SGPro failed to command North facing Meridian flip

During the course of recording an Exoplanet transit on 20220113, the system had been driven to the target star TYC 4424-736-1 using my planetarium program SkyMap Pro. Then a plate solve was undertaken to verify positioning, followed by auto-focusing.

A Sequence was defined so as to capture 119 180sec exposures through a red filter, but as the target was already centred and PHD2 guiding running the event was set to “do not move to location”

At the start of the run the target was at Alt: 37°, Azi: 341°(N), i.e. a few degrees from the Northern meridian. By midway through the run the mount would need to undertake a meridian flip to follow the target to it’s final position of Alt: 38°, 20° (N), what I’ve termed a West to East meridian crossing.

For whatever reason SGPro did not command the mount to flip, and therefore when the mount reached its pre-set tracking limit it flipped to avoid hitting the mounts hard stops. This caused PHD2 to lose guiding and thus SGPro to enter Recovery Mode. Once the flip had completed, I selected the “Try now” recovery option, which work satisfactorily but without re-centring the target star.

Looking at the sg_logfile_20220113174342.log it would appear that SGPro lists the telescope as being East of the mount, when in fact it started West of the mount after the initial target acquisition. At approx. time 01/13/22 21:52:17.945 the last reported ‘telescope on East side’ is listed. Soon after which the mount pre-set limits are reached, and a non-SGPro commanded flip occurs, as signified by the loss of guide star at 01/13/22 21:55:15.294, and subsequent entry into Recovery Mode.

Subsequent to the forced flip telescope is recorded as being West of the mount and the sequence continues without having first re-centred the target star. As it happens the misalignment was not too bad and so the run was completed without undue data loss.

What is not clear however, is why SGPro did not command a meridian flip to cross the Northern facing meridian when by contrast it has never failed to command a flip when crossing the Southern facing meridian. I am not aware of additional setting being required to make such crossings occur, and thus have reported this as a possible bug.

I was using v3.2.0.660 on this occasion but have seen the same thing under V4 beta as well I believe.

OS: Microsoft Windows 10 Pro
Mount: iOptron CEM60EC with Commander application
Guiding: PHD2 v2.6.10dev3
Log: sg_logfile_20220113174342.log

Right now SGPro does not support “below the pole” flips, but we will be adding support for them soon.

Hi Ken,

This explains things nicely thanks. Until this feature is supported I’ll use the manual Pause, Flip via planetarium command, Centre Now and Resume, which seemed to work better than allowing the Recovery to kick-in since that does not re-centre without pausing anyway.

Obviously, it would be very helpful to have the “below the pole” flips reasonable high on your To-Do list please :wink:

I’m looking forward to this feature appearing as many of the Exoplanet transits I track invoke this scenario. Needless to say having to engineer a smooth transition manually during such transits is a rather tedious exercise.

Hi Ken,
Any news on when this feature might appear within a Dev version, appreciating that there are quite a few topics on the To-Do list?

Yep, we are working on this now. Just not sure if it will appear in the 4.2 beta channel or the 4.1 release channel. We’ll need to make that call when the work is done and determine how invasive it is to existing flips.

This is great news Ken, and thanks for your speedy response. Much appreciated.

Hi Ken,

Are you able to provide any detail on how the work is coming along with introducing this ability, and the stream within which it will first appear? No pressure just a polite enquiry.

@Jared is working on this. Pinging him here.

Hi Ken,
Thanks for your heads-up, and I look forward to hearing from @Jared at his convenience.

Still in progress. I’ll try to dedicate some time to it this week to get some things cleaned up and in the beta by the end of the month.


Thanks for your update @Jared, much appreciated.

Hi Jared,

Noting that you’ve posted about the up and coming beta of version 4.3, I’m looking forward to be able to test out the new functionality for North facing Meridian Flips. Thanks for spending time addressing this request.