1. OSIRIS Observations of Comet 2004/Q2 Machholz
Miriam Rengel
MPS, Germany
Titelseite
Jones G. , Küppers M., Keller H.U., Hviid S.
MPS, Germany
MPS, Germany
MPS, Germany
MPS, Germany
7/11/2006
NASA/JPL-Caltech/UMD

2. Rosetta Orbiter Instruments
OSIRIS: Scientific cameras onboard Rosetta
Cameras
Optical, Spectroscopic, and Infrared Remote Imaging System
P.I : Horst Uwe Keller, MPS (Germany)
NAC
During commisioning Machholz was observed for around 3 hours on 20th January 2005.
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3. Machholz trajectory with respect to fixed Sun-Earth line
Ecliptic Plane
C/2004 Q2 (Machholz) in an orbit that kept it relatively close to Earth throughout its perihelion passage.
Distance Earth-comet= AU
Figure shows motion of comet with respect to fixed Sun-Earth line.
Excellent orbit for comparing comet ion tail structures with near-Earth solar wind data.
Perihelion at AU
Comet on January 20th
0.35 AU from Earth
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4. Goals To analyse the OSIRIS observations of 2004/Q2 Machholz
To investigate the ion tail orientation/appearance in the OSIRIS observations in order to provide indications of the solar wind velocity at the comet
To construct an anaglyph with OSIRIS-Earth- based observations to get a quantitative assesment of the 3D vector of the solar wind
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5. How? Ingredients
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6. Observations of 2004/Q2 Machholz
Narrow Angle Camera (NAC)
Pixel scale at the comet 1: 1247 km
Filters used: 4 medium bandwidth filters at 648 – 980 nm
Wide Angle Camera (WAC)
Pixel scale: 5962 km
Filters: red continuum, green, UV375, CN, CH, CS, and UV245
Observations
Start: 19:54 UT on 20. January 2005
End: 23:01 UT on 20. January 2005
Total number of images: 75
Exposure time: 20 and 60 s
Best time resolution: ca. 1 image per minute
Stereo angle Rosetta-Machholz – Earth 14º
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7. Example of images: NAC NAC Orange filter NAC Green filter
NAC Blue filter
NAC Red filter
649 nm
536 nm
481 nm
744 nm
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8. WAC red broadband green UV375 CN 376 nm 630 nm 537 nm 388 nm CS UV245CH
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309 nm
259 nm
246 nm

9. Emission of ion tail detected with the WAC red & green filters
High number of signatures of cosmic rays
Algorithm for rejecting cosmic-rays: L.A.Cosmic
P. G. van Dokkum, 2001, PASP, 113, 1420
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10. False Color Composite OSIRIS Image of Comet 2004/Q2 Machholz
Visible Ion tail of
Lenght of > km
(H2O+)
Its orientation remains a valuable method for inferring solar wind velocities
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WAC Red

11. Model of solar wind conditions
Modeled Solar wind conditions at Machholz
Solar wind conditions at comet’s orbit modelled using MHD simulation based on solar observations of photosphere.
(Matt Owens, Boston University)
Solar wind data obtained from OSIRIS observations can be compared to model, and to ACE near-Earth solar wind data.
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12. ACE near-Earth solar wind conditions indicate that January 20th was a period when several CMEs reached Earth, and hence also Machholz.
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13. Preliminary results
Solar-wind speed and orbital motion causes plasma tail to point several degrees away from the radius vector
Schematic showing the aberration effect and the orientation of plasma tails.
Courtesy: J. Brandt
Plasma tail would point :
very close to the anti-solar direction for a very high solar-wind speed (750 km/s) and larger angle for a v of 450 m/s.
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14. Results
Plasma tail points very close to the anti-solar direction  high solar-wind speed (~750 km/s).
WAC Red
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Anti-solar direction

15. Results
We do not detected with OSIRIS propagating disturbances in the ion tail in the temporal sequence, neither disconnection events or knots: we do not identify CME signatures
The comet appears to be immersed in a fast, steady coronal hole flow
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16. Ground-based observations
Survey of amateur images of Machholz being conducted by Geraint Jones (MPS) and Jack Brandt (University of New Mexico).
Extensive collection of amateur images collected.
Sequence at left shows rapid change of ion tail in response to arrival of a coronal mass ejection at the comet on January 18, 2005, 2 days before OSIRIS observations.
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17. Mike Holloway Van Buren, Arkansas January 19, 00:46 UT

