Multistar guiding

[Andrew Stott]

When I start imaging I have the target star in a green box as well as several other green boxes around stars, which I always assumed was the extra starts used for multistar guiding.   

The last couple of nights, when I wake up in the morning, I check my guiding and I don't have the green boxes around any other stars, only the main target star.  This morning I did have a warning that my guide camera had been disconnected and PHD2 would attempt to reconnect, which it must have, because I had no guiding failures reported and it was running well this morning.

In the PHD2 log viewer, under Section Heading I have this

Search region = 15 px, Star mass tolerance = 50.0%, Multi-star mode, list size = 7

I checked the log for the entire night and the list size was either 7 or 12 all night.  Does this mean multistar is working and I'm just not having the green boxes around the extra stars?

Thanks

[Bruce Waddington]

The section headings show the status of the guide star list at the beginning of each guiding session.  Depending on how you operate, those often reflect the status immediately after an auto-find has been done.  During the subsequent guiding session, secondary stars may be dropped for a variety of reasons and you may end up with only the primary star.  We would need to see your guide and debug log files to advise you on why stars are being dropped from the list.  This can happen a lot for people who are guiding at a long focal length and the stars in the list are faint.  You can probably help yourself by disabling star-mass detection but there could be other issues as well.

 

Log files should be uploaded using the mechanism described here:

 

https://openphdguiding.org/getting-help/

 

Regards,

Bruce

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[Brian Valente]

Also just to clarify, the # of stars available and used will vary through the imaging session. PHD controls this, so there won't be a result like '7 stars identified and used throughout the night' 

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Brian 

Brian Valente

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[Andrew Stott]

Thanks for the info.  I'll upload a log if it keeps happening, I don't want to waste your time.   We did have clouds roll through, so maybe it dropped all of the secondary and never acquired them again after the clouds cleared.   I'll disable star mass detection and see how it behaves.

thanks.

[Andrew Stott]

Last night was the first time I could image since my original post.   I woke up again this morning and I had an error the connection to the guide camera was lost and I only had on star guiding.  I forgot to disable star mass detection last night, which I did do this morning.  I'm not sure why I'm losing connection to my guide camera and if that has anything to do with losing the secondary stars.  I did upload my files.  

P.S. My guiding was horrible last night, which was not the case the other nights when I lost my secondary starts.  I don't think seeing was the best last night, the stars in PHD2 looked horrible.

https://openphdguiding.org/logs/dl/PHD2_logs_5H6u.zip

[mj.w...@gmail.com]

Could you clarify some points before the experts reply ?

1.  Cal was carried out on the 29th September - is this a permanent setup ?

2. The log mentions a SV106 in the Equipment Profile, which is a 240mm FL guidescope - you have 190mm entered for the FL ?

3.  Your Dithers are huge - up to 40 arcsecs. For a Dither of 12 pixels on the imaging camera that suggests the pixel scale is about 3.3 arcsec/pixel  - correct ?

Michael

[Andrew Stott]

1.  This is not a permanent set up in so much that I carry it in the house, but the guide scope and camera are left on the OTA

2.  The 50mm SV106 is 190 mm.  The 60mm version is 240mm

3.  I use a dither calculator to determine the correct number of pixels to dither with my OTA, imaging camera, and Guide setup.  I got horrible drizzle results with smaller dither which is why I used a calculator to determine the correct amount.

Hope that clears a few things up.,

[Bruce Waddington]

Since you’re struggling to get any consistency, you should be doing a fresh calibration at the start of each guiding session.  From looking at some of the guiding intervals, I’m suspicious that something has moved since the month-old calibration was done.  You also can’t afford to suffer through lost-connection problems with the guide camera – there should be zero of those.  The trouble-shooting section in the PHD2 manual has a fairly detailed guide for how to identify the source of these problems.

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/549e395a-9475-46d4-934d-f3a8a7292664n%40googlegroups.com.

[Andrew Stott]

Thanks for the info.  Looks like it may have been a bad usb c cable, which is odd.  It wasn't that old and was supposed to be decent quality but when I would move the camera it would lose signal.  I replaced it and it doesn't behave that way any longer.

[Brian Valente]

it's always the one you least suspect :) good job finding the source and correcting it

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/3160f1aa-a482-425e-a559-3abb6925b095n%40googlegroups.com.