SyncScan Star Alignment

[IvanT]

Hi,

I did a quick forum search for "syncscan alignment" and other similar terms (trying not to pollute the forum). Didn't find anything that seems to cover this one so here goes.

I've recently upgraded my 200P EQ5 with the SyncScan GoTo upgrade. It all seems to be up and running fine but the problem I'm having is that the tracking is way off.

I opted for 3 star alignment and chose

Star 1 = Vega

Star 2 = Mizar

Star 3 = Caph

Got the alignment successful message (after several unsuccessful messages on previous attempts). Before doing the star alignment I had polar aligned the mount.

Testing out the GoTo, to see if the alignment was accurate, I selected the Moon and then Jupiter, it missed them both by a country mile (not sure what the astro equivalent of a country mile is ).

I re-did the alignment using different stars but the problem persisted.

I could hear the motors tracking, so I manually pointed at M31 by releasing the RA & DEC clutches slightly then locking them up again (can I still do that with the SyncScan system or do I have to use the directional keys always now?). I used the SyncScan directional keys to centre it in the 25mm EP that came with the scope, and observed it for a few mins. It quite clearly was drifting NE in the EP.

I tried changing the auto-guide rate, not really being sure if that is what determines the sidereal tracking rate (forgot to mention I had it set to sidereal), but didn't notice a difference.

I'm sure it's something I'm not doing correctly. Any suggestions?

Thanks in advance.

[Starblazer]

Sounds like Polar alignment issue?

I've experienced similiar and i've narrowed it down to my lack of polar alignment skills, which hopefully over the next few nites I will get onto.

I've only just got the Synscan upgrade for my e6 so I really cannot be of much help. My view from where I setup is restricted to North, East and south east, anything more and it's either behind the house or obstructed by the roof >.<

At a guess, if everything is correctly polar aligned, on it's standard settings, should it not track? reasonably accurately without the need for custom rates?

[Merlin66]

Did you have the tracking rate set to Siderial?

There should only be the RA motor running during tracking with an Equatorial mount.

[Ben Ritchie]

Did you have the tracking rate set to Siderial?

It should automatically go to sidereal after alignment is complete.

I used the SyncScan directional keys to centre it in the 25mm EP that came with the scope, and observed it for a few mins. It quite clearly was drifting NE in the EP.

I just used to put my HEQ5 outside pointing roughly north and three-star align; that would show drift from poor alignment as you describe but GOTO would put the target fairly close, easy to hunt down with a short search. If you're out by a "country mile" then that suggests something else too. Wondering if it's incorrect time, timezone or something like that, as that's a common cause of large errors.

After "alignment successful" it should be able to GOTO the first alignment star correctly - does it? I usually do that as a quick check that alignment was correct.

[IvanT]

After "alignment successful" it should be able to GOTO the first alignment star correctly - does it? I usually do that as a quick check that alignment was correct.

Yes I checked that & it did indeed track to Vega & put it in the centre of the finder scope. It was the amount it was off by when I used GoTo Moon that surprised me, i.e. I was expecting it to be visible somewhere in the finder scope at least, maybe I'm expecting too much?

I setup coordinates, date, time, selected yes for BST (I'm in N. Ireland), thinking about it, I may have used BST during Polar alignment instead of GMT.

If those 3 stars are sufficiently distanced/located for the 3-star alignment, it must be the Polar that's off, I'll observe that tonight (weather permitting).

In addition to the Polar/3 Star alignment, for DSO photography, is that (if correctly carried out) still going to exhibit drift and subsequent trailing? I did take a couple of test shots (prime focused) last night to confirm that I was getting star trails.

My goal here is to setup for something like 10x5 min subs and leave it alone. I'm not getting into guiding for the time being as I believe the setup I have should be more than up to the task of DSO imaging.

[starstalker]

No disrespect but are u sure u have the daylight savings set correctly I didn't on my first outing and everything was out a lot?

[Merlin66]

Yes, you still need good polar alignment for accurate tracking.

You may find the inaccuracies in your gearing/ drive train don't allow you to get good images with a 5min exposure without the aid of guiding corrections.

[Ben Ritchie]

If those 3 stars are sufficiently distanced/located for the 3-star alignment, it must be the Polar that's off, I'll observe that tonight (weather permitting).

