Alternative Alignment Techniques?

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Alternative Alignment Techniques?

#1

Post by GCoyote »


With the leaves falling, my back yard is exposed to many more street lights, porch lights, and other visual annoyances. I can usually find a dark spot by repositioning my gear. As the subject line implies, that sometimes prevents me form getting a line-of-sight to Polaris.

Is there some generally accepted method for getting a polar alignment when you can't see the pole star?
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
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Re: Alternative Alignment Techniques?

#2

Post by ARock »


Drift alignment, assuming south and either east or west are visible.
http://astropixels.com/main/polaralignment.html

If this is for AP, you can also use the camera to do drift alignment
https://www.cloudynights.com/articles/c ... vice-r2760
AR
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Re: Alternative Alignment Techniques?

#3

Post by JayTee »


Start with a GPS compass that shows true north then do a drift alignment after that.

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Re: Alternative Alignment Techniques?

#4

Post by UlteriorModem »


Which mount?
Tom

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Re: Alternative Alignment Techniques?

#5

Post by John Baars »


For visual use a compass will do. Even better if you know your local deviation.( Can be searched for on the internet)
If you have a goto, after the compass alignment a three star alignment will do. The computer calculates and compensates for the error. Modern goto's even tell you how far you are off in Azimuth and Altitude.
If it doesn't tell you, you can do the drift-alignment. Drift alignment is not necessary for visual use.

Some goto's have an unaligned polar setting and an aligned polar setting. If you have one, do the three star alignment in unaligned mode.When ready switch to aligned mode. You will be warned if you do so. Look through the finder at the last alignment star. Give the enter command for aligned mode. The telescope will move to the position the computer calculated as if it were an aligned mode. Watch the movement of the star in the finder. By turning Alt and Az knobs center the star again. You are very well aligned this way. You will have to do another three star alignment though.
I do this a few times a year,when I return from holidays, for I cannot see Polaris from my backyard too.
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
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Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
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Re: Alternative Alignment Techniques?

#6

Post by bobharmony »


I have visibility to Polaris, but no desire to kneel down to try to look through a polar scope to align on it. I set up in a set of marks I have placed for the tripod legs and use drift alignment exclusively. My back thanks me every time.

Bob
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Re: Alternative Alignment Techniques?

#7

Post by GCoyote »


UlteriorModem wrote: Fri Nov 06, 2020 4:59 pm Which mount?
I have one GEM under my 114 mm Meade Newtonian and the DIY wedge I'm building. No automation.

A magnetic compass won't help me at home because of the buried metal utility pipes under my property and the nearby power lines. Magnetic north changes depending on where I stand. I'll definitely pack a compass if I get a chance to observe from a state park I recently scouted.

I've tried three android aps with a digital compass function but all three seem to be using the magnetic field for compass direction.

I did spend some time last night surveying my lot and noting what objects line up with true North from certain spots that are shielded from street and security lights. I think a combining a good plan for setting up with one of the techniques contributed by the group should get me on target.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Alternative Alignment Techniques?

#8

Post by KathyNS »


GCoyote wrote: Sat Nov 07, 2020 1:06 pm I've tried three android aps with a digital compass function but all three seem to be using the magnetic field for compass direction.
This is a good observation. Electronic devices have no source of orientation information other than the Earth's magnetic field. Even GPS only measures position, not direction. GPS devices that show direction incorporate a magnetic sensor, and are therefore subject to the same external influences as magnetic compasses.

I think your technique of having a good site survey with predetermined setup locations and orientations, followed by a drift alignment will give you what you need.
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Re: Alternative Alignment Techniques?

#9

Post by John Baars »


Compass doesn't work? You could try standing on an aluminium ladder. Or a stick in the ground as a gnomon during the day, the shadow points north with the sun in its highest position.( And is on its shortest) An improvised sundial. The right time can be simulated in Stellarium, so if you know the right time, you don't have to sit beside your gnomon all day.
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
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Re: Alternative Alignment Techniques?

