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  #1  
Old 11-02-2019, 07:03 PM
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OuterObsession (Jameson)
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Post Software for countdown of transits/eclipses

After several exciting ISS transit events I got slightly annoyed with having to look at my phone constantly to keep track of when the transit was going to occur.

So I decided to make a little app that automatically reads out the time left until the transit. This way I can keep my eyes on the camera/telescope/whatever.

It's completely free and open source. It can be run on both Windows and Linux/MacOs (with mono project)

Take a look on the github page and let me know what you think.
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  #2  
Old 14-02-2019, 11:48 AM
Wavytone (Nick)
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Q:

Does it sync the clock with an NTP time source ? PC/mobile clocks often are only roughly aligned and can have errors of several seconds.

Did you know about the Telstra time service - "George The Speaking Clock" - which can be called on 1194 ? The point is that this is synced to the national atomic time standard provided by CSIRO and is accurate to fractions of a millisecond.

Comments:

1. There's no point showing hundredths of second when human reaction times are of the order of 0.1-0.3 second, and the clock accuracy may not be much better if relying on NTP. Even 0.1 second is pointless.

2. I'd add a means to record events to a log, where an "event" is a key pressed (spacebar would do) or mouse click and it records the time of the event in UT or local time.

This could be used for example to do occultation timings (moon and planets) or Bailey Bead timings (solar eclipse).

3. If you had used XOJO you could make this

(a) a web app, for anyone with a web browser,
(b) a self-contained desktop app desktop for all-comers - Windows/Linux/OSX - without requiring MONO or compilers.
(c) iOS - iPhone/iPad app,
(d) Raspberry Pi.

And all from the same codebase.
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Old 17-02-2019, 07:56 PM
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Thanks for the feedback,

It uses system time which has the provisions to store .00 resolution. Of course you're still left with the task of ensuring the system time is actually accurate.

I haven't done any extensive research into the accuracy of time servers but I probably won't read too much into .00 accuracy...

I like suggestion 2 a lot. I was considering in a future version of the app to have all data/information for an event stored in a single file. If something interesting happens you could press a button or something and it would append a comment/timestamp to the data file.

Also with accuracy most laptops in the field don't have access to internet so you relient on them syncing the time before hand.

But as you said the human reaction time makes the additional accuracy pointless. Also the voice synthesiser has a unpredictable delay, in my tests the smallest delay before voice played was around a second. The .00 seconds was more for effect then anything.

I'll take a look at XOJO.

For mobile I'll probably end up just creating native apps (mainly as a programming exercise)

A self contained app for OSX would be nice though.
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Old 18-02-2019, 08:07 PM
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Long ago in the days of old-school chronometers you only correct a clock against a known time standard once at a known time and date, then let it run free for months (possibly a year).

Subsequently at a later time you then compare the unknown clock against the standard to work out the rate at which it is drifting, and repeat this numerous times, eg weekly or monthly.

When using the unknown clock to make a real measurement of an event, you then apply a correction (the offset at the last check, plus the drift rate times delta T) and again some time later compare the clock against the time standard to check the drift rate is still the same.

This avoids having to manually try to synchronise clocks which is virtually impossible to better than 1 second, whereas relative comparisons can be made by audible ticks or visual blinks to much better than 0.1 second and possibly 0.02 second.

The same should be done for computer and portable digital devices between synchronisations to say NTP because most are not all that good - it’s not uncommon to see an iPhone or iPad off by a few seconds when compared to atomic time as broadcast by radio, or the 1194 time service.

Last edited by Wavytone; 18-02-2019 at 08:18 PM.
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Old 19-02-2019, 10:36 AM
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Its certainly a good idea and useful too. I had something similar on PocketPC which I would use and was the only program I ever saw that allowed multiple/repeated timings. Bit late now but for the last transit of venus I planned on having a "string of pearls" photo from the event and manually worked out the times I needed to capture and I also wanted general periodic shots during the event . I had no idea what to expect weatherwise but I was able to photograph the whole event and planned out the times in a spreadsheet and just watched my watch basically, completely forgot to check camera time of course which was uniformly out by 15sec I later calculated.
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Old 21-02-2019, 10:36 AM
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Quote:
Originally Posted by Wavytone View Post
The same should be done for computer and portable digital devices between synchronisations to say NTP because most are not all that good - itís not uncommon to see an iPhone or iPad off by a few seconds when compared to atomic time as broadcast by radio, or the 1194 time service.
To my knowledge NTP calculates an offset value. Although with NTP the time does originate from high-precision timekeeping devices such as atomic clocks, GPS or other radio clocks it often goes through many mediatory time servers which complicate things. https://en.wikipedia.org/wiki/Network_Time_Protocol

Recently I had the chance to try out the program during a ISS transit of the moon. I did notice about ~1 second of lag. I wasn't looking at the screen so I don't know if it was just the voice systhersier lagging or the actual time being off.

I'm also not sure how accurate the transit data is but they show .00 resolution so I'd think that would be somewhat spot on.

Even with the time not being perfectly accurate from a functional viewpoint it performed fine. Maybe in future versions I can try and improve the accuracy.

You can watch the transit and hear the countdown in action here.
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