Trouble with Centering

I’m having a lot of trouble centering the scope to complete plate solve. I read a bunch this morning and will check into some of what I read but have a quick question.

Typically I align my NEQ6 mount to 3 stars with stallarium and EQMOD. The last few nights I just synced on one star and used SGP to slew to my target and plate solve. It put the target pretty much dead on but failed to center.

Is it my understanding that I need to have at least 3 points synced in for it to center? Or can I just shoot a picture of the parked position, plate solve it and then tell it to slew to target and plate solve?

Lastly. If I use an image I shot the night before in Ha can I use that image to set up my frame and mosaic target data since the program is set to use the LUM filter for plate solving?

I’m not sure how the NEQ6 works, but typically you do not need to do a
3-point alignment (or any star) at all. Just slew to some part of the sky
(I typically go in the east), and choose “solve and sync”. SGP will take
an image, plate solve, and sync your mount position to the sky. It helps
to be well polar aligned.

I don’t understand when you say “It put the target pretty much dead on but
failed to center.” If your target is “dead on” then didn’t it center?

You can use any image you want for your target coordinates (Ha, lum, red,
OIII, whatever). Open the image up in SGP, right click and choose plate
solve. When the solution comes up just tick the option “Use these
coordinates for target 1” (or something like that). BUT, you shouldn’t
need to do that at all. If you used the F&M Wizard and saved your
sequence, then the target coordinates will still be there the next time.

Yeah I get ya. Thats what I have been doing. I initially used an image of the Crescent Nebula from Astrobin for my Frame and Mosaic. However the nebula was not centered in the shot. So when I right clicked on the center of the nebula and told it to center there, it slewed the scope a bit and performed its plate solve but failed both times on the centering.

I then got an abort sequence for failure to center and kept having that issue.

My SkyWatcher NEQ6 mount is always down to the right of target unless I take the time to align it and sync it in eqmod in order to dial it in. So if I tell sgp to initially to slew there without performing that sync and align procedure prior to doing it. The target is going to be way off.

I can deal with that. But why it won’t center when all it is doing is moving a half a degree or so is my confusion.

I’m sure its me. No I’m positive its me!!!

But I gotta figure it out because it’s the only thing separating me from a great SGP Automated Experience! ha ha

I have a similar issue. I almost always fail to plate solve an image from my library. I have just tried again; opened up a very good 1200s sub of the North America Nebula, right click, plate solve…fail, every time. I tried with Ha, SII and OIII images and the same thing. I use Pinpoint with a blind failover and checked all settings and fine.

Pinpoint works some of the time but certainly not all. I’m using the USNO library which is on my route drive.

Sean, I wonder if your issue is a difference between JNOW and J2000
coordinates? They are slightly different and I “believe” SGP expects
J2000. So if your mount is JNOW that could account for the consistent
off-center down to the right thing. I’m not positive about that though…

I’m not sure what the mount is doing. I do know that there is a box for J2000 overlay in the Frame and Mosaic portion that is unchecked. Should that be checked?

Ray, mine is solving the image I shot but failing on the centering. I was going to try Pinpoint tonight instead of Plate Solve 2 but I hate to cause another problem when PS2 solves it in under 4 seconds.

Thanks Joel I’ll check on the mount. Let me know if I need to check that box.

What is the check box for J2000 Overlay for in the Frame and Mosaic Module? I have that unchecked but when I go to the help screen and pull up the module it is not in your help files.

I checked EQ ASCOM Setup and it is set for J2000

Probably not, most GEMs have cone error and syncing while pointed at the pole will likely make your mount get very lost.

It puts a grid over the top of the image with RA/Dec lines for reference. It has no bearing on your ability to solve and sync or center.

What do you have these values set to?

Also a log would be helpful as well. See here:


2, 10 and 3.0

I’m not sure why it is 10 I changed it back to 50

10 is likely too restrictive. What is your pixel scale? 50 is probably
better. I’d set the tries to higher than 2, at least while you’re


Jared Wellman
– Co-Founder and Developer

50 worked like a charm. Problem solved. Thanks everyone for your help big time

My pixel scale is 130

What camera, OTA, and reducer are you using to have a pixel scale of 130. Are you sure of that scale? This is a link to calculating your pixel scale…methinks this could be contributing to your problems.

