Getting the Tripod pointing toward true north #EXOS2 #polaralignment


Timothy Myers
 

I have read and watched so many videos on this subject that it makes my head spin. Many people use their phones to find true north. Mine is so horribly incorrect that there is no way it could be used with any confidence. As an example, I know which direction North is at my office desk, at least within a few degrees. I have tried about 10 different compass apps realizing that they are all using the hardware in my phone to find north so none are that much better than others. Still I tried to find the least bad app. Thinking about this at work today I got the phone out and the least bad app is swinging 30 degrees back and forth. I realize there is probably metal in the office that is messing with it but there is metal in the tripod and mount that will also mess with it.

I realize the tripod needs to be pointing as close to true north as it can be which points me to two questions.

1. What are others using as a point or reference for true north?

2. Hoe much swing is there in the azimuth adjustment of the EXOS tripod?


--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


bill rowe
 

Polaris is really easy to spot at night tracking from the lip of the big dipper.  There's really nothing near it that's very bright.  Even if you can't see much else in the sky the dipper and polaris are pretty prominent.  

I also find phone compasses pretty useless unless you're in a spot that's clear of metal and overhead wires.  People seem to use PSAlign Pro with success but that's on the same phone hardware.



From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> on behalf of Timothy Myers <tim_s_myers@...>
Sent: February 18, 2020 3:43 PM
To: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io>
Subject: [ESPMC-Eight] Getting the Tripod pointing toward true north #polaralignment
 
I have read and watched so many videos on this subject that it makes my head spin. Many people use their phones to find true north. Mine is so horribly incorrect that there is no way it could be used with any confidence. As an example, I know which direction North is at my office desk, at least within a few degrees. I have tried about 10 different compass apps realizing that they are all using the hardware in my phone to find north so none are that much better than others. Still I tried to find the least bad app. Thinking about this at work today I got the phone out and the least bad app is swinging 30 degrees back and forth. I realize there is probably metal in the office that is messing with it but there is metal in the tripod and mount that will also mess with it.

I realize the tripod needs to be pointing as close to true north as it can be which points me to two questions.

1. What are others using as a point or reference for true north?

2. Hoe much swing is there in the azimuth adjustment of the EXOS tripod?


--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Harry
 

Tim, have you tried the iPhone app Polar Scope Align Pro. It has a compass as part of it, but you can also use the “Daytime” function for rough polar alignment for day or night use if you can not see Polaris. It has a few other functions that I think are very helpful. However I do use a small wood “holder” with no metal parts to cradle the phone when I mount it in my iExos 100.
--
Harry
Vero Beach, FL
Scopes: ES  ED80CF, ES AR102,  Meade ETX 90 EC (Deforked)
Mounts: ES iExos 100-PMC Eight, ExploreStars IPAD & Fire HD8, Explore FirstLight EXOS Nano
Nikon D600, D5500


Dan Ward <warddl01@...>
 

I use Polar Scope Align Pro.  To avoid mount magnetic distortion, I cut a piece of wood 2’ long, the same width as the mount bracket.  Put a perpendicular cleat near the end to square my phone.  

On Feb 18, 2020, at 4:25 PM, Harry via Groups.Io <flykai1@...> wrote:

Tim, have you tried the iPhone app Polar Scope Align Pro. It has a compass as part of it, but you can also use the “Daytime” function for rough polar alignment for day or night use if you can not see Polaris. It has a few other functions that I think are very helpful. However I do use a small wood “holder” with no metal parts to cradle the phone when I mount it in my iExos 100.
--
Harry
Vero Beach, FL
Scopes: ES  ED80CF, ES AR102,  Meade ETX 90 EC (Deforked)
Mounts: ES iExos 100-PMC Eight, ExploreStars IPAD & Fire HD8, Explore FirstLight EXOS Nano
Nikon D600, D5500


Robert Babb
 

Hi Tim,

 

I have not tried to set up my new to me iEXOS-100 yet, but this evening it looks like it’s going to be clear here in my part of the world so I hope to try it out.

I figure I’ll have to read an article I saved to my laptop about how to set the mount to “home” and adjusted for my latitude, also get the mount to “think” it’s been polar aligned, or maybe once homed it already “thinks” it is polar aligned, I’m not sure on that point.