#10

Post by GCoyote »


John Baars wrote: Sat Nov 07, 2020 10:21 pm Compass doesn't work? You could try standing on an aluminium ladder. Or a stick in the ground as a gnomon during the day, the shadow points north with the sun in its highest position.( And is on its shortest) An improvised sundial. The right time can be simulated in Stellarium, so if you know the right time, you don't have to sit beside your gnomon all day.
A ladder won't help as the local magnetic field is distorted by all of the metallic and high voltage infrastructure around my yard. I remember the gnomon technique from land navigation training oh so many years ago. It's accuracy is limited by several factors that make it too imprecise for my purposes.

My first attempt at using a site survey last night went pretty well. I was able to use a nice straight vertical edge on my shed at about forty feet distance from the scope to get within about 2-3 degrees of true North just during set up. With a longer baseline and more careful observations of Polaris I'm sure I can improve on that. I plan to go out on the next clear night with large carpenter's protractor and a plumb line which should get me within one degree on the patio location I'm currently using most for planetary observing.

I set up a couple of patio umbrellas to block a few of the worst offending light sources. That gives me a larger useable area for set up. My wife is going to look for one that tilts so I can get bigger shaded area for the scope.

And I added a small hardware level to my observing kit.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
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(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Alternative Alignment Techniques?

#11

Post by SkyHiker »


What is your equipment and what is your goal, visual or AP? Is your mount motorized? If yes, drift alignment is a good idea. It would help if you filled out your signature so we don't have to guess.
... Henk. :D Telescopes: GSO 12" Astrograph, "Comet Hunter" MN152, ES ED127CF, ES ED80, WO Redcat51, Z12, AT6RC, Celestron Skymaster 20x80, Mounts and tripod: Losmandy G11S with OnStep, AVX, Tiltall, Cameras: ASI2600MC, ASI2600MM, ASI120 mini, Fuji X-a1, Canon XSi, T6, ELPH 100HS, DIY: OnStep controller, Pi4b/power rig, Afocal adapter, Foldable Dob base, Az/Alt Dob setting circles, Accessories: ZWO 36 mm filter wheel, TV Paracorr 2, Baader MPCC Mk III, ES FF, SSAG, QHY OAG-M, EAF electronic focuser, Plossls, Barlows, Telrad, Laser collimators (Seben LK1, Z12, Howie Glatter), Cheshire, 2 Orion RACIs 8x50, Software: KStars-Ekos, DSS, PHD2, Nebulosity, Photo Gallery, Gimp, CHDK, Computers:Pi4b, 2x running KStars/Ekos, Toshiba Satellite 17", Website:Henk's astro images
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Re: Alternative Alignment Techniques?

#12

Post by UlteriorModem »


I have one GEM under my 114 mm Meade Newtonian and the DIY wedge I'm building. No automation.

Henk I gathered from that it is a GEM mount with no motors so probably visual.

Why he needs a wedge I dunno latitude I guess.
Tom

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Scope: 130mm f7 APO
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Re: Alternative Alignment Techniques?

#13

Post by GCoyote »


Yes, visual only at the moment. The wedge is for another unfinished project. My main scope right now is a used Meade Infinity 114mm Newtonian. It's a model 4504 but missing the drive motors and analog controls. Scope Head Bill at Telescope Warehouse found the parts I needed to get it working and I was a bit surprised how smoothly it tracks considering it's age and the battle scars on the OTA.

I'm just learning to use the setting circles to find targets by RA and Dec. I had so much fun last night with the scope I forgot to finish my beer. That's the 2nd time in a month. I may be developing a bad habit here. :shock:
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Alternative Alignment Techniques?

#14

Post by mikemarotta »


GCoyote wrote: Fri Nov 06, 2020 4:44 am... that sometimes prevents me form getting a line-of-sight to Polaris. Is there some generally accepted method for getting a polar alignment when you can't see the pole star?
You know, for as engaged as you are here, your profile does not give your equipment, but does have a No for Astrophotography. If you want North, just use a magnetic compass or your cellphone with GPS.

When I was using my Celestron EQ-130, to align the Equatorial mount, I set the phone in the instrument tray and aligned on the compass by pivoting and horsing the telescope polar axis to the indicated North. When I used big SCTs last summer, I set the cellphone on the telescope and used both the GPS for North and the fake spirit level for horizontal.
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Re: Alternative Alignment Techniques?

