×
INDI Library v1.8.1 Released (09 Sep 2019)

Monthly maintenance release INDI v1.8.1

[Fixed] Plate solving giving wrong results with ANSVR

1 year 1 month ago 1 year 1 month ago by kengs.
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29494
I'm running Kstars 2.9.8 on Window 10 64 bit. Platesolving through Ansvr.
My target was NGC6822 (Barnards Galaxy) at (from KStars):
JNow: 19h 45m 58s -14° 45' 45"
J2000: 19h 44m 56s -14° 48' 23"
I get a successful solve and the mount slews. The next solve says it is within acceptable range.
But if I then take an image and solve at nova.astrometry.net it is around 15 arc-minutes off in RA.
Results from nova.astrometry.net (J2000) are:
Center (RA, Dec): (295.932, -14.862)
Center (RA, hms): 19h 43m 43.610s
Center (Dec, dms): -14° 51' 44.593"
Size: 38.1 x 28.8 arcmin
Radius: 0.398 deg
Pixel scale: 1.96 arcsec/pixel
Orientation: Up is 262 degrees E of N
I suspect the conversion of J2000 returned by nova.astrometry.net to JNOW is in the wrong direction. Perhaps as I'm in the southern hemisphere?
Had the same issue with 2.9.6 the other day which is why I upgraded.

Attaching Kstars log and image solved on nova.astrometry.net

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80
Attachments:

Please Log in or Create an account to join the conversation.

1 year 1 month ago
Copello
Senior Boarder
Senior Boarder
Posts: 49
Karma: 1
More
[Fixed] Plate solving giving wrong results with ANSVR #29496
Hi kengs,

I believe this is good question for Dustin Lang (the author) of astrometry.net --- either as an github
issue or a astrometry.net forum post.

I am not mistaken, then the astrometry.net web engine uses this generic parameter for solving:
solve-field --downsample 2 --tweak-order 2 --scale-units degwidth --scale-low 0.1 --scale-high 180.0

This is what I get, when I solve the image locally under Linux with the latest astrometry.net (master)

Field 1: solved with index index-4205-07.fits.
Field 1 solved: writing to file /tmp/Barnard.solved to indicate this.
Field: Barnard.jpg
Field center: (RA,Dec) = (295.931792, -14.862427) deg.
Field center: (RA H:M:S, Dec D:M:S) = (19:43:43.630, -14:51:44.739).
Field size: 38.1293 x 28.8327 arcminutes
Field rotation angle: up is -82.5227 degrees E of N
Field parity: pos
Creating new FITS file "Barnard_wcs.fit"...

Please Log in or Create an account to join the conversation.

1 year 1 month ago 1 year 1 month ago by kengs.
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29510
astrometry.net is doing the right thing. It returns coordinates in J2000 which Ekos converts to JNOW. Its the conversion to JNOW that appears to be wrong so the corrective slew to target is taking the target further away from the centre of the field instead of closer to it.

Added: I also solved locally and got the same result as online.

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80

Please Log in or Create an account to join the conversation.

1 year 1 month ago
TallFurryMan
Platinum Boarder
Platinum Boarder
Posts: 737
Karma: 13
More
[Fixed] Plate solving giving wrong results with ANSVR #29533
That may sound stupid and I do not suggest it could be the case in your test, but I need to mention that I had very weird results when I forgot to suspend guiding while plate-solving. Guiding corrections actually offset the mount model. PHD2 has an option to disable guiding while the mount slews, the internal guider does not.

-Eric

HEQ5-Pro - Atik 314E - Orion ED80T - DMK21 on Orion 50mm
DIY 3D-printed Moonlite and FWheel RGB/LPR
KStars and indiserver on two Atom 1.6GHz 1GB RAM Linux, VPN remote access

Please Log in or Create an account to join the conversation.