Anyway if I can get to that point then if I carefully adjust the tripod so that it’s level and so Polaris is in the field of view of the scope using a medium power eyepiece then all should be good to go. This is because Polaris is less than a degree out of true north.

 

Robert Babb  

 

Sent from Mail for Windows 10

 

From: Timothy Myers
Sent: February 18, 2020 5:13 PM
Subject: [ESPMC-Eight] Getting the Tripod pointing toward true north #polaralignment

 

I have read and watched so many videos on this subject that it makes my head spin. Many people use their phones to find true north. Mine is so horribly incorrect that there is no way it could be used with any confidence. As an example, I know which direction North is at my office desk, at least within a few degrees. I have tried about 10 different compass apps realizing that they are all using the hardware in my phone to find north so none are that much better than others. Still I tried to find the least bad app. Thinking about this at work today I got the phone out and the least bad app is swinging 30 degrees back and forth. I realize there is probably metal in the office that is messing with it but there is metal in the tripod and mount that will also mess with it.

I realize the tripod needs to be pointing as close to true north as it can be which points me to two questions.

1. What are others using as a point or reference for true north?

2. Hoe much swing is there in the azimuth adjustment of the EXOS tripod?


--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7

 


Timothy Myers
 

Harry,

I don't have an i-phone but instead an Android. I am able to download the app but it doesn't look or functi0on anything like the videos I have seen on it.
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Timothy Myers
 

Robert,

I was planning to get the tripod out tonight and see if I could get Polaris in the PA Scope but at almost 2200 the clouds still have it obscured. Since I have been using an Alt Az Celestron with Star Sense I haven't needed to see Polaris to align my scope. First I am trying to just figure out where in my driveway I need to be to miss the trees to my north. In the driveway I can easily mark locations for the three legs of the tripod and get it pretty darn close.

Our club has a Dark Sky Observatory that I will eventually get to and I am hoping the practice at home will make setting up easier when at the Dark Sky Site.

An update on my phone Compass is that it worked much better at home than it has in my office, but I feel kinda silly making figure eights with it to calibrate the compass.
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Robert Babb
 

Ya someone might think you have a problem watching you do those figure eights!

Isn’t that StarSense a nice accessory, I have one too. But if I get plate solving set up and working I wouldn’t need it any more.

Well I never got out with my iEXOS-100 tonight even though it was clear, I spent the best part of my evening going through the exercise in my dining room to set the polar home and I’m pretty sure I got it to work. I’ll do it again next chance I get then I’ll mark both axis so I won’t have to go through the exercise of finding polar home anymore.

It will be simple once marked, just line up the marks manually on both axis and polar home is done!

As well I’ll level the tripod and mount in my backyard next clear night and move the tripod until polaris is in view in the 80mm scope at a medium power, then mark the tripod leg tips in the ground.

Once that’s done all I need to do to set up in my yard would be to place the tripod on the marks on the ground, make sure the tripod and mount is level, line up the marks on both axis for polar home, power the mount and connect the serial cable to my laptop running ASCOM. I can then use my planetarium program, autoguiding, and camera control.

At least that’s the plan.

 

Robert   

 

From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> On Behalf Of Timothy Myers
Sent: February 18, 2020 11:23 PM
To: MAIN@ESPMC-Eight.groups.io
Subject: Re: [ESPMC-Eight] Getting the Tripod pointing toward true north #polaralignment

 

Robert,

I was planning to get the tripod out tonight and see if I could get Polaris in the PA Scope but at almost 2200 the clouds still have it obscured. Since I have been using an Alt Az Celestron with Star Sense I haven't needed to see Polaris to align my scope. First I am trying to just figure out where in my driveway I need to be to miss the trees to my north. In the driveway I can easily mark locations for the three legs of the tripod and get it pretty darn close.

Our club has a Dark Sky Observatory that I will eventually get to and I am hoping the practice at home will make setting up easier when at the Dark Sky Site.

