Requesting some analyses of my last guiding session

[nicholas disabatino]

 I seemed to get decent guiding but 1) it took several minutes for the Phd2 to start guiding after I locked onto a guide star. I also got error messages about being to close to the "celestial equator."? 

I was guiding in FOV of M82. 

Thank you so much!

https://openphdguiding.org/logs/dl/PHD2_logs_k4o2.zip

Nicholas DiSabatino

[bw_msgboard]

Hi Nicholas.  I think you’re confused about what message you got.  The message basically said that calibrating at a high Dec like 69 degrees is not a good idea when using ASCOM pulse-guiding – and it isn’t.

 

Best practices:

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

 

Since you’re using an ASCOM mount driver, there’s no need and no benefit to calibrating “on-target.”  Get a clean calibration near Dec = 0 and within an hour or so of the celestial meridian and just use that for whatever pointing position you need to use.  

 

You should probably follow the other advice offered by the Guiding Assistant – better focus of the guide camera and maybe a little better polar alignment.  Guiding at such a high declination is usually pretty forgiving because the RA gear and tracking errors in the mount have much less effect on your images.  Other than the huge guide star excursion at 23:33, your guiding looked pretty good, just under 1 arc-sec total RMS for the 2+ hour session.  The RA and Dec RMS values were similar so you should have been getting nice round stars.  Whether this is good enough probably depends on the image scale you’re using for your main camera.

 

That said, there’s some evidence your mount may have a lot of Dec backlash.  Have you measured that with the Guiding Assistant?  It looks like you may need to move the mount north immediately before starting a calibration to help clear the backlash.  But again, all of that should be done near the celestial equator (Dec zero).

 

Hope this helps,

Bruce

 

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[nicholas disabatino]

Thank you Bruce, Do you know what I might do to 1) get Phd2 to start guiding sooner than later, after I lock onto a guide star?   Also what do I need to do to get a calibration at Dec = 0?   DO I need to just go to that part of my sky chart and click "calibrate."  Not doing that, is that why I get messages like, "too close to celestial equator and results may not be good." ?

THank you again!

[Brian Valente]

Hi Nicholas

 

I’m not sure what you mean by get PHD2 to star guiding sooner than later”?

 

Once it acquires a guide star, it guides immediately

 

Your last log shows you ran the guiding assistant for quite a while, which is a one-time thing, so you don’t need to do that every time

 

And then there was a long period where it lost the guide star.

 

But generally speaking, once PHD finds a guide star and you (or your imaging app)  asks it to guide, it guides immediately.

 

 

 

 

Thanks

 

Brian

 

portfolio https://www.brianvalentephotography.com/

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[nicholas disabatino]

Well, when I start my guiding session, after I first do a SharoCAp PA, then a Goto alignment, I find my imaging target, check my focus, and start Phd2. I find the guide star, click that green button, and wait for guiding to begin. Sometimes it takes 10 minutes though before guiding will start.  Mind you , I never have pointed at a different part of the sky that I am not going to image in and done a Phd2 calibration. I read where Phd2 can calibrate itself. 

On Tuesday, May 28, 2019 at 2:28:35 PM UTC-7, Brian Valente wrote:

Hi Nicholas

 

I’m not sure what you mean by get PHD2 to star guiding sooner than later”?

 

Once it acquires a guide star, it guides immediately

 

Your last log shows you ran the guiding assistant for quite a while, which is a one-time thing, so you don’t need to do that every time

 

And then there was a long period where it lost the guide star.

 

But generally speaking, once PHD finds a guide star and you (or your imaging app)  asks it to guide, it guides immediately.

 

 

 

 

Thanks

 

Brian

 

portfolio https://www.brianvalentephotography.com/

 

From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of nicholas disabatino
Sent: Tuesday, May 28, 2019 2:16 PM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: [open-phd-guiding] Re: Requesting some analyses of my last guiding session

 

Thank you Bruce, Do you know what I might do to 1) get Phd2 to start guiding sooner than later, after I lock onto a guide star?   Also what do I need to do to get a calibration at Dec = 0?   DO I need to just go to that part of my sky chart and click "calibrate."  Not doing that, is that why I get messages like, "too close to celestial equator and results may not be good." ?

