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Old 13-04-2018, 09:48 PM
Startrek (Martin)
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HEQ5 Synscan - Alignment

I welcome comments in regards to the best method for star alignment and then polar alignment of the HEQ5 mount just using the Synscan hand controller and an illuminated reticle eye piece ( with no view of SCP )

I have seen previous posts by IIS members recommending the following -

Level the scope
Orientate your mount to true south ( use magnetic declination offset or solar noon meridian shadow stick centre line )
Set the latitude to your current position
Set up the hand controller as per manual
Perform a 2 star alignment (select first star and enter then tweek the AzAlt bolts and knobs to move the star in the centre of the reticle, select second star and enter then use the hand controller to move the star to the centre of the reticle and enter) Ensure all hand controller star centering operations end with using the Up and Right direction keys

If the polar alignment error is to great you can perform an additional polar alignment using the method described in the Synscan manual in section 11.3

**** My main query is when performing the initial 2 star alignment, should you just follow the Synscan instructions and not touch the Az Alt bolts and knobs , just use the hand controller for centering 1st star and then second star , check the PA error then use the additional polar alignment method described in the Synscan manual in section 11.3 which uses the Az and Alt adjustments on the mount

Polar alignment and Star alignment of the HEQ5 has been an ongoing issue raised by IIS members for years

At this stage I'm only using the hand controller and an illuminated reticle to achieve reasonably close alignments ( no guiding, no laptop , no camera , no software etc)

I welcome any comments and advice on the above ( especially to assist any newcomers to the hobby who may be finding difficulty in aligning their mounts )

Thanks
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Old 14-04-2018, 01:35 AM
StuTodd
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All good until the 2-star sync IMHO.
I would forget that and do a drift alignment Startrek.

Keep practicing this and you can be very accurately aligned in minutes, wherever you may be.

Last edited by StuTodd; 14-04-2018 at 01:36 AM. Reason: spelinz
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Old 14-04-2018, 04:23 AM
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Steffen
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Star alignment and polar alignment are conceptually different things. One affects goto accuracy, the other tracking accuracy. One aligns the telescope axis with SynScan's computer model of the sky, the other aligns the RA axis with the axis of Earth's rotation, so that tracking can be performed via rotation in RA alone. They are independent, meaning you can get good goto performance on a non polar aligned mount, and good tracking on a non goto aligned one.

The shortcut you mention in your procedure is based on the idea that if on power-up the mount is in its home position (counterweight bar at lowest position and OTA parallel to RA axis) then a polar aligned mount should be able to perform gotos without star alignment. This allows you to detect and correct gross polar alignment errors before commencing the actual star alignment, saving time later on.

For this to work the mount must be close to its home position, and date, time & location must have been entered correctly. Given this, slewing to the first alignment star will get you very close with a polar aligned mount, or show you the polar alignment error otherwise. You can correct the bulk of that error through physical adjustments before pressing enter. This can be useful if you have no reliable way of determining the south direction and are way off. It can reduce the number of polar alignment iterations later on.

This is meant to be a time saving shortcut, and is not required. It is no substitute for proper polar alignment. After 2- or 3-star alignment the polar alignment error will be displayed. It needs to be diminished via the SynScan PA routine (or drift alignment if you prefer). Keep in mind that every mechanical adjustment to the mount as part of polar alignment invalidates the pointing model, so the star alignment has to be redone after each polar alignment iteration, in order to obtain a new reading of the remaining polar alignment error.
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Old 25-04-2018, 02:11 PM
jimmyh1555 (James)
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In simple language - as I understand it - do a 2-star alignment just using the buttons on the controller and the Synscan instructions. After you have done this, go to utilities and do a polar alignment and with this procedure, you tweak the T-bar altitude screws and the azimuth bolts as prompted. Then switch off, and then do a 2-star align again. Sometimes I repeat these procedures 2 or 3 times, but after that, the scope seems to be spot-on.
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Old 25-04-2018, 03:34 PM
Startrek (Martin)
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Thanks James

Yes followed all the advice and now get my rig polar aligned good enough to take up to 2 minute exposures before the start of star trailing ( no guiding )

I’m using an Orion 20mm 70 deg illuminated reticle centering eye piece with good eye relief

I suspect if I use a Celestron or Orion 12.5mm illuminated reticle eye piece I could get more accuracy with my star alignments and polar alignments ?

Clear Skies

Martin
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