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Knighty2112

Celestron Nexstar 6/8SE Goto mount first light

29 posts in this topic

After collecting my new Celestron Nexstar 6/8SE Goto mount off Parallaxerr last Tuesday, I got a brief chance tonight earlier on to give it a brief first light. So, here is a brief summary of how things went. The scope I used on the mount was my Celestron 4SE Maksutov;

Setting up. Compared to my other Goto mount (Skywatcher Stardiscover AZ Goto mount), getting the mount levelled and set up was much easier. Trying to do this with the other Goto mount can take some time, especially when trying to fit the top Goto part to the mount itself in the dark, which requires a torch and some patience to get the securing screws located correctly. On the Celestron mount you can do this very easily, with notches in the top of the mount to allow easy alignment with the securing screws.

Alignment. As there were quite a few clouds in the sky, I went for the quickest alignment that the Celestron mount offers; one star alignment. Not expecting much after the initial alignment on Sirius, I was pleasantly surprised. After taking the tour option to look at some double stars, planetary nebula etc, all objects appeared in my 20mm EP fov. I then used the Constellation tour, and looked at objects in Auriga. M36, 37 & 38 fell nicely in the fov also.

Looking forward to doing a three star alignment as soon as weather permits, so I will do a more detailed report when possible. From just a brief hour session using just one star alignment if this mount can get most things in view doing just that then it should perform even better when a three star alignment is performed. :) 

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Do you store your mounts with the head separate from the base tripod? (not sure what you meant by 'Trying to do this with the other Goto mount can take some time, especially when trying to fit the top Goto part to the mount itself in the dark'.

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Posted (edited)

13 minutes ago, happy-kat said:

Do you store your mounts with the head separate from the base tripod? (not sure what you meant by 'Trying to do this with the other Goto mount can take some time, especially when trying to fit the top Goto part to the mount itself in the dark'.

No, I keep the mount and the top Goto part together, however I do need to take the top Goto part off the mounts to level the mounts with a small boat level, then re-attach the Goto head part. I am going to source a small button level that I can fit under the battery cover on the Goto mount that will hopefully mean that I don't have to separate the mount and the Goto head part to do this levelling.

Edited by Knighty2112

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If you use two star alignment did you ever try just setting the tripod as best as by eye and seeing how the GOTO responded accuracy wise?

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7 minutes ago, happy-kat said:

If you use two star alignment did you ever try just setting the tripod as best as by eye and seeing how the GOTO responded accuracy wise?

Two star alignment on the Skywatcher Goto mount was OK if you kept in the same area of sky, but got much worse when you went the further away from the initial alignment etc. This was regardless of how level you got the mount.

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The manual for the v3 synscan for AltAz does say pick stars within a certain distance of each other and alititude range, I guess that might then lead to less accuracy when a full 180 degrees away.

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27 minutes ago, happy-kat said:

The manual for the v3 synscan for AltAz does say pick stars within a certain distance of each other and alititude range, I guess that might then lead to less accuracy when a full 180 degrees away.

Yep. I need to try to an alignment with much further separation I guess. However, the Celestron Goto seems to have coped much better with just one star alignment, even when I then went to parts of the sky that where 180 degrees away from the initial alignment star Sirius. If that proves to be the case consistently then it will be the Celestron mount that will be my de-facto Goto mount from now on. 

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I'm glad to hear that your mount is performing well. I use my Nexstar SE for short exposure DSO astrophotography (FL≤700mm) , and I find it a reasonable performer, not perfect, but acceptable. May be the more refined EVO mount would be better, but it costs too much to consider replacing the SE, just to find out. I only ever do a 2-star manual alignment, with one of the chosen alignment stars near where I want to image. Normally I'd expect the mount to place the target pretty close to the centre of the frame and to keep it there for 2-hour periods. Normally! It doesn't always work like that, but I think that may be down to my inadequacies!

I like the fact that the tripod has a nice flat top which allows me to level accurately and easily in advance of needing it. I use a standard spirit level for that as I've found the cheap button things to be hopelessly inaccurate. It seems to me that for precision you need a bit of length to the level; the button devices have too small a foot-print, and are often attached by a sticky foam pad, which doesn't ensure parallelism to the mount surface. I agree, attaching the mount to the tripod is easy-peasey. I usually set the time from a time app on my tablet, like time.is, and I try to choose alignment stars separated in azimuth close to 90°, and avoiding those in a directly southern (or northern) direction.

I'm actually about to embark on getting a Starsense and seeing what it can achieve.

Good luck with your new mount.

