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Is there a way to polar align during the day?

28 replies to this topic

#1 Eric Dunn

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Posted 03 January 2024 - 01:57 PM

I would like to do some solar imaging to get some experience before the eclipse in April. Don't want to be trying to figure everything out on the day of ...

 

... and I don't know how to align my mount during the daytime.

 

I suppose it's not a terribly big issue as I can set the latitude before hand and more or less eyeball north when I go to set up the mount. This ought to track well enough with the occasional manual corrections, but I would still appreciate any thoughts on the matter.

 

Thanks,

Eric



#2 Peter Natscher

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Posted 03 January 2024 - 02:04 PM

I would like to do some solar imaging to get some experience before the eclipse in April. Don't want to be trying to figure everything out on the day of ...

 

... and I don't know how to align my mount during the daytime.

 

I suppose it's not a terribly big issue as I can set the latitude before hand and more or less eyeball north when I go to set up the mount. This ought to track well enough with the occasional manual corrections, but I would still appreciate any thoughts on the matter.

 

Thanks,

Eric

A good compass will point to north better than your eye. If the Moon and Venus are locatable, maybe you could do a two or three object mount alignment on DSC's along with using the Sun as first object.
 


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#3 vtaDan

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Posted 03 January 2024 - 02:07 PM

I've used the PS Align Pro app in the past with some success. It depends on your phone's compass accuracy which will be affected by the metal in your mount but there are ways to mitigate that. There's a good discussion of it here: https://www.cloudyni...olar-alignment/


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#4 Eric Dunn

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Posted 03 January 2024 - 02:09 PM

A good compass will point to north better than your eye. If the Moon and Venus are locatable, maybe you could do a two or three object mount alignment on DSC's along with using the Sun as first object.
 

Thanks



#5 Eric Dunn

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Posted 03 January 2024 - 02:09 PM

I've used the PS Align Pro app in the past with some success. It depends on your phone's compass accuracy which will be affected by the metal in your mount but there are ways to mitigate that. There's a good discussion of it here: https://www.cloudyni...olar-alignment/

Thanks. I'll check it out.



#6 TOMDEY

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Posted 03 January 2024 - 02:17 PM

Polar align it before sunrise. Even better, especially if you have never witnessed a Total Solar Eclipse before --- plan to do only visual for the event. If you're imaging, you will miss the best part entirely. Look at other peoples vastly superior pictures later, while you describe to them what they missed.    Tom


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#7 triplemon

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Posted 03 January 2024 - 02:22 PM

Polar axis elevation you can easily get as accurate as sighting Polaris by elevation measurement. A classic plumb and a suitable scale somewhere on the side of you mount can get an accuracy of a fraction of a degree with quite conventional means.

 

For heading its harder. Most compass won't get you even to a single degree accuracy, for multiple reasons. Drift alignment may help, track the sun with a suitable high magnification. But in case of the eclipse you're likely to do that in the morning and drift alignment to the east will only tell you the polar axis elevation error, which is likely not your biggest problem.

 

I also sucessfully used headings to distant landmarks and maps. Or just any aerial or sattelite image of the immediate vicinity of your observing location. They are all true north aligned with much more accuracy than you'd ever need for polar aligning. Just need to spot some references in there that are unlikely to move.

Even google earth is quite usefull, but it lacks a readout of camera heading. I enable the "grid" in there and its at least possible to get a fairly exact indication of the four cardinal directions. Here is how I know which rooftop is true south from my deck:
 

Attached Thumbnails

  • true_south.jpg

Edited by triplemon, 03 January 2024 - 02:47 PM.

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#8 Eric Dunn

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Posted 03 January 2024 - 02:36 PM

Polar align it before sunrise. Even better, especially if you have never witnessed a Total Solar Eclipse before --- plan to do only visual for the event. If you're imaging, you will miss the best part entirely. Look at other peoples vastly superior pictures later, while you describe to them what they missed.    Tom

Unfortunately, doing it before sunrise is not an option for the main event. It's a 5 hr drive for me to get to the total eclipse zone. I have no problem with getting there the night before, but I've been completely unable to find a campground or motel along that path that isn't already booked. Apparently I'm not the only one looking to enjoy this rare event.

 

I have little interest in visual astronomy. My interest in the event IS the imaging ... and I've seen one before, back in the 80s.

 

(of course I can easily watch the event while my camera is filming the event, no reason to limit myself to one or the other.)


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#9 vtornado

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Posted 03 January 2024 - 02:36 PM

The last eclipse, I used a compass and an angle guage to set the EQ mount.

I used a short focal length telescope (ST80) on a CG4 with an RA drive.  The sun does not require long exposure, or large magnification, so a precise polar align is not necessary.  I think I had to tweak R/A or Dec about every 20 minutes to keep the sun more or less centered.   You want to be good enough so  you don't have to fuss with the mount all the time, but close is good enough.  A few minutes before totality, I centered the image, and made sure I could remove the white light filter without jerking the scope.  Then I spent 95% of my time visually with no scope.  I pressed the shutter button a few times and prayed, but I did not fuss with the scope.  The pics turned out fine. (not award winning due to CA, but they are fine for me).

