Repeated Guiding Failures with Vixen SXD2 mount and PHD2

[regul...@gmail.com]

Hello,

I had a magnificent clear sky last night and set up my astrophotography rig as follows:

William Optics 2018, 20th anniversary edition of GT102 Apo refractor (F6.9 / FL 703mm);Vixen SXD2 mount with Star Book Ten hand controller; ZWO ASI 290MM mini guide camera attached to an Orion F4 60mm (240mm FL) guidescope; ZWO ASI 071MCPro imaging camera; Targus USB hub (7 USB ports); HP laptop.

Software: Sky X Pro (for imaging) and as a planetarium.

Using Sharp Cap Pro , I obtained an excellent polar alignment (see image), though stupidly, I tightened the altitude lock which may have thrown it all out of alignment, I opened PHD 2 guiding and all seemed well during my first imaging run, but very quickly, the guiding went haywire, especially with the DEC axis and it did this every time I stopped and restarted the program. I thought the Dec aggression was too high and adjusted it down from 100 to 90, though this made no difference. Immediately prior to each failure (especially in the dec axis), I noticed a soft but high-pitched whine from the mount. In the end, I gave up and just used the SBT and Sky X without guiding. The mount tracked but only 60-second exposures were possible before stars trailed.

 

I have attached logs. Can you please advise me on what can be done? I even thought all the cables may have caused drag on the mount (see picture), as it rotated. Twice during the evening, Sky X simply shut down, without warning, but I was able to restart it as the SBT had still remained fixed on its target.

 

Any possible solutions and / or explanations would be very welcome.

LOG FILES UPLOAD link:

 https://openphdguiding.org/logs/dl/PHD2_logs_MPJV.zip 

Cheers,

Richard

[bw_msgboard]

What I see is that you're still trying to use a poor-quality calibration that you did in April 2021.  Can you be 100% sure that your guide scope and camera are in the same rotational organization as they were last April?  If the guiding assembly is rotated at all, you must re-calibrate.  It looks like you tried to re-calibrate at the end of the session but never let it run to completion.

 

As a side note, the ASCOM driver for the mount is reporting bogus guide speeds, 0 degrees/min.  That's ok but it means you must know what the real guide speed is.  You should start over by creating a new profile and following this procedure:

 

https://www.dropbox.com/s/os1thorvswmzaul/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0  

 

Since you're still struggling with the basics, it would probably be best if you also recalibrated at the start of each night's guiding.

 

Good luck,

Bruce

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From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of regul...@gmail.com
Sent: Sunday, February 06, 2022 7:06 PM
To: Open PHD Guiding
Subject: [open-phd-guiding] Repeated Guiding Failures with Vixen SXD2 mount and PHD2

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[Richard Grudzien]

Hi Bruce,

Thank you for your reply and advice. Re the rotational orientation of my guidescope and camera being in the same rotational organisation, I did make a change by mounting the guidescope assembly onto the top of the telescope, but that is the only change I made. I think I am impatient to start guiding and sometimes just click the guide button before a calibration can be completed, (as I think you suggest has happened). So the only clue that a calibration has been done is that the guiding commences automatically? I will create a new profile and start from scratch. I will also use the Guiding Assistant during this process. In the enclosed picture of my setup (see below) is there a chance that these multiple cables could have created drag and upset the scope's tracking and guiding? And what could have caused that whining sound each time the mount failed?

 

    

I don't understand your comment about the ASCOM driver for the Vixen mount giving a bogus guide speed of 0 degrees/minute guide;  the scope is presumably tracking at sidereal rate, so wouldn't this be the same for the guider?

Anyway, I'll do my best. Sorry I am such a chimp; as you suggested, I am still struggling with the basics!

Cheers,

Richard

 

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[Brian Valente]

Hi Richard

A good calibration is the foundation of good guiding. A poor calibration almost always degrades guiding results.

For your first time, I suggest you do a baseline guide setup by following these steps, this will help you avoid the most common pitfalls

https://www.dropbox.com/s/zrf0au7jaisvt85/How%20to%20create%20a%20baseline%20for%20guiding%20results%20using%20OpenPHD2.pdf?dl=0

regarding your question:

>>>So the only clue that a calibration has been done is that the guiding commences automatically?

