Help with tracking with my AZGOTO mount :(

[tingting44]

HEY guys i have had a skywatcher 130p AZ GOTO for several months now, it is accurate to a certain extent, i think an illuminate recticle would be nice to get that 1st alignment bang on other wise if thats out everything is going to be out,

one thing i cant get my head around is tracking? my scope has sidereal, PEC + sidereal, Solar and lunar??? but none of these seem to work? the last time i tried tracking i pointed it at the moon tried all the above tracking modes but when i come back 10 mins later the FOV is out or nearly gone? what are all these different tracking modes for as the instructions are rubbish! as for example the description in the manual says

Sid. Rate: This activates tracking in Sidereal rate (R.A. Tracking).

Lunar Rate: This activates tracking in Lunar rate (R.A. Tracking).

Solar Rate: This activates tracking in Solar rate (R.A. Tracking).

PEC + Sidereal Rate: Sidereal rate with Periodic Error Compensation.

Stop Tracking: This stops the tracking instantly.

which is really helpful....NOT! lol

im wanting to be able to take a lot of images of nebula and clusters next but if its this out on the moon? i would think it would be near on impossible on anything further away right?

my synscan has also got an auto tracking feature, which im not sure how this differs between tracking modes (lunar/sidereal/sidereal+pec/polor)

and my PAE (pointing accuracy enhancement) has not been set up, would i need to do this before any tracking works?

sorry i really am trying to get my head around tracking for my next session or i wont be able to capture any images and sorry if this has been asked before

edit, i also downgrade my firmware as the latest firmware for my azgoto says for use with dobs also, which is not for mine right, so was i right in downgrading from the latest firmware?

i went down to V3.07.....?

> AZ SYNSCAN FIRMWARE V3.08 ( size:401KB )

Notes: The firmware of SynScan AZ Ver.03.08 is available for SynScan Dobsonian GOTO mount, and it also works with other AZ GOTO mounts. You may also choose to use the earlier firmware version 3.07, if your AZ telescope mount is not SynScan Dobsonian GOTO mount.

>> AZ SYNSCAN FIRMWARE V3.07 ( size:404KB )

Notes: The Version 03.07 firmware improves the system's initial setup and fixes a bug in the SAO catalog. See release note for details. Download the V03.05/03.07 Manual.

[DirkSteele]

Sidereal rate is the rate that the stars move across the sky due to the earth’s rotation. If you were intending to photograph deep sky objects this is the tracking rate you should use.

Lunar rate is the one you should use for tracking the moon if you want to take pictures. Because the moon has a real measurable relative motion against the background stars, an adjustment to the tracking rate is required to accurately track the moon. Under normal visual usage sidereal should be more than sufficient. To give you sense of its relative motion against the stars, the moon orbits the earth in about 27.3 days, which means it covers 360^o in that time. Simplistically, that equates to just over 0.5^o every hour, which is approx the diameter of the moon. Hence the need for specialised tracking rate over longer periods of time.

The Solar rate is comparable to that of the moon but for use when observing the sun.

PEC+Sidereal is periodic error correction. No worm gear in a mount is 100% perfect and PEC allows corrections to prevent trailing appearing in photographs. As the worm turns, irregularities in its shape cause the drive to move in a wavelike pattern. To use PEC, you need to train the mount by guiding on a star for one rotation of the worm gear, and it will reference the current worm position at each point. Then when in use, the mount will play back your corrections to improve the tracking accuracy.

I have never bothered to use anything other than sidereal on my Alt Az GOTO mount.

What magnification were you using when you tracked the moon? I am wondering whether you were high mag and hence that 0.5^o actual movement caused the moon to drift out of your field of view.

