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Online Astro Calculator

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Online Astro Calculator was created by DaveGrennan

Guys,

I have a test version of a little web app that I'd like you guys to help me test.

Its an app which calculates the transit times (in UT) of the GRS (Great Red Spot on Jupiter. If this works out I have a whole pile of such ephemeris type scripts ready to deploy.

webtreatz.com/component/option,com_wrapper/Itemid,83/

Please don't share this address outside of these boards just yet as this is very much a beta test.

Thanks for any feedback.

Update - 21 June 08

I've added a Sunrise/Sunset/Twilight calculator;

webtreatz.com/component/option,com_wrapper/Itemid,84/
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here
14 years 7 months ago #70168

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Replied by dave_lillis on topic Re: Online Astro Calculator

Hi Dave,
looks great !
One thing if possible, do the dates gave to refresh back to Jan1 2008 after you run it?
Why bother with the password thingy.
Would a button showing the next 7 days be useful? like the ISS passes in heavens above.
The only thing now is will the weather allow us to actually test it anytime soon. :(
Dave L. on facebook , See my images in flickr
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Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor
14 years 7 months ago #70170

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Hi Dave,
looks great !
One thing if possible, do the dates gave to refresh back to Jan1 2008 after you run it?


Good point.

Why bother with the password thingy.


The calculations take up processing time on a hosted server, therfore I don't want messers clicking like mad for no good reason. Also to prevent robots from farming the data. Also helps limit 'denial of service' attacks.

Would a button showing the next 7 days be useful? like the ISS passes in heavens above.


Excellent idea.

The only thing now is will the weather allow us to actually test it anytime soon. :(


I'm actually pretty confident about the timings. It's all of the sort of useful suggestions you mentioned above which I really want to hear about
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
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14 years 7 months ago #70172

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Replied by eansbro on topic Re: Online Astro Calculator

Dave G,

This is great! I've just used it. It's a nice handy calculator.

What about the second red spot and the more recently manifested small red spot? ( for fussy astronomers like me).

Thanks for sharing this useful tool.

Eamonn A
MPC J62
www.kingslandobservatory.com
14 years 7 months ago #70176

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Replied by DaveGrennan on topic Re: Online Astro Calculator

What about the second red spot and the more recently manifested small red spot? ( for fussy astronomers like me).


See I knew this place is awash with great ideas. Very little change is needed to predict times for other features.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
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14 years 7 months ago #70177

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Replied by michaeloconnell on topic Re: Online Astro Calculator

Nice work Dave.
I think the suggestions above are very good and I can't add much more than that at this time. I just cross-checked it with todays times from the S&T page and it's looks pretty accurate.
www.skyandtelescope.com/observing/object...piters_Red_Spot.html
However, your calculator allows a month's worth of calculations, which is very handy.
Thanks for sharing it here.
14 years 7 months ago #70184

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Replied by Seanie_Morris on topic Re: Online Astro Calculator

Good going Dave, it does work. I hope the times it gives are correct! :P

See I knew this place is awash with great ideas.

Then how about a picture representation?


Kidding!

Also, I am sure you can add a line of code to read the date on one's own computer everytime that applet loads, therefore defaulting to that person's date. A handy technique to just simply going to your applet on the web, and if already defaulted to that date (for both date options given), simply click 'Calculate', and voilá - you have that days/nights time(s).

;)

Seanie.
Midlands Astronomy Club.
Radio Presenter (Midlands 103), Space Enthusiast, Astronomy Outreach Co-ordinator.
Former IFAS Chairperson and Secretary.
14 years 7 months ago #70193

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Replied by dave_lillis on topic Re: Online Astro Calculator

Here is another idea,
How about io/europa/ganymede/callisto transit times along with shadow transit times, now that would make it even more useful.
Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor
14 years 7 months ago #70208

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Replied by michael_murphy on topic Re: Online Astro Calculator

Hi Dave,

I've tested it in Firefox 3 and it worked fine.

I found the passwords a bit difficult to read tho' (maybe I need my glasses changed).

Michael.
14 years 7 months ago #70209

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Replied by albertw on topic Re: Online Astro Calculator

I found the passwords a bit difficult to read tho' (maybe I need my glasses changed).


Good, its not just me who thought that! Or perhaps I'll see you in specsavers!

Looks good DG, any plans to share the code or even the algorithms used? I'd be pretty interested in seeing whats involved in the calculation.

Cheers,
~Al
Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/
14 years 7 months ago #70211

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Replied by Calibos on topic Re: Online Astro Calculator

Cool, I can find out if I'll ever be able to see the red spot through the 5 minute gap in the trees next door.

Now I just need a calculator to find out what times Jupiter is in the gap every night and then compare results to find a match :wink:

On a serious note, is this calc not a bit moot for the next 2 or 3 years for us here though. Will we be able to see/image the GRS with 15-20 deg altitude seeing anyway or will this calc come into its own in about 2011 for us.
Keith D.