If it's successful, it will start guiding. If it cannot complete the calibration, it will notify you. The third possibility is it will complete but bring up warnings about issues it found during calibration that you should review to decide if you need to re-do your calibration.

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAF7ZTWnZvvuSxvPXSUny1TnK1vSsSmWAiPi8wp6_oLc7BOankw%40mail.gmail.com.

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Brian 

Brian Valente

portfolio brianvalentephotography.com 

[bw_msgboard]

Hi Richard.  No offense, but I have the impression you've just plunged into this without doing much homework.  I think it would be a good idea to read the user manual, at least the parts that cover things like Basic Use and calibration.  We try to make calibration as easy as possible but you have to take responsibility for the basics - when and where to do a calibration for example and whether or not you want the calibration to be automatically re-used between sessions.  The software can't know that you changed the orientation of the guide scope, for example, that's on you.  Here are the online links if you don't want to use the built-in help manual in PHD2:

 

https://openphdguiding.org/man/Basic_use.htm

 

And if you read the section on the 'Main screen', you can learn about the status icons that tell you things like calibration status:

 

https://openphdguiding.org/man/MainScreen.htm

 

I would say the cabling situation is a mess - it looks like you haven't made any attempt to route them carefully.  For example, the two cables that run to the guide camera are dragging across the main camera attachment and probably rubbing against the two thumbscrews there.  Dangling and dragging cables are a recipe for headaches.  The next time you're out, start PHD2 looping on a star field, then gently move the various cables around and watch what it does to the guide star locations.

 

Regards,

Bruce

 

 

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From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of Richard Grudzien
Sent: Monday, February 07, 2022 7:31 PM
To: open-phd...@googlegroups.com
Subject: Re: [open-phd-guiding] Repeated Guiding Failures with Vixen SXD2 mount and PHD2

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAF7ZTWnZvvuSxvPXSUny1TnK1vSsSmWAiPi8wp6_oLc7BOankw%40mail.gmail.com.

[bw_msgboard]

Sorry, I forget to answer your question about the guide rates.  Yes, the mount will be tracking at the sidereal rate, but the guide rates are set differently in the mount.  They are described as being multiples of the sidereal rate - 0.5x, 0.75x, 1.0x, etc.  When the ASCOM driver reports this info correctly, it helps PHD2 to sanity-check calibrations and for us to provide better support.  The information isn't crucial to making guiding work, but there's no excuse for the ASCOM driver to not report the rates.  You will have to take this up with the author/provider of the driver.

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From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of bw_msgboard
Sent: Tuesday, February 08, 2022 2:02 PM
To: open-phd...@googlegroups.com
Subject: RE: [open-phd-guiding] Repeated Guiding Failures with Vixen SXD2 mount and PHD2

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/484D52961F874A8994CA358775F9C0C3%40HomeDesktop.

[Richard Grudzien]

Thanks for all of your advice, Bruce. No offense taken!  I will start from scratch with the PHD2 manual. Yes the cables are a mess. I have two friends urging me to buy into a system like the ASI Air Plus (wifi and convenient as my cameras are ASI), but there are always drawbacks (I have a brand new Starlight Instruments Stepper motor focuser and Sky X can run it , but not the ASI Air). And there are power boxes such as those offered by Pegasus which can help with cable management (and it will drive my focuser, as will Sky X)

In the meantime, velcro will have to do.

The author of the ASCOM driver for my mount is Vixen, so I'll look into that too.

Once again, many thanks.

Cheers,

Richard

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/415D6954DCC54D5A9A18C03576EB2430%40HomeDesktop.

[Richard Grudzien]

Thanks, Brian. between you and Bruce, I have received much valuable advice. Will start from scratch and just practice guiding!

Cheers,

Richard

To view this discussion on the web visit https://groups.google.com/d/msgid/open-phd-guiding/CAJa45i4aMKeTNusXTPbBsE7maU7fLt5npsTHwTRrpedAL%2BV%3DYQ%40mail.gmail.com.

[Bryan]

Richard

A couple comments

There is LOTS of information on the Internet about 'telescope mount cable management'.  One common approach is to bundle all data together and all power together and route the 2 bundles along the scope axis and down the mount with sufficient slack to avoid binding.  This allows the cables to stay away from the cameras, as well.

Note that the guiding software in the ASI AIR is a ZWO modification of open source PHD2 and is supported by ZWO.

Bryan