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Old 25-07-2021, 08:54 AM
bluesilver (Peter)
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Which star maps for ASTAP

Hi, I am thinking about giving ASTAP a go for image solving in Pointcraft, a program inside Astro Photography Tool.
Just looking over the recommendations for which star map to use, they give you two maps, H17 star database or the H18 Star Database

They say to go with the H18 star database if you fov is less than 1 degree.

So i am having a bit of trouble trying to work out what my actual fov of view is.
Scope is Skywatcher Evostar 150ED and camera is ASI2600MC

Looking at astronomy.tools, when i enter the details i get an answer of
field of view of 1.12 x 0.75
I kind of worked it out to be 1.12 X 0.83

Not sure if i am correct or not, but dose simply mean that the field of view that i have is 0.93 ( 1.12 x 0.83 )

Last edited by bluesilver; 25-07-2021 at 09:10 AM.
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Old 25-07-2021, 09:20 AM
AnakChan (Sean)
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You can download both & within ASTAP select which one you want to use. You can try the H17 first to platesolve (as that would be the faster of the two, if it can platesolve), but if you run into errors in trying to platesolve. Then switch to the H18 in ASTAP.
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Old 25-07-2021, 09:31 AM
bluesilver (Peter)
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That sounds like a good simple way to do things, just download the H17 star map, if that doesn't platesolve then remove that one and install the H18 star map
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Old 25-07-2021, 02:40 PM
AnakChan (Sean)
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That's what I did initially. I downloaded the H17 (or back then the G17). Then no matter what parameters I tweaked for ASTAP in NINA I couldn't platesolve and someone alluded that my resolution was a lot higher and I should go G18. That worked for me.

Since then, I had moved my computer/camera setup to a refractor with 2deg FoV and forgot to switch the database from G18 to G17, but I didn't have any problems platesolving with G18 on a larger FoV either. It probably just took longer than with a G17 database.

Of course now all the databases have gone to the H-series.
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Old 25-07-2021, 03:48 PM
AdamJL
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Definitely install the H18 one.

Make sure you manually switch to H18 if you previously installed H17. I had platesolving errors on the Helix Nebula recently in NINA, which was fixed after I selected H18 in ASTAP. Nothing to do with FoV, more to do with a better catalogue
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Old 25-07-2021, 04:45 PM
stephen2615 (Stephen)
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ASTAP sometimes won't platesolve in NINA if the stars are too out of focus or the exposure is not long enough or seeing is poor. I have been using H17 without any issue once I got focus correct before using ASTAP. I do 10 sec exposures for broadband filters and I force the use of the Luminescence filter when I am doing NB imaging. That is using a 645 mm focal length.
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Old 25-07-2021, 05:00 PM
bluesilver (Peter)
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Thanks for the replies,
Will go with the H18, looks like my field of view is fairly close to the 1 degree
I haven't even worked out how long to set exposures for to allow it to sole.
With my DSLR i was taking a 2 second exposer and solving with that.
These dedicated cameras might be a tad different in that way
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Old 26-07-2021, 09:01 AM
stephen2615 (Stephen)
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Quote:
Originally Posted by bluesilver View Post
Thanks for the replies,
Will go with the H18, looks like my field of view is fairly close to the 1 degree
I haven't even worked out how long to set exposures for to allow it to sole.
With my DSLR i was taking a 2 second exposer and solving with that.
These dedicated cameras might be a tad different in that way
2 seconds is nowhere near long enough. If you have a filter like the L-Extreme, you should be using at least 10 second exposures.
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