Amp Glow with ASI183MM in PI Using Calibration Frames

[Juan Conejero]

This is just a note to stress the importance of generating valid metadata in acquired images. This is astronomy, and we are acquiring astronomical observations, not casual daylight pictures. Without a minimum of valid metadata, an astronomical image has essentially no documentary value, and its possibilities for further analysis are essentially nullified.

Metadata for the time of observation, approximate image scale, and approximate location in the sky are the absolutely essential minimum; without them, you are not doing astronomy but just gathering a nonsensical array of numbers.

 

[fredvanner]

I've never used SGP. But that list you provided looks like a mechanism for adding things to the filename of images, not to the FITS header.

I've never used SGP either, but I agree. Looking at the SGP manual (p. 106 of the latest version), the FITS header does not seem configurable - you "get what you get" - but it automatically includes all the items you need (provided SGP is connected to the mount during the sequence capture).

 

[bulrichl]

In SGP, the pixel scale in "/px at 1x1 binning has to be input in the Equipment Profile Manager, camera tab. Scope focal length can be optionally input in the telescope tab. After a complete equipment profile is created, the 'New Sequence from Profile' command should be used for generating new sequences.

The first attachment in post #17 shows the filename pattern. This is not related to FITS keywords. SGP writes XPIXSZ and YPIXSZ keywords in the FITS header if the configuration is complete, although this is not mentioned in the documentation (my frames captured with SGP contain XPIXSZ and YPIXSZ).

I don't use SGP any more. For questions regarding correct configuration, the SGP forum should be used.

Bernd

 

[dugstruble]

This is just a note to stress the importance of generating valid metadata in acquired images. This is astronomy, and we are acquiring astronomical observations, not casual daylight pictures. Without a minimum of valid metadata, an astronomical image has essentially no documentary value, and its possibilities for further analysis are essentially nullified.

Metadata for the time of observation, approximate image scale, and approximate location in the sky are the absolutely essential minimum; without them, you are not doing astronomy but just gathering a nonsensical array of numbers.

Remind me not to quit my day job then. lol Astrophotography is just a hobby for me, all be it a challenging hobby. Always something to learn. I get what you are saying, though, and it is something I have to figure out.

 

[dugstruble]

I've never used SGP either, but I agree. Looking at the SGP manual (p. 106 of the latest version), the FITS header does not seem configurable - you "get what you get" - but it automatically includes all the items you need (provided SGP is connected to the mount during the sequence capture).

Yup you guys are right. That was the file naming and not the metadata. I'll have to figure out what is going on.

 

[dugstruble]

In SGP, the pixel scale in "/px at 1x1 binning has to be input in the Equipment Profile Manager, camera tab. Scope focal length can be optionally input in the telescope tab. After a complete equipment profile is created, the 'New Sequence from Profile' command should be used for generating new sequences.

The first attachment in post #17 shows the filename pattern. This is not related to FITS keywords. SGP writes XPIXSZ and YPIXSZ keywords in the FITS header if the configuration is complete, although this is not mentioned in the documentation (my frames captured with SGP contain XPIXSZ and YPIXSZ).

I don't use SGP any more. For questions regarding correct configuration, the SGP forum should be used.

Bernd

Thanks! Yeah I have all that dialed in correctly. Perhaps I need to move this conversation over to SGP. It's just really weird because I have been using SGP since 2016 and never had a problem with any other camera except this ASI183MM Pro Cooled.

 

[fredvanner]

It's a strange choice to put the image scale ("/pix) in the camera tab. Lots of folks use the same camera with several different telescopes, with a different image scale for each different focal length. I guess with SGP you create a different profile for each configuration, with varying camera settings modified for the associated focal length.

 

[Marcelofig]

I use the same old version of SGP and have never had a problem with the metadata.

Now to note, if I remember correctly, there are two ways to configure this data in SGP, via user profile Equipment Profile Manager and via control panel. Using the former will apply to any future sequences, using the latter will only affect the sequence currently in use.

 

[cloudbait]

Thanks! Yeah I have all that dialed in correctly. Perhaps I need to move this conversation over to SGP. It's just really weird because I have been using SGP since 2016 and never had a problem with any other camera except this ASI183MM Pro Cooled.

