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kirkster501

MESU/Sitech questions

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Hi all,
Powered up the MESU and so far so good.  Thanks for excellent guide by Steve Richards :)

A couple of questions please?  Could research this more but thought I'd quickly ask the SGL oracle first. The full Sitech manual looks pretty ferocious!

When first powered from new the mount clearly has no idea where it is pointing.  OK, I could use the hand controller, slew to a star and use a EP to center it then SYNC.  Same as with EQmod.  

However, I want to eliminate that EP bit.  I don’t want to be faffing with EP’s-  I want to plate solve.  So my mount at the minute has no idea where it is.  How do I seed the mount with a “start” position like I did with EQMod?  In EQmod I would have declutched, pointed the scope at the NCP, reclutched, resynced the motors and then did my first slew.  That process gives me my start point to slew from and it would often be quite accurate in the vicinity of the star I wanted to slew to.  I'd then plate solve and bob’s your uncle.

How do I do that in Sitech please?  How can I say to the mount “you’re starting from here" at the beginning of a session ?  The "here" being a known point in the sky? Again, I could do that with an EP but I want to do this via platesolve.  I know there must be a way to do this.  I see a lot of folks with this mount use SGP.  I have trialed that and it looks good but with EQmod and found it was an unnecessary extra step in my sequence.  With the MES/Sitech does SGP abstract the Sitech bit out?

Also, When you create the star model that is only accurate for the scope on the mount until you move it right?  Put on another scope, or even move the existing scope on the dovetail and the star model is no longer valid right?  Indeed, even f you have a dual scope side-by-side arrangement you’d need two star models right? Depending on which scope you were using because the model for scope A would not apply to scope B and vice versa?

Thanks, Steve

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With respect to pointing I guess you could try the following (warning: I'm think out loud from memory here so it might not work or may have it wrong!):

First you need to make sure the scope is tracking. Simply point the scope at the sky and do an Init offset. The mount should now track, although probably not very well. Then do a blind plate solve using the software of your choice. When the plate solve has finished you should get the "init offset" dialogue box from SciTech. Before you hit "ok" make sure the radio buttons at the bottom of the dialogue box reflect the direction your scope is actually pointing. Then hit OK.

When I first did it, I used the eyepiece method as I had no idea then how to use SGP. Nowadays I just use SGP to slew to my target, use plate solving to let it correct the scope to the right position, doing init offsets each time and then start imaging. So even if you do have to use an eyepiece for the first init, its a one time only operation :)

I haven't done a pointing model so I can't help you with that. I must get round to it sometime, but I'm not sure it will make a big enough improvement to be worth the effort.

Cheers, Ian

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SiTech has a Park function, so it can remember roughly where it is pointing. Its not tremendously useful though.

 

UnPark the mount, slew to a visible start of the sky, blindsolve and job jobbed. You can also issue a Sync to your planetarium of choice at this time. SiTech now includes platesolving from within the program (from version 0.90A), though you have to download the necessary catalogues.

"To use the powerful capability of the included PlateSolve2 program (Plate Solution Program, current version is v2.20), you will need to download one or both of the customized Catalogs it uses for a reference. PointXP5 (Mount Modeling Program, current version is v5.28) and PlateSolve2 are programs written and provided by Dave Rowe that are included in the Sitechexe installer and are automatically installed. Both of these programs are significant updates from the original programs that Dave also had graciously provided in earlier Sitech versions.
PlateSolve2 provides the capability to solve CCD images for their center coordinates, allowing you to perform Initializations by simply taking an image, or to build a model with the automated Scripting tool within Sitechexe. To use Platesolve2, you must download one or both Star Catalogs for use with the new PlateSolve2. The Catalogs are:

UCAC3 Catalog 411 MByte Zip File. Read more about the UCAC3 catalog at the US Naval Observatory. NOTE: This download is a customized much smaller version of the full UCAC3 catalog. The program will not run with the full catalog, so to use UCAC3 data, you must use this customized version
 APM Catalog 525 MByte Zip File. Custom Catalog that is unchanged from the version used with the earlier Sitechexe versions and PlateSolveXP.
c) Download one or both of the Catalogs (and a tip o’the hat to PlaneWave for graciously hosting them on the PlaneWave website download page) at:
http://planewave.com/index.php?page=4 Look for the PlateSolve2 download area, and download the catalog(s) that you want to use (the UCAC3 is highly recommended). There is no need to download the file PlateSolve2.exe, since the Sitech Installer will have already downloaded it and installed it for you.
d)Unzip the catalog(s) and place the files anywhere you choose (each catalog must be in its own folder however). Remember where you unzipped and saved them, since when you first open PlateSolve2.exe, you will need to use PlateSolve2's menu "File/Configure Catalog Directories" to point to the folders where you saved the unzipped catalog files." (from here: http://siderealtechnology.com/SiTechExeReleaseNotesVersion0.90.pdf )

 

Personally I use SGP because it integrates mount control, plate-solving, camera control, auto-focus, image capture and more into a single package. Harry's video above shows the concept, but it's now out of date as SGP now also uses PlateSolve2 from Plane Wave. Some of the dialogue boxes are different and the workflow is slightly different too.

See here: http://mainsequencesoftware.com/Content/SGPHelp/SequenceGeneratorPro.html?SettingupPlateSolve2.html

22 hours ago, iansmith said:

First you need to make sure the scope is tracking. Simply point the scope at the sky and do an Init offset. The mount should now track, although probably not very well. Then do a blind plate solve using the software of your choice. When the plate solve has finished you should get the "init offset" dialogue box from SciTech. Before you hit "ok" make sure the radio buttons at the bottom of the dialogue box reflect the direction your scope is actually pointing. Then hit OK.

When I first did it, I used the eyepiece method as I had no idea then how to use SGP. Nowadays I just use SGP to slew to my target, use plate solving to let it correct the scope to the right position, doing init offsets each time and then start imaging. So even if you do have to use an eyepiece for the first init, its a one time only operation :)

I haven't done a pointing model so I can't help you with that. I must get round to it sometime, but I'm not sure it will make a big enough improvement to be worth the effort.

 

Bang on :icon_salut: ^^ though the first line may not apply. My mount is set to start tracking as soon as it's unparked, so the first Offset Init is not needed.

A pointing model improves the pointing (the clue is in the name :icon_biggrin:) and GOTOs as it models the mount and telescope, polar alignment accuracy, flex and so on. I personally don't think that it's that important if you are blind-solving and autoguiding. Who cares about GOTO accuracy when you can blind-solve in under a minute? Purely visual observers may differ.

 

One thing that you definitely do not need is an eyepiece! To be honest, I can't even remember where my motley collection of EPs even is!

Edited by Zakalwe
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As above - great advice!

It is always a good idea to build a small sky model just to get you started. Point to a bit of sky to your east and plate solve then sync but stop the (default) Offset Init and click on the Offset CalStar. Swing to another two or the bits of sky (at least one in the west) scattered around and plate solve - sync - Offset CalStar those positions. The mount now has a rough idea of what is where as it has a small 'map'. Use the hand controller to move the mount to your chosen 'Park' position (I do this the conventional way of weights down and telescope up but very accurately so that I can engage the RA and DEC 'hooks'. Issue a 'Set Park' command followed by the 'Park' command and you now have a small map and a park position stored. At the start of the next session, ensure that the mount is still in the Park position, unpark it, issue the command to slew to your chosen object using your planetarium software, carry out a plate solve and issue an Offset Init then reissue the slew command to arrive right on target.

Think of CalStar Inits as setting the coordinates for the map and the Offset Inits as telling you where on that map you are. If you have a permanent installation, run that wonderful PlateSolve 2/PointXPscript built into SiTech and enjoy the magic of a fully automated sky model!

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The way that I understand the offsets is that SiTech has an internal sky map. Issuing an Offset Init just syncs the mount to the internal map. Calstar Inits are only used to build a customised skymap, pone that takes into account polar alignment error, tube flex, focuser flex, tracking rate errors, refraction errors and so on. This new map is stored and automatically loaded when SiTech is initialised. You still have to do an Offset Init to tell the mount where it's pointing in relation to the customised sky model. is that correct?

I don't bother building a sky model as an initial plate solve is easier. However that might need to be revisited if a sky model is deemed as necessary.

