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INDI Library v1.8.0 is Released (27 Jul 2019)

INDI Library v1.8.0 is mostly a maintenance release to fix a few bugs in several drivers.

Widefield Plate Solving

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Widefield Plate Solving was created by Gina

I'm wondering if there's a maximum FOV that astrometry can plate solve. I am using a 28mm FL lens on an ASI1600MM-Cool camera with a FOV of around 36 ° in the X axis. Calculated FOV is 2172.26' x 1642.26'. I see that the maximum FOV index file is 2000' or 33.3° which is less than the width of my image. I tried taking a previous Light frame and cropped it to around 30° x 24° and tried Load & Slew and it worked in that it solved the image and slewed the mount to about the right position (as far as I could tell because it was daytime). The full size image produced a Solver error, hence my question.
Last edit: 1 month 1 week ago by Gina.
1 month 1 week ago #40950

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Replied by Gina on topic Widefield Plate Solving

I've proved for myself that astrometry will not plate solve a FOV bigger than 2000'.
1 month 1 week ago #40959

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Replied by Copello on topic Widefield Plate Solving

Gina, can you upload the image?
1 month 1 week ago #40960

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Replied by Gina on topic Widefield Plate Solving

Which one? The one that works or the one that doesn't?
1 month 1 week ago #40972

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Replied by han.k on topic Widefield Plate Solving

Normally you need the index files up to about 20 % of your size.

Did you try an upload the large image to the online version of astrometry.net? Provide us with the link so we can download it.

An other problem is the severe distortion of the image using 28 mm lens.

Cropping the center is a technique used by some other solvers, but unfortunately not by astrometry.net.

Is there any practical purpose? Annotation? I have a program where you can solve an image by manually mark two reference stars and addding their position and it will add the astrometric solution. That will always work except for the distortion in the corners.

Han
Last edit: 1 month 1 week ago by han.k.
1 month 1 week ago #40974

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Replied by Gina on topic Widefield Plate Solving

Here is the file that wouldn't solve. Well, tried to attach it but the forum won't accept FITS files so converted to PNG in PI. I think this is the one.
1 month 1 week ago #40981
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Replied by han.k on topic Widefield Plate Solving

That images solves online. Size is 35.9 x 27.1 deg See:

nova.astrometry.net/user_images/2935958#annotated

The online version has all indexes and they are a little better then the local version. Due to a different star catalog which is copyrighted these indexes can't be distributed.

You don't have to upload here. You can upload to nova.astrometry.net/upload and provide the link.

Han
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1 month 1 week ago #40982

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Replied by Gina on topic Widefield Plate Solving

Thank you. Interesting that the online index files are better - never thought of that. I'll try online then, I have a fast internet connection - 50MBps up and down.
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1 month 1 week ago #40984

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Replied by Copello on topic Widefield Plate Solving

Hello Gina,

I solved the image locally with command (and catalog):
solve-field -D /tmp --no-plots \
                    --overwrite \
                    --downsample 2 \
                    --tweak-order 2 \
                    --scale-units degwidth \
                    --scale-low 0.1 \
                    --scale-high 180.0 Light_020.png
Reading input file 1 of 1: "Light_020.png"...
Read file stdin: 1999 x 1512 pixels x 1 color(s); maxval 255
Using 8-bit output
Extracting sources...
Downsampling by 2...
simplexy: found 1386 sources.
Solving...
Reading file "/tmp/Light_020.axy"...
  log-odds ratio 173.91 (3.37336e+75), 43 match, 1 conflict, 149 distractors, 62 index.
  RA,Dec = (306.427,37.2838), pixel scale 64.3222 arcsec/pix.
  Hit/miss:   Hit/miss: +--+--+--+-++--++-+++-++++---+++----+----+---+++---++-------+--+--------++--+++-----------c---+-----
Field 1: solved with index index-4117.fits.
Field 1 solved: writing to file /tmp/Light_020.solved to indicate this.
Field: Light_020.png
Field center: (RA,Dec) = (306.430876, 37.289469) deg.
Field center: (RA H:M:S, Dec D:M:S) = (20:25:43.410, +37:17:22.089).
Field size: 34.87 x 26.695 degrees
Field rotation angle: up is 88.9147 degrees E of N
Field parity: neg
Creating new FITS file "/tmp/Light_020.new"...

Catalog (Tycho-2 index files)
add_path /data/astrometry/4100
>ll /data/astrometry/4100/      
total 347312
-rw-r--r-- 1 tstibor tstibor        58 Nov  8  2018 cfg
-rw-r--r-- 1 tstibor tstibor 164995200 Nov  8  2018 index-4107.fits
-rw-r--r-- 1 tstibor tstibor  94550400 Nov  8  2018 index-4108.fits
-rw-r--r-- 1 tstibor tstibor  49772160 Nov  8  2018 index-4109.fits
-rw-r--r-- 1 tstibor tstibor  24871680 Nov  8  2018 index-4110.fits
-rw-r--r-- 1 tstibor tstibor  10206720 Nov  8  2018 index-4111.fits
-rw-r--r-- 1 tstibor tstibor   5296320 Nov  8  2018 index-4112.fits
-rw-r--r-- 1 tstibor tstibor   2733120 Nov  8  2018 index-4113.fits
-rw-r--r-- 1 tstibor tstibor   1382400 Nov  8  2018 index-4114.fits
-rw-r--r-- 1 tstibor tstibor    740160 Nov  8  2018 index-4115.fits
-rw-r--r-- 1 tstibor tstibor    408960 Nov  8  2018 index-4116.fits
-rw-r--r-- 1 tstibor tstibor    247680 Nov  8  2018 index-4117.fits
-rw-r--r-- 1 tstibor tstibor    187200 Nov  8  2018 index-4118.fits
-rw-r--r-- 1 tstibor tstibor    144000 Nov  8  2018 index-4119.fits
-rw-r--r-- 1 tstibor tstibor     38278 Nov  8  2018 log
-rw-r--r-- 1 tstibor tstibor      4853 Nov  8  2018 log10
-rw-r--r-- 1 tstibor tstibor      6699 Nov  8  2018 log7
-rw-r--r-- 1 tstibor tstibor      6634 Nov  8  2018 log8
-rw-r--r-- 1 tstibor tstibor      6376 Nov  8  2018 log9
-rw-r--r-- 1 tstibor tstibor      1054 Nov  8  2018 README
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1 month 1 week ago #41047

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Replied by Gina on topic Widefield Plate Solving

Unfortunately, I don't understand that. However, I shall be trying online plate solving next time I get a chance.
1 month 1 week ago #41075

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Replied by Herrhausen on topic Widefield Plate Solving

The picture was solved in 7 seconds on my local machine so it definitely should be possible to do.
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1 month 6 days ago #41107

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Replied by phomer60 on topic Widefield Plate Solving

Is there some way to crop the image before getting it plate solved.
1 month 6 days ago #41109

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