Trying to Get Better GOTO Alignment HEQ5 Pro

[Vela Pulsar 11]

Hello.

I was hoping someone might be able to help me???

This is my first post, so first off I just want to say a big "hello" to everyone here at Stargazers Lounge.

My equipment is: Skywatcher ED 80 + FF/HEQ5/V2.04 Skyscan handcontroller/Tracer 12v battery/Canon 6D, I am not guiding or using a PC.

My issue is......I can't get the GOTO function to work perfectly.

My HEQ5 GOTO keeps on missing its target everywhere when I do a 2 star alignment. The target is just outside the field of view using a ED80 and 28mm eyepiece.

When I do a 1 star alignment I seem to get much better GOTO results  but start missing targets when I move further away from the star 1 used for alignment. 

I have done all the basics...I have callibrated the polar scope, levelled mount, entered correct info into the controller (date in US/Co-ordinates in hrs+mins) Polar aligned ok, tightened Dec and RA bolts and made sure HEQ5 is in home position before turning on the power, tried to centre the star when aligning etc.

A few things I noticed over 3 nights of using my HEQ5 were:

Night 1) Tried a few two star alignments with Alkaid and Betelgeuse but i found that the Goto was off on Jupiter and the moon in the East. I could see the light of the moon through the telescope but had to the center using the handset. Same issue with Jupiter.Tried again from scratch 3 times but always the same result. I used the same alignment stars because I'm not so sure on others yet apart from the obvious and some of those were not on the list the skyscan controller gave me.I gave up on the goto in the end and just looked at Jupiter and the moon for a few hours....they were superb, I was amazed at how far I could push Jupiter with the ED80, almost better than my 200p in ways.I can see why people like refractors!

Night 2)Set the mount up. Tried the same 2 stars and got the same result.However this time I tried some targets to the West in Auriga without thinking about it and the Goto seemed more accurate????Is this because I aligned with Alcaid near the North and Betelgeuse in the West, therefore it tracks better in the Western side of the Meridian?

Night 3) I then tried out a 1 star alignment just to see what the difference would be (I used Alkaid) I can get M51 and M101 bang in the centre of my Canon 6D but M81/82 start to appear to the top left corner and not in the centre....the tracking seems to be going off the further I move away from my alignment star.I then chose M44 in Cancer because it is to the South and it was off in the frame to the left, like the 2 star alignment was giving me......I assumed though that maybe this is the case with one star alignment, it can cope in an area near the alignment star but as you move further away it gets worse????

Using the 1 star alignment gave me a chance to do a bit of imaging for the first time so I stuck with that.

I have not tried 3 star alignment yet and I know that this helps compensate for cone error...I will be trying this next anyway to see what I get.

Is there a way to get the Goto to work on targets all over the Sky?

Do most imagers just choose a star near the area of sky they want to image in and use the 1 star alignment??

For visual I thought the 2 star alignment should work but to be honest the 1 star was better!!

I would really like to get the GOTO to work on any target i choose wherever it is in the sky. 

Anyway I've just started so I have a lot to try and experiment with but I thought I would try some suggestions here because I might be missing something obvious?

Any help would be fantastic

Thank you and clear skies to all.

PS.I have included 3 pics to show how the first 2 targets are central but the third is starting to go amiss.They are also my first ever Images so thought I would share.

If anyone knows what those black marks are on my images any advice to get rid of them would be really usefull...looks like something on the sensor...or from deep outer space..lol.

 

Edited April 26, 2017 by Vela Pulsar

[Ger 146]

Hi there and welcome to sgl, I have my goto since Christmas and to be honest even though I have gained some experience I still run into the same issue as yourself with the setup. 

One method I use to check the accuracy of the goto when using a two star alignment is when I finish I go to the object list, then named stars then I pick the first star that I started with when setting up the alignment.

Last night I used capella, then when the alignment was finished selected capella again because in theory it should be the easiest star to get into the centre of the eyepiece. I did get capella but it was slightly off centre. 

I am interested in what other people advise because I do run into similar problem.. although I would need to check how many metres above sea level I am just to make sure. Sometimes I feel my setup may be rushed which leads to errors.. by the sounds of it you are very careful with this.. if you haven't already tried to do so use the goto to find your first star in your two star alignment and see. 

I also try to use a combination of stars that I know and  can pick out with the naked eye and / two stars that are not to far away from an alignment point of move. I sometimes do this for a quick sets and when successful  just give me a little confidence boost that I'm moving in the right direction.

