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Old 19-07-2020, 07:31 PM
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PHD Guiding...star does not move enough.

I built a dark library.
I get a message after calibrating that it failed and that "star does not move enough" and suggestion for scope location. + or - 20 degrees I gather from celestial equator.
Well I have tried all over ..maybe it's finding a hot pixie but I did select manually to hopefully eliminate to possibility.
Any ideas on what I am doing wrong...now the mount was tracking but somewhat poorly so the star was moving...I think the focus is as good as I can get...in the end I tucked the don't ask again box and gave up.
Anyways it's annoying I resolved to auto guide tonight but I am now taking 60 sec exposures to get something...it seems a decent night but maybe be there is something up there causing this issue.
Any help will be greatly appreciated.
Alex
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Old 19-07-2020, 07:36 PM
Imme (Jon)
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Try increasing step size Alex.

It’s in the brain tab from memory
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Old 19-07-2020, 08:31 PM
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The_bluester (Paul)
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Did you set it up with the wizard to begin with? If you follow that through step by step (Including the focal length of the guider) it should pre-populate most settings reasonably well, including the caibration step size.

If you bring up the manual guide dialog and set a long guide pulse amount (like 1000ms) does the star move in all directions when you hit the manual guide buttons? Just to make sure PHD2 is actually able to move the mount.
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Old 19-07-2020, 08:42 PM
Startrek (Martin)
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Alex
Maybe check the items below
Select Brain then the “Guiding tab”
Increase search region to 15 pixels
Tick Star Mass Detection and set Tolerance to 60
Under Calibration make sure your focal length is set correctly for your guide scope not main scope focal length

For your Calibration select a star within 10 deg of the celestial equator and with 1 hour of the north meridian on the east side

Set your guide camera exposure to 2 seconds, it’s a good starting point

Also the PHD2 manual is a great guide ( under Contents ) I read it a few times and it helped me sort out some gremlins

Good luck
Martin
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Old 19-07-2020, 09:32 PM
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Thanks everyone I really appreciate your help.
Step size was out..focal length was wrong how that happened I have no idea..anyways playing with it whilst capturing was causing dropped frames so I will finish my run and try again...I need to move the scope as suggested for a start as my object is not in the right place for calibration.
On the positive I have stars on the screen..It was not working earlier due to a corrupted dark file and man it took ages to find it, but after I deleted that file the camera worked and it at least went thru calibration routine...I feel it will work when I try it with correct focal length, this was set last time out but why I entered a fl double reality is beyond me...damn cold ..it's down to 4 C ...not far off I feel...I will finish my run at 12 and have another go if I don't freeze to death.
Thanks again.
Alex
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Old 19-07-2020, 11:41 PM
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OK three quarter frozen but it is working and I am very happy. I have no idea why I had the focal length double what it should have been..also and luckily I had the sense to check for few on the guide scope..it was drowning ..that would have sent me bats if I had not noticed. The graph is not so hot but I am not worried my polar alignment needs checking as I tightened the pier bolts today which would possibly thrown the lignement out...anyways I took a three minute of a region of sky and the stars were good enough for me...trying ten minutes now just for fun.
Alex
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Old 20-07-2020, 07:00 AM
Startrek (Martin)
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Alex
That’s great news getting your PHD2 Guiding up and running !!!
I may have sent you this before but I’ll send it again , here’s some tips for PHD2 to assist or improve your guiding

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”


PHD2 Extra Guiding Tips
1/Try and keep your min mo in RA and Dec just above your arc sec error in both axis or leave as default (0.20) and see how the guiding performs over a few minutes
2/ Only make small adjustments in RA and Dec Aggressiveness. Wait for guiding to run for a few minutes to see any change or improvements
3/ If guiding is saw toothing in RA ( blue ) badly you maybe over correcting , reduce RA Aggressiveness and increase Min mo in RA only
4/ If guiding is saw toothing badly in DEC (red) then you could be over correcting, reduce DEC Aggressiveness and increase Min Mo in DEC
5/ If DEC ( red ) is staying for the most part above or below the centre line you are under correcting , so increase DEC Aggressiveness a bit and reduce Min mo
6/ If RA (blue) is receiving 2 or more consecutive pulses to correct it , then RA Aggressiveness is to low so increase by 5 at a time over a while to monitor its performance
7/ A random big spike in RA ( blue ) could be caused by many things like cable snag or drag , gust of wind , slight bump of the tripod , loose equipment or lost Guide Star
8/ A big random downward spike in DEC (red) can be caused by a “dither” command from your capture software through PHD2 , but you should see the word “dither” above the spike area on the PHD2 graph
9/ If guiding is still bad , go to the Brain and change the Guiding Algorithm from Hysterisis to “Predictive PEC”
It usually takes 20minutes of guiding on this algorithm to run 2 worm cycles of the mount and allow PEC training of the mounts performance. Sometimes the mount performs better using this PEC algorithm
10/ You can also try the Guiding Assistant which will make suggestions after letting the mount track after a test period of 2 minutes
11/ Only use the Backlash Compensation setting If Guiding Assistant advises to do so.
Go to Brain then Algorithms
Use only if your backlash value from the Guiding Assistant is 3 seconds or less or if the Guiding Assistance says to use this function
Cheers
Good Luck

