Does this look like cable snags?

[irtuk]

output from PHD, I am gathering more IC1396 data and where I am its virtually straight up. I am wondering if a cable is getting a slight snag or putting some load on the rig.  I have been out for a look and nothing obvious stands out, but I guess it would not have to be obvious to cause an issue.

The FITS file coming out looks like this with the disturbance in the stars, just using fits liberator for a quick look.

 

These are 600 second subs as well, would I be better off getting more, shorter subs ? maybe 180 seconds?

Edited October 6, 2021 by irtuk

[irtuk]

This is one of the subs open in APP. I don't get it. this is well polar aligned, its calm, no wind, its tracked and guided and my subs are useless

[irtuk]

sometimes you just have to pack it in for the night so I did and when I went out to put the covers back on I had a more detailed look with the lights on, I think the polemaster cable was snagged.

fortunately I have 4 days off so I will have time to fully rewire it.

More telling is that fact that the first two subs are ok, then it all goes to pot.

[Jonk]

First thought if it's not cables - are your clutches ok? What mount are you using?

Edit - ok good that you've found it. If it started off fine then failed, then that makes sense as the snagged cable would get tighter and tighter.

I always remove my alignment camera once PA'd to remove a potential issue.

Edited October 6, 2021 by Jonk

[michael8554]

Screengrabs only say so much.

A PHD2 GuideLog that includes a Cal would be much more helpful.

Michael

[irtuk]

Here we go, this is a sub timed at 21:16 so, probably started at about 21:06 with guidelog and debuglog. I dont know how to get the calibration info in a file from PHD but this is the calibration:

The mount is an NEQ6, I think removing the polemaster camera is a good shout as well, my alignment is pretty good I think and its pier mounted so, pretty solid.

 

Ed.

 

IC1396 Panel 2_LIGHT_2021-10-06_21-06-30_HA_-10.00_600.00s_139_0005.fits PHD2_DebugLog_2021-10-06_201142.txt PHD2_GuideLog_2021-10-06_201142.txt

[irtuk]

Quick trip to Screwfix and I have improved the cable situation  a bit...

 

[david_taurus83]

If I'm not mistaken it looks like Dec movement based on the left/right motion of the stars in your image. It might be too well balanced and the gears not perfectly meshed so when pointing up its teetering from side to side.

Or it could be the cable!

[jacko61]

Will the extra weight of the cable tidy not put added stress on the connectors?

Graeme

[irtuk]

Good point, I will see what I can do, maybe take some weight off it, I think its probably just a snag because I have not had the same issues on other targets. when the interminable clouds clear I will give it another go.

[michael8554]

Hi irtuk

From your 6th October GuideLog:

"Last Cal Issue = None, Timestamp = 24/09/2021 21:09:04"

So that's why there's no Calibration data in the Log, because you haven't done a Cal since 24th September !

A Cal from 24th September is probably not going to work very well on 6th October, unless you have a permanent setup.

Although I don't think your "Review Calibration" screenshot is from the 24th September Cal, I should point out:

"Expected RA Rate:  NA"  points to a cable or Driver problem, there should be a RA figure reported from the mount similar to "Expected Dec Rate: 13.5"

The RA Guide Rate Calculated by that Cal was 3.046 as/s, which is very low compared to Dec.

Dec was 12.819, close enough to the "Expected : 13.5" figure.

That Cal was carried out at Dec = 74.2, Cals are best carried out near Dec = 0 and pointing near south.

Until you re-Calibrate I don't think any of your guiding since 24th September is representative.

Except to say that the way the directions of guide graph movements are mirrored in both RA and Dec suggests that the guidcam has been rotated since 24th September.

Here are some Guidelines to read:

https://openphdguiding.org/phd2-best-practices/

Michael

 

 

Edited October 8, 2021 by michael8554

[irtuk]

Thanks for the advice Michael. I am a bit restricted on what I can calibrate on because of the location, but the setup is permanent. 

I found another candidate for the source of the problem as well, camera not tightly screwed in! I think over time its become a bit loose.

The whole rig needs a reset now anyway as I have just received a new scope that I need to get dialled in, and I will be doing this with the benefit of lots of learning

Ed.

 

[Starflyer]

You've got weight in the cables / cable tidy that will shift around as your mount tracks.  I'd keep the cable tidy from the mount to just power and ethernet, and try and run it from a central point like the dovetail clamp.  All other cabling is better run along the scope, between your mini PC and cameras etc, keep the cables hanging loose to a minimum.