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Pier location - viewing considerations?

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#1 CinciJeff

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Posted 22 October 2020 - 11:26 AM

My current focus is astrophotography, so I’m thinking about building a pier in my yard to minimize the time it takes to set up equipment and polar align. Aspects of pier construction are well-covered and I will cross that bridge when I come to it, but a more fundamental need at this stage is to figure out the best physical location for the pier.

 

I’ve got a fairly large yard, but there are also many tall trees in and around it. I’d like to maximize the number of targets I can see within the constraints of the obstacles present. It’s kind of like being inside an open box - if I move to the center I can maximize how much sky I can see in all directions, but everything lower than 50 deg. (as an example) elevation is not visible. If I back into a corner I can see a much lower elevation but only in one or two directions.

My initial idea was to use a planetarium app to cycle through a full year and track targets of interest, then optimizing pier position by maximizing their visibility. An easier option would be to just build it close to the house for ease of access and just “get what I get”, knowing I could switch to a tripod if the need arose.

 

I know I’m not the only one who’s dealt with this problem, so I’m curious to hear thought processes/strategies from folks who’ve already made this decision. I’m not looking for specific answers at this point, I just want to make sure I’m thinking through the problem in a reasonable way.

 

Thanks!



#2 AstroBrett

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Posted 22 October 2020 - 11:41 AM

Don't forget to consider the increase in airmass and the degradation of the images at lower elevations. Most session, I can start to see the effects below about 60 degrees elevation, and I rarely image below 45 degrees elevation unless the particular target is so far south that it's elevation at culmination is below 45 degrees. I have the same layout as you on my property, and my imaging rig is located centrally, while my visual work is from a spot the maximizes my view to the south, and along the ecliptic. 

 

Two other considerations, First, take into account that trees grow. In the last 20 years that has really changed the horizons on my property. Second, you really don't want to observe across heating buildings, and I'd avoid lines of sight over top of unheated buildings and driveways if I could.  The "heat shimmer" can seriously degrade your seeing. 

 

Good luck making your selection.

 

Brett


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#3 ssagerian

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Posted 22 October 2020 - 11:45 AM

what is causing the hard limit on the 50° view? Trees, fence?



#4 eyeoftexas

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Posted 22 October 2020 - 12:02 PM

Taking into consideration what your targets are most likely to be will help solve the problem.  If you're looking mainly for nebulae and/or star clusters, being able to see towards the south will be important.  Galaxies will be favored more overhead (follow where Virgo and Coma Berenices travel).  If you use Stellarium or the app Observer Pro, you can upload your horizon and move your location around to see what is blocked.  AstroBrett makes a good point about those trees growing with time.



#5 macdonjh

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Posted 22 October 2020 - 12:02 PM

I think the rule of thumb is to maximize your elevation range in the south, since far southerly targets will never get high in the northern hemisphere.  Of course, AstroBrett's thoughts about air mass and refraction may impose another limit on how low in elevation it is practical to try to image.



#6 rgsalinger

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Posted 22 October 2020 - 12:24 PM

If you can, position the pier slightly to the north as others have suggested. With my mounts, getting much below 40 degrees when imaging starts to affect the guiding. Of course, that's always going to depend on exactly where you live, etc. I can go farther due south than due west because of the San Diego light cone. If your budget permits, PierTech makes a telescoping pier which allows you to have high walls but still get above the walls to try to hit targets nearer the horizon.

 

Rgrds-Ross



#7 Mike G.

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Posted 22 October 2020 - 12:37 PM

I installed a pier so I could have a permanent setup on my deck (6"x6"x1/4" square tubing bolted to a concrete base).  the problem with it is you can't move it.  I'm considering adding a second pier optimally placed for the objects that are difficult to see from my present position.  depending on your situation, maybe build 2 piers and have the ability to move the mount based on your targets?



#8 TOMDEY

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Posted 22 October 2020 - 12:40 PM

The Mreidian from Polaris to the South(ern horizon) will eventually catch everything. The more of that you can avail, the better.    Tom


Edited by TOMDEY, 22 October 2020 - 12:41 PM.


#9 t-ara-fan

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Posted 22 October 2020 - 12:48 PM

I tend to shoot more East than West.  Because as DSO targets come into view with changing seasons, they are in the East first.

 

Planets of course are best right on the meridian to the south if that is of interest. 

 

Anything that is low in the North will be high in the North a few months later.



#10 CinciJeff

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Posted 22 October 2020 - 11:18 PM

Thanks all, those are some great tips!

 

I think I've got what I need for now, but as an exercise I went to the NE corner of my yard, looked due South and shot the attached photo with the wide angle lens on my iPhone. There is a "wall" of tall trees right behind me. I also bumped the contrast to better delineate earth and sky. For reference, the moon (center of frame) was right around 25 deg. at the time this photo was taken. If I put the pier in the location I'd certainly have a good view to the south, but then nothing to the north (and no way to find Polaris). I like the idea of a more central location so I'll set up my tripod further south from this spot and see how that goes. I will also take the 360 deg. image from that location and apply it to the Cartes view. I had done that before but from my driveway and not this location.

 

Again, thanks for all the ideas.

 

PS - for what its worth, I'm also attaching an image of the moon shown in the first picture. It was last-minute using a DSLR on my old Celestron Celestar 8, but even with the moon being behind the big tree most of the night I thought it was a pretty neat shot. 1200 frames stacked using Autostakkert3 and slightly sharpened in Photoshop.

Attached Thumbnails

  • SouthView - 1.jpeg
  • Moon-P25.jpg


#11 Binary Star

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Posted 24 October 2020 - 10:18 PM

The lack of Polaris visibility is not necessarily an issue in an observatory or on a fixed pier. All you need to do is point in the general direction North within a few degrees and you can drift align after that.  In fact, that's what you need to do eventually anyway to get your mount aligned precisely so it's not a big deal.  There are more objects to view and image in the South compared to the North, and you'll get many of the Northern objects regardless.  

 

Good luck with your new pier, you won't regret it!

 

Jim R.


Edited by Binary Star, 24 October 2020 - 10:18 PM.

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