#15

Post by Graeme1858 »


In the positions where you can't see Polaris, can you see above where Polaris is? From my location Stellarium tells me that Navi will be due north at 20:18 tonight at about 80° altitude.

Regards

Graeme
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Re: Alternative Alignment Techniques?

#16

Post by GCoyote »


Graeme1858 wrote: Sun Nov 29, 2020 9:46 am In the positions where you can't see Polaris, can you see above where Polaris is? From my location Stellarium tells me that Navi will be due north at 20:18 tonight at about 80° altitude.

Regards

Graeme
That's sort of what I was attempting on my own before the bell went off and I started this thread. Based on the discussion here, I've gotten a pretty good system now for having everything level and within a degree or so aligned before I leave it to cool down. When I come out later the tips on drift alignment and other ideas give me a more than adequate alignment for my visual observations.

I like your suggestion because some nights I'm not able to see Polaris when the light pollution is worse than usual to the North because of evening sporting events. A reference star a little higher in the sky should help circumvent that problem.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Alternative Alignment Techniques?

#17

Post by OzEclipse »


When observing solar eclipses, the mounts always have to be set up in daylight unless the eclipse is at sunrise or you are at your observing location the night before. Rare in my 17 eclipses.

Once the eclipse site is known, I look up the magnetic declination (D) for that location. I use the jig below with a magnetic orienteering compass. I have one compass for the northern hemisphere and one for the southern hemisphere. This jig is for positive magnetic declinations - compass points east of true north. Which is the case for all of Eastern Australia. If I go to a location with a negative magnetic declination(west) I have to redraft. In Laurel, your "D" is about -11. ie west so you need to use the mirror reverse of this jig.
POLAR-ALIGN-JIG-A4.jpg
The jig is mounted on a piece of foam core board and the edges cut accurately. I set the compass bearing to 0 and use the markings on the board. The foam core jig is A4 size and so puts some distance between my mount, motor magnets, and the compass.

After setting the azimuth, I set the altitude with a clinometer. Using this technique, my mount has tracked and kept the Sun centred in the field of a 430mm FL refractor for 3 or more hours with only minor drift during multiple eclipses. Not accurate enough for astrophotography but fine for visual.

The technique relies upon the compass not being affected by metallic structures nearby, rail lines, power lines, underground water pipes and so on.

Joe
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Re: Alternative Alignment Techniques?

#18

Post by OzEclipse »


You mentioned that your mount has setting circles? Setting circles can be used to align a mounting.

Roughly set up the mount then set the siderial time to the meridian position of the setting circle.

Choose a bright star about 20 degrees above the east or west horizon and move the mount to those coordinates.

Using only ALT and Az movement of the polar axis, centre the star. A low altitude star will mostly give you an accurate azimuth setting adjustment.

Next, choose a star on the meridian and move the mount to those coordinates using the setting circles. Centre that star. If the azimuth is close you should mainly adjust the ALT of the polar axis.

Repeat the procedure to check and refine.

Joe
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Amateur astronomer since 1978...................Web site : http://joe-cali.com/
Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80.
Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's.
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Re: Alternative Alignment Techniques?

#19

Post by Shabadoo »


I set before sundown. I cemented a little water filled compass, that I pulled off a military style watch band, yrs ago, on the front leg of my tripod.
1.I face the tripod North.
2. Then I put my phone on the tripod flat top and situate it so the North is at 347, 348 degrees.
3. I level the tripod.
4. I check 347, 348 again.
5. I put the mount on, the spreader plate.
6. I check my latitude on the mount.
7. I put the weights on, the tube and accessories. Setting up at 90. Deg parallel.
8. I do a quick balance.
I’m in the ball park. (I can see Polaris - but need a little help)
9. From there I can check coordinates of other known stars.

Hope this helps.
Jeff
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Re: Alternative Alignment Techniques?