Martin
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Old 20-07-2020, 08:26 AM
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Thank you Martin.
I had some fun reducing the chip size to 600 x 800 and photograph a tiny gallaxy that appeared in my first test shot and it was amazing how good the result.
The graph suggests to me polar is out but as I have mentioned before it is my belief that the 115 mm is just a little too much for the mount. I balanced everything during the day but needed to move the counter weight over the night and when I did my test shot did not re address balance...Anyways for tonight I will go with the longest exposure it can manage and slowly dial PHD in by following your very helpful advice.
I did away with the long sub and have the sub hub only about half a meter from the lappy and made cabling fall into that set up.
Alex
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Old 20-07-2020, 09:25 AM
Startrek (Martin)
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Alex
Do you slightly off set your balance “East Heavy” as it does help your tracking and guiding to some degree
All my mounts I adjust the balance slightly east heavy
Some folk do and some folk don’t bother, but I found it helpful particularly with nights of less than favourable seeing
Martin
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Old 20-07-2020, 09:55 AM
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Quote:
Originally Posted by Startrek View Post
Alex
Do you slightly off set your balance “East Heavy” as it does help your tracking and guiding to some degree
All my mounts I adjust the balance slightly east heavy
Some folk do and some folk don’t bother, but I found it helpful particularly with nights of less than favourable seeing
Martin
Yes I do yet things change and remember because I am only tracking I am very aware of my mount...when I start guiding it will be interesting to see if I have to pay so much attention to the counter weights. All good.
And I have not yet pulled this mount down and fine tuned it ...so all things considered it ain't too bad.
I am so looking forward to tonight, like last night, some auto guiding and lower gain if I can break the habit..although last night I reduced my gain on what I have been doing in the past but so far having had one unsuccessful processing run I have had opportunity to look for improvement but can't notice it yet.
And given things are starting to work will probably do some darks..even a dither.
I ordered a dew strip but had purchased a small wind screen heater/fan from a car place..Auto Barn? And set it up on the floor blowing up and over the scope which seemed to work ok but hopefully the dew strip will be here tomorrow...Usually I get by with shields but the dew has been terrible recently.
I want to get the two units (old eq 6 and the little heq5) working before I take delivery of the eq8 and whatever scope I get..after last night's experience with the little gallaxy I am thinking 16 inch again
And a big score..my daughter decided to replace the wonderful desk she built, mother gets it but I get mothers old (as new) desks)for the roll off..one less thing to source.
And I plan to run the eq8 on its tripod to get a feel for things before I build the pier so that gives me so much more time for other things seeing I don't have to move 2 ton of rock right away.
Just doing a short Lagoon now, from last night, maybe, hopefully my last unguided high gain photo..but really I am amazed what I can get away with using high gain...good to know if you are in a rush.
Alex
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Old 20-07-2020, 03:23 PM
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The_bluester (Paul)
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Rather than specifically east heavy I tend to go slightly counterweight heavy, by enough to ensure that while it will swap sides on the worm and ring gear on the meridian flip it does apply enough pressure to keep them in mesh when the mount flips to be east of pier, pointing west. And I balance the Dec just a sniff rear heavy to try my best to keep that meshed too.
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Old 20-07-2020, 03:32 PM
Startrek (Martin)
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Alex
Seeing what Galaxies my humble 6” and 8” GSO newts can resolve with an old DSLR , I suspect a 16” Scope with a cooled mono CMOS would capture mind boggling images of similar galaxies
Good luck with your final decision of scope
Martin
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Old 20-07-2020, 04:01 PM
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Originally Posted by The_bluester View Post
Rather than specifically east heavy I tend to go slightly counterweight heavy, by enough to ensure that while it will swap sides on the worm and ring gear on the meridian flip it does apply enough pressure to keep them in mesh when the mount flips to be east of pier, pointing west. And I balance the Dec just a sniff rear heavy to try my best to keep that meshed too.
I doubt if I will be doing meridian flips..as I have to stop staying up past 1 am, so data will be gathered from the East..I also hope to get the mounts to behave very well being confined to say 50 degrees movement or whatever I finally go for...plus at least with the 115 mm it is a tag too big for the little observatory so you need to watch it hitting the wall.
alex
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Old 21-07-2020, 09:14 AM
Startrek (Martin)
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Alex
Another handy visual aid in PHD2 is the Guide Star Profile Tool
I started using it only a month ago after guiding for nearly 3 years and it’s a very useful tool
Some info below -

PHD2 Guide Star Profile Tool
This tool is accessed in the main screen via the “View” drop down menu

Star Profile Tool displays both
FWHD ( Full Width Half Diameter)
HFD ( Half Flux Diameter)
measurements

HFD is a more stable measure of a stars size and shape and more reliable than FWHM

A HFD measurement of between 2.0 and 4.0 generally means excellent to good seeing conditions
A HFD measurement of between 4.0 and 5.0 generally means good to average seeing conditions
A HFD measurement above 5.0 generally means poor to bad seeing conditions