Ian

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9 minutes ago, The Admiral said:

I'm glad to hear that your mount is performing well. I use my Nexstar SE for short exposure DSO astrophotography (FL≤700mm) , and I find it a reasonable performer, not perfect, but acceptable. May be the more refined EVO mount would be better, but it costs too much to consider replacing the SE, just to find out. I only ever do a 2-star manual alignment, with one of the chosen alignment stars near where I want to image. Normally I'd expect the mount to place the target pretty close to the centre of the frame and to keep it there for 2-hour periods. Normally! It doesn't always work like that, but I think that may be down to my inadequacies!

I like the fact that the tripod has a nice flat top which allows me to level accurately and easily in advance of needing it. I use a standard spirit level for that as I've found the cheap button things to be hopelessly inaccurate. It seems to me that for precision you need a bit of length to the level; the button devices have too small a foot-print, and are often attached by a sticky foam pad, which doesn't ensure parallelism to the mount surface. I agree, attaching the mount to the tripod is easy-peasey. I usually set the time from a time app on my tablet, like time.is, and I try to choose alignment stars separated in azimuth close to 90°, and avoiding those in a directly southern (or northern) direction.

I'm actually about to embark on getting a Starsense and seeing what it can achieve.

Good luck with your new mount.

Ian

Thanks! Got one of these coming from FLO today 

https://www.firstlightoptics.com/slt-series/celestron-skyportal-wifi-adapter.html 

Not only will this allow me to use my IPad to control the mount (just like the Evo mount I believe), also some users report that this makes the mount more accurate too. I also was considering to fit the Starsense too on the mount, but am going to hold out first to see how the Skyportal goes first. Yeah, I had a feeling that the small button spirit levels would be too innaccurate really, so may just carry on using the boat level to level up the mount. As it is much easier that the Skywatcher mount to do this this it is no real problem. Let me know how the Starsense camera goes. Cheers! :) 

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:icon_biggrin: that'll be my next purchase! I'll need an AUX splitter as well I think, if I am to use both wi-fi and StarSense together.

Ian

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Glad you're happy with it Gus. I found the auto two star with tripod levelled to be the best alignment routine, it's what I used for Alt/Az AP like Ian. I had the handset set for final goto approach up and to the right, so if you make your final adjustments in the same direction, GOTO's will be very accurate :)

I forgot to give you the synscan cable & USB adapter so PM your address and I'll post them up to you.

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37 minutes ago, The Admiral said:

:icon_biggrin: that'll be my next purchase! I'll need an AUX splitter as well I think, if I am to use both wi-fi and StarSense together.

Ian

Yes, I believe you do. 

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12 minutes ago, parallaxerr said:

Glad you're happy with it Gus. I found the auto two star with tripod levelled to be the best alignment routine, it's what I used for Alt/Az AP like Ian. I had the handset set for final goto approach up and to the right, so if you make your final adjustments in the same direction, GOTO's will be very accurate :)

I forgot to give you the synscan cable & USB adapter so PM your address and I'll post them up to you.

Thanks Jon. I'll PM my address for the cables. I got into the habit of doing the final approach to the objects when aligning to up and to the right on my other mount too, so followed that last night too. I'll try the two star alignment next chance I get and see how it goes, but if it's anything as good as the one star alignment also then I'll be well chuffed! :) 

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Great stuff, Gus!  I often use one-star and it does work well, esp. in the immediate vicinity.  Solar system align is good too.  But I usually use the two named stars method.  

FWIW I did try the WiFi control, but got fed up with holding a tablet and tapping a screen instead of touching real buttons.  And the connection had a habit of dropping out.  Just personal preference I suppose.  But the GPS Module is a great way to avoid bothering about entering date, time, and location.

Doug.  

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16 minutes ago, cloudsweeper said:

Great stuff, Gus!  I often use one-star and it does work well, esp. in the immediate vicinity.  Solar system align is good too.  But I usually use the two named stars method.  

FWIW I did try the WiFi control, but got fed up with holding a tablet and tapping a screen instead of touching real buttons.  And the connection had a habit of dropping out.  Just personal preference I suppose.  But the GPS Module is a great way to avoid bothering about entering date, time, and location.

Doug.  

Hi Doug. Yeah, heard some people didn't get on with the wifi connection well. Yet quite a few sing it praises too with no problems, so hoping to fall in the later category (fingers crossed). At least with FLO I get 30 days to send back if not completely satisfied. I should be able to use either my iPad Air or iPhone 6+ with the mount, so will see how it goes. :) 

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9 hours ago, Knighty2112 said:

Yep. I need to try to an alignment with much further separation I guess. However, the Celestron Goto seems to have coped much better with just one star alignment, even when I then went to parts of the sky that where 180 degrees away from the initial alignment star Sirius. If that proves to be the case consistently then it will be the Celestron mount that will be my de-facto Goto mount from now on. 

