Frequenly Asked Questions
Please also read the Help File.  If after reading the FAQ's and the Help File you still have questions you can email me at

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What is the effect of the lunar limb profile?
How accurate is a cell phone's time/clock?
Can I use my phone camera while Solar Eclipse Timer is running and hear the announcements?
How do I stop eclipse event notifications?  They are continuing with the all closed?
Does Solar Eclipse Timer also time partial solar eclipses?
What is the best way to use the 1st demo program "Load Demo Contact Times?
Are the times in the Play a Practice Eclipse Movie adjustable?
What happens if I practice with the app during the eclipse time period during the day now?
Will the app be updated for future eclipses?

Lunar Limb Profile and It's Affect On the Shadow
The edge of the Moon is not smooth, it has mountains and valleys.  As this uneven edge covers the Sun at the final moment before totality begins (C2) and the final moment as totality ends (C3) a mountain may make the shadow duration last a little longer at certain places along the path.  Or, a valley may make the shadow duration be a little shorter at certain places along the path.  The maximum variation can be about 3 seconds, but this is only at very specific places along the path.  The effect of the lunar limb can now be included in the calcuated time for the duraiton of totaltiy.  The Google Interative Map by Xavier Jubier presents this variation if you want to use it to be more accurate with you C2 and C3 time.  The times are presented with an accuracy into the tenths of a second.

In Solar Eclipse Timer, if you want to make the adjustment for the lunar limb profile for your observing loaction, you can use the ADJUST buttons on the main timer screen to add or subtract some time.  However, you can only make the adjusment in increments of a whole second.

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Accuracy of the Time in Cell Phones
This is actually a question that I have asked myself, researched and found that the answer is complicated.  The cell phone industry has been improving their time stamp and timing protocols/standards continually.  I have spoken personally to a sales engineer for a company that provides the very expensive timing devices to the cell phone industry.  The present technology at the level of the carrier's infrasturcture is extremely precise in synchronizing with GPS time, to the level of milliseconds.  The present technology at the level of the cell phone towers is extremely precise in broadcasting that sychronized time to your phone.

I have tested multiple phones side by side with a syncronized atomic clock and a handheld GPS device.  The phones have always been within 1 second of the atomic clock and the handheld GPS.  Sometimes they can be 1 second fast, or 1 second slow.  The variation is mostly due to the delay that gets caused to display the time on the LCD screen.  The internal time at the level of the phones operating system is actually much more accruate.  The displayed time can also vary some as you open and close apps and even open and close the Solar Eclipse Timer app.  The displayed time can actually improve and update as the phone has more time to triangulate cell towers.

This is why is is my recommendation, on eclipse day, to turn off or disable all apps on your phone that are not essential.  You want to free up system resources so your processor can update the LCD display as rapidly as possible.

For more in-depth reading on this subject look up Precision Time Protocol IG.8275.2

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Using the Phone's Camera
If you use your phone camera during the eclipse, the camera becomes the "app" in the foreground of the operating system.  Therefore, Solar Eclipse Timer gets pushed to the background.  The operating system in phones has "rules" for how apps use the system resources and for basically all apps, the one that is running in the background will be limited in it's interaction with the user.  This is the design of the operating systems of phones.  So, if you open your camera Solar Eclipse Timer is prevented from playing the announcements.

However, Solar Eclipse Timer is still running in the background and the sequencer is still timing the eclipse for you.  So when you re-open Solar Eclipse Timer it picks up where it should be.  Also, when Solar Eclipse Timer is in the background the notification protocols still work and you will get the banner notification that an eclipse event is about to occur.  The operating system rules allow the notification protocols to break through the app theat is in the foreground.

Note:  During the eclipse It is NOT recommended that you use the camera in the device that is timing the eclipse.  It is NOT recomended that you continually open and close apps in the devce that is timing the eclipse.  In fact, as outlined in the Help File, I suggest that you turn off or disable all other apps that maybe running in the background to free up system resources and the processor.