18. Masaaki Uto, Itawa, Japan January 20 2005, 11:40 UT
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19. Isao Ootsuki (Miyagi, Japan)
2005 Jan :32 UT

20. Mike Holloway
Van Buren, Arkansas
January 21, 02:14 UT
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21. Earth from Machholz during the OSIRIS ion tail observations (20:42 on 2005 January 20)
Extensive cloud cover over northern Europe, but Italy, Spain clear.
Moon ¾ full.
No images taken during OSIRIS observations located so far.
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22. ...we can recostruct the 3D velocity vector
Nevertheless....if solar wind direction does not change significantly in few hours....
...we can recostruct the 3D velocity vector
Observations:
Same resolution
Consider comet‘s orbital motion
Two problems of Stereo:
Correspondence
Reconstruction
Non-parallel cameras
14 degrees
0.4 AU
0.405 AU
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23. Results Original resolutions: Arkansas:2159,4 km/pixel
WAC: ,7 km/pixel
WAC OSIRIS
Arkansas image
Half-colour
Colour
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Stereo-imaging

24. 7/11/2006

25. Plans *Improve stereo images
Schematic of stereo imaging setup
*Improve stereo images
If you have/know Machholz Earth-based observations taken
around 21 UT on 20th January 2005
Please let me know it!
*construct the epipolar geometry - to perform the 3D reconstruction by triangulation
* Compare the results with the available modeled Solar wind conditions
                                                                                 
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26. OSIRIS Publications & Proceedings
Rengel, M. , Kueppers, M.; Keller, H. U.; Gutierrez, P.; Hviid, S. "A Study of the Velocities of the Ejected Dust and of the Rotational Variability of Comet 9P/Tempel 1 around the Deep Impact Event ". American Astronomical Society, DPS meeting 38, California, USA, October 2006.
H.U. Keller, M. Rengel , M. Kueppers, P. Gutierrez and S. Lowry "Monitoring of Comet 9P/Tempel 1 around the Deep Impac event with the OSIRIS NACCamera ". IAU XXVIth General Assembly, Prague, Chezk Republic, August 14-25,2006.
M. Rengel , M. Kueppers, H.U. Keller, and P. Gutierrez. "Modeling of the Terminal Velocities of the Dust Ejected Material by the Impact ". Deep Impact as a World Observatory Event - Synergies in Space, Time, and Wavelength, Brussels, Belgium, 7-10 August Proceedings in the ESO / SPRINGER series (eds. Ulli Käufl & Chris Sterken).
H.U. Keller, M. Kueppers, M Rengel , S. Fornasier, G. Cremonese, P. Gutierrez, W. H. Ip, J. Knollenberg, L. Jorda "Observations of comet 9P/Tempel 1 around the Deep Impact event with the OSIRIS cameras on Rosetta". The 36th COSPAR Scientific Assembly, Beijing, China, July 2006.
Rengel M., Küppers, M.; Keller, H. U.; Gutierrez, P. "Analysing the Post Deep Impact Brightness distribution of the Cometary Dust of the Comet 9P/Tempel 1 with OSIRIS". General Assembly of the European Geosciences Union, Vienna, Austria, April 2-7, 2006.
Horst Uwe Keller, Michael Küppers, Sonia Fornasier , Pedro J. Gutierrez, Stubbe F. Hviid, Laurent Jorda, Jörg Knollenberg, Stephen C. Lowry, Miriam Rengel, et al. "Observations of Comet 9P/Tempel 1 around the Deep Impact event by the OSIRIS cameras onboard Rosetta". Special issue of Icarus on the Deep Impact mission (accepted).
DI will continue to produce new results!
END
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27. Next Slides
Possible questions
Possible answers
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28. Geometry for comet Machholz on 20-Jan-2005 22 UT:
Heliocentric distance of the comet:
Geocentric distance of the comet:
Distance Comet-Rosetta:
Distance Earth-Rosetta:
Heliocentric distance of Rosetta:
Solar elongation of the comet as seen from Rosetta:
Phase angle of the comet as seen from Rosetta:
Phase angle of the comet from the Earth:
Angle between the Earth and Rosetta as seen from the comet:
Heliocentric velocity of the comet:
Geocentric velocity of the comet:
Distances in AU, Angles in degrees, velocities in km/s
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