Astrometric v Local Astrometry.net solution differences

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lodrigj
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Joined: 02 Aug 2019, 08:57

Astrometric v Local Astrometry.net solution differences

Post by lodrigj » 02 Aug 2019, 13:00

Hi Han,

I'm seeing a little difference between the solve by ASTAP's Astrometric Alignment and the Local Astrometry.net solved from the same file.

Wild guess... the index files the astrometry.net server are using a different epoch from the GAIA dataset you are using?

I'm attaching a screen shot showing the differences.

The data populates into the the main window coordinates after the ASTAP Astrometric Alignment solve, but after the local astrometry.net solve, I get an error dialog box that says "could not load solution", and a red error message in the main display window that says in red "Error Accessing File".

This is both with a Canon 6D CR2 raw file original, as well as a FITS file converted in ASTAP from the CR2 original.

Jerry
ASTAP_02.gif
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han.k
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Re: Astrometric v Local Astrometry.net solution differences

Post by han.k » 02 Aug 2019, 14:22

Hello Jerry,

Both solvers should report in J2000.

First I was a little worried about the 20 arc second difference in RA and 41 arccsec in DEC, but the image has an 13.51 degrees height. With your settings ASTAP is only looking to the 3 degrees in the center. For such a large field of view, optical distortions are getting influential. Astrometry.net is looking to the whole image field so includes the (warped?) stars from the corners.

Assuming your image has a 3000 pixel height, the 41 arc seconds equals 2.5 pixels difference. As an experiment, I think you can get the two solvers results closer by doing the following:

- Increase the 3 degrees crop setting of ASTAP. Maybe it will work up to 10 degrees or more.
- Cut out the center and let both ASTAP and Astrometry.net solve it.

So resume it doesn't worry me.

Han

lodrigj
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Joined: 02 Aug 2019, 08:57

Re: Astrometric v Local Astrometry.net solution differences

Post by lodrigj » 03 Aug 2019, 01:37

Hi Han,

Any thoughts on the error messages when the astrometry.net solve finishes?

That solve is not being populated into the view window RA and Dec display.

Jerry

han.k
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Re: Astrometric v Local Astrometry.net solution differences

Post by han.k » 03 Aug 2019, 09:37

The option "keep console open" is checked. Uncheck it and the CMD window will be closed after the solve. You can also close the CMD window manually.


Han

lodrigj
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Joined: 02 Aug 2019, 08:57

Re: Astrometric v Local Astrometry.net solution differences

Post by lodrigj » 04 Aug 2019, 03:57

Hi Han,

I get the error messages with the console closed too.

And I get the error message when I manually close the console.

Both errors come after successful solves. It just does not populate the solve into the main window, so I assume it is not syncing after a solve either.

Jerry

han.k
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Re: Astrometric v Local Astrometry.net solution differences

Post by han.k » 04 Aug 2019, 11:52

Jerry,

Here Astrometry.net ends with the following lines:

Field 1 solved: writing to file C:/astap.fpc/test files/M16/M16_200s_20180803_222752.solved to indicate this.
Field: C:/astap.fpc/test files/M16/M16_200s_20180803_222752.fits
Field center: (RA,Dec) = (274.7, -13.81) deg.
Field center: (RA H:M:S, Dec D:M:S) = (18:18:44.032, -13:48:33.197).
Field size: 1.73937 x 1.31743 degrees
Creating new FITS file "C:/astap.fpc/test files/M16/M16_200s_20180803_222752.new"..


So the message "Creating of a new file..." is missing. I can see in your screenshot you entered some extra options/parameters. Looking into the parameters at:

http://manpages.ubuntu.com/manpages/dis ... eld.1.html

it is the parameter: "-N none"

Remove this parameter and it will work. ASTAP uses the new file created to read the solution.

lodrigj
Posts: 10
Joined: 02 Aug 2019, 08:57

Re: Astrometric v Local Astrometry.net solution differences

Post by lodrigj » 05 Aug 2019, 08:47

Hi Han,

New problem.

I didn't change anything except taking out the -N none command line parameter, but now the astrometry solver is saying it can't find the FIT file.

I also tried putting the original CR2 file in E:\ to eliminate the long file name with spaces being a potential problem.

I also changed the command line to just what you have on the instructions page and no luck.

I searched the entire computer and I can't find an IMG_2827.fit file anywhere.

I'm running the latest version B0.9.247 2019/8/4.

Here's the screen shot with the settings I used:
ASTAP_03.gif
ASTAP_03.gif (118.79 KiB) Viewed 17234 times
Jerry

han.k
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Re: Astrometric v Local Astrometry.net solution differences

Post by han.k » 05 Aug 2019, 12:58

Hello Jerry,

That's strange. I tried it here with a file on a memory stick and it works. Is the E: drive not almost full? Astrometry.net needs to be able to write some files. Could you try it with a file on the C: drive?

Han

lodrigj
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Joined: 02 Aug 2019, 08:57

Re: Astrometric v Local Astrometry.net solution differences

Post by lodrigj » 06 Aug 2019, 00:54

Hi Han,

I get an error message when I put the CR2 raw file in the root of C:\

It says "error accessing the file".

It does open and solve in the root of D:\ and E:\, two physically separate drives. Neither is close to being full (800GB free on D: and 1TB free on E:)

I can not save a FITS file out of ASTAP to the C:\ root either. This is in Win10, it must be some kind of security "feature".

Now, oddly, I can save a FITs file to D:\ and then copy it to C:\, and the FITs file will open and solve in ASTAP astrometric alignment, and it will solve in the astrometry.net server...

BUT, after it solves and the console closes, another error message pops up that says "No astrometric solution found."

I'm guessing because it can't write C://IMG_2827.solved to the C drive because of security permissons.

If I solve it with astrometry.net in another drive, the FITs file solves, and there are no error messages,

BUT... the solve results do not populate into the RA and Dec readout boxes on the main ASTAP page, like they do with an astrometric alignment solve.

Attached screen shot shows the different RA and Dec values.

Jerry
ASTAP_04.gif
ASTAP_04.gif (173.39 KiB) Viewed 17200 times

han.k
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Location: The Netherlands
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Re: Astrometric v Local Astrometry.net solution differences

Post by han.k » 06 Aug 2019, 11:53

Hello Jerry,

Yes file written in the C:\ root location requires administrator permission. I have tested the Astrometry.net solving with a CR2 file. As soon you close the Astrometry.net CMD window (or uncheck previously the "keep console open") ASTAP will take over the solution. So keep "the option "keep console open" unchecked it should work as long you don't place the files in the C:\. Can you test that?

Han

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