An update on my phone Compass is that it worked much better at home than it has in my office, but I feel kinda silly making figure eights with it to calibrate the compass.
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Skull HQX
 

I have noticed my iEXOS 100's metal isn't really magnetic. So any phone's MEMS (magnetic field) sensors shouldn't be bothered too much. Or a classic compass. Be aware of where your compass is pointing, true magnetic north or geographic north. They are something like 500 kilometers apart, so depending where you are located it could mean a degree or so.


Robert Babb
 

Hi, if using a true compass you can look up your area’s offset from true north and compensate for that with the compass.

I think the phone indicates true north meaning it auto compensates as it has the programming to do that, better double check that though.

 

Robert

 

 

From: MAIN@ESPMC-Eight.groups.io <MAIN@ESPMC-Eight.groups.io> On Behalf Of Skull HQX
Sent: February 19, 2020 5:31 AM
To: MAIN@ESPMC-Eight.groups.io
Subject: Re: [ESPMC-Eight] Getting the Tripod pointing toward true north #polaralignment

 

I have noticed my iEXOS 100's metal isn't really magnetic. So any phone's MEMS (magnetic field) sensors shouldn't be bothered too much. Or a classic compass. Be aware of where your compass is pointing, true magnetic north or geographic north. They are something like 500 kilometers apart, so depending where you are located it could mean a degree or so.


Jennifer Shelly
 

Have tried using an actual compass?  I use a Suunto MC-2 compass that works well for me.  I had adjust it for a the declination/offset for my location and I have zero view of Polaris.
--
Sincerely,

Jennifer Shelly
AstroPorch, VA

Mounts
: ES PMC-8 G-11, ES PMC-8 EXOS-2
Scopes: ES ED127 FCD-100, ES Levy Comet Hunter, ES N208CF, QHY Mini Guide Scope, Solomark F60 Guide Scope
Cameras: QHY128C, QHY168C, Nikon D5600
Misc: MoonLite CFL 2.5 / High Res Stepper / V2 Mini Controller, Baader SteelTrack NT / SteelDrive II, Baader UFC, Optolong 2" L-Pro / L-eNhance
Imaging Software:  APT, BYN, SharpCap Pro, ASICap
Processing Software: PixInsight, Lightroom, Premiere Elements


 

Skull,

I have noticed my iEXOS 100's metal isn't really magnetic. So any phone's MEMS (magnetic field) sensors shouldn't be bothered too much.
Ah, but as Wes pointed out in another post - the motors will be, when the mount is powered on... 
 

--
Mounts: ES PMC-8 EXOS2
Scopes: SV 102EDT, ZWO 60/280 Guide
Cameras:  Nikon D5300, Altair GPCAM2-IMX224C
Software: ASCOM, CdC, AstroTortilla, BYN Pro, Sharpcap, PHD2
Computer:  Thinkpad x230, Win7Pro/64


Wes Mcdonald
 

Right. Do your mount north alignment and mount alignment with the mount unpowered.

Wes

--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Skull HQX
 

All true, however I have not noticed my iPhone's compass to really change a lot when near the mount. I'm also not sure how large the stepper motor's magnetic field will be.

Apple's standard compass app can be switched regarding true north and geographical north.
However I usually force it to recalibrate before usage. Otherwise my experience is it can be off by -a lot-.  


Kent Marts- Explore Scientific Customer Service
 
Edited

Here's a process I've used. I don't link using a phone app because of what seems to be an innate inaccuracy -- good enough for general use, but NOT for an application where accuracy is important.

Get an old-fashioned yardstick (meterstick for our non-USA users) and a compass with a base plate. For this to work you must know your magnetic offset. I use https://www.ngdc.noaa.gov/geomag/calculators/magcalc.shtml

For Springdale, Ark., here at Explore Scientific, the offset is 1.19 East.

