SyncScan on HEQ5 out of sync?

[Switch10]

Hey everyone,

I received delivery of my HEQ-5 mount yesterday and have spent today putting it together and playing about with SynScan to get familiar with it while I wait for clear skies.

I've noticed that some of the data in the SynScan seems to be different compared to various apps i'm using, see two examples below taken from today. Note I've entered the correct time / long / lat / elevation info into the mount prior to these checks:

1. RA / Dec coordinates are marginally different to Stellarium so it will always slew to a slightly different position. An example is SynScan shows M31 as 00h43.7m RA, +41 24' DEC, while Stellarium shows it as 00h42.4m RA, +41 16' DEC. Not massively out but still out.
2. P.Scope position / Polaris HA are different to PolarFinder. An example is SynScan shows p.scope position as 10:06 and HA as 15h 48m. PolarFinder shows p.scope as 09:56 and HA as 16h 7m. Again not massively out but not the same.

My understanding is that RA/DEC coordinates for objects don't change (excluding obvious objects like planets etc) so why would they be different. My worry is that my mount will forever be skewing to slightly "off" coordinates.  I initially thought it may be because of the SynScan version being older but it is v4.39.04 and the latest on the website is v.4.39.5 so doesn't seem to be that.

I'm stumped, any ideas?

Edited November 6, 2019 by Switch10

[Owmuchonomy]

Hi there.  Regarding point 1, the equatorial system coordinates of objects do change with time.  This is due to the precession of the Earth. However the effect is small, for example for objects near the CE the effect is to change RA by about 15 arc minutes every 18 years.  The datum point of your particular software is denoted by the term 'Epoch'.  So Epoch 2000 is based on the year 2000.  M31 is also very large (about 3 degrees in the sky, or 6 full moons).

For visual purposes, the slight differences you describe will not affect the GoTo accuracy sufficiently to cause a problem.

[Switch10]

25 minutes ago, Owmuchonomy said:

For visual purposes, the slight differences you describe will not affect the GoTo accuracy sufficiently to cause a problem.

Thanks for the reply Chris, good to know that impact will be minimal for visual use.

I'll be mounting a S/W 200P-DS on the HEQ-5 for astrophotography, will the coordinate differences have an impact there?  Assume the mount will be properly polar aligned to not complicate matters...

[Jiggy 67]

Can’t explain your issues but if it helps to put your mind at rest , I’ve recently been using a brand new SynScan, probably from the same batch as yours (with a 200PDS) and it’s bang on every time, appears to be far more accurate than my last one

[Owmuchonomy]

51 minutes ago, Switch10 said:

Thanks for the reply Chris, good to know that impact will be minimal for visual use.

I'll be mounting a S/W 200P-DS on the HEQ-5 for astrophotography, will the coordinate differences have an impact there?  Assume the mount will be properly polar aligned to not complicate matters...

Short answer, no. Don’t bother with a polar scope it’s just a pain. Use the Polar Alignment routine in SynScan instead after doing a very rough North alignment. It’s much easier and I found it very accurate.

[Switch10]

1 hour ago, Owmuchonomy said:

Short answer, no. Don’t bother with a polar scope it’s just a pain. Use the Polar Alignment routine in SynScan instead after doing a very rough North alignment. It’s much easier and I found it very accurate.

Doesn't the SynScan routine require you to use the polarscope? If not, could you explain how to do it?

This is my first GoTo mount so excuse all my questions 😁

[Switch10]

1 hour ago, Jiggy 67 said:

Can’t explain your issues but if it helps to put your mind at rest , I’ve recently been using a brand new SynScan, probably from the same batch as yours (with a 200PDS) and it’s bang on every time, appears to be far more accurate than my last one

Puts my mind at ease hearing that!

[cletrac1922]

Hi Everyone

Where I am in southern hemisphere, everything is different

Do not have a Polaris to polar align with 

When set up my EQ5pro mount, north leg faces south

I use a compass to align the north leg, allowing 12deg east for magnetic variation where I am

I am now also using the WiFi adapter with the SynScan APP

Find I am about 2 degrees out initial setting, which is easy to adjust with the SynScan APP

The APP takes the guess work out of GPS location, time/date, as set from your mobile device or tablet

I am using a Samsung Android mobile phone

John  

  

[Owmuchonomy]

50 minutes ago, Switch10 said:

Doesn't the SynScan routine require you to use the polarscope? If not, could you explain how to do it?

This is my first GoTo mount so excuse all my questions 😁

No it doesn't.  The method is covered in the Synscan instruction manual. 🤓

[Thalestris24]

It's maybe worth bearing in mind that alignments are only as good as your inputs e.g. lat long, time of day. Time of day on computer also. Likewise inputs to your Stellarium or other planetarium software.

Louise

[Switch10]

Thanks Louise. All my inputs are spot on so will report back once I've tried the synscan out if the weather permits any time soon.

It just seemed odd that the coords where different. 

[Switch10]

Quick update. Managed a few hours outside tonight for the first time with my new SW 200PDS on the HEQ5.

Took a few attempts to align the mount using the 2 star alignment function but after a few tries, the tracking and slewing was spot on from the SynScan so not so worried now as I was initially in the original post. 

Couldn't check it against any DSOs though due to the gibbous moon lighting up most of the sky in my FOV but managed a few double stars and open clusters.

Thanks all for the advice.

[Ronclarke]

I also used the WiFi dongle and SynScan app on my late HEQ5 and it was so accurate every time.

Using it now on my NEQ6 with the same great results!

 

Ron