Finally, I would get the stellarium app for your phone or tablet as it is invaluable and will help with the identification of stars etc.

Ger 

[LightBucket 617]

Metres above sea level makes no difference, as far as I am aware, the scope does not need that information, and GPS units are terrible at plotting that figure....  

[D4N 824]

Height mostly effects the horizon, if set incorrectly the mount may refuse to slew to objects as it thinks they are below the horizon.

Remember the GPS height is height above the WGS84 spheroid which is a best fit spheroid that isn't exactly the same as the Earth so it is possible to have negative heights and be above sea level.  However if the mount is expecting height above datum then that's what it should be given.

 

 

The dark marks do appear to be debris on the sensor, they appear to be moving though.  Do you have a sensor cleaning function turned on?  These are supposed to remove dust from the sensor but they generally just move it around invalidating your flats.

Dithering helps with dust bunnies.

 

 

Poor goto is often due to poor polar alignment (especially if goto degrades away from your alignment star) I used to get frustrated with mine until I stuck it on a pier and suddenly the goto works perfectly every time.

 

[SteveA 208]

Hi,

This does sound very much like an issue with your polar alignment and I would suggest re-visiting this and double check that you do in fact have good alignment. Leaving the GOTO functionality and imaging aside for a moment,  pop an eye piece in the telescope and  fire up the mount. I'm not sure if you can ignore the Synscan alignment prompts at this stage, if you can don't bother going through the alignment routine, just get the mount tracking at sidereal rate. Unlock the clutches on the mount and manually point the telescope at a nice bright easy to find star, then lock the clutches and see what happens whilst monitoring the star in your field of view. If you have a good polar alignment the star should obviously stay bang in the centre of your eye piece, if it doesn't and it drifts away you know for sure that there is an issue with the polar alignment. The images you posted definitely indicate that this is likely to be the case, though you don't say how long the exposures are, so how big a problem is difficult to say.

Many of us on SGL have been through the same, some what steep learning curve and with most problems the cause is quite often a fundamental one. Polar alignment is up there as one of the most fundamental....and I talk from experience!

Let us know how you get on 

Steve

[Yearofthegoat 152]

If you're certain your polar alignment is good, and you're checking the alignment by looking at your 6D's images, maybe the camera is sagging when the mount is in different positions? Or some flexure somewhere in its connections? Just a thought.

I use the Synscan GoTo on my HEQ5 and when my PA is good, it's usually bang on or very near, e.g. in the field of view of a 10mm plossl on my 150PDS.

Hope you get it sorted.

[Vela Pulsar 11]

16 hours ago, D4N said:

The dark marks do appear to be debris on the sensor, they appear to be moving though.  Do you have a sensor cleaning function turned on?  These are supposed to remove dust from the sensor but they generally just move it around invalidating your flats.

Dithering helps with dust bunnies.

Poor goto is often due to poor polar alignment (especially if goto degrades away from your alignment star) I used to get frustrated with mine until I stuck it on a pier and suddenly the goto works perfectly every time.

 

Ah Thank you so much for confirming that this is dust on the sensor D4N.

I hoped it was dust, as you say it seems to have moved along the frame because I have sensor cleaning on,  I have never seen it before so i was a bit worried that my camera had an issue.

Ok..I didn't realize that GOTO was so dependant on PA. I will spend then next few nights perfecting this and see GOTO improves.

Many thanks for responding.I can't thank you enough for helping me!

[Vela Pulsar 11]

Thank you all for replying...i'm still trying to get my replies to you all in some sort of correct order.

It means a lot to me that you have all taken the time to post your ideas and help me out, keep them coming and thank you all so much!!

[Vela Pulsar 11]

1 hour ago, SteveA said:

Hi,

This does sound very much like an issue with your polar alignment and I would suggest re-visiting this and double check that you do in fact have good alignment. Leaving the GOTO functionality and imaging aside for a moment,  pop an eye piece in the telescope and  fire up the mount. I'm not sure if you can ignore the Synscan alignment prompts at this stage, if you can don't bother going through the alignment routine, just get the mount tracking at sidereal rate. Unlock the clutches on the mount and manually point the telescope at a nice bright easy to find star, then lock the clutches and see what happens whilst monitoring the star in your field of view. If you have a good polar alignment the star should obviously stay bang in the centre of your eye piece, if it doesn't and it drifts away you know for sure that there is an issue with the polar alignment. The images you posted definitely indicate that this is likely to be the case, though you don't say how long the exposures are, so how big a problem is difficult to say.