[tingting44]

hey dirk! WOW thank you for such a detailed explanation buddy! well thats the tracking modes covered, i dont think i got a worm in my azgoto have i? lol i might leave that mode alone as thats getting a bit technical for now

so lunar for moon, sidereal for stars and nebula, and solar for planets (i wont be viewing sun as i have no filter)

mhh so you used sidereal for everything then?

when i was tracking the moon i think i was using my 10mm + x2 barlow if memory is correct, i have been reading up so much when i actually get a chance to get out i will probably forget most stuff this sucks, last time i had a clear night is coming up to 3 weeks ago

[DirkSteele]

You can use sidereal for the planets as well.

The barlow EP combo would have yielded about 0.4^o field at 130x magnification (assuming it was plossl eyepiece with an apparent field of 50^o). So you can see how the moon would have started to drift across the field given its relative motion versus sidereal motion over the timescales you talked about.

Clear skies,

[brucen]

When using GOTO the tracking mode will automatically be set by the object selected so you shouldn't need to do anything. It helps to get the mount perfectly level when doing the initial setup and to complete it as quickly as possible. The higher the magnification the more obvious the drift will be however. I have to use the Pointing Accuracy Enhancement (PAE) option every now and again to keep things going smoothly but I would be quite happy with 10 mins at that mag I think.

[tingting44]

You can use sidereal for the planets as well.

The barlow EP combo would have yielded about 0.4^o field at 130x magnification (assuming it was plossl eyepiece with an apparent field of 50^o). So you can see how the moon would have started to drift across the field given its relative motion versus sidereal motion over the timescales you talked about.

Clear skies,

i get you, thanks

When using GOTO the tracking mode will automatically be set by the object selected so you shouldn't need to do anything. It helps to get the mount perfectly level when doing the initial setup and to complete it as quickly as possible. The higher the magnification the more obvious the drift will be however. I have to use the Pointing Accuracy Enhancement (PAE) option every now and again to keep things going smoothly but I would be quite happy with 10 mins at that mag I think.

hey there bruce!!! finally found someone that has used PAE loool so to set it up i take it you just hold the esc button for 2 seconds right? then centre object then click ok right? and it can be any object right buddy? :D

[Capricorn]

Another factor is how accurately aligned the unit is to the ideal.

When it is being used as a goto the scope has to determine where to point to next. That is not the same as tracking.

When doing the alignment it is working out the various errors for it's position where you say to what it measures. For all you may set it up well you cannot realistically get it exact. Consider how level the mount is - can you guarantee that it is level in both directions to less then 5 degrees, better yet less then 1 degree ?

Do you sett eh start up as North by compass, or Polaris?

Neither are accurate enough even Polaris is a degree off. A compass being about 4 degrees wrong.

A goto determine where to move to, tracking for a period relies on the scope being set up better.

A final point an Alt/Az mount is unsuitable to DSO imaging. The mount moves differently and so you get rotation of the object/image on the sensor and a blurred image.

PAE is to help locate difficult objects. The idea is to go to something close to what you want, say a bright star. Centre this, press for PAE, then tell the scope tp go to what you really want.

The idea being that you have redefined the datum for the scope as this nearby object so when the scope works out the change required it now has an accurate start position (the selected bright star) and only a small change so less calculation/movement errors.

Best I can suggest is to read the setup, look at the mount and work out if there is a "prefered" start position for the mount and scope. You may not need to start from this but the scope will operate more accurately finding out. I know that the Meades do have this written in their blurb, the mont screws are off set meaning you can only put the scope on one way, one tripod leg is different. This so that the scope is on the right way round and that you have something to aim North/South.

[tingting44]

thanks cap!

i think i will order an illuminated recticle soon then to get the 1st alignment bang on then...

with this scope you do not set alignment up from from just polaris or compass, i think the scope or mount does not even need to be pointing north with the new firmware, i set up with 2 stars usually arctucus and deneb/vega

i do need to make sure it is level as the bubble has not been perfectly in the middle so will do that next time

AH THAT SUCKS! i wont be able to get any images of nebula with this scope/mount! NOOOOOO that really sucks so im limited to planet imaging and stars only : (

nice info on the PAE will do it next time im out

i allways park the scope and put it back in the same posistion but i all ways have to go through the re align procedure, so not sure i ll bother parking it any more

sorry to do your heads in lol

edit, i have been reading through and through the manual, will read through it several more times to try to get my head around things, thanks

