.3!) • (219) Thusnelda • And that's just in the HI-1 A data!

  10. SECCHI – Early Results:HI-1 Observations • Comets: • C/2006 M4 (SWAN) at m9.6 • Spectacular C/2006 P1 (McNaught) at m-5.5! • High-resolution images of dust tail and striae • Five SOHO-discovered Kreutz-group comets • Visible prior to their LASCO C3 appearance! • HI-1 more sensitive than LASCO C3

  11. SECCHI – Early Results:COR-2 Observations • Apparent limiting magnitude: at least m11 • Lots of stars • Observed comets: • Surprisingly few! • Over 40 “SOHO” Kreutz have passed through COR-2 • We have seen just four of them • What's the problem? • Exposure times? Bandpass? Polarization?

  12. SECCHI – Early Results:COR-2 Observations • SECCHI: A salt-free diet? • Kreutz comets show up well in the sodium-D line (589.0nm, 589.6nm) • LASCO C3 (Clear) bandpass: 400-900nm • LASCO C2 (Orange) bandpass: 520-640nm • SECCHI COR-2 bandpass: 650-750nm • SECCHI HI-1 bandpass: 630-730nm • Sodium-D not visible in COR-2 or HI-1! • But... • HI-1 is more sensitive to Kreutz than LASCO C3

  13. SECCHI – Early Results:COR-2 Observations • So why so few COR-2 Kreutz comets? • Polarized images? • Kreutz still show in LASCO C2 polarized images, though are noticeably fainter • Exposure time? • LASCO C2 exposures are quadrupled for polarized C2 images (to 100 secs) • Answer: • Probably both (but I think longer exposures would really help...)

  14. Scientific Potential • Discoveries of new comet populations would add to what is known from SOHO of the end life of a comet • HI observations of “SOHO” comets will extend light curves to much greater distances • Greatly improved orbit determinations • Detailed images of comet tails (e.g. McNaught) lead to better understanding of solar wind / comet interaction • Possible CME-comet interactions • First 3-D reconstruction of comets

  15. SECCHI Object Discovery Prospects • HI-2 • Discoveries extremely infrequent • Other surveys have it covered • HI-1 • Discoveries very likely and relatively frequent • COR-2 • Could still surprise us... • COR-1 • Very unlikely to make new discoveries due to limited field of view

  16. Some Highlights For This Year... • Comet 2P/Encke • Mag 6, will pass from HI-1A into HI-1B (also LASCO C3) (late April) • Comet 96P/Machholz • Mag 8 (very approx), LASCO C3 (faint) and HI-1B (early April) • C/1999 R1 = C/2002 R5 (SOHO) • Predicted 3rd perihelion passage (~September) • Mag 6; LASCO C2, C3 and (hopefully) HI-1B • Many more asteroids...

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