HEQ-5 - Last update of Synscan and Polaris Position wrong

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dreamsandmonsters avatar
Hello everyone,

I started astrophotography recently on my HEQ-5 and while it was making more and more sense, I'm at complete loss now.

To start with, here's a bit of my situation: many of my pictures were showing motion of stars, making the pictures unusable and time wasted. There was no wind, I used an intervalometer, didn't touch the mount. From shots taken minutes apart: some were perfectly sharp, some weren't. I figured my polar alignment wasn't super accurate anyways and since I'd like to take long exposures for nebulas, I decided to invest in a Polemaster.

I also updated my Synscan to the latest version 4.39.20, in case it would solve potential slewing issues that could cause my problem.

I leveled the mount, used the QHY Polemaster to align to Polaris, made sure the mount had an accurate home position, started the stars alignment and... I couldn't recognize any star in the sky. I used Vega to start with and couldn't notice any difference of brightness between stars (using my DSLR camera directly). I couldn't recognize where I was, or how far off Vega I was, even tho the overall aiming of the mount looked ok. In all my recent last tries I could recognize the stars, do an easy 3 stars alignment and always managed to navigate to the deep-sky objects, which is why I'm so confused. I tried other stars I've used before too, just in case, but same issue: I felt totally lost in the sky. No stars look way brighter than the others, unlike what I saw before. I did a factory reset just in case too after that and tried again without success.

Also, I never really paid attention to the Polaris location indicated on SynScan before (I use phone apps instead), but taking a look at it now, it's completely off compared to the apps. My coordinates are correct and my timezone is correct. It was showing Polaris location at 8:06 on the mount and the apps were both saying that it should be 7:41 and the Hour Angle was 19:46 instead of 20:37.

What setting could make the Polaris location wrong? Could that be the reason why I'm so off? Or would it be the system update?

For the motion issue, is that a sign of poor star alignment, or Polar alignment? (pictures attached below, I didn't have the Polemaster yet)

I'd really appreciate any help, as I just wasted hours trying to understand why... while the only clear sky of the week passed me by

Thank you!
L


andrea tasselli avatar
The problem you are experiencing has nothing to do with polar alignment, I mean some pictures showing no trace of drifting and other do. It is called periodic error and all GEM mount have it, to an extent or another. The cure is to use a autoguiding device which can either be a additional small scope with small camera connected to the mount or a off-axis guider (with a camera) attached to the main scope.

As for the other bit, i.e. pointing. Not sure why you can't recognize the star field but I suggest you take a step back, remove the DSLR and use a EP with some magnification (say around 100x) and align the finder with the main scope using Polaris as a reference with the mount's motors turned off. Once this is done the next time you should be able to match what you see in the finder with the image in the DSLR. I cannot venture to say more as I don't know what kind of scope you've got and how you use it.
Helpful
dreamsandmonsters avatar
andrea tasselli:
As for the other bit, i.e. pointing. Not sure why you can't recognize the star field but I suggest you take a step back, remove the DSLR and use a EP with some magnification (say around 100x) and align the finder with the main scope using Polaris as a reference with the mount's motors turned off. Once this is done the next time you should be able to match what you see in the finder with the image in the DSLR. I cannot venture to say more as I don't know what kind of scope you've got and how you use it.

Hello,

I never used anything other than the DSLR to align to the stars. I usually saw a big difference of brightness and always ended up spot on or very close to my deep-sky targets. Polaris alignment should be spot on, since the Polemaster seems to be pretty accurate. I just tried again tonight and same thing, I ended up around that same triangle of stars.

It looks like the mount needs "wrong information" to show the right location for Polaris positions. I marked the time as Daylight saving time off (even tho we should still be in it) and took 7 minutes off the current time to get the same Polaris position as the two apps on my phone show. Is this a common issue, or trick people do to force it to a correct position? I haven't had time to give a try with these changes, but I find it odd to have to manipulate the data like this, since I'm using the latest update from their website. I thought it'd be automatically calculated.

That's all I can think of that would make sense. I'm assuming a wrong calculation of Polaris position would throw off the estimated location of the stars, is that correct?

Thanks!
L
andrea tasselli avatar
In general terms you only need your exact geocentric location and your UTC to calculate everything. Any intial offset will be removed by the software once you execute you first star alignment. So this is why it is important that you can move the mount so that you do that using the finder, assuming you have one.
David Goldstein avatar
I have had the experience with the hand controller of my Orion Atlas after an update requiring a resynch of the encoders from the park position.   That may be why you are not winding up where you expect in your display. 

I don't use the controller anymore, (to cumbersome for me), so I am directly attached with a serial to USB cable to a laptop and resyncs are easy if needed.
dreamsandmonsters avatar
The clouds finally lifted so I can finally test again. Looks like everything went back to normal after setting up the Daylight savings to be off and changing the timezone. The general area was pretty close for the star alignments.

I used the finder to help me out a bit when it was just a bit out of the frame. The finder that came with my AR102 102mm f/6.5 feels really flimsy. Not sure if you have any suggestions for a finder + camera for autoguiding? (nothing too crazy in price preferably!)

I'll probably take a look for using a laptop instead of a controller, seems like it'd be more convenient.

Thank you both!

L
Adel Kildeev avatar
Please check a tripod’s legs to be sure that all are stable and fixed. I had unexplainable loss of accuracy for the HEQ-5 Pro mount, lousy contruction and legs are not properly fixed. I have to drill mount anf install metal stopers in all three legs). If the tripod is OK and you use Polarmaster for the allignment - it may be problems with motors, unlikely, it us update’s issue.
https://www.astrobin.com/a2r9x4/?nc=&nce=