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Additional Help Needed H-a Imaging With AVX Mount

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#1 fjwallace


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Posted 06 August 2020 - 07:28 AM

I appreciate all the help I got a couple of weeks ago. I finally had a chance to try out your advice.
I set-up the mount during the day to capture a large prominence, adjusted Alt to my latitude, leveled it, and oriented it to true north using a good compass and then checked with an app on my cell phone. Everything seemed spot-on. Moved the Ra and Dec to line up the marks and started the unit up. I set-up time and date, etc. and typed in my latitude and longitude. Then it forced me to do an alignment so I chose 1 Star (the Sun was not enabled and I couldn’t get passed this step). After the ‘alignment’ I turn on the Sun and went to Solar System and chose Sun. It slewed but ended up upside down and quite a bit off the object (about 30 degrees!). Now that the Sun was enabled, I decide to turn everything off and try again. I chose Solar System for alignment and went to the Sun and it was off again but at least oriented correctly and only off in RA (about 15-20 degrees). I decided I wasn’t going to get any better that day and loosened the RA clamp and moved it and hoped the Solar Tracking would be close. The tracking was OK but moved a fair distance and I had to keep re-positioning.
So, finally my question, does anyone know what I might have done wrong or have any other suggestions for getting this to work properly? Do I need to do a nighttime alignment before it will work for daytime use?
Thanks again for any help you can give me!

#2 Michael Covington

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Posted 06 August 2020 - 08:01 AM

To get accurate tracking, you need accurate polar alignment.  That explains why the tracking was poor.  You'll probably have to align at night to do well enough.   

To rule out the obvious, did you account for the difference between magnetic north and true north?

Now as to the slewing to the wrong place and ending up upside down -- Look for a major error in the mount's knowledge of your location, time zone, or time of day.  If there's none, I suggest resetting the mount to factory settings and starting over.

#3 sg6



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Posted 06 August 2020 - 08:20 AM

15 degrees is generally the DST option. Although I notice that a few sites are giving the wrong timezone. Saw one today for me that said my Timezone was BST. There not a BST timezone. My Timezone is UTC 0 and then I have to state that BST is operating.


I did notice similar on a Utah "timezone" last week. Instead of giving the actual timezone the site gave the one next to it. So wrong. As you have no location cannot suggest the correct data for you.


Afraid that goto's require data and for others to suggest the correct your location is required.


If you didn't add a timezone then Celestrons used to default to Pacific, UTC +10, I believe. Once data is added the system appears to perform calculations and fill variables. What it doesn't seem to do is clear and over write when new correct data is supplied and as Michael says a reset is usually required.


Celestron usually want data added as Longitude, Latitude, Timezone. People talk of Latitude then Longitude so get the values round the wrong way. In the UK quite a few end up thinking they are around the equator and 50-55 degrees West. Somewhere in Brazil I think.

#4 MalVeauX



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Posted 06 August 2020 - 08:36 AM



The only two things you need in an EQ mount for solar:


1) RA tracking

2) Solar slew rate (its not the same as side rail and lunar)


Very best,

#5 fjwallace


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Posted 12 August 2020 - 08:14 AM

Thank you all for your replies. I will try to get out at night and check my polar alignment. I did adjust for magnetic declination and checked using an app to be sure. I may have input the DST wrong but I looked it up. Anyway, thanks for all the ideas to check. When I have a clear sky I will try some of these and hopefully that will fix it.

Take care and stay safe!


#6 walkman


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Posted 12 August 2020 - 07:37 PM

Hi, fjwallace,


I have an AVX that I use for solar without setting up the night before.  I do know where Polaris is relative to some landmarks and I just visually align the mount in the daytime as close as I can.  The trick to use the Sun for Solar System Alignment is that you have to enable the Sun in the Sun Menu within the Utilities Menu.  Click Enter on the Sun Menu and you will have the option to have the Sun available for Solar System Align.  It is not enabled by default for safety reasons.  Once enabled it will still warn you to use proper filtering but clicking Enter will  slew to the Sun.  Or where it thinks the Sun is.  Use one of the Sol-Searcher type non-visual finders, put the small bright dot in the proper position on the screen and you should be pretty close.  Do the final align just like any of the night time aligns-Enter when in "finder", Align when in center of eyepiece.


You only have to enable the Sun once, then it is always an option in Solar System Align.  You can disable it in the Sun Menu later if you decide to not have it be an option.


Hope this helps.



#7 FlankerOneTwo


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Posted 15 August 2020 - 05:58 PM

Fortunately you don't really need Goto for solar; just point the mount/scope at the sun manually and turn on tracking. Helpful if you know how to set solar tracking rate, but not 100% essential. If you are imaging at high resolution then tracking accuracy is helpful, but for full disk or imaging specific small (relative to field of view) it's not a huge deal to just keep bumping the buttons to keep the sun or ROI centered in the view. As usually one would image by stacking video with exposures of only a few milliseconds, this doesn't cause any problems.


If you image from the same location as night, definitely align at night and mark the tripod foot locations. My front porch pavers point true north/south; I just visually align the  RA axis with the stones, level the tripod, and call it good.

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