Streaking in images, is this a polar alignment issue? PEC? Something else entirely?

Sigh, it never ends...

On my never ending quest to get my friend up and running, after getting the autofocuser working we tried 2min exposures on the rosette nebula hoping for success but only to see that we still have some sort of tracking issue.

The setup:
Astrophysics 6 inch refractor F-9 focal length
AP 1200 mount
SBIG 402 ME camera
DF-2 focuser
SG -4 autoguider

AP 1200 was set to sideral time with the hand control, we did not use periodic error correction.

We used the astrophysics right angle polar alignment scope, checking the position of polaris at 8 and then 5 hours later and it seemed to be the correct location according to the astrophysics iphone app.

I've attached a representative FITS files, the rosette nebula is without autoguiding and the ngc 2903 image is with autoguiding. The "streaks" seems to be in conjugate directions. Does anyone have a good guess as to what might be wrong? It doesn't feel like polar alignment since the alignment appears to be good and I think the relatively modest exposure times (2min) are long enough to worry about PEC on this mount. But I have no other guesses after that. Would love any advice that any of you have.

P.S. I've also attached two autoguider log files (it isn't clear to me why they appear to be in different formats...this is something to do with how my friend captured them) in case that makes anything obvious.

 

Great advice thanks!
Will follow through on these and get some more exposures (will be a few weeks as I am away).

Only reason that I haven't upgraded the MaximDL version is that I really want to get stuff to the point of "working" ; will happily upgrade once we eliminate all these sources of error.

 

Just a quick update.
I think we were able to address some of the Colin's suggestions: site info etc., certainly weren't any cables tugging (picture of cords attached). I got a hold of PemPro to check the polar alignment and PEC; I'll be posting my PEC data to the ccdware forums to cross check, but (assuming I am interpreting the graphs correctly) I was able to see a clear improvement in tracking after improving the polar alignment and applying the PEC correction. The polar alignment adjustments were significant.

Still not sure if we are tracking credibly (autoguiding is turned off), I've attached images today for 2 and 4 minute exposures of M3. The 2 min exposure looks ok to my eyes and the 4 min exposure clearly is clearly streaking (uploaded 2 images of each). We were anxious to see what things looked like with autoguiding but the SG4 interface was, somehow, being problematic. We've gotten it to work before but today we could connect to the autoguider fine, but clicking "calibrate guider" would just freeze the SG4 interface. Tried shutting down all other programs, checked the phone cable to the mount and no obvious signs of something being wrong. No real changes to the computer either and tried following the manual to the letter. Any ideas would be welcome (just attached a picture of the interface, I swear "take image" works fine).

 

Thanks Colin and Doug.
Will upload fit files from autoguider next chance I get.

Just to be clear, I *could not* get the autoguider working last night, the fit files in the previous message taken unguided. Doug I presume you are suggesting that the "wavy" image quality may be due to poor mounting, which also might prevent "calibrate guider" from coming up correctly in the interface.

Will follow advice on trying cables and check the guide guidescope.

Thanks again!

EDIT: Meant to add that the C-14 edge ED tube has built in mirror lock system so the mirror does not flop when it crosses the meridian

 

Aggh. Still so much pain.

After obtaining what appeared to be semi-respectable unguided tracking (I believe primarily as a result of PEC with a newly installed GTOCP3) 2 days ago, I tried autoguiding today.

One thing that worked better is that the software buttons all worked (they, somehow, didn't always work earlier even when the camera was successfully connected), I have a sneaking suspicion this was due to the general pokiness of the PC that is controlling things and running windows 7. I did some standard things to eliminate windows 7 lag and things are much snappier now.

Now in trying to eliminate the problem step by step:

As a control I tried 100s exposures that now I'm confident should not be problematic unguided, and they seem to look fine (I've attached a representative image, through blue filter to avoid saturation on longer exposures). This supports the notion that dragging cables etc. are not contributing to error in unguided tracking.

- Now I believe a 100s exposure with the guider should give at least the same image if I've done things correctly. We focused and calibrated correctly (arrg I forgot to save the FIT file from guider...I won't forget next session), calibration log attached. My backlash correction is set to 0 in the ASCOM panel, which I understand to be the correct setting for automated guiding. Is there anything jumping out in the log file that seems fishy at the calibration stage?

- I then took 100s exposure with automated guiding ("ag") and you can see that tracking is poor with a streaky double image. The guiding log file is attached.

-The SG4 manual suggests, with good PEC, one can reduce the aggression. I tried some runs with aggressions set to 0.1, the log files looks "sparse" (lots of zeros), which makes sense, there shouldn't be a whole lot of correction going on. A 100s guided image looks ok (not included for brevity), but perhaps this isn't informative with the short time and low aggression.

-I tried a 10min exposure unguided and guided. The 10 min unguided exposure is not as nice as the 10 min I unguided image I posted 2 days ago with some elongation. The low aggression guided image is "jumpy".

-I also have 5 min exposures showing that guiding is decreasing the quality of the image (the 5min unguided exposure seems to look fine), left those out for brevity.

The unguided images certainly aren't always high quality as there was small trailing some 5min exposures where there didn't seem to be very much at all in a 10min image in the images I posted yesterday (as Colin noticed). PEC seems to have helped a lot but there is some more error that I haven't isolated yet. Still, autoguiding seems to be responding too "strongly" to (what I think) are small movements as the autoguided images are never better than unguided. I must be making a very fundamental/elementary mistake somewhere.

Should I be dropping the aggression to something miniscule (0.02?)Mn and Max move are set to 0.05 and 0.5 (per manual). Hard to think of solutions as there just aren't many knobs to turn on the SG4!

 

Ok, got a pretty clear night yesterday and redid the the focus and calibration on the SG4. Log files made much more sense, with only sparse corrections even at the default aggression. I'll post on my thread in the General forum, but I think I did ok.

I think the direction vectors were wrong on the last try; I suspect it was due to poor focus.