Statistical studies of trend and gradients in the venusian magnetosheath
FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria...
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Transcript of FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria...
![Page 1: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/1.jpg)
FOV/Attitude
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What Are We Imaging?• Lunar Atmosphere – interaction with S.W.
– What criteria should be applied?
• Magnetosheath – interaction with S.W.
– Primary driver for aspect selection criteria
• Heliosphere–interaction of neutral ISM with S.W.
– Sample region small
• X-ray Background
– A bonus, does not drive aspect selection criteria
![Page 3: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/3.jpg)
Magnetosheath Model• Bowshock/Magnetosheath model of Spreiter,
Summers, & Alksne (1966)
• Scaled by nominal Solar Wind– ρ=2.0 cm-3
– v=400 km/s
• Exospheric Neutral Model– N(r)=25.0(10.0 RE/R)3 cm-3
• X-ray Emission proportional to– N(r)ρ(r,θ)[v(r,θ)2+3kBT(r,θ)/m]½
![Page 4: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/4.jpg)
Magnetosheath Model• Distances/sizes to scale
• X-ray emission strength unnormalized
• MP~11.95RE
• BS~15.09RE
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Baseline Instrument• Zenith telescope at selenographic (λ,µ)
=tilted telescope at some other (λ,µ)
• Incapable of pointing
• Field of view diameter of 10°
• Detector on at all times
Model FOV as f(t)Given (λ,µ)
![Page 6: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/6.jpg)
Lunar Model• Lunar Orbit
– e=0.05490
– i=5.15° from the ecliptic
– a~384,400 km ~60RE
– dΩ/dt=19.35°/year (18.6 year precession period)
• Moon– Obliquity=6.87° from orbit, 1.54° from ecliptic
– ω=13.17635815 deg/day
![Page 7: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/7.jpg)
Lunar ModelConsequences:
• Cis-lunar space is not scanned evenly
• LOS from moon can pass above/below the Earth-sun line
• LOS from moon has nearly constant ecliptic latitude
![Page 8: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/8.jpg)
Lunar Model• Lunar Orbit
– e=0.05490
– i=5.15° from the ecliptic
– a~384,400 km ~60RE
– dΩ/dt=19.35°/year (18.6 year precession period)
• Moon– Obliquity=6.87° from orbit, 1.54° from ecliptic
– ω=13.17635815 deg/day
JPL DE405 ephemeris
IDL implementation by Markwardt
P.K.Seidelmann, IAU Working Group (2000)
LCaMD (JPL D-32296)
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Lunar Model• Assumed telescope at lunar barycenter
• Width of MP-BS at subsolar point:3.14RE~3°
• Radius of bright subsolar “spot”: 8RE~7.5°
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Model for (λ,µ)=(0°,0°)
☼
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Model for (λ,µ)=(0°,0°)
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Model for (λ,µ)=(0°,0°)
☼
10° FOV
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Model for (λ,µ)=(0°,0°)
Over entire 18.6 year cycle
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Model for (λ,µ)=(0°,0°)
Ecliptic Coordinates, FOV centers only
1.57°
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Model for (λ,µ)=(0°,0°)
Ecliptic Coordinates, full FOV
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Model for (λ,µ)=(0°,0°)
Galactic Coordinates, FOV centers only
Subsolar point appears uniformly along band
![Page 18: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/18.jpg)
Model for (λ,µ)=(0°,0°)
Galactic Coordinates, entire FOV
![Page 19: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/19.jpg)
Sel
enog
raph
ic L
atitu
de
Selenographic Longitude
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“Conclusions”|µ|≥10° removes the
paths of both the sun and earth from the FOV
“Spot” remains in the FOV
MP-BS line on the edge of field
Tolerances are fairly tight!
Need sun/earth constraints.
![Page 21: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/21.jpg)
Model for (λ,µ)=(10°,10°)
Galactic Coordinates, entire FOV
![Page 22: FOV/Attitude. What Are We Imaging? Lunar Atmosphere – interaction with S.W. –What criteria should be applied? Magnetosheath – interaction with S.W. –Primary.](https://reader030.fdocuments.in/reader030/viewer/2022032523/56649d7e5503460f94a60c83/html5/thumbnails/22.jpg)