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Total Solar Eclipse of 2017 August 21
in the United States of America or airborne
#eclipse2017, #tse2017, #2017eclipse
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The point of greatest eclipse (totality phase during 2 min 40 sec) lies in Kentucky. However the point of longest duration with 2 min 41.6 sec is located in southern Illinois. Although there is not any material difference between points of greatest eclipse, maximum eclipse, and corrected longest eclipse, local boosterism will likely be intense with claims and counter-claims about the best location. More importantly, people have to understand and adopt a strategy for eclipse success factoring weather, mobility, etc. These points of longest eclipse are almost meaningless in that context, nevertheless I can envision people crowding on a farm at the cloudy point of longest duration refusing to budge even if clear skies are reachable. The eclipse whose path crosses 14 states —not just the 12 or 13 only that many wrongly advertize—, one of them, Montana, very slightly in a mountainous area so that nobody staying in this state is likely to witness the unimaginable beauty of totality, will likely create a new "Generation Eclipse" much like the March 1970 did.
             
Seeing the eclipse from the ground in its surrounding natural environment is the way to go and get the full experience, particularly if it’s from your home country. However for those willing to have a slightly different experience, I’ll propose one eclipse flight over the Northern Pacific Ocean (one special flight in a brand new Falcon 5X with a zenithal window was another possibility, but the certification of the aircraft has been delayed). It’s unlikely that I will offer any ground tour for a group as organizing one on an individual basis is straightforward. Moreover I’ll also have to take care of some complex scientific measurements with huge constraints.
More comprehensive information and useful eclipse goodies can be found on the Great American Eclipse website maintained by my friend Michael Zeiler. The maps have been created using the data computed by my Solar Eclipse Maestro software. Please take also a moment to read those comprehensive instructions on how to observe the eclipse safely.
You can use this solar eclipse calculator to compute the local circumstances of the eclipse, and the solar eclipse timer notifies the beginning of the various events. A time exposure calculator is there to help you choose your camera settings.
Click on thumbnails for a larger version
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Before you can successfully observe a solar eclipse, the first thing to do is to ensure by all means that the sky will be clear enough at the right time on your selected viewing location. If this is not the case then keeping some mobility can be paramount, and in this case the use of the geolocation tool below can prove to be extremely useful or even essential to make sure you’re inside the eclipse path.
How to optimize your position using your smartphone
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To know in real-time how well you’re doing in terms of position in relation to the totality path you can use this auto-tracking geolocation tool
http://xjubier.free.fr/tse2017map?Map=ROADMAP
or a more complex map (all the URL on one single line with no spaces)
http://xjubier.free.fr/xSE_GM?Ecl=+20170821&Acc=2&Umb=1&Lmt=1&Mag=1&Max=1&MapT=ROADMAP
Remove the ?Map=ROADMAP at the end of the URL if you want to stay in the default SATELLITE mode. Of course the map mode can still be selected once the map is loaded. And the road traffic can be displayed as well.
The tool has been tested with success on a variety of devices from iOS to Android, Windows Phone and Blackberry. Nevertheless please report any problem you may encounter and don’t forget to provide a screenshot and a detailed description.
Then to activate the tool click on the lower icon on the left side, the one looking like a blueish shooting target  . Once activated you should be prompted to accept being geolocated, so answer positively and the map should center on your current position and track your movements (it will work as well on a desktop computer connected via an Ethernet cable and even better via Wi-Fi). To deactivate the tool and stop the tracking click again on the button.
Depending on your device you may have to authorize geolocation in the general settings as well. For example on iOS or OSX you should do so in the privacy settings.
The detailed circumstances bubble is disabled while the auto-tracking geolocation is activated in order not to clutter the screen too much.
More detailed information there
http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3_Help.html#geolocation
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This tool can also be used while airborne.
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What you can experience from being inside the eclipse path
Usually first-timers should aim for longer duration and solar corona, which means a location near the centerline. However you don’t have to be on the centerline to get the longest duration, because the central line is computed using a smooth lunar limb. Once you apply lunar limb corrections you usually find the longest duration may be up to several kilometers away from the centerline, nevertheless don’t be obsessed solely by duration because a difference of only a couple of seconds is meaningless particularly if the sky is not clear.
More generally, people should first think about what they want to observe and as a result position themselves for an optimum viewing of their priority observing objectives. That said when it is your first time, it’s particularly difficult to imagine what to expect, then you should position yourself close to the centerline. If you already have seen one or more totals with a clear sky then you should really start thinking about your priorities. To summarize the main choices:
- a longer view of the solar corona means near the centerline,
- a long view of the pinkish red chromosphere and shorter view of the solar corona means toward the path limits,
- an extended view of the Baily’s bead phenomena also requires being near the edges of the eclipse path,
- for prominences or longer diamond rings it gets more tricky and you’ll have to select a position within the eclipse path that matches various criteria. For prominences you’ll have to observe the Sun in H-α a few hours before the event to see where any prominences are located and then position yourself across the path such that the position angle (PA) of the contact corresponds to the PA of the prominence. Similarly for a strong diamond ring effect you’ll have first to find a large depressed area on the lunar limb before positioning yourself accordingly within the width of the eclipse path to match its position angle. All of this can be accomplished by using my solar eclipse maps and looking at the lunar limb profile that you can obtain by clicking on the LC column header inside the local circumstances bubble. However be aware that the lunar limb profile for TSE 2017 is not great for strong diamond rings.
Cartoons by Bill Kramer
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