PHD2 / Sequencer Editor Question

[Al Loan]

Hi folks,

Firstly, I'm a big SC fan and truly appreciate the ease and functionality of the program.

I had a first time ever issue whilst running an imaging session using SC sequencer. The imaging scenario was 50 x 180s light/OIII images, dithering every 3 images, followed by a park command and 30 x 180s of darks. For some unknown reason, (not clouds / maybe a USB connection?), PHD2 did not connect after the dithering sequence completed for light frame 45. The result was the imaging sequence was held in limbo with the mount continuing to track, ie no park command after the completion of the 50 lights. This is not an issue if the telescope is attended, however many times I will setup a imaging session and leave it run unattended under the thought the the scope would park at the given calculated time. So...is there a line that I can add to SC sequencer that would allow for a jump to the next block of commands after "x" minutes of non-confirmation from PHD2?

I have added the sequencer .scs file and the PHD2 file. Note that the PHD2 file contains two events, the failure occurs ~2.10am.

Much appreciated.

[admin]

Hi,

yes, from about 9100s into the second guiding sequence, it looks like PHD2 had issues (it would be nice if they included the actual time in every line in the log, not just the time in seconds since guiding started!). I suspect cloud was the culprit as there are lots of star lost warnings from then on.

If you want to limit on time then use the 'Stop running these steps at <time>' step. Put the things you want to limit inside that block. When the time runs out SharpCap should exit the block at the next end of frame, or when moving from one step to the next. I must admit that I am not sure exactly what will happen in the situation you have, since the sequencer is trying to resume guiding before taking a still frame - I will check and correct if needed.

Another option is to set the 'require guiding' option to false when capturing - this will allow SharpCap to continue capturing and finish the sequence even with PHD2 not guiding.

cheers,

Robin

[Al Loan]

Hi Robin,

Thank you for the speedy response, very much appreciated.

The time step limitation could certainly be used to prevent a telescope / mount crash. I can operate ~15 degrees past meridian when imaging near zenith, (worst case scenario).

For clarification, will there be an impact on the dithering if I uncheck the "required guiding active while capturing" box?

Thanks Robin,

Cheers,

[admin]

Hi,

that last question is an interesting one...

Looking at the code, the current behaviour is that if PHD2 is not guiding when a dither is requires, SharpCap will make one attempt to get PHD2 back into guiding state, and if that fails it will raise an error. I think that will stop the sequence dead. I'm not sure if that is desireable behaviour or not.

If you have 'require guiding' set to true then you are very unlikely to hit the situation described above - why? Well, if cloud comes over, SharpCap will get stop capturing frames and wait for the guiding to re-establish, so it is unlikely to get to the dithering stage while the cloud is in place.

If you turn off 'require guiding' then SharpCap will keep capturing frames in spite of the guiding failing, so it will try to dither in spite of the guiding failing, which will then trigger the failure.

Having written all of that, I'm struggling to see a situation where stopping the sequence because an automatic dither cannot happen is an advantage - I will add some code to suppress that error.

cheers,

Robin

[Al Loan]

Hi Robin,

Please see the attached .scs file. I added a "Stop running these steps" when 5 degrees past meridian on the lights capture block. My thoughts are that if I experience a similar PHD2 star loss, the program would jump to the next block "park" and commence the shoot darks sequence. Essentially preventing the telescope from crashing into the mount.

Do I have this right?

Again, I really appreciate your help with this, your going way and above the call to duty.

Cheers,

[admin]

Hi,

yes, that looks right, although as with any automated imaging, I would suggest rigging it up with a small number of frames and an appropriate 'from meridian' setting so that you can test it while watching it the first time.

I'd also suggest updating to the latest SharpCap 4.1 available from the downloads page (updated yesterday) - I tweaked the code to make sure that it could not become stuck in trying to re-establish guiding and ignore the limitation of the 'STOP AT' block.

cheers,

Robin

[Al Loan]

Hi Robin,

Thanks for this,

For sure, I always run a 1 image type trial with each filter and 1 dark acquisition prior to running a full night time imaging sequence.

I'm looking forward to testing the "stop running steps" in a full sequence next imaging session. I might program it to fail, ie imaging past the meridian, just to confirm it jumps to the next block.

Again, thanks for all of your hard work and effort you put into this program. I truly enjoy the layout and functionality, Well Done sir!!

Cheers,