[Tinker1947]

All i use on my mount is "Solar tracking" and make sure it Polar Aligned, mine will keep a star ect in the FOV all night if i didn't go looking for other DSO's , as for your GoTo get a star centered then change to a high power EP that's low MM and center it again slew to your second Star and repeat, center with low power then change to high power. Should all be sorted then, if it says it has failed try going to a object in its list it will properly find it....

[tingting44]

All i use on my mount is "Solar tracking" and make sure it Polar Aligned, mine will keep a star ect in the FOV all night if i didn't go looking for other DSO's , as for your GoTo get a star centered then change to a high power EP that's low MM and center it again slew to your second Star and repeat, center with low power then change to high power. Should all be sorted then, if it says it has failed try going to a object in its list it will properly find it....

lol so you only use solar for tracking lol thanks for your input tinker mate, my brain is getting over loaded now

my synscan has no option for polar aligning mate, i can align with no troubles with my 10mm with no probs my finder scope is bang on, so i dont need to start off on low power ep to get in in fov, when my 12mm illuminated recticle comes i am going to try aligning with that and the x2 barlow what setup have you got to get the polar alignment feature mate?

edit, i swear polar aligning is for

Equatorial mounts only? am i wrong here also???

if so i cant see north from my garden so im pretty stuffed here too *SIGH*

[brucen]

i get you, thanks

hey there bruce!!! finally found someone that has used PAE loool so to set it up i take it you just hold the esc button for 2 seconds right? then centre object then click ok right? and it can be any object right buddy? :D

That's right. I usually do it if the drift seems too quick or if the GOTO function does not get the object pretty much in the middle of the eyepiece when it slews onto it. I usually put my 32mm eyepiece in when moving to an object so it's usually in view - somewhere. Some nights I hardly seem to use the function but on other occasions it can be every 10 - 15 mins which probably means I haven't got the mount perfectly level or I have not been that careful when changing eyepieces or focusing. I would imagine that any resistance you put on the scope when the GOTO is active will affect the mount. I tend to do everything with the lightest touch I can but do sometimes find I have my hands on the focuser even when I don't need to.

[DirkSteele]

edit, i swear polar aligning is for

Equatorial mounts only? am i wrong here also???

if so i cant see north from my garden so im pretty stuffed here too *SIGH*

Polar alignment is for equatorial mounts. I guess the comments abut north align (I don't know your specific mount) means the home "start" position is with the telescope pointing north, and as others have said on this thread, a level mount is also important. If you cannot see North, you could buy a cheap compass (just make sure to hold it a small distance from the mount in case there are any magnetic materials in there) and a spirit balance from a DIY store. These two simple additions could make the world of difference to your pointing and tracking accuracy (your mount assumes that it is level and pointed North which might help explain your tracking issues). If you have something like an iPhone you might find apps that already do both compass and spirit balance for no cost.

[tingting44]

thanks mate, im going to re read over this whole topic b4 i post any more as im getting a bit confused, thanks a lot tho and will re post once my brain has had a chance to calm down, kids are driving me mad

[brucen]

The beauty of the later AZ GOTO is, as you have already mentioned, that you do not need to Polar align. Any stars visible from your location can be used. I check on Stellarium before I go out to see which are going to be visible as this helps keep the process simple. I usually have a couple of 'spares' as clouds have a habit of not being in the right place. It's a shame Stellarium doesn't tell you where they are as well.........

[Tinker1947]

Srri didn't realize your mount wasn't a EQ, forget the Polar aligne, just get it level and pointing north and bear in mind its motors will affect a compass so keep this a good yard away.....

[tingting44]

thanks bruce things seem a lot clearer now lol, thanks also tink i was keeping my compass on the eye piece tray....ooppss lol