Many of us on SGL have been through the same, some what steep learning curve and with most problems the cause is quite often a fundamental one. Polar alignment is up there as one of the most fundamental....and I talk from experience!

Let us know how you get on 

Steve

Thank you Steve.

My images were taken at roughly 120secs so 2mins each I think.

I really did not realize that PA was so important for the GOTO side of things.I know it is for imaging I have tried to get good PA but as I assumed that for the GOTO to work well I did not need accurate PA I have not concentrated on PA it as much as other things so that's where I will concentrate my efforts from now on.

That's a great tip about getting a star in the eyepiece with the mount tracking in sidereal rate.I will try this.

Thank you

[LightBucket 617]

59 minutes ago, Vela Pulsar said:

Thank you Steve.

My images were taken at roughly 120secs so 2mins each I think.

I really did not realize that PA was so important for the GOTO side of things.I know it is for imaging I have tried to get good PA but as I assumed that for the GOTO to work well I did not need accurate PA I have not concentrated on PA it as much as other things so that's where I will concentrate my efforts from now on.

That's a great tip about getting a star in the eyepiece with the mount tracking in sidereal rate.I will try this.

Thank you

PA is very very important, if you think about it the first GOTO will assume that your scope started off pointing straight at the NCP, and so calculates from there, any amount your are off with PA is pretty much the amount your GOTO will be off, in theory anyway, but it will differ from one to another....  that's how I understand it anyway...

[SteveA 208]

I think if you do a 3 star alignment then Synscan can accommodate some error in your PA for GOTOs, but tbh it makes sense to ensure you have as good a PA as possible. As you say it is pretty much crucial for unguided imaging.

I seem to recall some debate on here about the first star alignment with Synscan and whether to use the handset or a manual adjustment to get the first star centred. If you you use the handset to nudge the scope when getting the first star aligned you could try the manual approach and see if this improves pointing accuracy. To do this unlock the clutches and gently nudge the scope by hand until you have the star centred, then lock the clutches and accept the alignment before then moving to the second and third stars. 

Its worth trying this approach...it may possibly help..

Steve

[Vela Pulsar 11]

1 hour ago, LightBucket said:

PA is very very important, if you think about it the first GOTO will assume that your scope started off pointing straight at the NCP, and so calculates from there, any amount your are off with PA is pretty much the amount your GOTO will be off, in theory anyway, but it will differ from one to another....  that's how I understand it anyway...

Really appreciate this LightBucket...this is really the help I needed.I have been overlooking PA and concentrating on Levelling the mount...star aligning/co-ordinates etc. What you say makes perfect sense..i assumed the GOTO was not so reliant on the PA...so thank you!

By the way...Do you have any theories for why my 1 star alignment is giving me better results than my 2 star???

I used Alkaid (*1) and Betelgeuse (*2) for the 2 star alignment.

Using 2 stars M51 was on the side of My 6D frame, chopped in half....M101 was way over to the left of the frame...off on Jupiter and moon in the east.

I used Alkaid for the one star on the same night.Subjects near Alkaid (the images from my post) were bang on, so was the moon and Jupiter?M82 was a bit off but still caught it in the frame as you can see from the picture.

 

[Yearofthegoat 152]

The SynScan system divides the sky into regions, so if you align on a star and then goto another star in the same region, it ought to be bang on. This is why the 2-star (and 3-star) alignments pick stars from different areas of the sky. You can also fine-tune the database by telling it the star is bang on (Pointing Accuracy Enhancement, P37-38 in the handset manual v161208). Maybe you have incorrect PAE data in your SynScan? Perhaps try clearing it then go through your routine with a clean slate?

I've had success with the 2-star and 3-star alignment and I mostly then use the Polar Alignment option which only appears in the handset afterwards. The last time I had the scope out I did actually do an underneath-the-scope 'polar scope' polar alignment (used PolarFinder application to find where to put Polaris) and GoTo was fine after that too, as expected.

A tip I read on here for star alignment is to de-focus until the star is a lot bigger in the eyepiece view, making it a lot easier to centre it if you don't have crosshairs/a reticule in your EP.

Edited April 27, 2017 by Yearofthegoat

[Thalestris24 3,668]

Hi

I wouldn't bother with star alignment and just do platesolving instead. I use APT/Astrotortilla but APT also supports it via another package. The marks on your subs are likely dust on the camera sensor. Stacking with flat frames will get rid of them.

