Does a Dense Atmosphere Exist
Around Io?
John Menke
June 2014
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Origin of Study
Degenhardt papers SAS2010, 2013, etc
Observed Io(F)/Europa(R) occultations (video)
Observed dimming before/after occultation (wings)
Interpreted as dimming from thick atmosphere
(Jovian Extinction Events..JEE)
My investigation was for a decision whether
to take data in 2014 (I decided not to)
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Degenhardt observations
(two observations of many)
Wings
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Occultation
R
F
Images converge
Eclipse
R
Earth,F&R in
perfect line
R likely not
in shadows
F&R in line
R in shadows
F
Images do NOT converge
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Critical Problems
Pro-Astronomers see no thick atmosphere
Eclipses show no wings
Duplicate observations show null results
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1
Pro-Astronomers see no thick atmosphere
Telescopic searches w/big scopes and HST have never
imaged atmosphere
Advanced spectroscopic searches w/big scopes show
only very faint (10^-9) atmospheres
Note: JEE references out of context)
Satellite probes near Jupiter see none
Satellites within 200km of Io saw/felt none,
would literally have slowed down or burned up
Extended JEE atmosphere not gravitationally
feasible (Menke)
See Mallama paper for details
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2
Eclipses show no wings, but they should
Io atmosphere should cast shadow during eclipse,
but not seen
No explanation
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3
Duplicate observations show null results
Redding (in JEE group) had null observations explained
adhoc -PDE, threshold (no physics, no predictive value)
Others also see no wings, eg Gerhard Dengl (one of many)
20090901 occult
s
1000 sec
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Any ONE of the foregoing
problems
is a fatal flaw for JEE
JEE does not exist if even ONE
of these is true
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Lesser Problems
Inadequate documentation
Photometric methods not used (eg, ref, linearity)
Why video, why not CCD observations,
no confirmations from am or pro
Overly defensive criticism of objections,
many words, but non-rebuttal on physics
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But if not real, what was it?
Some other Jovian effect-hard to think of one
Analytical (eg., software)-Lots of data,
but only LiMovie used
Instrumental-potential for video
non-linearity
Obtained video data from Degenhardt of six events
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Typical video frame...
Ganymede
Jupiter
Io/Europa
Callisto
Event 20090901
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Technique:Convert video to JPGs
Use VirtualDub to select
~100 frames
Export/ImageSequence/..JPG
Paste into Maxim or
other photometry prog,
examine pixels, take
averages, etc.
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Analytical problem?
Test:Did I reproduce wings?
VideoData
LiMovie
VideoData
JPGs
YES
MaximDL
YES
Wings NOT an artifact of processing
Test validates JPG/photometry methods
Only thing left is a sensor/system problem..
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Video non-linearity concerns
Video cams not tightly specified
Hidden algorithms, large/small scale features
Gamma used in video
Output=input ^ gamma
Gamma=1 linear
Gamma applied in camera and/or LiMovie
Saturation and Roll-Off issues..
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Saturation and Roll-Off issues, cont
Unknown behavior approaching
saturation (Roll-Off)
Actual saturation –
8bit=255 limit
Linearity/roll-off
not measured
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Can we tell whether system is generally linear?
Test: Linearity (when no sat)..
Convert to JPGs, measure ratio intensities
Prediction
Actual
(I+E)/
Gany
Gany (I+E)/
/Cal Gany
Gany
/Cal
0120UT
1.20
2.75
1.19
2.66
0200UT
1.20
2.75
1.07*
2.43
... Linear Video
Dimming (wing)
Yes, sensor appears roughly linear
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If generally linear, then how about saturation or Roll-Off?
What is happening in images?
During occultation, images merge
(During eclipse, do not merge)
Saturation MUST cause light loss
and, ANY saturation shows out of control
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Simulate saturation…
Can saturation cause wings?
Software, slide one PSF over another, measure intensity
Qualitative, features only
Can adjust saturation,
gamma, spacing, noise,
etc
Saturation is plausible
cause of wings
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Is saturation present in JEE video?
Note:LiMovie poor tool for evaluating video, so used photometric methods
Convert to JPGs, inspect all objects, different times,
Jupiter-heavily saturated
Ganymede-seldom saturated
Io/Europa-increasing saturated pixels as merger/
occultation proceeds (Io+E>G)
Callisto (faintest) – never saturated
Yes, extensive Io/E saturation present
in all JEE events (but not in Null observations)
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Typical frame near occultation
Saturation
Io
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Is the saturation sufficient?
Hard to measure or calculate – lost information. Use surrogate:
Note-Io+Europa = 1.2xGanymede..use G. as surrogate
Multiply Ganymede pixels by 1.2, measure intensity:
gives UNsaturated equiv. of Io+Europa
Apply saturation limits (tool in Maxim)
Remeasure intensity..
gives SATurated equiv of Io+Europa
Result—Saturation dims intensity 10-14%
~same as wings
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One last item..
Remember - some JEE group occultation videos
show NO wings (PDE, etc given as cause)
But examining video data shows they were taken with
longer fl scope-larger images, lower pixel values, no sat.
plus, other video observers do not see
wings when properly using video
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Conclusions
3 critical problems w/JEE: astronomic data,
eclipses, other observers null results, plus
Saturation in video is shown sufficient
to cause apparent dimming (JEE wings)
Root problem-insufficient attention to sensor,
and failure to use photometric methods
Interpretation of data incorrect:
there is no thick Io atmosphere
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Comments on “the debate”…
Given the extraordinary claim, one must resolve,
not bypass, all the major problems before taking
JEE seriously
One can ALWAYS make arguments and find
some data to support any view, but critical
thinking (and Occam) is key in evaluating
Most of our debates are political debates about
values: This is a scientific debate about evidence
and physics. JEE is true or it is not
Continued debate or investigation after a problem
is solved may be a sign of bad science.
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