Further separation was for EQ, Skywatcher synscan was very specific for AltAz star selection distance range.

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2 minutes ago, happy-kat said:

Further separation was for EQ, Skywatcher synscan was very specific for AltAz star selection distance range.

In what way was it very specific for AltAz star selection distance range? Surely further separation would help the AltAz mount too along with the EQ versions too?

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It is in the manual for the handset, I can't quote the exact figures off the top of my head to post here and be accurate.

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My take on alignment is that the mount needs to adjust the 'tilt' of it's inbuilt celestial hemisphere map to match what you are observing, and for that it needs to calculate that tilt in two planes, at right angles to each other. If your alignment stars are around 90° apart in azimuth then I would have thought the mount gets the best information. Conversely, if the alignment stars are 180° apart in azimuth (i.e. in the same plane) then the mount won't get any information on the tilt in the plane at right angles to this, and the alignment won't be good. Interestingly, the Nexstar handbook advises "to select alignment stars that are as far apart in the sky as possible". I don't understand this advice, for the above reasoning.

That's my 2d worth anyway.

Ian

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To follow on from my previous comment synscan v3 manual pages 16 and 17, for Alt-azimuth mount:

• It is recommended that the altitude of the two alignment stars are between 15 and 60 degrees and the deviation of altitude is between 10 and 30 degrees.

• The azimuth deviation of the two alignment stars can be between 45 and 135 degrees, it is best to be close to 90 degrees.

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34 minutes ago, happy-kat said:

To follow on from my previous comment synscan v3 manual pages 16 and 17, for Alt-azimuth mount:

• It is recommended that the altitude of the two alignment stars are between 15 and 60 degrees and the deviation of altitude is between 10 and 30 degrees.

• The azimuth deviation of the two alignment stars can be between 45 and 135 degrees, it is best to be close to 90 degrees.

Thanks. I will try that next time I use the Skywatcher mount again and see if things improve with it. :) 

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Just a quick update on the Celestron Goto mount; was out again earlier for just under 2 hours. This time I did a full 3 star align, but connected up via SkySafari with the Celestron Skyportal wifi module I got through from FLO today. I have to say every object I viewed fell easily with the 20mm EP fov again, and managed to see a few things today that I've never seen too (if only I'd noted down what they where! Hehe!). Only issue I had using the Skyportal was it wouldn't let me view M81 or M82 due to been out of range, but this I think is a setting in the mount I need to change as they were close to zenith. However, I did also do a one star alignment without the wifi connection and the mount let me Goto M81 and M82 no problem that way, so will have to look into that. Overall so far I am extremely happy with the mounts performance so far from my LP battle zone in my garden. If I get this to a darker site I would have a field day! :) 

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I'm glad to hear it went well. I shall keep a watch on any feedback on the SkyPortal, but it is strange that you couldn't view M81/2 when using it, yet you could without using it. Perhaps it is a timing issue, where the target was within limits at one time and not at a different time? One can set slew limits with the Nexstar, under SCOPE SETUP/SLEW LIMITS, which is something I have to do because my OTA (102mm Altair Wave)  is long and can foul the base. Even if the target is within the altitude limit it sometimes warns me that it is not, but presumably that is because of the way the mount homes in on a target, which seems to be from a higher altitude. Also note that this feature doesn't restrict movement when one manually slews the 'scope, only with GOTO, unfortunately.

Incidentally, what 'scope are you using on it?

Ian

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Yep, check the slew limits as Ian says Gus. I set max alt to 60° when using the ST120. You can clear the limits if you're using the 4SE or any other scope that won't hit the base.

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31 minutes ago, The Admiral said:

I'm glad to hear it went well. I shall keep a watch on any feedback on the SkyPortal, but it is strange that you couldn't view M81/2 when using it, yet you could without using it. Perhaps it is a timing issue, where the target was within limits at one time and not at a different time? One can set slew limits with the Nexstar, under SCOPE SETUP/SLEW LIMITS, which is something I have to do because my OTA (102mm Altair Wave)  is long and can foul the base. Even if the target is within the altitude limit it sometimes warns me that it is not, but presumably that is because of the way the mount homes in on a target, which seems to be from a higher altitude. Also note that this feature doesn't restrict movement when one manually slews the 'scope, only with GOTO, unfortunately.

Incidentally, what 'scope are you using on it?

Ian

Currently using a Celestron 4SE Mak on the mount. I did check th limits on the scope and it was set for 90 degrees, so a little puzzled what the issue might have been to not allow me to view M81 & M82 via Skyportal.

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