Louise

[LightBucket 617]

1 hour ago, Vela Pulsar said:

Really appreciate this LightBucket...this is really the help I needed.I have been overlooking PA and concentrating on Levelling the mount...star aligning/co-ordinates etc. What you say makes perfect sense..i assumed the GOTO was not so reliant on the PA...so thank you!

By the way...Do you have any theories for why my 1 star alignment is giving me better results than my 2 star???

I used Alkaid (*1) and Betelgeuse (*2) for the 2 star alignment.

Using 2 stars M51 was on the side of My 6D frame, chopped in half....M101 was way over to the left of the frame...off on Jupiter and moon in the east.

I used Alkaid for the one star on the same night.Subjects near Alkaid (the images from my post) were bang on, so was the moon and Jupiter?M82 was a bit off but still caught it in the frame as you can see from the picture.

 

As has been said above it may be due to the Stars you have picked and the area of sky they are in, it makes sense to pick two in different regions of the sky to get the best align, as for why your one star was better, again like it's been said above, Mayer the first GOTO was in the same region of sky as the alignment star, try it again but doing a one star align in the east, and then picking a GOTO from the west, and I bet it will be further out than a two star align...

if it was in the same region of sky then the issue needs investigating further, also if you were not syncing the handset after centring the star then the more stars you align on the further out it will be, so a one star align in that situation would be better...hope that makes sense, it does to me ...lol 

[SteveA 208]

5 minutes ago, LightBucket said:

if it was in the same region of sky then the issue needs investigating further, also if you were not syncing the handset after centring the star then the more stars you align on the further out it will be, so a one star align in that situation would be better...hope that makes sense, it does to me ...lol 

I had one of the earlier releases of Synscan and it didn't have the synch ability...As in EQMOD that's a very useful function and allows you to build your pointing accuracy.

 

[SteveA 208]

One last thought from me..and I only mention it because I've done it myself!

Are you sure you are identifying the stars correctly?

If you are doing your alignment with a camera attached it can some times be easy to miss identify a star and its often easier to use a wide field eye piece.

In the past I've gone off on wild goose chases looking for complex solutions when actually the issue  is relatively simple. Anyway...just a thought

[Vela Pulsar 11]

Just now, SteveA said:

One last thought from me..and I only mention it because I've done it myself!

Are you sure you are identifying the stars correctly?

If you are doing your alignment with a camera attached it can some times be easy to miss identify a star and its often easier to use a wide field eye piece.

In the past I've gone off on wild goose chases looking for complex solutions when actually the issue  is relatively simple. Anyway...just a thought

Thanks Steve.

Ah yes..i did do that a couple of times but that's why I chose Alkaid and Betelgeuse because I know them very well.

I'm going to choose some new ones next to continue my GOTO issue investigation.Actually I think the hardest part of setting up at first is the star align.

Your just left there after doing everything, looking up at all those stars thinking...errrrr where the hell is bloody MIRZAM!!!! Although..i do use Stellarium to locate the stars I don't know.

I would never trust doing a star alignment through a camera...maybe if i had a good CCD I would.

I always do alignment with an eyepiece before I pop the camera on..Then goto a bright object such as the moon, planet or visible cluster far away from my alignment stars, like M44 thats in the south (in realtion to Alkaid) to check the GOTO accurracy.

If the GOTO looks good and the subjects in the middle of the viewfinder then I attach the camera and go after the obscure DSO's that I can't see through the scope but a long exposure can detect.

I'm sure the issue is simple...it's just figuring out which part of the chain I'm messing up......your help is amazing thank you mate.

[SteveA 208]

1 minute ago, Vela Pulsar said:

your help is amazing thank you mate

You are absolutely welcome....I'm sure you will get to the bottom of this

[Vela Pulsar 11]

1 hour ago, Yearofthegoat said:

The SynScan system divides the sky into regions, so if you align on a star and then goto another star in the same region, it ought to be bang on. This is why the 2-star (and 3-star) alignments pick stars from different areas of the sky. You can also fine-tune the database by telling it the star is bang on (Pointing Accuracy Enhancement, P37-38 in the handset manual v161208). Maybe you have incorrect PAE data in your SynScan? Perhaps try clearing it then go through your routine with a clean slate?

I've had success with the 2-star and 3-star alignment and I mostly then use the Polar Alignment option which only appears in the handset afterwards. The last time I had the scope out I did actually do an underneath-the-scope 'polar scope' polar alignment (used PolarFinder application to find where to put Polaris) and GoTo was fine after that too, as expected.