 

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I need to read up on this more guys, thanks for your inputs.  I am a big fan of plate solving.  I had my routine down to a fine art with the NEQ6 and EQmod but this is very much more involved with Sitech and MESU.

How does the mount know not to crash into itself when you do a blind solve and the mount has no idea where it is pointing because the MESU upper axis cannot spin 360 degrees??????  Do the encoders somehow know that in relationship to the body of the mount it is in position X and will not allow it to go too far?

The sky model is only valid if same scope on the mount?  Change the scope and the model would minutely change I would imagine....  Indeed, take same scope off, put it back on again and the model will still change because the scope has very slightly moved...?

Edited by kirkster501

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3 hours ago, Zakalwe said:

Personally I use SGP because it integrates mount control, plate-solving, camera control, auto-focus, image capture and more into a single package. Harry's video above shows the concept, but it's now out of date as SGP now also uses PlateSolve2 from Plane Wave. Some of the dialogue boxes are different and the workflow is slightly different too.

Thanks.  Many folks seem to use SGP so I have bought it too. I used the trial version but thought I could manage without it before....  I also want to use the mosaic tool (not bought that yet though - got enough of a learning curve to climb as it is!)

Edited by kirkster501

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17 minutes ago, kirkster501 said:

How does the mount know not to crash into itself when you do a blind solve and the mount has no idea where it is pointing because the MESU upper axis cannot spin 360 degrees?????? 

On your first time out with the mount, you can point it via the handset, and so make sure it doesn't crash. Alternatively mount the scope so it's approximately pointing at the pole. Plate solve this and do the init offset. Now the mount knows its location and from now on will know where it is, so long as it doesn't slip, get jogged, etc. After parking the mount remembers this information, so when you power on again the next time, it will know roughly where it is. It just requires another plate solve and init offset to properly refine its understanding of where its pointing (or to realign the pointing model if you have one).

You can set the SciTech controller with movement limits so it won't crash the mount.

Cheers,Ian.

Edited by iansmith
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Don't forget that once you set a park position then the mount has a rough idea where it is pointing. It will also "tell" that position to any planetarium- either an external one (Stellarium or Cartes du Ciel) or it's internal planetarium Skymap. What I do is power everything up, start SGP, load the observatory and equipment profiles and then hit Connect All. That fires up SiTech, PHD and so on. Open SkyMap (or CDC once connected), UnPark and then issue a slew command to a star from within the planetarium. Then go into SGP and do a platesolve. or just slew to the target, do a platesolve and sync and then re-centre.


You can also create a local horizon file which tells SiTech the height of your obsy walls/any trees/house. SiTech won't then allow a slew below this horizon. Anything that you did in EQMOD you can do in SiTech (and a lot more)...at teh end of the day they are both mount control software. Your startup routine in EQMOD (using an eyepiece, declutching and all that) looked a bit involved an laborious to me, to be honest. SGP will have you up and running in a fraction of that time.

You can also run a lot of the imaging routine from within SiTech itself. It can do plate-solving, auto-focus and rotator control. You also have a very powerful scripting capability for camera control, building imaging runs and so on.

31 minutes ago, kirkster501 said:

The sky model is only valid if same scope on the mount?  Change the scope and the model would minutely change I would imagine....  Indeed, take same scope off, put it back on again and the model will still change because the scope has very slightly moved...?

Correct. The PointXP models for tube flex, focuser flex and a lot more. Change any element and the model is obsolete.

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Thanks guys!  An invaluable mine of information is SGL! :)

I'm not worried about this, just trying get my ahead around the workflow.  Not had one even semi clear night since I mounted it last weekend.....  I also have to get it Polar aligned :help:  I've got a Polar Cam to help me with that .

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3 hours ago, kirkster501 said:

Thanks.  Many folks seem to use SGP so I have bought it too. I used the trial version but thought I could manage without it before....  I also want to use the mosaic tool (not bought that yet though - got enough of a learning curve to climb as it is!)

I was actually having a play with the mosaic tool last night and it just blew me away how good it is.  I love SGP anyway, but I was so impressed with how easy the mosaic wizard is, I love it even more now.

