Incorrect obs-date in saved stacks

[admin]

Hi Mike,

yes, that was the only other change I allowed into the replacement 12371 build, since it was a clear bug fix with no chance of breaking anything Glad it is all fine now!

Robin

[MikeB838]

Hi Robin,

I'm sorry to say that in the current version (V395) a bug has crept up (I did not check V371 again):
The value for OBJCTRA is correct in the stack (live or in folder monitor) but it is not correct in the single frames.

single frames:
OBJCTRA = '15 03 10.000' / Epoch : JNOW (wrong)
OBJCTDEC= '+00 25 15.000' / Epoch : JNOW

stack:
OBJCTRA = '20 55 51.000' / Epoch : JNOW (correct)
OBJCTDEC= '+00 25 15.000' / Epoch : JNOW

I have a PlayerOne Neptune-C II with the current driver:
ASCOM_PlayerOne_Camera_Setup_V6.5.6.3 and DirectShow_PlayerOne_Camera_Driver_V1.8.1.0

I add this bug report here, as it may be related to the changes of the obs-date.

I do not recognize it in my first tests, so I think it is introduced in V395 or with a problem with the new driver from PlayerOne.

I would expect the single frame as correct if anything and not the stack

Thanks and cheers,
Michael

[admin]

Hi Michael,

just tested in the latest code and I'm not seeing anything like that happen - the RA/Dec co-ordinates read in from the frames are coming through in both the saved raw frames and the stack as expected. Note that if you have a GOTO Mount configured and connected in SharpCap while using the folder monitor camera, the co-ordinates from the mount will be taken and will overwrite those read from the source FITS files. With no mount connected then the source fits data should come through.

I would not expect any behaviour here to be linked to the make/model of camera or the drivers in use - the data relating to position is all handled by SharpCap itself with no contribution from the camera other than to provide the raw bits of the image data!

cheers,

Robin

[MikeB838]

Hi Robin,

very strange. This seems to be a glitch in one frame. By chance I used frame 3 for my measurements:

Frame 1: OBJCTRA = '20 55 53.000'
Frame 2: OBJCTRA = '20 55 58.000'
Frame 3: OBJCTRA = '15 03 10.000'
Frame 4: OBJCTRA = '20 55 51.000'
Frame 5: OBJCTRA = '20 55 51.000'

Stack: OBJCTRA = '20 55 51.000'

When using the folder monitor I do not have my goto mount connected, but thank you very much for that hint!

But I noticed another strange thing. I use the folder monitor for ngc6030 (10 frames), perform a plate solve and
use the deep sky image annotation to show other deep sky objects in this field.

SC says ngc6030 is 181 pixels above the image, although it is in view (near the center of the picture).

The stack contains:
OBJCTRA = '16 02 56.000' / Epoch : JNOW
OBJCTDEC= '+17 53 25.000' / Epoch : JNOW

Plate solving delivers:
Solution : RA=16:01:49.9,Dec=+17:56:42 (J2000)
Field of View : 0.2921x0.1657 degrees
Time : Mon, 22 Jul 2024 15:19:31 GMT
Orientation : up is 0.0 degrees E of N

The value of the Plate solver (I use PlateSolve3) is correct, the value in the fits files is not.
But this is with only this session, many other times with other sessions it works flawlessly.

If you are interested an any data, I can provide it.

Thank you very much for your time!

cheers,
Michael

[admin]

Hi Michael,

if you want to share the (original) images with me, I will have a look and see if I can work out what is going on. There have been a couple of cases where the catalog data is wrong, which could be part of the issue, or it could be related to live stacking as there are extra considerations to annotation when the current mount position may not match the position at the beginning of the stack.

cheers,

Robin

[MikeB838]

Hi Robin,

thank you very much for taking a look. Here are the zipped files:

https://www.transfernow.net/dl/20240724o9uBiywj

(117MB, link valid 7 days)

Cheers,
Mike

[admin]

Hi Mike,

thanks - I have the files and will have a look to see what is going on.

cheers,

Robin

[admin]

Hi,

I tried plate solving individual frames and also stacking, then plate solving the stack, and the labelling for NGC 6030 always showed up in the correct place, as shown below. Same results for PlateSolve3, Astrotortilla and SharpSolve

Screenshot 2024-07-24 210354.jpg (155.9 KiB) Viewed 665 times

Did you have a mount connected in SharpCap during your use of the folder monitor camera? If there is a connected mount then SharpCap will try to offset for changes in mount co-ordinates between the time that the plate solve happened and the time that the annotation is displayed. That works great for a real mount and camera, meaning you can move around a bit and the labels move correctly, but isn't right for the folder monitor camera.

I did notice that the raw frames are in RGB24 format - that's not ideal, since it means you are throwing away a lot of faint detail in the images by having them in a bit depth of 8 bits and not the native 12 (I think it's 12) of your camera. You should set your camera into RAW16 (or RAW12/14 depending what is available) for deep sky imaging or live stacking. This actually makes the raw files smaller (2 bytes per pixel rather than 3), improves quality and allows for tools like hot pixel removal (as an alternative to dark subtraction) to work effectively.

cheers,

Robin

[MikeB838]

Hi Robin,

thank you very much for looking!

I only use the folder monitor without the mount connected.

As I repeat it now (with the stack), it is not correct, but NGC6030 is in view. The last time "Objects Nearby" told me, it is 189 pixels above image. And when I think again, another time it was over 200 pixel above (not always the same distance).

screenshot_michael.jpg (86.65 KiB) Viewed 654 times

I'm wondering if it has to do with the selected catalogs?

catalogs1.jpg (18.5 KiB) Viewed 654 times

catalogs2.jpg (3.18 KiB) Viewed 654 times

But when I select only NGC, it does not help. But now (after a restart of SC) NGC6030 is at a slightly different position. Very strange!

screenshot_michael2.jpg (59.86 KiB) Viewed 654 times

Thank you very much for the tip about RGB24 format. I read a hint about it, when I started up SC some days ago, wanted to investigate it and forgot about it.

Cheers,
Mike

[admin]

Hi Mike,

OK, I checked again with the processed image, exactly the same as you have in your screenshots.

It looks like it is a bug with PlateSolve3 - I can get Astrotortilla and SharpSolve to solve that image and when I do that the annotations appear in the right place. When I change to PlateSolve3, the annotations are out of position (I see the annotation for NGC6030 about half way between the true position and the bottom of the screen). If I go back to SharpSolve or Astrotortilla and solve again then it's back in the right place.

I don't see the same effect in other images when I solve using PlateSolve3 (star annotations tend to be right on the star), so I think it is something odd happening for this image - perhaps the small field of view doesn't help.

Note that the field of view here is actually below the recommended minimum size for SharpSolve (even with the bigger database installed), but it happens to work on this image - if you moved the telescope around randomly with that field of view and SharpSolve selected you would find that it would sometimes work, sometimes not - it will depend on the number of stars in view and how many in SharpCap's database in that area.

cheers,

Robin