2013 Annual IOTA Meeting, October 4-6, 2013 Toronto, Ontario, Canada

What is a JEE? Jovian Extinction Event describes a dimming in photometry lightcurves as objects pass behind regions of gas and dust associated with the Jovian System. Since the discovery of this phenomenon about 100 data sets have been acquired from 6 different countries documenting atmospheric diameters and densities surrounding moons and gas and dust trapped in the Torus of Io.

Can video provide accurate photometry? When used within its limits, photometry with video is possible as we will demonstrate. Collaborating with Arne Henden (AAVSO Director) his initial estimates were that video photometry would likely be able to reach magnitude standard deviations. Using techniques derived from Brian Warner’s “Lightcurve Photometry and Analysis” and years of video experiences we routinely achieve magnitude standard deviation.

How we record and process video NTSC video produce frames per second, 25 frames per second at 8 bit resolution. Using carefully placed background and measurements apertures in video photometry reduction software such as LiMovie we obtain a background corrected photometry measurement for each individual frame. To significantly reduce scintillation and other noise contributions we then bin 10 seconds of data into a single data point, i.e. 300 frames for NTSC or 250 frames for PAL into one point. This yields 256 x 300 = 76,800 or > 16 bit statistical resolution, easily reaching magnitude stnd dev.

Proposed source of dimming: Reduction techniques introduce a dimming trend as two intensity sources merge.

Proposed source of dimming: Reduction techniques introduce a dimming trend as two intensity sources merge.

Separate photometry confirms Europa dimming

2 different reduction methods from 2 different observations of the same event yield identical overlapping trends.

Proposed source of dimming: Camera response introduce a dimming trend as two intensity sources merge. This implies one of two things: 1) Either the anomaly is introduced randomly as a result of two merging light sources. or 2) It is systematically introduced and would be tied to the field of view geometry, i.e. a specific pixel spacing produces a specific intensity anomaly.

Proposed source of dimming: Camera response introduce a dimming trend as two intensity sources merge. This implies one of two things: 1) Either the anomaly is introduced randomly as a result of two merging light sources. or 2) It is systematically introduced and would be tied to the field of view geometry, i.e. a specific pixel spacing produces a specific intensity anomaly.

JEE2010 After finding repeated atmospheric extinction JEEs, PI Degenhardt theorized that the Torus material of Io should cause Io to self extinct at the tips of the Torus where the material is line of sight collimated.

All these are just squiggly lines unless they can be linked to the Jovian system… Ahhhhhh, thanks to JPL we can do that! The ephemeris they use to guide our spacecraft is available free to anyone.

JEE2012 Major shift using JPL ephemeris Recent introduction by Wayne Green of the Horizons JPL ephemeris for the accurate data of Jovian moons has revolutionized our data reduction and future prediction methods. Reducing all past JEE lightcurves by overlaying the intensity data on top of JPL ephemeris has derived potentially useful scientific data.

Using JPL ephemeris

Conclusions Video data used within its limits is capable of magnitude standard deviation. Anomalous dimming are independent of camera, observing system or reduction technique. O-C comparisons to JPL Horizons ephemeris show the JEE phenomenon is linked to consistent geometries of the Jovian System. Raw images from the Hubble Space Telescope of Io transits reveal intensity gradients surrounding Io consistent with JEE data.

Conclusions (Cont.) JEE atmosphere diameter measurements: Io: ~8 Io radii Europa: ~18 Europa radii Ganymede: none detected so far Consistent with published diameters.

Observe! Predictions, results, and discussions Yahoo Discussion Group JEE_Talk

Appendix I have added reduced lightcurves here just for extra data review.

AAVSO Alert Notice 464: Observers requested for Jovian Extinction Events (JEE2012), Arlot, J.-E., Thuillot, W.,Ruatti, C. and 116 coauthors observers of events: 2009, The PHEMU03 catalogue of observations of the mutual phenomena of the Galilean satellites of Jupiter, Astronomy and Astrophysics, Volume 493, Issue 3, pp Michael E. Brown & Richard E. Hill Discovery of an extended sodium atmosphere around Europa Nature 380, (21 March 1996); doi: /380229a0 Burger, M.H. et al. “Mutual Event Observations of Io's Sodium Corona” (2001) 37X/563/2/1063/52792.text.html Burger, M.H. et al. “Europa’s neutral cloud: morphology and comparisons to Io Matthew H. Burger & Robert E. Johnson” Icarus 171 (2004) 557–560, Degenhardt, S. et. al (2010), Io and Europa Atmosphere Detection through Jovian Mutual Events, The Society for Astronomical Science: Proceedings for the 29th Annual Symposium on Telescope Science, p Degenhardt, S.M., “JEE2012 Call for Observers” (2012) Degenhardt, S.M., “JEE2013 Call for Observers” (2012) Degenhardt, S.M. (2012), Yahoo Discussion Group JEE_Talk, Degenhardt, S. M., Jovian Extinction Event Predictions and Reduction Methods, Author and developer: Observations and data from S. Aguirre, S. Degenhardt, M. Hoskinson, A. Scheck, B. Timerson, D. Clark, T. Redding, J. Talbot, JPL Horizons On-Line Degenhardt, S.M., “Io atmospheric extinction predictions for 2009 Jovian Mutual Events” (2009) References

Degenhardt, S.M., “Jovian Extinction Event (JEE) predictions for 2010” (2010) Kuznetsov, A.A. et. al, “Formation of zebra pattern in low-frequency Jovian radio emission” (2012), arXiv: v1 [astro- ph.EP], Planetary & Space Science Lang, K.R., flux tube diagram, (2010) Lersch, Thomas, Zebra photo, LiMovie Miyashita, K., LiMovie, (2008) software to photometrically reduce AVIs. net.ne.jp/k_miyash/occ02/limovie_en.html NASA, Juno Space Probe Mission, NSDC (Natural Satellites Data Center) database web address: Schneider, N. M. et al., “The structure of Io's corona” (1991), ApJ, 368, 298 Solar System Dynamics Group, Horizons On-Line Ephemeris System, Author : Warner, B., “Lightcurve Photometry and Analysis”, (2006), Springer Science+Media, Inc. References (cont.)