The pixel scale in the header (which is clearly from a solver, not from the SGP settings) is not read by ImageSolver. It pulls in the telescope focal length, but absent an entry for the pixel size (which really should be in there) it can't calculate a scale, so is likely to fail unless you're lucky to have previously used ImageSolver with the correct scale already present.

I'm not sure why ImageSolver doesn't use the plate scale under these circumstances, unless the FITS key is a poor choice (there are two used in your headers, SCALE and PIXSCALE).

 

[dugstruble]

It's a strange choice to put the image scale ("/pix) in the camera tab. Lots of folks use the same camera with several different telescopes, with a different image scale for each different focal length. I guess with SGP you create a different profile for each configuration, with varying camera settings modified for the associated focal length.

Yes there is a separate Equipment Profile Manager that I use as well.

 

[dugstruble]

I use the same old version of SGP and have never had a problem with the metadata.

Now to note, if I remember correctly, there are two ways to configure this data in SGP, via user profile Equipment Profile Manager and via control panel. Using the former will apply to any future sequences, using the latter will only affect the sequence currently in use.

Exactly.

 

[dugstruble]

The pixel scale in the header (which is clearly from a solver, not from the SGP settings) is not read by ImageSolver. It pulls in the telescope focal length, but absent an entry for the pixel size (which really should be in there) it can't calculate a scale, so is likely to fail unless you're lucky to have previously used ImageSolver with the correct scale already present.

I'm not sure why ImageSolver doesn't use the plate scale under these circumstances, unless the FITS key is a poor choice (there are two used in your headers, SCALE and PIXSCALE).

I am not sure either.

 

[dugstruble]

I was looking at the fits header. Pixel scale and focal length are in there.

 

[cloudbait]

I was looking at the fits header. Pixel scale and focal length are in there.

But ImageSolver seems to want to calculate the pixel scale, not import it directly. Which it can only do if it the pixel size values are written in the header.

 

[fredvanner]

But ImageSolver seems to want to calculate the pixel scale, not import it directly. Which it can only do if it the pixel size values are written in the header.

... and sadly the camera pixel size is not one of the parameters that SGP writes to the header (in fact I don't think there is anywhere in SGP that you can define it). The same seems to be true (amazingly, for an astrophotography app) for focal length. Only the combined image scale is specified.

Sound to me like not using SGP was one of the right choices I made.

 

[cloudbait]

... and sadly the camera pixel size is not one of the parameters that SGP writes to the header (in fact I don't think there is anywhere in SGP that you can define it). The same seems to be true (amazingly, for an astrophotography app) for focal length. Only the combined image scale is specified.

Sound to me like not using SGP was one of the right choices I made.

The focal length (FOCALLEN) is being written. I assume that is configured in the telescope settings. I wouldn't expect it to be in the camera settings.

 

[fredvanner]

I wonder where it comes from. I can't se it in the "telescope" settings:

Although I can't find any mention of it in the manual, it is possible that it gets written as part of the consequences of an (optional) plate solution.

 

[cloudbait]

I wonder where it comes from. I can't se it in the "telescope" settings:
View attachment 22592
Although I can't find any mention of it in the manual, it is possible that it gets written as part of the consequences of an (optional) plate solution.

While that dialog is called "Telescope" it seems to be about the mount. Not the optics. Software I've used distinguishes between the two. Relevant to Juan's comment above about metadata, I think including the focal length, aperture diameter, and aperture area are pretty important!

 

[fredvanner]

While that dialog is called "Telescope" it seems to be about the mount. Not the optics. Software I've used distinguishes between the two. Relevant to Juan's comment above about metadata, I think including the focal length, aperture diameter, and aperture area are pretty important!

I searched the (256 page) manual from end to end and this was the only telescope configuration.

 

[cloudbait]

I searched the (256 page) manual from end to end and this was the only telescope configuration.

Well, something is putting the focal length into the header. It's obviously gone through a solver. Does SGP provide that service? Otherwise some other software may have been involved, as well.