 

THank you again!

 

 

 

On Tuesday, May 28, 2019 at 1:28:49 PM UTC-7, nicholas disabatino wrote:

 I seemed to get decent guiding but 1) it took several minutes for the Phd2 to start guiding after I locked onto a guide star. I also got error messages about being to close to the "celestial equator."? 

I was guiding in FOV of M82. 

 

 

Thank you so much!

 

https://openphdguiding.org/logs/dl/PHD2_logs_k4o2.zip

 

Nicholas DiSabatino

 

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[Steve Winston]

>Sometimes it takes 10 minutes though before guiding will start.  Mind you , I never have pointed at a different part of the sky that I am not going to image in and done a Phd2 calibration. I read where Phd2 can calibrate itself

Are you re-doing your calibration every time?   Is this what you mean by "it takes 10 minutes"?   Or are you saying that even after doing calibration it is taking a long time to start guiding (which should not be the case)?

[nicholas disabatino]

I do not do calibration except in the brain/guide I click "clear mount calibration."  Plus I have "auto restore calibration" checked.

I really do not understand what is meant otherwise by calibrating other than I read on the documentation that the software should be able to calibrate on its own.

[Brian Valente]

When you click the green guide button, guiding will start immediately

 

The only way it could start “it takes 10 minutes” is if it has to re-calibrate itself. The settings you checked are the ones to look at, especially “restore calibration”.

 

 

You can check next time if it starts to calibrate when pressing the guide button. It will start to measure moving north, south, east, west, etc.

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[bw_msgboard]

Hi Nicholas.  What you’re doing with these UI controls makes no sense at all – you really shouldn’t be interacting with them at all.  I think you may not have an understanding of how calibration works and what it does.  Please review the Help content that explains how calibration works:

 

https://openphdguiding.org/manual/?section=Basic_use.htm#Automatic_Calibration

 

To get an explanation that is more of a high-level approach, please look at the Best Practices document – the slides after the basic connection material.

 

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

 

When the docs say to calibrate on a star near the celestial equator and the celestial meridian, that means slew the scope to a convenient point in that general area of the sky, let PHD2 auto-select a star, and start guiding.  It doesn’t matter how you do the slew, it can be via hand-controller, a planetarium application, whatever.  When you click on the ‘guiding’ button, calibration will only be done if there isn’t already a valid one.  There are many UI cues to tell you when calibration is being done, and it shouldn’t take anything like 10 minutes if you’re pointing somewhere near the celestial equator (Dec zero).  If you don’t keep forcing new calibrations, guiding will start immediately as long as you have a usable guide star.

 

Bruce

 

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From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of nicholas disabatino
Sent: Tuesday, May 28, 2019 2:16 PM
To: Open PHD Guiding
Subject: [open-phd-guiding] Re: Requesting some analyses of my last guiding session

 

Thank you Bruce, Do you know what I might do to 1) get Phd2 to start guiding sooner than later, after I lock onto a guide star?   Also what do I need to do to get a calibration at Dec = 0?   DO I need to just go to that part of my sky chart and click "calibrate."  Not doing that, is that why I get messages like, "too close to celestial equator and results may not be good." ?

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[bw_msgboard]

Just as a final point – you’ve quoted this warning message a couple of times and it is backwards.  Assuming you’re using an English version of PHD2, the message looks like this:

 

 

Note the “this far from”.  If you really are seeing something with an opposite meaning, perhaps there’s a problem in the translation.

 

Thanks,

Bruce

 

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[nicholas disabatino]

Hello, I do not think I saw the words "error-prone"  It was more like, 'results will not be reliable.' sorry I cannot recall the exact wording but in any case I did something dumb last night. I went out, it was late and That yielded really poor results. My fault, I know.  Firstly, I did not realize it, but my guire scope got all dewed up. Then, M13, being pretty much in transit to begin with, I presume was too close the meridian to get a good calibration. is that possible? Looking at my Phd viewer it all says "star lost low SNR" . o can I assume it was all the dew that i forgot to check on the guide scope? Since I only use the guide scope for guiding, could I just wipe it down w a safe cloth during session? Thank you!