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Event Notifications
The two practice sessions in Solar Eclipse Timer load eclipse event notifications into the operating system.  Exiting the app does not clear them.  To clear them do this:  Open the app, go to the Settings Screen, tap the 1st demo program, tap OK in the pop up dialogue box, tap the square STOP icon in the top banner, that will clear the notifications.

Explanation: Eclipse event notifications are loaded at a level in the operating system that is lower than where the app runs.  The app is designed like this.  It's because the notifications have to wake the phone from Sleep/Lock to remind you to unlock the phone and open the app so you do not miss important eclipse events.  Therefore, when using one of the demo programs, if you are not going to complete the session you must stop the demo by using the square STOP button in the upper banner BEFORE you exit and then close the app.  Simply exiting the app does not clear the notifications.

Furthermore, if you live in the path of totality and you are testing the app with real coordinates at the time of day when the eclipse is going to occur, you will get notifications.  The app will think it is eclipse day because it is not linked to the calendar day!

This instruction for using the STOP icon is in the 1st paragraph on the Settings Screen and in the Help File.

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Partial Solar Eclipses
No, the app is not designed to time partial solar eclipses because it must be able to calculate 2nd contact and 3rd contact, (totality) to play all of the announcements.  Therefore, Solar Eclipse Timer is only useful for observers in the path of totality seeing a full total solar eclipse.

Explanation:  Precise timing for 1st contact and 4th contact is not necessary because these are mathematical points in time when nothing important photographically occurs.  These two contact times and be timed effectively with your watch.

Precise timing, where Solar Eclipse Timer is crucial, is for 2nd Contact and 3rd Contact and these only occur when you are in the path of totality seeing a total solar eclipse.

For the August 2017 eclipse, the entire country experiences a partial eclipse.  So if you are out of the path and use the app to geolocate the app will find the C1 and C4 time.  But you do not get an option to load the times into the main timers because Solar Eclipse Timer must have a C2 and C3 time for function properly.

However, you can go the GPS Screen and manually enter latitude and longitude coordinates that are in the path of totality and then the app with calculated 4 contact times and you can load them into the main timers.

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First Demo Program
Use the 1st demo to hear all of the announcements that Solar Eclipse Timer will play.

Explanation: The best way to use this demo program is as follows: Set you phone's screen lock time to 30 seconds. Put your phone down and let it go to lock. In about 2 minutes you will hear a custom ring tone, see a banner and hear an announcement that says "eclipse event open app". This process is designed to teach you how your phone and the app will behave on eclipse day when you phone goes to lock. Take 61 minutes and go through the entire demo and listen to all of the announcements.

The app is designed to prevent your phone from going to sleep/lock during totality. Three minutes before totality, during totality and for 5 minutes after totality the app will force your phone to stay awake.

Furthermore, all of the times in this demo are adjustable. You can make the contact times what ever you want as long as they are times in the immediate future

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Practice Eclipse Movie Times
No, the C2 and C3 times are entered to be synchronized with the 120-second totality.  This is not adjustable because it must fit the edited movie.

Explanation:  This demo program is designed to allow you to have an eclipse movie synchronized to the timer functions so you can practice your observation and photography plan with the excitement of an eclipse movie playing.

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Eclipse Time Period Now
You can test contact times in advance of eclipse day on the main timer screen during the day in the range of time when the actual eclipse will be occurring.  Solar Eclipse TimerTM will think it is eclipse day and behave as such and play announcements.  For this year, Solar Eclipse Timer is NOT date specific.

Explanation:  In this instance, if testing and geolocating in advance, but during the actual eclipse time, the Totality Duration will display zeros between C3 and C4 even if you geolocate in this time period (it thinks totality is over). To be able to calculate and display your Totality Duration time, you have to geolocate before C3 or after C4.

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Updates For Future Eclipses

Absolutely!  As soon as this eclipse is over I will be working on the next version.  At that point I will add the data sets (elements) that are needed for the formula to calculate the contact times for upcoming eclipses.  I am not sure how many I will add, but probably up through 2024.

I also have plans for new features.

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