Hope you're enjoying the new toy :thumbright:

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1 hour ago, RayD said:

I was actually having a play with the mosaic tool last night and it just blew me away how good it is.  I love SGP anyway, but I was so impressed with how easy the mosaic wizard is, I love it even more now.

Hope you're enjoying the new toy :thumbright:

I would agree with the above as a long time SGP user.  The Framing & Mosaic Wizard may seem like another feature to learn when you already have lots to learn about your new mount, however, using the F&M tool will potentially save you some time and frustration when you start imaging with your beautiful new mount.  It is quite intuitive and a marvel to use for either a single pane or a mosaic.

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I use SGP Pro with my Mesu and it is really very straightforward.  I cannot add to Zakalwe's excellent post, so I wont even try.  I'm just posting to say that if you wanted to see my set up in operation, you would be very welcome.  (Of course I may not be using it optimally.)  I'm not sure, of course, if we are going to get a clear sky this decade, and, if we do, you may prefer to play with your toys than watch me playing with mine.

You did ask about different sky models for different scopes.  I believe that ideally you would do that.  However, I just have the one sky model (and I know it needs rebuilding because I've polar aligned since it was built).  However, the thing is working fine with the duff model.  I'll get round to doing it as some point, but if the sky ever clears I'll be imaging not building sky models.  (Don't tell steppenwolf!)

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Incidentally, just get the 'Framing and Mosaic' wizard.  It will make you purr with delight.

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You can automate the building of the SkyModel. Tell it how many Calstar points you want, press the button and stand back and watch it whizzing about. It'll take an exposure, platesolving it, record record the centre point and then move move to another point in the sky and repeat the process. Very satisfying and not a little amazing to see it in action.

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Have you managed to get Skymodel automation working via SGP, Stephen?  Last time I tried it nothing happened - but that was some time ago.

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3 minutes ago, gnomus said:

Have you managed to get Skymodel automation working via SGP, Stephen?  Last time I tried it nothing happened - but that was some time ago.

Not via SGP. I struggled with Nebulosity even though SiTech supports it. I ended up downloading a trial version of Maxim and it worked straight away. To be honest, I've had my head full of trying to get the mount to behave with the RA jumping problem. Now that I think that i'm seeing the light at the end of that nasty little tunnel I can get on with learning more about how the SiTech system works. Assuming that I ever get to see a clear night again!

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I have but I have to use Maxim Dl as the capturing software.

Make sure to check maxim DL box in sitech.exe config

It works like a dream.

Keep an eye on your wires to make sure they do not get caught in the mount during the run.

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I'll buck the trend here - I don't bother with a sky model. Just point and shoot.... so to speak :D 

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2 minutes ago, swag72 said:

I'll buck the trend here - I don't bother with a sky model. Just point and shoot.... so to speak :D 

Unless someone says otherwise I can't see the point of one when imaging with autoguiding. If you are visual only then there'd be a big improvement in GOTO pointing accuracy and tracking (would a visual user have a Mesu?).  Maybe for unguided imaging, but who could be bothered with all that faff?

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3 minutes ago, Zakalwe said:

Unless someone says otherwise I can't see the point of one when imaging with autoguiding. If you are visual only then there'd be a big improvement in GOTO pointing accuracy and tracking (would a visual user have a Mesu?).  Maybe for unguided imaging, but who could be bothered with all that faff?

I don't know.  I think the SkyModel has an effect on tracking.  If so, is it possible that an inaccurate model (or no model) could cause the mount to move offline, requiring a guiding correction that otherwise might not be needed and, thereby, reducing overall guiding accuracy?

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Just now, gnomus said:

I don't know.  I think the SkyModel has an effect on tracking.  If so, is it possible that an inaccurate model (or no model) could cause the mount to move offline, requiring a guiding correction that otherwise might not be needed and, thereby, reducing overall guiding accuracy?

I could see that. I guess that the mount should track at sidereal rate, rather than try to correct a bad tracking rate with a sky model?

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I did use a model for a time - I saw no improvement in guiding and so didn't bother after that

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Just now, swag72 said:

I did use a model for a time - I saw no improvement in guiding and so didn't bother after that

I am sure your right.  But then what is the point of the model?  

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