1 year 1 month ago
TallFurryMan
Platinum Boarder
Platinum Boarder
Posts: 737
Karma: 13
More
[Fixed] Plate solving giving wrong results with ANSVR #29534
Looking at the log, it seems to me we're dealing with an API change here:
[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"jobs\":[62],\"processing_finished\":\"1\",\"processing_started\":\"1\",\"user\":\"0\",\"user_images\":[]}"
[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"status\":\"success\"}"
[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"dec\":\"-14.816192073\",\"epoch\":\"JNow\",\"orientation\":97.5146272814133,\"parity\":1,\"pixscale\":1.96562592485983,\"ra\":\"296.199887826\",\"radius\":0}"

RA/DEC seem to be returned in JNow here.
-Eric

HEQ5-Pro - Atik 314E - Orion ED80T - DMK21 on Orion 50mm
DIY 3D-printed Moonlite and FWheel RGB/LPR
KStars and indiserver on two Atom 1.6GHz 1GB RAM Linux, VPN remote access

Please Log in or Create an account to join the conversation.

1 year 1 month ago
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29535

TallFurryMan wrote: That may sound stupid and I do not suggest it could be the case in your test, but I need to mention that I had very weird results when I forgot to suspend guiding while plate-solving. Guiding corrections actually offset the mount model. PHD2 has an option to disable guiding while the mount slews, the internal guider does not.

-Eric

I was using PHD2 but guiding was off. I re-ran the platesolve under controlled conditions.

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80

Please Log in or Create an account to join the conversation.

1 year 1 month ago
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29537

TallFurryMan wrote: Looking at the log, it seems to me we're dealing with an API change here:

[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"jobs\":[62],\"processing_finished\":\"1\",\"processing_started\":\"1\",\"user\":\"0\",\"user_images\":[]}"
[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"status\":\"success\"}"
[2018-09-12T21:59:09...][     org.kde.kstars.ekos.align] - "{\"dec\":\"-14.816192073\",\"epoch\":\"JNow\",\"orientation\":97.5146272814133,\"parity\":1,\"pixscale\":1.96562592485983,\"ra\":\"296.199887826\",\"radius\":0}"

RA/DEC seem to be returned in JNow here.
-Eric

As far as I understand it, astrometry.net returns only J2000 coordinates. I've not found any option to return JNOW coordinates.
I tested again today on another target and Ekos consistently puts the target some 15' off centre in RA. I then switched to Astrotortilla using the same engine and it correctly centred the object.

What I suspect now is that the J2000 to JNOW conversion is being applied twice. Astrometry.net returns RA of 19h43m44s as J2000 which converts to JNOW of 19h44m48s which is the value in the log (296.199887826 degrees). A further J2000 to JNOW conversion is then applied to 19h44m48s which results in 19h45m50s as shown in the next part of the log. 1m of RA corresponds to 15 arcminutes which is the error I am seeing.

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80

Please Log in or Create an account to join the conversation.

1 year 1 month ago
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29538
Looks like JNOW is an ANSVR config option which is why I couldn't find it in the astrometry.net API documentation. I'll see how to switch it off an hopefully then the solves will work.

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80
The following user(s) said Thank You TallFurryMan

Please Log in or Create an account to join the conversation.

1 year 1 month ago
kengs
Expert Boarder
Expert Boarder
Posts: 141
Karma: 2
More
Topic Author
[Fixed] Plate solving giving wrong results with ANSVR #29552
SOLVED!! (excuse the pun)
Altering the ANSVR config to return J2000 coordinates fixed the issue. I must have set it to JNOW once when messing around with SGP on Windows.

Ubuntu 16.04 AMD64 VM, RPi3 Ubuntu Mate 16.04, Windows 10 AMD64, Ubuntu 16.04 AAEON UP Core
Avalon M-Uno, EQ6 Pro, Atik420, ASI1600MM-C, ASI120MM-S, DBK21AU04, ZWO EFW, Optec TCFSi
Vixen R150S, GSO RC8, ST80
The following user(s) said Thank You knro

Please Log in or Create an account to join the conversation.

Time to create page: 0.369 seconds