Approximate autoguiding for Solar, Lunar sessions

[sweiller@free.fr]

Hi all,
I am doing a lot of H alpha imaging with an LXD75 mount, a 102/900 refractor and a Coronado filter.
I have tried all the tracking configuration options but SharpCap always fails during calibration
My observation sessions are typically of 6 hours or more (waiting for a flare) !
As most of the times the capture window is large and sunspots are rather small, could you implement some approximate autoguiding. On screen I can see that the features are nicely tracked. Then what I only need is that the control of the mount would keep them say within 100 x 100 (or even up to 400 x 400) pixels from the starting position ?
This would allow me to leave the PC unattended for some time without fearing that the Sun will "go away" during capture !
Best regards,
Sylvain

[admin]

Hi,

sadly it's the calibration that is the hard part - working out which direction the image moves (and how fast) when the mount moves + in RA or - in DEC... I actually have a lot of respect for the PHD2 developers, since they have made it work pretty much flawlessly despite having to cope with a massive range of different mount hardware.

It may be worth trying the 'guiding rate' option if you haven't already - that uses pulse guiding which may have less backlash, which in turn *may* make calibration more likely to succeed.

If not, feel free to post a log or two captured after a failed calibration attempt - there may be data in the log that helps me improve the calibration routine.

cheers,

Robin

[sweiller@free.fr]

Hi Robin,
Thanks for reply !
I will post logs asap

BR
Sylvain

[sweiller@free.fr]

Hi Robin,

Are those logs Ok ?
Best
Sylvain

GuidingLog_2022-04-17T13_36_58-1236.log

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GuidingLog_2022-04-17T12_48_30-9708.log

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GuidingLog_2022-04-17T12_28_23-2440.log

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GuidingLog_2022-04-17T12_00_31-5508.log

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[sweiller@free.fr]

Robin,

BTW I have seen that during sessions the Sun image is always moving in the same direction (as long as I don't flip the scope) in RA and DEC !
This could be helping approximate guiding as no backslash involved !
The user would tell if RA+ or RA-, DEC+ or DEC- wanted.
If still problematic, the user could, after manual evaluation and trials tell SharpCap a speed of the mount as available on the handle, an interval and a length of time to move; example for my LXD75 Autostar :

Speed 2, every 10 sec, 1 sec of RA+
Speed 2, every 10 sec, 1 sec of DEC-
This would already be very helpful as now I have to do it manually (mainly because I don't see Polaris from my location then alignement is approximative).

Thanks !
Best
Sylvain

[admin]

Hi,

I have a question for you... when you try to do the calibration, how fast is the drift of the image when the mount is just tracking? The calibration code is designed around the idea that the image will stay largely still unless the mount is nudged, so if there is a significant rate of drift then that might explain the problem getting a calibration.

Having looked at your application that monitors the sun and controls SharpCap, could you make that application also connect to the ASCOM mount and send the intermittent movement commands that you described?

cheers,

Robin

[sweiller@free.fr]

Hi RObin,
Thanks !

About having a look on the drift I have please see : https://youtu.be/5NWzb-aIRaQ

About ASCOM, except using it I have no knowledge of interacting ...*
Could you focus your question more specifically ?

Best

Sylvain

[admin]

Hi,

I think the random motion of the features from the seeing fluctuations is part of the problem - SharpCap expects to find a relatively good correlation between the distance the mount has been asked to move and the distance the image has shifted, but there is so much randomness on top of the movement that the correlation is poor. You might just find that choosing one of the higher movement rates available in SharpCap will help avoid this problem.

As for the ASCOM - I was thinking that if you are writing the FlareCapture software (which looks quite advanced), you may want to consider making that talk to the ASCOM mount. Most ASCOM mount drivers can be accessed from more than one piece of software at a time (and those that can't do this natively can be used via the ASCOM device hub). Programming against ASCOM is fairly easy aside from cases where the individual drivers have interesting quirks due to interpreting the specifications in odd ways - see https://ascom-standards.org/Help/Platfo ... copeV3.htm for documentation on the mount control interface.

cheers,

Robin

[sweiller@free.fr]

Hi Robin

Thanks !

About the randomness I of course already tried all the speeds before writing my post here
Maybe Sharpcap could try a lot of times (until the user aborts himself if wanted) then at some time the seeing could be good enough to go to the next step then try again a lots of times until process is completed.
There is also my idea Sharpcap would try only in the users said directions for no backslash problem.

About ASCOM for a start, is there a specially particular and problematic feature FlareCapture commands could help solve ?
Best
Sylvain

[admin]

Hi Sylvain,

I was really thinking that you could add a feature in FlareCapture to do the interval movement thing that you mentioned in post #5 above - from a SharpCap point of view it's a rather niche feature, so I am unlikely to prioritize implementing it, but for users of FlareCapture it may be a more important feature if people are imaging for many hours at a time.

cheers,

Robin