1) I set the offset on the compass base plate, then line up the yard stick on that north-south line. 
2) Place the tripod's north leg at the end of the yardstick -- being careful to not move the yardstick.
3) Position the tripod's southeast leg and southwest leg evenly away from the yardstick. I use a tape measure to get them as evenly away from the yardstick as I can.
4) Level the tripod.
5) Verify that the tripod remains aligned north and the southeast leg and southwest leg remain even.
6) If your mount's latitude has been previously set, then you MAY have decent polar alignment.
7) Use the app PS Align Pro to determine the hour-angle of Polaris. Move the mount -- NOT THE TRIPOD -- to get Polaris into the correct spot. If you're using the iEXOS-100, get Polaris just inside the polar peephole.
8) If you're doing astrophotography, use the Robert Vice drift alignment method to check how close you are. https://www.cloudynights.com/articles/cat/articles/darv-drift-alignment-by-robert-vice-r2760
9) Adjust azimuth and altitude as needed to fine tune.
10) Having the Azimuth Adjustment Adapter for the iEXOS-100 makes fine tuning much easier, but I've done it without that device.

Kent Marts
Customer Service
Explore Scientific




Wes Mcdonald
 

Kents method is a good one, but too much trouble for me.  

The EXOS2 motors basically nail the phone compass to a fixed orientation if they are energized.  I know this.  With them off I find the compass plenty good enough for my purpose.  This purpose is to achieve a decent orientation relative to polaris so that my polemaster alignment has an easy time of it.  The polemaster BTW mounts nicely on the finder scope hole in the EXOS2.  For those with an IEXOS Mike Leemhuis combination polemaster mount and mobile phone tray will serve well (https://www.thingiverse.com/thing:3642636).  Note the polemaster does not require the DEC offset to be zero, so you can use this on your Exos products with no need to worry about polar home (except you need polar home to get good GOTO performance, just as you will need good level (assuming you are not doing the 2-3 star alignment via Explorestars, which correctly solves for tilt/tip, polar alignment and RA polar home error, but will still have issues with DEC home and cone error -- cone is taken care of in the alignment for the three stars used but its impact is felt elsewhere in the sky -- so even with Explorestars alignment I recommend you get a level mount and a good polar home for the best GOTO performance with Explorestars)

One thing the phone app is really good at is alt adjustment of the EXOS2.  It is usually very close to the correct value.  Azimuth swings on my iPhone are about +- 3-4 degrees, so I also use my known NCP facing alignment points to verify.  And I sometimes let the oscillation happen to see where the center point is.  All of this gets me in great position for Polemaster.  

Another thing you can do is to get a good polar home position with your mount and telescope.  At some point in time prior, get your finder scope or red dot bang on collimated with the scope.  Then after getting polar home set, Dial in polaris in the correct position relative to the center of the guide scope.  Imagine the guide scope has a ring around its center at 48 arc minutes displacement (A telrad or a Rigel red dot has a reticle that would give you this).  Then find the hour angle of Polaris, which will tell you where around the circle polaris should be.  Then adjust the AZ and Alt bolts of the mount until polaris is there.

Dr Clay Sherrod has a document out there, the Kochab Clock (http://arksky.org/Kochab.htm).  It ha an interesting method for polar alignment, but in particular it has a section on how to use your finder scope to place polaris in the correct position.  Note Polaris orbits around the pole, so it will already be in the correct clock position I think (if we are in polar home) so all we really have to do with our PMC8 mounts is adjust the Az and Alt bolts.

In the end though, if you are doing astrophotography with these mounts you should be using serial ASCOM.  With a camera you should also use plate solving.  Plate solving removes goto error automatically, so it removes the hardship of establishing perfect polar home position.  You still need to get the RA axis polar aligned so you can track well, but after that you have nothing to worry about -- including level or DEC home error.  And while you are at it, you should also look into guiding.  With these adds, these mounts will perform like rockstars on a  cost/performance basis.

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired


Timothy Myers
 

I am hoping tonight will be a good night to get out and sty to get things set up. Clear Outside, is showing good sky tonight. I will let you know how it goes.
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Timothy Myers
 
Edited

OK, here goes.

The skies did not cooperate as much as they could have, but I got out early and set the tripod + mount in the driveway. Someone had mentioned Polar Scope Align Pro. I had tried this app earlier and could not get it to work. Since is was a paid app I immediately clicked for a refund. I decided to try it again and contacted the author. This time it worked. Since the EXOS has the vixen mount I can't set the phone inside the jaws of the mount but had to hold it up against one side at an angle. The Altitude seemed to work but the Azimuth, not at all. Is was all over the place. I pulled it away from the metal head and it started to react more normally. Yes I did some figure eights with it!!!

