27 replies to this topic

[GeneralT001]

My guiding has gone to hell and I can't figure out why. Here is a snap of my chart last night:

 

 

Each time I tried doing a calibration it would fail. I know my PA is pretty reasonable, at least according to PoleMaster:

 

 

My trendlines for RA and Dec look pretty good in PHD2 as well.

 

The calibration fails and the RA Osc stays in the red?:

 

 

Any ideas, my mount is an AP1100GTO and guide camera is an Ultrastar on a COAG. As far as I know I have all the correct parameters set:

 

[GeneralT001]

Heres my Guiding Assistant run:

 

 

 

I also ran the calibrations within +/- 20 degrees of the celestial equator.

 

Heres the result of that Guiding assistant run:

 

Edited by GeneralT001, 03 September 2017 - 04:02 AM.

[Tapio]

Less than 1" error in graph does not sound bad.
But I'm confused of your settings as there's 2800mm focal length so indicates like c11 guided with oag. Is this correct?
Yet in your guiding window there's svq100 which indicates shorter focal length.
So how does your images look like? Now and before?
Any chance in gear or software ?

Edited by Tapio, 03 September 2017 - 04:24 AM.

[spokeshave]

That's a surprisingly large amount of DEC backlash for an AP1100. It's taking PHD2 8 seconds to take up the backlash, and that's at sidereal rate. I believe that there is a gear mesh procedure for the AP1100 to reset the worm mesh. You might want to try that for the DEC axis. I suspect that the backlash is the source of your problems

[shawnhar]

Could it be the mount is set to solar/lunar tracking rate instead of sidereal?

[GeneralT001]

Less than 1" error in graph does not sound bad.
But I'm confused of your settings as there's 2800mm focal length so indicates like c11 guided with oag. Is this correct?
Yet in your guiding window there's svq100 which indicates shorter focal length.
So how does your images look like? Now and before?
Any chance in gear or software ?

Hi,

 

I just hadn't changed the profile name, which I originally set up with the SVQ, but then changed the settings over to the C11. I've been using the mount with the C11 for sometime successfully so that's shouldn't be the problem. I have noticed my stars are getting a bit out of round but was attributing it to seeing - but this was on short subs of 30s?

[GeneralT001]

Could it be the mount is set to solar/lunar tracking rate instead of sidereal?

 

I did check but it is set for 1.0x sidereal.

[GeneralT001]

That's a surprisingly large amount of DEC backlash for an AP1100. It's taking PHD2 8 seconds to take up the backlash, and that's at sidereal rate. I believe that there is a gear mesh procedure for the AP1100 to reset the worm mesh. You might want to try that for the DEC axis. I suspect that the backlash is the source of your problems

 

I had that thought as well and will explore remeshing today. Funny thing is that Dec has always been the better performer and RA was usually twice as bad as Dec.

[Peter in Reno]

Is there a play in Dec axis? Is your mount with the newest gearbox that has self adjusting meshing? If so, I don't think you can manually adjust meshing. It may be similar to what Ladyhawke had in her Mach1 and it was a loose worm that had to be tightened with a spanner wrench and this procedure is not in the manual. You have to contact A-P.

 

Peter

[GeneralT001]

Is there a play in Dec axis? Is your mount with the newest gearbox that has self adjusting meshing? If so, I don't think you can manually adjust meshing. It may be similar to what Ladyhawke had in her Mach1 and it was a loose worm that had to be tightened with a spanner wrench and this procedure is not in the manual. You have to contact A-P.

 

Peter

Hi Peter,

 

Yes its the GTOCP4 gearbox. I have a post in with AP and I'll see where that goes. The only thing I have done different recently is do the through the mount cabling. The mount seemed to work fine when I first used it after that. Can't see how that would affect it though?

[Peter in Reno]

While you are manually moving both axes, look inside and see if anything unusual with the cables. Never spin both axes more than two revolutions in same direction because it will twist the cables inside the mounts and may make the cables less flexible. Make sure the cables are nicely routed and loose.

 

Take a look at my cable management at http://peternagy.smu...ent/i-TzV2kpJ/A and notice the cable holder at the left side. I got it at Home Depot in the electrical department. Touch the left side to view more pictures.

 

Peter

[Peter in Reno]

Did PHD2 specifically display why calibration failed like "star did not move"? In your first picture, at bottom left showed "Guiding" so how could calibration failed? Also did you capture a few images during guiding and were the stars not round? If the stars were round, I would ignore calibration and go on but save the data to post at PHD2 forum.

 

Peter

[GeneralT001]

While you are manually moving both axes, look inside and see if anything unusual with the cables. Never spin both axes more than two revolutions in same direction because it will twist the cables inside the mounts and may make the cables less flexible. Make sure the cables are nicely routed and loose.

 

Take a look at my cable management at http://peternagy.smu...ent/i-TzV2kpJ/A and notice the cable holder at the left side. I got it at Home Depot in the electrical department. Touch the left side to view more pictures.

 

Peter

I have looked at the cables and they are free. I don't see an issue there. I like you setup, very nice. Where did you get the 90 degree plug for the autoguider, I like that idea. Also, wrt to the autoguider how do you know if it is orientated correctly (perpendicular to the RA axis)?

[GeneralT001]

Did PHD2 specifically display why calibration failed like "star did not move"? In your first picture, at bottom left showed "Guiding" so how could calibration failed? Also did you capture a few images during guiding and were the stars not round? If the stars were round, I would ignore calibration and go on but save the data to post at PHD2 forum.

