#1  
Old 01-06-2020, 10:18 AM
xelasnave's Avatar
xelasnave
Gravity does not Suck

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PHD guiding

I have used it before and tried to use it last night and every star was lost...not enough mass I think was the message.
Now conditions were poor could that be it?
I use a little two and a Orion guide scope and wonder what gain I should set for the camera..I don't recall setting it in the earlier version.
Anyways no matter what star I chose either manual or auto it was lost..immediately..the graph did not even start.
Any tips or pointers greatly appreciated.
Alex
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  #2  
Old 01-06-2020, 11:04 AM
Startrek (Martin)
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Alex
Some of my PHD2 procedures and tips below I set up last year -

PHD2 Set Up and Guiding tips

1/ Try to Polar align to around 1arc minute error on Alt and Az

2/ “Auto select guide star” (recommended by PHD2) or manually select star that’s not too bright or saturated to avoid lost stars

3/ If guiding is poor ( above 2 arc seconds ) utilise the Guiding Assistant

4/ Check and adjust focus of your guide scope and camera to minimise lost stars

5/ Set your guide camera exposure time between 2 and 4 seconds ( Looping ) 2 seconds is a good starting point

6/ The SNR value of the guide star should be between 15.0 and 40.0 to avoid losing the guide star

7/ Don’t over correct settings , under correcting will let you manage your guiding performance better

8/ If Guiding is poor try and keep your min mo above 0.25 in RA and DEC . Don’t go above 0.6. A good starting point for min mo is 0.20 or 0.25

9/ Important- Build a Dark Frame library and a Bad pixel map to provide good calibration and stable guide star. PHD2 will only allow you to use one or the other

10/ The RA Osc value should be between 0.3 to 0.5
If it drops to 0.1 or lower then increase the RA aggressiveness or decrease the hysteresis
If it gets quite high say 0.8 then reduce the RA aggressiveness or increase the hysteresis

11/ Use Ascom Guiding - Laptop direct connect to mount ( preferred by PHD2 Developers) in lieu of ST4 connected guiding via camera to mount

12/ USB 2 cable to camera is not to exceed 5 metres

13/ Try and avoid cabling through a hub even a Powered hub, direct connect to the computer , you will have less issues

14/ Ensure you have the latest driver installed for your guide camera

15/ If guide camera is USB2 make sure you connect into a USB2 port with USB2 cable
If the guide camera is USB3 it most probably will connect with a USB2 cable

16/ Ensure you enter all the correct data for your guide camera into PHD2 brain tabs

17/ Make sure you get good Calibration. Calibrate within 10deg of celestial equator and within an hour of meridian
Once Calibrated save it and reuse it ( go to Brain in guiding tab and tick box “Auto restore Calibration”)

18/ if you lose guide star often , go to Brain in guiding tab and increase “Search region” and increase “ Star mass detection”

Hope this helps

Cheers
Martin
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  #3  
Old 01-06-2020, 01:23 PM
jahnpahwa (JP)
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Martin, another of your posts that I'm adding a bookmark for.
Thank you

JP
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  #4  
Old 01-06-2020, 01:35 PM
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xelasnave
Gravity does not Suck

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Quote:
Originally Posted by Startrek View Post
Alex
Some of my PHD2 procedures and tips below I set up last year -

PHD2 Set Up and Guiding tips

1/ Try to Polar align to around 1arc minute error on Alt and Az

2/ “Auto select guide star” (recommended by PHD2) or manually select star that’s not too bright or saturated to avoid lost stars

3/ If guiding is poor ( above 2 arc seconds ) utilise the Guiding Assistant

4/ Check and adjust focus of your guide scope and camera to minimise lost stars

5/ Set your guide camera exposure time between 2 and 4 seconds ( Looping ) 2 seconds is a good starting point

6/ The SNR value of the guide star should be between 15.0 and 40.0 to avoid losing the guide star

7/ Don’t over correct settings , under correcting will let you manage your guiding performance better

8/ If Guiding is poor try and keep your min mo above 0.25 in RA and DEC . Don’t go above 0.6. A good starting point for min mo is 0.20 or 0.25

9/ Important- Build a Dark Frame library and a Bad pixel map to provide good calibration and stable guide star. PHD2 will only allow you to use one or the other

10/ The RA Osc value should be between 0.3 to 0.5
If it drops to 0.1 or lower then increase the RA aggressiveness or decrease the hysteresis
If it gets quite high say 0.8 then reduce the RA aggressiveness or increase the hysteresis

11/ Use Ascom Guiding - Laptop direct connect to mount ( preferred by PHD2 Developers) in lieu of ST4 connected guiding via camera to mount