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14 years 7 months ago #70213

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Replied by michaeloconnell on topic Re: Online Astro Calculator

While you are at it Dave, can you write one for transits of the ISS across the disc of the Moon and Sun as visible from Ireland? Should be a *simple* task for someone like yourself.
:wink:
14 years 7 months ago #70230

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  • DaveGrennan
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Replied by DaveGrennan on topic Re: Online Astro Calculator

While you are at it Dave, can you write one for transits of the ISS across the disc of the Moon and Sun as visible from Ireland? Should be a *simple* task for someone like yourself.
:wink:


Would you beleive I'm on that one. I've already written code to calculate a satellites XYZ vectors as per NORADs SGP4 algorithm. I've done the bit to transform these into alt/az co-ordinates for the ground viewer. Where I'm at now is finding an effecient way to calculate actual pass timings. This involves a lot of calculus and I was never brill at calculus. I've also been playing with Ed Moran's java ISS transit code and made some interesting mods. I removed much of the restrictions such as 160km radius and 11 day limit. The problem I see with turning all this into a web app is it involves a huge amount of processing. That's why Ed Morana (I think) used a client side java applet, to push the processing burden to the users PC.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here
14 years 7 months ago #70247

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Looks good DG, any plans to share the code or even the algorithms used? I'd be pretty interested in seeing whats involved in the calculation.


Albert, the algorithm used is described in the book 'Astronomical Algorithms' by Jean Meeus (Willmann-bell ISBN 0-943396-35-2). The algorithm used here is described on pp 277-283. For anyone interested in such calculations this is 'The Bible'. As for the source code, it is so highly custom it would be pretty meaningless in many ways. When I'm done with all this I might be able to publish the PHP class module which is in effect the heart of the calculations. The problem is unless you know what your looking at even that would be hard to use.

A better approach might be to compile all my work into a dll class which could be used in your favourite spreadsheet or other app.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here
14 years 7 months ago #70249

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Hi Dave,
I found the passwords a bit difficult to read tho' (maybe I need my glasses changed).


Me too, however lookin g at that again may have to wait. I found that you never have to click the word refresh button more than once or twice max to get one thats easy to read. My intention is that thiese types of app are used not that frequently, so maybe this isn't such a bad thing.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here
14 years 7 months ago #70250

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Here is another idea,
How about io/europa/ganymede/callisto transit times along with shadow transit times, now that would make it even more useful.


Another one in progress. This is obviously a completely different app to the GRS transit calculation. Nonetheless, I have written code to calculate the co-ordinates of the 4 moons. Its on my list to put this into a format to provide event timings.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here
14 years 7 months ago #70251

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Also, I am sure you can add a line of code to read the date on one's own computer everytime that applet loads


Excellent idea and I can make it so the 'to' date is 7 days ahead thus including Dave Lillis's idea in one swoop.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
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14 years 7 months ago #70252

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Replied by albertw on topic Re: Online Astro Calculator

Albert, the algorithm used is described in the book 'Astronomical Algorithms' by Jean Meeus (Willmann-bell ISBN 0-943396-35-2).


Ah... I've been looking for a copy of that for years (at a reasonable price!) but never managed to pick it up. I've read some software modules/classes based on the book but its hard to understand the reasoning behing the calculations without the book.

I do have Practical Astronomy with your Calculator which is good, but does a very poor job of explaining how the algorithms work too!
Albert White MSc FRAS
Chairperson, International Dark Sky Association - Irish Section
www.darksky.ie/
14 years 7 months ago #70253

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Ah... I've been looking for a copy of that for years


My copy is one of my most valued books and as such I protect it with dear life. You would be welcome to borrow it at some point in the future but at the moment you couldn't find a crow bar big enough to prise it away from me :P
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
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14 years 7 months ago #70254

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Replied by John D on topic Re: Online Astro Calculator

Very nice Dave,

Very useful :)
John
14 years 7 months ago #70255

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Replied by carlobeirnes on topic Re: Online Astro Calculator

Hi Mate,

That is a great programme well done
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14 years 7 months ago #70285

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Replied by DaveGrennan on topic Re: Online Astro Calculator

Guys,

I've now added a Sunrise/Sunset/Twilight calculator here;

webtreatz.com/component/option,com_wrapper/Itemid,84/

Once again feedback would be appreciated.

This time I made some changes;
The page state is preserved between submissions;
The default start date is today's date and the default end date is today + 7 days;
Please tell me if the captcha without the background is more readable;

Thanks for helping me test this.

PS: Before you mention it, the determination of your location is based upon your IP address and so is very hit and miss. It should get your country right and I'd be interested to hear how good it is at guessing your city too please
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
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14 years 7 months ago #70299

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Replied by michael_murphy on topic Re: Online Astro Calculator

Hi Dave,

The text is much easier to read. It is guessing my location correctly but I'll try the 3G connection later and see if it works.

Michael.
14 years 7 months ago #70301

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Replied by DaveGrennan on topic Re: Online Astro Calculator

I'll try the 3G connection later and see if it works.


That will be interesting. I would expect the location it gives will be the location of the base station of your service provider.
Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
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14 years 7 months ago #70304

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Replied by dave_lillis on topic Re: Online Astro Calculator

Its much easier to read, although it thinks I'm in Dublin.
Dave L. on facebook , See my images in flickr
Chairman. Shannonside Astronomy Club (Limerick)

Carrying around my 20" obsession is going to kill me,
but what a way to go. :)
+ 12"LX200, MK67, Meade2045, 4"refractor
14 years 7 months ago #70305

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