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John Lawley

EQMOD SGP/PHD2 guiding - sidereel turning off during calibration

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Hi - I've not posted here before as only just launched into this hobby, although I've always been massively interested in astronomy.

I had first light on my rig last night, which is:

Esprit 100, HEQ 5 Pro, ZWO EAF, ZWO mini filter wheel, skywatcher 50ED guidscope with ASI120, ZWO1600mm Pro, Lynx dew controller w 2 astro zap tapes

A big endeavour to get that lot working from zero experience, but I love a challenge and have really enjoyed the computer side (I'm a grade A nerd)...


So - what went well... I got the guide scope in focus (was stressing about this), and also the main scope. Even more awesomely, the autofocus routine in SGP is working perfectly :) Filter wheel also working perfectly and I'm getting lovely smooth pics from the main camera (I've already done the flats and darks while I was waiting for clouds to clear). Final good thing (well, good-ish), is that I got the platesolving working eventually, and was able to get the scope to align from Park to the Soul Nebula and centre fine. For some reason the "number of attempts" in my SGP profile hadn't applied, so it was giving up after 1 go, but I got it working in the end.


So the bad...

I couldn't take any data because every time it finished the platesolving and started PHD2, PHD2 would start the calibration process and then halfway through, the sidereel tracking on the EQMOD panel would turn off. Obviously, that would lead to a "lost the star" error. Is there some reason why sidereel tracking would turn off like that? I'm generally a bit confused as to whether I should be controlling the telescope from SGP (i.e. unpark) or using the park and unpark + tracking button on the EQMOD panel. Both PHD 2 and SGP are setup to use EQMOD ASCOM HEQ5/6?

So at the moment I can't do anything, because there's no way of guiding without it turning tracking off :(


Also I was cold. Very Very Cold.

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I never bother using the unpark option as sgp throws up a message and I click ok. I will use eqmod to park the scope though (just habit).

I would slew to your target and when it fails then just run calibration in phd.

If you have a permanent set up you only need to run calibration once unless you move your guide cam or scope.

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at the risk of causing controversy, you could try doing without EQMOD altogether.

There's an Ascom driver for Skywatcher mounts now that will work directly, 4th from bottom here - https://ascom-standards.org/Downloads/ScopeDrivers.htm .  If you install that, you can get SGP and PHD talking to the mount directly instead of through EQMOD.

if that doesn't work either, you can try connecting your guide cam to mount directly with an ST4 cable and setting PHD to guide 'on camera'

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If you make a change to your profile, you will need to re-apply the profile to the current sequence. It is not a 'live' update. Think of the profile as a template for creating a new sequence. That template sets the 'default' options but you can change/tweak the sequence via the Control Panel.

Calibration - check if you have limits enabled in EQMOD, and what is set for limits. It could be that the calibration process is pushing the scope beyond the limits and then EQMOD is turning off. If this is the case, EQMOD will flash LIMITS in the RA/DEC coordinates display.

PHD2 can sometimes be funny about where you do the calibration - a good place would the guiding assistant, it will at least give you a starting point.


Cold. Yep. Carbon hand warmers. Carbon back warmers. Layers. Thermals. Tea. :D:D


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Thanks for the replies, they are all definitely things I’ll try.

I’ve been playing with it a bit more and think it may be a communication thing as the eqmod com logs are getting RX timeout errors. It also lags a lot sometimes when I use the slew commands on the eqmod panel. I got the 5m eqmod cable and it’s plugged into a 1m usb3 hub. It behaves a bit better plugged into the laptop direct, but still seems to have connection issue and it’s that that is stopping the tracking (I think). I’ve ordered the 2m cable from FLO now so will see if that works better. Also the mount isn’t well balanced as the auto focuser and guide scope are both on left hand side. I have a pocket power box arriving this afternoon so will see if I can get a better balance when I take it all apart again 😕 

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Is the USB hub powered? If not, take it out of the loop - it will just cause more issues! 

If you need the hub, invest in a 12v powered one. It will save a lot of headaches!



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Another thing to maybe check is whether the USB ports on your laptop are timing out under power save..  

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15 hours ago, daz said:

Is the USB hub powered? If not, take it out of the loop - it will just cause more issues! 

If you need the hub, invest in a 12v powered one. It will save a lot of headaches!



It isn't - is there a model people generally use? I can't find anything that looks half decent on amazon. I'm using a Surface Laptop Pro, which is a fantastic computer other than the fact it only has one USB port (arg).

FYI - I fixed the balance issues last night, which should also help as there should be much less strain on the mount.

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