[nicholas disabatino]

"When the docs say to calibrate on a star near the celestial equator and the celestial meridian, that means slew the scope to a convenient point in that general area of the sky, let PHD2 auto-select a star, and start guiding.  It doesn’t matter how you do the slew, it can be via hand-controller, a planetarium application, whatever.  When you click on the ‘guiding’ button, calibration will only be done if there isn’t already a valid one.  There are many UI cues to tell you when calibration is being done, and it shouldn’t take anything like 10 minutes if you’re pointing somewhere near the celestial equator (Dec zero).  If you don’t keep forcing new calibrations, guiding will start immediately as long as you have a usable guide star."

Bruce, re the above, how long do we need to guide for on that calibration star?

[Brian Valente]

Nicholas

 

The calibration process takes care of itself – it will run the calibration routines and then when it’s complete will report any issues and start guiding.

 

Usually it takes just a few minutes

 

 

 

 

Thanks

 

Brian

 

portfolio https://www.brianvalentephotography.com/

 

From: open-phd...@googlegroups.com [mailto:open-phd...@googlegroups.com] On Behalf Of nicholas disabatino
Sent: Wednesday, May 29, 2019 12:21 PM
To: Open PHD Guiding <open-phd...@googlegroups.com>
Subject: [open-phd-guiding] Re: Requesting some analyses of my last guiding session

 

"When the docs say to calibrate on a star near the celestial equator and the celestial meridian, that means slew the scope to a convenient point in that general area of the sky, let PHD2 auto-select a star, and start guiding.  It doesn’t matter how you do the slew, it can be via hand-controller, a planetarium application, whatever.  When you click on the ‘guiding’ button, calibration will only be done if there isn’t already a valid one.  There are many UI cues to tell you when calibration is being done, and it shouldn’t take anything like 10 minutes if you’re pointing somewhere near the celestial equator (Dec zero).  If you don’t keep forcing new calibrations, guiding will start immediately as long as you have a usable guide star."

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[nicholas disabatino]

Brian, so then why do I get those messages "too close to the equator." etc?    I presume that is because, and can you confirm this, if I am getting error messages like those, then I need to choose a better location to calibrate Phd2 to my mount, then when that calibration is completed, slew to the location where I want to image (the same location where I got the error message to begin with?

Like last night I tried to start at M13, but that was straight up, where all the dec/ra/ converge into small area values and therefore I ran in to trouble? Though, my trouble could have been from a completely dewed up guide scope.  

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Nicholas DiSabatino DC QME

San Diego, CA 

www.sandiegochiropractictherapy.com

[Andy Galasso]

Hi Nick,

The exact message from PHD2 was "Calibration was too far from equator, recalibration is needed."   In other words, it is recommending that you calibrate closer to the equator.

When you are ready to start your imaging session (after polar alignment), slew your telescope so it is positioned like this with the scope OTA approximately perpendicular to the mount's RA axis and the counterweight bar near horizontal (either side of the meridian is ok):

1. Press the Loop button to start looping exposures in PHD2

2. focus the guide camera if it is not already focused

3. Briefly press the up arrow (North) on your mount's hand control to nudge the scope North, just enough until you see the stars move (removes Dec backlash in preparation for calibration)

4. Press Alt-S to auto-select a guide star

5. Hold down the Shift key and click the Guide button. This will start calibrating; wait for calibration to complete

6.- Optional - open the guiding assistant (Tools > Guiding Assistant) and let it run for several minutes to get recommendations for RA and Dec min move settings and optionally measure Dec backlash.  You should do this at least once, but it is not necessary to run it every session.

7. Press the Stop or Loop button to stop guiding

Now you can use your imaging app to capture images anywhere in the sky, no need for any additional calibrations.

Andy

[nicholas disabatino]

Andy, Very helpful. In fact I will print that for a cheat sheet.

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[Brian Valente]

I think you got the best answer from Andy on this one ;)

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