A tip I read on here for star alignment is to de-focus until the star is a lot bigger in the eyepiece view, making it a lot easier to centre it if you don't have crosshairs/a reticule in your EP.

Ah I see, the sky is divided up onto regions..i didn't realise that!

I have also not heard of PAE...i'll check that out.Also I have not seen the PA optiion after 2 star alignment..maybe that is not on my handset as I have the older non-updatable v2.04 Skyscan handset...but I will check.

Yes I do defocus the stars when I align.

Thanks for your help Year of the Goat...all your help is amazing....but your name is even better! I have a goat in trees calander...i think you need to get one...http://www.saltartists.com/goats-on-trees/

[Vela Pulsar 11]

1 hour ago, Thalestris24 said:

Hi

I wouldn't bother with star alignment and just do platesolving instead. I use APT/Astrotortilla but APT also supports it via another package. The marks on your subs are likely dust on the camera sensor. Stacking with flat frames will get rid of them.

Louise

Platesolving...oh my.......maybe in a bit...what is that lol? I will look it up online.

Thank you for confirming the dust issue...i was pretty sure my camera had a non-reversable problem and I was pretty heartbroken.I thought it might be an issue with the sensor over heating and I was going to get this every time...phew.

It's so amazing when people on here can confirm what the issue is so quickly and put my mind to rest..your a star. Thank you!

[Vela Pulsar 11]

I'm really taken  back at how amazing everyone has been in helping me.

I thought no-one would reply and instead loads of lovely people I have never met have tried to help me.

Thank you all...I really mean it...in fact there are so many posts I'm not sure who I've thanked...so this ones for all of you!

Thank you!!!!!!!!!!!

I'm going to give all your suggestions a go over the long Weekend

Edited April 27, 2017 by Vela Pulsar

[D4N 824]

The community here really is quite helpful

 

 

Plate solving requires a computer to work.  You take an image and give it to the plate solving software, that then works out what you are pointing at and tells the mount.  It then tells the mount to slew to where it should have been in the first place.

When it works it works really well and it is all I ever use for imaging.  However when it doesn't work it can be a real pain to get it working, although once you have it working it tends to stay working.

My setup I turn everything on and issue a slew command to my target, plate solve, fine focus then start imaging.  Since it is on a pier there is no need to align everything every time.

[ronin 3,800]

I  would not get too concerned by Jupiter being a bit out for 2 reasona: The position of a planet is calculated by the software and the data is has to go on will be a few years out, the Planets do not do nice simple circular orbits. Additionally at this time, Feb to June Jupiter is in "retrograde" we have caught and passed it so against the stars it is appearing to move backwards. I doubt that the software takes care of this, with regards RA and Dec, although to some extent it might, certainly the sidereal tracking rate will not.

So ultimately I can understand Jupiter problems. One aspect is if at all possible avoid using a Planet for the goto alignment process. Although usually nice, big, bright their movement and calculation of that makes it prone to errors.

Not sure about your handset and the firmware on it but I recall someone saying that pressing and holding the Esc button down for a second or two gave you the option to perform a Sync on a star. Not going to guarantee it on your handset and firmware but it might.

Battery if 12v it may be a bit low, even if a Tracer LiPo if I recall, you will have used it a bit and it will be cold. The Skywatcher mounts need a good 12v, as in about 13v. Cannot recall what a Tracer outputs as the max it may be 13.2v.

After that it is likely to be a simple case of get the initial set up of the mount as accurate as possible, in effect minimise what the mount needs to correct for.

Betelguese must have been farly low to have been used, Suggest you try Capella in Auriga or Pollux in Gemini, Daft question but weren't by chance on Pollux as i is an orange star and I would have thought that Betelguese could have been very low as in below the horizon almost. Betelguese is close to the horizon at this time 19:00 and it is daylight.

[LightBucket 617]

2 hours ago, Vela Pulsar said:

I'm really taken  back at how amazing everyone has been in helping me.

I thought no-one would reply and instead loads of lovely people I have never met have tried to help me.

Thank you all...I really mean it...in fact there are so many posts I'm not sure who I've thanked...so this ones for all of you!

Thank you!!!!!!!!!!!

I'm going to give all your suggestions a go over the long Weekend

Where abouts in Cornwall are you, we love it there, and have our house up for sale, ready to retire down there....as soon as it sells...

then I plan on building one nice big obsy...looking forward to that.