Yes I left out the decimal point sorry. It’s actually 1.31 for the ED102 and 4.54 pixel size of the ATIK 460.

So what kind of Nikons are you shooting. Ive been shooting the D750 and D810.

I have two that I use for “Up Photography, a Nikon D800e that was modded by Spencers with both Ha and a head reduction system. I also made the insane decision to buy the D810a when it was released. The modded D800e, with the heat reduction system, was all that I needed when using a DSLR.

I bought an Atik 383L mono two plus years ago and just recently added the ZWO ASI1600MM-c and really really like this camera. Incidentally, I never was very pleased with my Atik….that camera and the D810a are two of my many spending blunders as I traversed the “upshooting” learning curve.

I am totally dependent on SGP. Not to sure I would want to go back using ATP or Backyard EOS for Nikon plus Astrotortilla again.

RayD, if your images are bin 1x1 and plate solve is set to 2x2,3x3, etc, it may not solve. It happens to me when I forget. Someone correct me if I’m wrong.

I hear ya. I did the same thing with the D750. Got my 810 off KEH for about what I paid for the D750 new.

I am waiting on my ASI1600mm mono to come in right now. So far I like the ATIK but I am looking forward to the larger sensor in the 1600.

I hooked on SGP as well. Still trying to work out some minor details but I’m getting there. This plate solving one was one of them. I’m on a NEQ6 mount through EQMOD and Stallarium but would like to move up to a bigger mount. I need to figure out where I want to go and what effects it will have with SGP. I’m guessing not much. EQMOD might be a different subject. .

I have several mounts but my preferred mount is an Orion Atlas Pro EQ/AZ mount. The biggest reason - EQMOD. It is a good but not great mount…it is sort of on the high end of the budget mounts - I have tons of backlash but have figured out how to make that a non issue with PhD2. EQMOD does not interfere with the SGP software’s behavior in any way.

My best performing mount is the IOptron ZEQ25. It is cheaply made budget mount that has a 30 lb max load limit but this little jewel is a guiding miracle. I can carry it with one hand plus tripod. Great to take when traveling. Before I bought the Polemaster by QHY to handle PA, I would use the PA routine in PhD2 and I always got my best results with the ZEQ. I also have a Celestron AVX and consider it as worthless as the Atik camera. The ZEQ can handle a larger payload than the AVX and can out-guide it.

I haven’t used a hand controller in so long I would have to re-read the directions on how to use……the same for star alignments. I stopped doing those when i found Astrotortilla ….and two years ago added SGP.

When I first started out - I used the AVX, I would sometimes spend 2 hours doing a star alignment and PA……by the time I was ready to image - I had lost so much time - not to mention I would occasionally bump the mount and have to start over. Also, I didn’t know a lot of the alignment stars and I know that I aligned on the wrong star more than once. Making the entire routine a bust. The AVX, when PA and balanced never centered the target on it’s best days…

BTW, I think we will end up really liking the ASI1600MM-C. I haven’t used it much but the results so far are exciting.

Have a great week, for me, it is going to rain every afternoon through Sunday and cloudy skies when not raining. But that is life in the southern US during the summer. The nights are so short, hot and humid, that imaging is a challenge without clouds and rain.

You pretty much described my exact history. I also bought into the AVX and it is still sitting in the other room unused. I jumped to the NEQ6 shortly after when I realized my error. Tried to sell it a few times but decided in the end to make it a second rig. I actually bought a used C8 and Hyperstar for it with the ZWO 071. I figured if it had problems with guiding that the HS would help it out with the short exposures.

I have not really had any problems with EQMOD other than it shut down once or twice during an imaging session, but then SGP has done that too. I also have astrotortilla and have tried it once or twice and it seems to work fine. I just got used to Stellarium and have not taken the time to learn it.

I just bought the new Ioptron Sky Guider which is a fun grab and go tool. They installed a ST4 guide port on it and made it into an EQ type mount. It is able to carry an 11 pound payoad and works remarkably good. I got some 10 minute exposures of the Lagoon Nebula the other day and was pretty surprised at its abilities. That’s going to be my throw in the car for Gulf Shores Beach trips.

I added the pole master a month or so ago and love it. Last weekend I had a 0.1 error on my PA from that thing. Thats nuts.

We have rain here is well. You must not be to far from me. I’m in South Louisiana. I walked out last night and couldn’t believe the skies were clear. Missed out.