 

You can play with all of this long before the eclipse.  If you have sun lol.gif .  Coincidentally you can use the moon as a surrogate.

 

I highly recommend a pair of eclipse glasses so you can monitor the progress without always having to peer into a scope.  This allowed me to leave the scope and get a leisurely lunch.


Edited by vtornado, 03 January 2024 - 02:45 PM.

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#10 Eric Dunn

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Posted 03 January 2024 - 02:51 PM

Polar axis elevation you can easily get as accurate as sighting Polaris by elevation measurement. A classic plumb and a suitable scale somewhere on the side of you mount can get an accuracy of a fraction of a degree with quite conventional means.

 

For heading its harder. Most compass won't get you even to a single degree accuracy, for multiple reasons. Drift alignment may help, track the sun with a suitable high magnification. But in case of the eclipse you're likely to do that in the morning and dift alignment to the east will only tell you the polar axis elevation error, which is likely not your biggest problem.

 

I also sucessfully used headings to distant landmarks and maps. Or just any aerial or sattelite image of the immediate vicinity of your observing location. They are all true north aligned with much more accuracy than you'd ever need for polar aligning. Just need to spot some references in there that are unlikely to move.

Even google earth is quite usefull, but it lacks a readout of camera heading. I enable the "grid" in there and its at least possible to get a fairly exact indication of the four cardinal directions. Here is how I know which rooftop is true south from my deck:
 

So, eyeball it?

 

I do that all the time at night and it works fine. I can't see Polaris from my front yard, yet my front yard is the only place around my house blocked from street lights, so I set up there often. I know where to set the tripod and where to point the mount well enough that it isn't really much of a problem. Slight corrections throughout the night is all I need to do, generally.

 

I suspect this is what I'll have to do. Adjusting on the fly, shouldn't be too much of a problem. I'll just practice between now and then so hopefully I know 'if the sun drifts down in the frame, adjust the mount in this direction or if up, adjust in that direction' and so forst.

 

It's not like I'll lose the sun and have to find it again.

 

Thanks for the insight.



#11 Eric Dunn

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Posted 03 January 2024 - 02:57 PM

I highly recommend a pair of eclipse glasses so you can monitor the progress without always having to peer into a scope.

Excellent tip. Just added a pair to my cart.



#12 photoracer18

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Posted 03 January 2024 - 03:09 PM

Here is what I do but depends on your mount. All of my primary GEM mounts have a large flat area on the back of the RA axis (AP900QMD, AP400QMD, even my iOptron HEM15) I load Sky Safari into my smart phone place it on the flat area then bring the NCP (North Celestrial Pole) target up on it and adjust the mount polar alignment to keep the mount aimed at the NCP when I magnify the image. This method is especially good when doing solar work. Never have to setup my mount the night before.


Edited by photoracer18, 03 January 2024 - 03:10 PM.

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#13 bob b

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Posted 03 January 2024 - 03:13 PM

for the 2017 eclipse I mounted 2 canon cameras on an IOPTRON GEM---a 7o-200 f2.8 and a 100-400 f4.4 .....i used 2 sequence timers to automate the picture taking --i used Bader film over the lenses ---took them off at 100% total.....the mount was set up i 5 minutes and only neededslight adjustment towards the edn of the sequence .i enjoyed LIVE and Filmed at he same time.

 

goog luck and enjoy the event !!

 

bob


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#14 ButterFly

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Posted 03 January 2024 - 04:24 PM

Firecapture offers guiding on the object.  You will be taking very short exposures, so keeping the sun on the chip is the goal, rather than trailing.

 

Polar align as best as you can with a compass, correcting for magnetic declination.  Let the guiding take care of the corrections.



#15 ButterFly

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Posted 03 January 2024 - 04:25 PM

Don't forget to bracket your exposures.



#16 Eric Dunn

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Posted 03 January 2024 - 04:50 PM

Firecapture offers guiding on the object.  You will be taking very short exposures, so keeping the sun on the chip is the goal, rather than trailing.

 

Polar align as best as you can with a compass, correcting for magnetic declination.  Let the guiding take care of the corrections.

Thanks.

 

I was thinking video photography here, not still photos. Video is where I'm coming from, astrophotography is a new hobby to me. I'm really excited about the eclipse because ...

 

---> flowerred.gif flowerred.gif VIDEO!!! flowerred.gif flowerred.gif <---

 

 ... is more my thing. Astrophotography may get added to the list of 'my things' but I'm still new to still photography at this point.

 

Unfortunately, I don't have any kind of guiding equipment yet.



#17 ButterFly

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Posted 03 January 2024 - 07:21 PM

Thanks.

 

I was thinking video photography here, not still photos. Video is where I'm coming from, astrophotography is a new hobby to me. I'm really excited about the eclipse because ...

 

---> flowerred.gif flowerred.gif VIDEO!!! flowerred.gif flowerred.gif <---

 

 ... is more my thing. Astrophotography may get added to the list of 'my things' but I'm still new to still photography at this point.

