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Platesolving in APT using ASTAP


Bottletopburly

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The latest beta version of APT allows Astap to be used for platesolving instead of ps2 , initially on my imaging pc I had problems so rolled apt back , but I installed on spare laptop and all seems to work the only difference is I never installed ps2 , image  blind solved in 5 sec on one image and 18 sec on another,using Astap standalone the 16 sec image solved in 0.4 sec so I’m sure once a few glitches smoothed out Apt will solve quicker though I’m happy with 5 sec , now to see if I can get the imaging pc configured correctly.

Edited by Bottletopburly
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Morning Dave. I've never heard of Astap, have always used ps2. I use ps2 in APT and Sequence Generator Pro. Is it known to be a lot faster then?

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1 hour ago, Derbyshire Dave said:

Morning Dave. I've never heard of Astap, have always used ps2. I use ps2 in APT and Sequence Generator Pro. Is it known to be a lot faster then?

Yes Astap is supposed to be quicker which I can confirm is a lot quicker , initially I couldn’t get it working but have it working on spare laptop, will now see if I can get backup laptop configured before installing on imaging pc , I think I may have had trouble at first because I had the path to ps2 in apt I will try deleting the path and hopefully that was what the issue was , you just need to make sure focal length of telescope and camera used  are input into your profile settings in Apt . 

 

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@Derbyshire Dave more info from Apt forum 

Ivo reply 

ASTAP many advantages - it is live project which Han actively develops and improves. His purpose is one day to give alternative of both PS2 and ASPS 😉 Han is very responsive and if there is interesting idea we can easily alter ASTAP and APT to provide it. 

PS2 is not actively developed and is based on very old technology which can have hard time with the images size from modern cameras. It is property of PlaneWave which has developed for their needs and don't plan to give the new versions for free use 

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Hans reply Astap developer 

For the record, ASTAP reports the image center in Equinox J2000 (and epoch 2021) since the star database is setup like that. So coordinate system J2000 and using the database star positions calculated for their position in year 2021 using there proper motion. The epoch influence is really nihil, but you will notice the equinox. 

PS2 has an epoch setting but, since star proper motion is super tiny, you will not notice any difference. Only the used coordinate system J2000 is important. Astrometry.net itself is also reporting in J2000 since all star data bases used to compare are stored in that coordinate system. If I change the epoch in PlateSolve2 a hunderd years (using ucac3), I see no difference in the result.


Most telescopes well polar aligned will report in equinox of the current date by nature, because the sky is turning with that axis. The stars is sees are offset by atmospheric refraction and tiny abberation you most likely will never notice. I think you could safely call the telescope position the mean position ignoring these factors. Leaving only a conversion between equinox current date and J2000 which is relative easy,

Comparing PS2, Astrometry.net (including All Sky Solver) and ASTAP the reported image positions are maybe within one pixel accuracy difference, so an insignificant error for telescope centering. So it is safe to say that only the conversion of the reported equinox is important.

An epoch, so taking into account the star proper motion is only important for occultations of stars by minor planets and so on. Not for plate solving.

Sorry for this long reply. It turns out to be longer then intended.

 

info taken from link below 
 

https://aptforum.com/phpbb/viewtopic.php?f=24&t=2066

 


 


 

 

Edited by Bottletopburly
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