As Ken says, good polar alignment is required for accurate tracking - and the drift you describe suggests alignment was poor - but my experience was that you can get acceptable goto with very poor alignment, and certainly within the FOV of a finder. Which is why I wonder if there's an error with time, timezone etc. that's throwing everything off by a sizeable amount.

[IvanT]

No disrespect but are u sure u have the daylight savings set correctly I didn't on my first outing and everything was out a lot?

I entered BST date time, i.e. I didn't subtract 1 hr to get back to GMT. When doing the Polar alignment I used GMT (at least I think I did). So on the SycnScan (I was out at 2300 BST) I entered 2300 as the time and confirmed that it was BST. On the Polar scope I would've used 2200 as the RA time off-set, is that correct? I certainly had Polaris in the little dot in the Polar Scope.

You may find the inaccuracies in your gearing/ drive train don't allow you to get good images with a 5min exposure without the aid of guiding corrections.

I'm hoping to find the boundaries of what my setup can do and then select my targets based on which will likely yield the best results if I stay within those boundaries.

I, already have a notebook and the SyncScan has an auto-guiding port, so I should be able to auto-guide without any more expenditure if it turns out I can't track reliably.

[Merlin66]

Hmmm

There's always addition expense....astrophotography is like that;)

You need a guide camera (and possible a guide scope) to send the required correction signals from the guide camera to the laptop and then onto the mount.

Depending on the guide camera, the connection cabling can be easy (!!) or complex (!!!!).

PHD seems to be the guide software of choice.

Ken

[MarkF]

Silly question maybe, but did you set the time zone as 0 then entered your current local time with daylight saving as yes?

[IvanT]

Silly question maybe, but did you set the time zone as 0 then entered your current local time with daylight saving as yes?

Yes, that's exactly what I did, should I have entered it as +1 as well as indicating BST?

[IvanT]

Think I've found the (main) problem, RA cog not installed correctly which has been mentioned on SGL in the past I believe. Thought I'd post an image of what I did wrong & how I fixed it.

Hopefully that'll be of use to others in the future.

Does that count as my 1st contribution

[IvanT]

You need a guide camera (and possible a guide scope) to send the required correction signals from the guide camera to the laptop and then onto the mount.

Oh goody, will you break the news to my wife

Ah well, Christmas is close

[MarkF]

Yes, that's exactly what I did, should I have entered it as +1 as well as indicating BST?

No you did it correct the way I understand it is the Daylight saving auto adds the hour for you and will only ask you when it is possibly in force.

Looks like you found your problem though

[IvanT]

Let's see what difference it makes tonight. Sounds like (from forum reading) that I need to also do PEC. Any thoughts on SkyWatcher 12.5mm Illuminated Reticule Eyepiece, are there cheaper alternatives that would suffice?

[IvanT]

Well, fitting the cog correctly seems to have done the trick. 3-Star alignment went a lot better and GoTo was in the ball-park for the objects I sent it to.

Managed to take a pic of Vega (after several tries with different settings), this was a single 2 min sub at ISO 800 prime focus (no photoshop processing as I don't know how just yet).

There is some drift that I'm hoping PEC (when I get the reticule) will help reduce.

Still, happy chappy right now, long way to go, but it's a start

[Digz]

Glad its all sorted. I was having awful trouble on Friday until I realised I wasnt aligning to the correct stars.

Nice shot of Vega too. I just shot this tonight to confirm my focus for M57 which Im in the middle of the darks for.

[Ben Ritchie]

Any thoughts on SkyWatcher 12.5mm Illuminated Reticule Eyepiece, are there cheaper alternatives that would suffice?

I have one, and it's a useful bit of kit - for alignment with bright stars I tend to use it with a slightly defocused star and the illuminator off though, so the crosshairs are seen in silhouette, as it's a touch on the bright side for me. Would say that it's from the older "no frills" Skywatcher style of kit rather than the newer, more polished stuff.

At one point I had a screw-in crosshairs filter-type thing which attached to any 1.25" eyepiece, that was much cheaper (few quid) and worked acceptably for alignment. Not seen them for sale recently though, but i'm sure someone will know.

[IvanT]

Thanks Ben, yeah I don't really want to go for the bells & whistles on the reticule just something that will help me correct the drift by reasonably good PEC training.