 

Unfortunately, I don't have any kind of guiding equipment yet.

Video is nothing more than a series of still images!

 

Firecapture doesn't need separate guiding cameras or scopes.  It uses where the target is on the frame to reposition.  Because of the much, much faster frame rate than video, and especially astrophotography, the images themselves from the main camera are used for guiding.



#18 Eric Dunn

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Posted 03 January 2024 - 07:45 PM

Video is nothing more than a series of still images!

 

Firecapture doesn't need separate guiding cameras or scopes.  It uses where the target is on the frame to reposition.  Because of the much, much faster frame rate than video, and especially astrophotography, the images themselves from the main camera are used for guiding.

Thanks, I'll look into it.



#19 kfiscus

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Posted 03 January 2024 - 08:27 PM

There is another fun & educational way to find true north EXACTLY.  It's called the "shortest shadow method" and I learned it while teaching the Boy Scouts' Astronomy Merit Badge.  It takes a few hours and would be ideal IF you were able to be in your solar eclipse viewing spot a day in advance.  It would be a no-go for the day of the eclipse with too much going on and too little time.

 

Reply if you want to know more.



#20 MeteorBoy

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Posted 05 January 2024 - 12:00 AM

My GoTo Evolution can align on a single solar system object (like the Sun).  I've had no tracking issues for imaging that way.

 

Or, if you can find what object on your horizon is zero degrees AZ then point your 'scope at it.  Then use a digital inclinometer (~$30) to find the correct EL.  I've done that too and it also works.

 

Ken



#21 kjkrum

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Posted 06 January 2024 - 01:01 PM

I don't have much experience with this, so I'm interested in others' thoughts. I usually only roughly align for visual with a manual EQ mount, so I get a little dec drift that's easily corrected. Shouldn't you be able to tell which way your alignment is off based on your dec drift? Especially if your mount is level and RA angle is set to your latitude. Any remaining error must be in the tripod's az alignment. So observe the sun visually with a crosshair EP and see which way to rotate the mount?

#22 KellyMcGrew

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Posted 06 January 2024 - 05:54 PM

I would like to do some solar imaging to get some experience before the eclipse in April. Don't want to be trying to figure everything out on the day of ...

 

... and I don't know how to align my mount during the daytime.

 

I suppose it's not a terribly big issue as I can set the latitude before hand and more or less eyeball north when I go to set up the mount. This ought to track well enough with the occasional manual corrections, but I would still appreciate any thoughts on the matter.

 

Thanks,

Eric

The good folks at Astro-Physics describe this in their manuals for their keypads.  For example, see the section, "Polar Aligning in the Daytime – Northern Hemisphere", beginning on page 22, and available at this link:

 

https://astro-physic...nual-4-19-5.pdf

 

YMMV, depending on the settings and their controls on your system.  I've used a variation of the routine for my iOptron EQ45, too. 

 

My advice is to practice this several times so that it becomes familiar. 

 

Clear skies!



#23 ecuador

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Posted 07 January 2024 - 01:35 PM

I've used the PS Align Pro app in the past with some success. It depends on your phone's compass accuracy which will be affected by the metal in your mount but there are ways to mitigate that. There's a good discussion of it here: https://www.cloudyni...olar-alignment/

Note that while I designed the feature for the 2017 eclipse and used it myself as it is (quite successfully), I have since added a "solar shadow calibration" option, which allows you to give your phone's compass a calibration point. It does depend a lot on your setup as you need to be able to use the solar shadow (see the in-app instructions), but should help get a bit tighter polar alignment for those who have trouble otherwise. I'll be flying to Austin and will be using it myself in April ;)


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#24 ButterFly

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Posted 07 January 2024 - 01:57 PM

That's why I like my Celestron mount.  One can do an end-run polar alignment during star alignment.

 

The Celestron mount has me line up index marks, then set the time and location.  When I start a star alignment, it gets near the first object.  When my index marks are lined up exactly, and the time and location is exactly right, and the mount is exactly level, the difference between the object and where the mount is pointing is exactly the polar error.  So, before I use the slew buttons to center the first object, I use the alt/az polar alignment knobs to center the first object.  That gets me pretty close to polar aligned.  The difference is how far off my level, time and location are, as well as how well my scope points where my mount points.

 

Many mounts have nearly the same routine.  It gets near the first object by assuming a level mount, that you lined up index marks or initial position (if any) correctly, then set the time and location correctly.  One can use this end-run technique in the same way with those mounts.



#25 hdt

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Posted 24 January 2024 - 03:42 PM

I would like to do some solar imaging to get some experience before the eclipse in April. Don't want to be trying to figure everything out on the day of ...

 

... and I don't know how to align my mount during the daytime.

 

I suppose it's not a terribly big issue as I can set the latitude before hand and more or less eyeball north when I go to set up the mount. This ought to track well enough with the occasional manual corrections, but I would still appreciate any thoughts on the matter.

 

Thanks,

Eric

Here's how I would align an equatorial mount in the daytime. https://youtu.be/zgZOiDQQ8gw. This is a 10 minute video, but you can watch it at 1.5 speed or 2x speed. 





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