7 replies to this topic

[gsaramet]

So, it's been a bad night

 

Story setup: I guess the kids got attracted by the big shiny focusing knob. And turned it until the tube was all in. 

 

Now, I changed the IRcut filter to the duoband. Went outside, setup, waited for reasonable dark, polar aligned, then tried to autofocus. No luck, of course. Waited for darker dark, same. Slew around until I was quite sure I was pointing at Vega. All in all, took me a good half hour of uttering unprintable words until I got a disc on my screen about half the size of field of view. Of course, I didn't even tried to run an autofocus sequence, so I keep entering manual values. It improved a bit, than stopped. Took me 10 minutes or more to notice that the focuser reached the calibration limit and it won't pull the tube more. I am lucky enough I don't have to disconnect my Sesto Senso, so I manually got closer to focus, then finally did the autofocus routine. Took my flats. Started my sequence and ran inside to doctor my mosquito stings.

 

Guiding was not great, so I took a peek at the guide camera images... quite very out of focus. It's been 42 Celsius here, and even at the beginning of the night there were 29C. Didn't stop the sequence and went outside to refocus the guide camera. Not trivial with varifocal glasses, let me tell you. Did a reasonable job with that, went inside, waited for the camera to finish it's 5 min image (which was, of course, very shaky). 

 

Well, next image had some very bad DEC excursions. Cursed a bit, waited 5 more minutes... worse. Stopped and restarted guiding. Same. Closed PHD and guide camera interface software, reconnected from NINA, same. Or worse. 

 

This persisted until I stopped the sequence and restarted it. What could have caused this dance? I did not recalibrate guiding. Guide camera is very solidly attached to the  mount (iOptron guider system).

 

 

Bigger image, because of CN

 

 

Looks very strange to me because the excursions are very similar. Like a periodic error issue, but the exposure was only 5 minutes, the CEM40 is not that bad a mount and the excursion must have been quite fast to go both ways in 5 minutes.

 

Totally stumped, never saw this before. Lost more than an hour of imaging with this and that.

 

 

[Tapio]

Are you sure that's DEC trails?
How did the guiding graph look like?
And fina, why didn't you recalibrate?

[gsaramet]

Well, the camera is set "normally" - that is with it's upper part upwards when scope is in home position. So I guess left-right is DEC, unless I am wrong, and if so, I'll ask a moderator to change the topic title

The guiding graph looked normal - as usual.

And I didn't recalibrate for precisely the same reason I did mess with the guide camera during imaging - sometimes I am a lazy donkey Next troubleshooting (first time I wrote troubleshouting, and it was also proper ) steps would have been recalibration and total reboot, not sure in which order. 

[DeepSky Di]

If you get the free phd2 log analyzer app you should be able to display the log chart and post a screen shot.

[Chaser of Photons]

The CEM40 is a fantastic mount.

 

Looking carefully at your posted images it appears that the fast translation has repeatable pattens within them, which to me indicates that the total length of the 'streaks' are not contiguous but rather broken up with periods of time where the movements were stationary.  Seeing a guide graph that DeepSky Di posted about will be of greater help in isolating the root cause.

 

[gsaramet]

This is weird... 

The three images in the group posted above have timestamps of: 

 

23:22

23:34

23:39

 

And a duration of 5 minutes. Here are the logs

 

23:22:

 

23:34

23:39:

 

 

Something is obviously weird. However I swear that I didn't touch the thing between the last wonky image and the next good one. All I did was stop and start the sequence.

[michael8554]

The first Log Viewer image has such coarse axis scales it's hard to see what's going on.

 

But appears to show RA (blue line) Settling after Dithers.

 

The second image shows two RA spikes, possibly due to grit on the worm.

 

Post a LINK to the GuideLog ?

[gsaramet]

Let's see if the share works.

 

https://drive.google...iew?usp=sharing

 

The issues are in the 300 sec images timestamped:

23:22

23:34

23:39

 

Before that the scope has been hand touched, so any jumps are likely due to that