 

Peter

 

Yes, it said too much difference between the two axis, but it gave me the option of accepting it anyway. I did capture a bunch of images throughout the night and will check them today.

 

What RMS numbers are you getting with your setup?

[Peter in Reno]

 

While you are manually moving both axes, look inside and see if anything unusual with the cables. Never spin both axes more than two revolutions in same direction because it will twist the cables inside the mounts and may make the cables less flexible. Make sure the cables are nicely routed and loose.

 

Take a look at my cable management at http://peternagy.smu...ent/i-TzV2kpJ/A and notice the cable holder at the left side. I got it at Home Depot in the electrical department. Touch the left side to view more pictures.

 

Peter

I have looked at the cables and they are free. I don't see an issue there. I like you setup, very nice. Where did you get the 90 degree plug for the autoguider, I like that idea. Also, wrt to the autoguider how do you know if it is orientated correctly (perpendicular to the RA axis)?

 

I got the right angle USB cables from http://www.l-com.com...emblies?cmp2=LM . The right angle power cables came from https://www.bentroni...e-c-86_115_182/ . When ordering right angle USB cables, it's very important to note the orientation of the connectors. They come in two different styles (Up/Down angles), one is 180 degrees oriented from the other. Hope it makes sense.

 

The USB connector on auto guider is squared with the CCD sensor so I orient the auto guider so the USB connector is squared to either RA or Dec axis. In my case, the USB connector is perpendicular to Dec axis saddle.

 

Peter

Edited by Peter in Reno, 03 September 2017 - 02:47 PM.

[Peter in Reno]

 

Did PHD2 specifically display why calibration failed like "star did not move"? In your first picture, at bottom left showed "Guiding" so how could calibration failed? Also did you capture a few images during guiding and were the stars not round? If the stars were round, I would ignore calibration and go on but save the data to post at PHD2 forum.

 

Peter

 

Yes, it said too much difference between the two axis, but it gave me the option of accepting it anyway. I did capture a bunch of images throughout the night and will check them today.

 

What RMS numbers are you getting with your setup?

 

It's been over a year since I last imaged due to lousy weather and minor health issues. If I remember correctly, if the seeing was good, the RMS is less than 0.5" and if seeing is not so good, the RMS may be close to 1". I usually ignore these errors as long as the stars are round in images. Don't go OCD on RMS numbers.

 

Was the seeing condition bad when you saw PHD2 calibration failed? Do you have smokey sky due to fire from all over the USA? We have lots of smokey sky pretty much all summer which is why I have not imaged.

 

Peter

[GeneralT001]

No,

 

It was absolutely beautiful and clear - except for the full moon. We had our smoke a few weeks back, although it may come back tomorrow.

Thanks for the links on the USB connectors. Your numbers seem similar to mine. Not sure whats going on but will be back at her tonight GW.

 

 

Thanks

[GeneralT001]

Heres a couple of pics from last night. Fully 20% or more are like this:

 

 

 

These are short 30 sec exposures.

[Peter in Reno]

Did you set mount settling in SGP under Telescpe and Auto Guide tabs? I set mine to 8 seconds which may be an overkill but I want to be sure.

 

Peter

Edited by Peter in Reno, 03 September 2017 - 10:16 PM.

[GeneralT001]

They are both set to 2.0 pxs for 4 sec.

 

I am at the scope now and have done a new profile and a calibration. The calibration so I'm going to let the guiding assistant run for 10 - 20 min and plug those numbers in.

[GeneralT001]

Heres a pix of a 15 min guiding assistant. Should the RA be that far gone?

 

 

[GeneralT001]

I plugged in the numbers from the guiding assistant and so far all looks normal again. I have turned PEC off though. I do see the occasional RA bump - but I guess that is normal?

 

[Peter in Reno]

How different were the original numbers from guiding assistance numbers? I would guide longer to make sure the mount remains stable. I am hoping the worm or gear shaft(s) are not loosed like Ladyhawke's from another thread.

 

Peter

[GeneralT001]

Yes, I read up on that thread. The numbers last night were definitely higher and not stable. I had a look at some of the subs and still I see some with the oblong shape. Will look closer tomorrow.

[GeneralT001]

So I think I may have made some progress. As I mentioned, I was able to get a good calibration earlier, but the numbers were still suspect as well as the guiding graph. I checked the subs I took tonight and sure enough close to half of them were garbage (oval stars). This was with trying PEC enabled and PEC disabled. Why couldn't I get good subs without PEC enabled on 60 sec subs???

 

So in desperation (frustration) I went ahead and tried to do a new PEC curve using PEMPro v3 (why aren't there any tutorials for this software??). I read through the help file as I tried to run the curve and eventually wound up with a new PEC curve and uploaded it to the mount (with fingers crossed   as I had no idea if I did it right or not). I don't find the help file to be all that intuitive, especially when they start talking about X this and Y that....what the heck??.

 

Anyway, I ran PHD2 and so far the guide numbers are better - but most importantly - the stars are round in all the subs (10) so far. Still too early to officially celebrate - but there is hope.

 

I guess I'm going to plan on doing a new PEC curve every 3-6 months, if this proves to be the issue . Don't think theres any harm in doing that and I may actually eventually get comfortable with that software???