12/ USB 2 cable to camera is not to exceed 5 metres

13/ Try and avoid cabling through a hub even a Powered hub, direct connect to the computer , you will have less issues

14/ Ensure you have the latest driver installed for your guide camera

15/ If guide camera is USB2 make sure you connect into a USB2 port with USB2 cable
If the guide camera is USB3 it most probably will connect with a USB2 cable

16/ Ensure you enter all the correct data for your guide camera into PHD2 brain tabs

17/ Make sure you get good Calibration. Calibrate within 10deg of celestial equator and within an hour of meridian
Once Calibrated save it and reuse it ( go to Brain in guiding tab and tick box “Auto restore Calibration”)

18/ if you lose guide star often , go to Brain in guiding tab and increase “Search region” and increase “ Star mass detection”

Hope this helps

Cheers
Martin
That is fantastic Martin. Thank you I really appreciate this.
You alert me to things that I have never addressed in the past.
I would like to see your post a sticky.
Alex
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  #5  
Old 01-06-2020, 01:41 PM
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xelasnave
Gravity does not Suck

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Just thinking..I have a 10 meter usb cable which was not in the mix when PHD worked successfully for me last year..funny I ordered a new heavy duty sub last week as I had a feeling the long one may go..well it will..retired.
I might ask about a better sub hub I think I would have been cheap with the current one.

Thanks so much.
Alex
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  #6  
Old 01-06-2020, 01:45 PM
Pepper (Steve)
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Good post. That give me some good tips. Thanks.
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  #7  
Old 01-06-2020, 03:11 PM
Startrek (Martin)
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Glad to be of some help
Most of the issues with getting PHD2 up and running is either camera drivers, cable faults , focus or Incorrect settings in the Brain
Even in poor conditions I still manage to lock onto a guide star and guide after double checking everything in my procedures , checklist and tips
It’s almost “Push Here Dummy“ if all the little things are done right in the first place !!
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Old 01-06-2020, 07:24 PM
Jackstar
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Thanks so much for putting that up Martin, i have struggled to the point where i have just been doing unguided for most of the last 6 months. I have recently got it going but this will be so helpful. Just need the clear sky which in the Huon valley is not happening much of late.
jack
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  #9  
Old 02-06-2020, 07:06 AM
Startrek (Martin)
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Jack star
Hope the information improves your guiding
Just remember your guiding will only be as good as the atmospheric conditions allow it to be. I’ve imaged on one night where guiding was 0.80 to 0.90 arc sec error ( excellent for my rig ) and the following night is was running at 1.5 to 1.8 arc sec ( terrible but still getting round stars ) that’s how Mother Nature can be !!
Good luck with your guiding
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  #10  
Old 02-06-2020, 07:21 AM
Hemi
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Brilliant Martin,

I haven’t guided ever but this might get me to, one day.
I want to echo everyone’s thoughts.....you always reach out to help, with very detailed and thoughtful reply’s, not just in response to which scope people should buy .

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  #11  
Old 02-06-2020, 07:54 AM
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The_bluester (Paul)
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If you have the parameters set too tight it can lose the guide star while it is still there plainly visible. In the brain, try turning off star mass detection and see if that helps. If it does you can probably turn it back on but increase the percentage bit by bit until it reliably keeps the star.

I am not sure how it is calculated but it relates to the average brightness of the detected star over the pixels it is detected on, so seeing variations will change the star mass value frame by frame, if the tolerance is too tight it will loose the star. As far as I know it is intended to keep PHD from jumping to the wrong star if there is a bit of movement (Gust of wind etc) and a different star might creep into the search area.

Last edited by The_bluester; 02-06-2020 at 09:21 AM.
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  #12  
Old 02-06-2020, 09:05 AM
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xelasnave
Gravity does not Suck

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I am starting to think seeing may have been the problem. I went out last night and realistically assessed the conditions which were the same as my night of problems and noticed the Moon had a huge sphere around it due to moisture in the air.
Things are not going well...I stacked all my NGC 6188 data via DSS and used 3 X drizzle took three days all up and now Startools won't load the 1.6 gig files...so started again with no drizzle..now DSS has been registering since 9 pm last night and says it won't finish up ntil around 1 pm...and that is just registering...axe time.
Good news my new ( second hand) large roll off roof observatory is on its way ...the one I built recently is just a little to small and the new one is 3.8 never square. Also I have abandoned getting another scope for the present and think I will just get the eight inch working the way I expect it to...which .Dan's a decent focuser or some sort of fix for the current one. Probably get a new eq6 or larger a d a second camera...that's still a lot of stuff.
One day I hope to get the his final dragon image complete...just from DSS the HA image ( maybe five or six hours) looked rather decent.
And after it that hopefully will be the end of my unguided times and down to correct gain settings, darks and flats.
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