Anyway I looked around the garage and found a yardstick that was about the same width as the vixen mount and lightly clamped it into the mount, held the phone up against one edge of the yardstick (not very scientific), and it seemed to work. I got everything as close as I could, marked the location of the legs on the driveway and put the setup away as we were going to my daughters to play cards.

Returned about 2100 and I moved the tripod back to my marks. When I uncapped the Polar Scope I saw a very faint star I assumed was Polaris in the lower right quadrant of the Polar Scope but then it faded. I looked up to see high clouds. Rather than freeze, I went inside for 20 minutes and went back outside. After about 10 minutes I looked up, saw a break in the clouds and also saw Polaris shining brightly. It was still in the lower right quadrant so I started to adjust Altitude, and chased a beginners mistake of forgetting everything was mirrored. No matter how much I lowered the Altitude, Polaris moved farther down. Figured out my mistake and raised the Altitude moving Polaris up a bit, set the HA on the setting rings of the Polar Scope, and was able to get Polaris nicely centered in the etched circle of the Polar Scope.

Some take-aways:

1. Definitely learned some things, which was my goal
2. Was amazed at how little illumination it took to see the etchings of the Polar Scope.
3. The Polar Scope Alignment Tool app was a benefit, and I will fabricate something I can clamp in the mount to hold my phone a foot or so away from the interference caused by the metal in the mount. I have seen some ideas on YouTube, and will post what I come up with.
4. Focus is your friend with the Polar Scope but is a one time effort
5. experienced just how precisely you can move the Altitude and Azimuth with the tools provided on the EXOS

One thing I forgot after alignment was to re-tighten the mount to the tripod to see if things moved.

Also I did remove the telescope and the counter weight in that order and moved the tripod with the mount attached. Velcro was good to hold the cables out of the way while it was being carried and it was easily moved. I also need to double, triple check to make sure the legs are fully spread, as i forgot to do that.

Lots left to learn, but the night has been chalked up as a success.

Maybe the forecast for clear skies will actually appear tonight.
--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Timothy Myers
 

Weather cooperated with me last night and I got the mount plus scope plus computer and camera out.

Polar alignment went the same as the night before with no issues other than realizing I forgot to turn the polar scope illumination off and the batteries were dead. Good thing I bought a bunch.

I though I should make my first go to Polaris, but instead of moving a degree the mount headed way off to the east centering on who knows what. I parked it and tried again with the same result, so I saw Venus up and bright and headed there. It popped up a little low in the eyepiece but not horribly so. Slewed to M-42 and wasn't exactly sure where I was, close but not quite. Tried M45 and it landed pretty close. I took the eyepiece out and put the ASI 1600 in, used the arrows on CDC to get the picture I wanted and did 26 - 30" subs 10" apart. I know short subs but a start. I tried for M42 again and moved around but never got anything into focus, also tried M44 and M31 but my seeing conditions were not the best and I am in a fairly light polluted location.

I thought I would try the Sharp Cap Polar Alignment, and got a good first image, but when I tried to move 90 degrees RA the mount moves so slow that it was going to take forever. So I took my cold shivering self and equipment back inside.

My question:

The slow slews are great for aligning the camera to get the picture you want but how do you speed things up enough to do something like a Polar Alignment in SharpCap? I did turn the speed from 4 to 10 but still way to slow. I know I am just missing something, but what?

Also there is an up and down carrot to the left of my slew buttons, what do they do?

--
Tim Myers

Telescopes:     Celestron 4SE, Celestron 8SE
Mounts:           4-5 SE, 6-8SE, EXOS-2GT with PMC-Eight
Cameras:        ASI1600ME, Cooled
Tablets:           Asus Nexus 7, Amazon Fire 7


Wes Mcdonald
 

Tim remind us all of the configuration you are using.  Sounds like you have Explorestars running to drive the mount, and what else?

Wes.


--
Wes, Southport NC
PMC-8, ES ED 127, 10" LX200GPS, Astro-Tech 8" Newt, ETX-90
Polemaster, Orion ST-80 and SAG
Electrical Engineer, Retired