#20

Post by OzEclipse »


LASER ASSISTED POLAR ALIGNMENT


Living in the southern hemisphere, the two stars 8' and 10' from the SCP are mags 6.8 and 7.8 respectively. Sigma Octantis at mag 5.4 is a bit over a degree away. My mount loaded up weighs 35kgs. It's no fun pushing it around trying to find the faint pole stars while craning my neck to look through the 10mm diameter polar scope. If I don't load it before aligning it, the mount sinks into the soft ground a little after I load it sending it off alignment.
Laser bracket-cropped.jpg
In September 2018, I designed and built myself a simple 2-axis jig for a 50mW green laser module I purchased on ebay. I built the module into the jig. The jig attaches to the south-facing tripod leg of my EQ mount about 150mm below the polar finder. The jig has Teflon slip discs in each axis tensioned so that the laser moves easily to exactly where I point it without jumps or jerks. I've given it the acronym APPS - Artificial Projected Pole Star. Total cost of materials including the laser module was under AUD40 = USD27.
laser-jig.jpg
Using a pair of lightweight 7x35mm binoculars in one hand, I can easily see the trapezium of 5th and 6th magnitude stars and the much closer pair of 6.8 and 7.8 stars <10' from the pole. It's very easy to point the laser within a couple of minutes of the south celestial pole. Now I have an artificial pole star that is about as bright as Jupiter with a big bright green beam leading to it. I lower the polar axis latitude a few degrees lower than my latitude. Next I sweep the mount in azimuth until I see the beam. I wind the altitude of the polar axis up to point the polar finder directly at the artificial pole star. This process is accurate, easy and quick. It takes about 5 mins and I usually don't need to make dec corrections unless the pointed feet of the tripod settle into soft ground. I press the tripod in hard with my bodyweight before attaching the equatorial head to prevent this settling. On rare occasions when I do have a problem, another 5 min alignment fixes it up.


Teflon slip discs and nyloc nuts stop the threads from coming loose. The laser can be precisely pointed by hand.



I made my jig from machined aluminium and teflon but the jig could be made of maple or ash wood with a minimum of tools, some sandpaper and use danish wax between the sanded hardwood slip surface.
CALI-PA-Laser-5669.jpg
This is an illustration of the view I see, first through the 7x35mm binos then through the polar finder, albeit without all the faint stars.
laser PA finder.jpg

While I have been using and polar aligning equatorial mounts for more than 40 years, I have never found a method as efficient as this.

Before I hear you call out the name of your favourite polar alignment software, just bear in mind that this method takes 4-5 minutes from the time the mount is set up. That includes getting the device out of its bag, attaching, pointing the tool and aligning the mount. Can you even set up a table and computer, connect the camera and launch the software in 4 minutes? The hardware cost me USD13 for the laser module, $6 for the power supply. The rest was made in my workshop from scraps. Ok, so I machined pieces for the jig from aluminium however I could easily make the jig from wood and some basic hand tools.

Accuracy of course depends upon three things : -

• Your ability to find the polar stars
• How accurately you point the laser at the SCP
• Accuracy of your mount's polar scope


Probably not much application for the OP of this thread because he said he can't see the polar region. But hopefully someone else finds it useful.
Also no good if you observe with an astro club where they have lasers/ lights prohibition.

I find this method very simple, quick, easy, it works so well! It has been a game changer.

Joe
Image
Amateur astronomer since 1978...................Web site : http://joe-cali.com/
Scopes: ATM 18" Dob, Vixen VC200L, ATM 6"f7, Stellarvue 102ED, Saxon ED80, WO M70 ED, Orion 102 Maksutov, ST80.
Mounts: Takahashi EM-200, iOptron iEQ45, Push dobsonian with Nexus DSC, three homemade EQ's.
Eyepieces: TV Naglers 31, 17, 12, 7; Denkmeier D21 & D14; Pentax XW10, XW5, Unitron 40mm Kellner, Meade Or 25,12
Cameras : Pentax K1, K5, K01, K10D / VIDEO CAMS : TacosBD, Lihmsec.
Cam/guider/controllers: Lacerta MGEN 3, SW Synguider, Simulation Curriculum SkyFi 3+Sky safari
Memberships Astronomical Association of Queensland; RASNZ Occultations Section; Single Exposure Milky Way Facebook Group (Moderator) (12k members)
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