When selecting a guide star either using “Auto Select Star” from Tools or manual selection, make sure your Star Profile graph shows a sharp peak or tapered peak not a flat or sloped peak
When selecting your guide star ensure the “Signal to Noise Ratio” SNR is generally between 20 and 40 depending on seeing conditions
Don’t select a bright guide star as it will be saturated and will show a very high SNR ( say +50 SNR )You cannot guide on a saturated star
Don’t select a guide star to dim ( say below SNR of 20 ) as you may lose the guide star during guiding

Cheers
Martin
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Old 21-07-2020, 05:57 PM
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Thanks Martin. Although I did not get to guide on my selected object afterwards, like the night before, got it working and did various tests up to 10 minutes..the really great thing unlike my first and early experiences was it just kept working, no lost star, and no it was not a hot pixy, and although the graph was seemingly a bit saw toothed the corrections were not too many and , which is what one should be more concerned about than the graph, was my stars..not perfect at ten minutes but only noticeable when you blew the image up and certainly better than the many stars I have had to round up with various tricks..which I did not do with that recent Lagoon..no deacon even.
But I am not sure tonight will see action so I am adding the additional Lagoon data, at low gain, stacking everything again and of course reprocess..I have done two in StarTools and first time ever got some joy with deconvolution and these are really looking very promising ..just hope I dont stuff them up going overboard.
Thanks again for all your help...
Have you ever thought of doing a you tube video? I have been thinking of doing one for my star trail method for getting a reasonable PA for folk starting..my polar in that Lagoon shot was started via the star trail method because I simply could not find Sig oct for what ever reason..but I dialed in via star trails and tried to see how close I could get before using Pole master.. well star trails got it within a quarter of an inch on screen at normal screen size but I neglected to quantify it in terms of degrees..but my point is I think a video would have folk starting understanding the method which I think when I post it here as I have many times I get no questions and I doubt if anyone is taking advantage of the method when just starting out.
If nothing else beats drift align by miles.
Thanks again for your wonderful help..in fact I think I could say without the help from everyone yourself in particular I doubt if I would have stuck at it.
Alex
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Old 22-07-2020, 08:15 AM
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The_bluester (Paul)
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Are you using EQMOD to drive the mount Alex? If you are and you don't plan on doing meridian flips any time soon, go into the settings if you have not done it already and turn on the mount limits so if you happen not to go to it at the right time, the mount will stop at the meridian (Or some time after if you decide it is safe to do that and set EQMOD accordingly) and help avoid any messy stuff like equipment crashes.
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Old 22-07-2020, 08:28 AM
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Originally Posted by The_bluester View Post
Are you using EQMOD to drive the mount Alex? If you are and you don't plan on doing meridian flips any time soon, go into the settings if you have not done it already and turn on the mount limits so if you happen not to go to it at the right time, the mount will stop at the meridian (Or some time after if you decide it is safe to do that and set EQMOD accordingly) and help avoid any messy stuff like equipment crashes.
Thanks for the tip.
Yes EQMOD for me...when I set up the new scope and mount, whatever the scope I will have room in the roll off observatory so I will try and get things better organised. Wifi and video cameras would be nice and a remote for the roof. I think I will put he 80 mm on the HEQ 5 and use 5he old EQ 6 to mount two DSLR cameras for wide field as the eq6 can go unguided forever just for wide fields. This has gone way past holding a camera at the ep for Moon shots.
Alex
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Old 22-07-2020, 11:54 AM
Startrek (Martin)
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Alex
If you intend to use EQMOD, I can send a procedure to use Stellarium for your Planetarium for navigation (tracking and Goto) it works unbelievably well , I can find dim galaxies in minutes which gives you more capture time
As I assume you have the older HEQ5 and EQ6 mounts they will require the EQ direct method using the shoestring cable ( not the new USB connection )
Let me know when your ready and I can send if your interested !!
Cheers
Martin
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Old 23-07-2020, 03:49 AM
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Alex
If you intend to use EQMOD, I can send a procedure to use Stellarium for your Planetarium for navigation (tracking and Goto) it works unbelievably well , I can find dim galaxies in minutes which gives you more capture time
As I assume you have the older HEQ5 and EQ6 mounts they will require the EQ direct method using the shoestring cable ( not the new USB connection )
Let me know when your ready and I can send if your interested !!
Cheers
Martin
Only if it's no trouble Martin. I did try to do it ages ago but at that time as I recall I was unable to devote the attention up here and things never got to work so in effect I will be starting from scratch. I still have Stelarium on the Lappy. I have always had some pride that I was as good as goto but I admit sometimes, when someone has moved an object, they can be annoyingly hard to find so I guess I should get that aspect sorted..thanks.
Alex
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Old 23-07-2020, 06:54 AM
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What software are you using for capture Alex? Stellarium with Stellarium scope will shown you where your mount says it is pointed, but that is only as good as your alignment. You can manually sync things yourself so the mount and the sky agree on where you are pointed, but plate solving with the likes of APT, SGP and others will allow you to sync the mount pointing very easily.
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