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Topic: Polar drift


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  Polar Aligning
Drift polar aligning is accomplished by monitoring the declination drift of a star at high power in the eyepiece and adjusting the polar axis of the mount based on the direction of drift.
Two corrections are necessary based on two observations: one of a star on the meridian for the azimuth of the polar axis of the mount, and one of a star near the eastern or western horizon for the elevation of the polar axis.
Technically, drift due to polar axis misalignment in azimuth is independent of the declination of the star, but a star between the zenith and celestial equator is easiest to use for polar alignment purposes.
www.astropix.com /HTML/I_ASTROP/I07/I0701/I0701.HTM   (2425 words)

  
 Comprehensive Polar Alignment Procedure
The polar alignment procedure works on one simple principle: The polar axis of the telescope must be made parallel to the Earth’s axis of rotation, called the North Celestial Pole (NCP).
Before we can be certain that the telescope's polar axis is accurately aligned with the rotational axis of the Earth, we must first be certain that the finderscope (which will actually be used to polar align the mount) is aligned with the telescope's polar axis.
Polar alignment, as performed by many amateurs, can be very time consuming if you spend a lot of time getting it more precise than is needed for what you intended to do with the telescope.
www.celestron.com /polar.htm   (2529 words)

  
 Polar bear - Ursus maritimus   (Site not responding. Last check: 2007-11-01)
The polar bear is perhaps the symbol of the Arctic, so it is no coincidence that Greenland’s Home Rule uses the polar bear as an illustration in the official national coat of arms.
Polar bears live and breed in the northernmost parts of Western and Northeastern Greenland, although it is sometimes encountered in other parts of the country.
This accounts for a number of polar bears being killed in the area around Tasiilaq, where there is still a tradition for the skin of a bear to belong to the first person who catches sight of it, not the person who shoots it.
www.greenland.com /Adventures/Animal_Life/Polar_bear.php   (449 words)

  
 Theory of Drift Polar Alignment
If the telescope mount were perfectly aligned, the polar axis (pointed toward true north) would rotate exactly parallel to the lines of declination in the sky.
The star drifting south tells you that the mount is too far below the pole and the mount must be adjusted accordingly.
By watching a star drift in declination it is possible to accurately align the telescope mount.
www.darkskyimages.com /theory.html   (520 words)

  
 LX200 Polar Alignment Procedure - Drift Method
For example, when recording a long exposure of a wide field object near the pole, polar alignment needs to be highly accurate, whereas when recording a short exposure of a small field object near the equator, polar alignment does not need to be very accurate.
In practice I have found that a slight drift during the 5 minute period can yield virtually undetectable field rotation over a 2 hour exposure provided that the object is not at high declination.
By 'slight drift' I mean that the star may have moved either side of the guiding line during 5 minutes, but is still so close that it 'brushes' against the line.
www.astrocruise.com /polarnew.htm   (5016 words)

  
 Climate change   (Site not responding. Last check: 2007-11-01)
Polar bears are totally reliant on the sea ice as their primary habitat.
Polar bears are a keystone species in ice-covered Arctic marine ecosystems and alterations to the distribution, density or abundance of this top predator will likely have impacts throughout the arctic ecosystem.
There is little doubt that polar bears and other ice-inhabiting marine mammals in the Arctic, are being, or will be, negatively affected by the effects of climate change via changes to their habitats.
pbsg.npolar.no /Threats/climate.htm   (481 words)

  
 Polar Alignment
Polar alignment is simply setting up your telescope so that you may easily follow a star (or other object) across the sky.
For fine polar alignment the drift star method is used by amateur and professional alike.
The basic idea with drift star alignment is to let the telescope run and observe which way the star drifts.
www.tucsonastronomy.org /polalign.htm   (1459 words)

  
 Inner earth mysteries (3)
The idea of an open polar sea took a long time to dispel, but we now know that there is no iceless ocean beyond 80°N. However, polynyas, temporary areas of ice-free water, occur in both the Arctic Ocean and the Southern Ocean surrounding Antarctica, and are not yet fully understood.
Lamprecht suggests that the land in question may lie on the inward-curving surface of a polar opening, and that from Peary or Macmillan's vantage point the lower (inverted) image was blocked by the sharp curvature, even though it was seen from locations over 100 miles apart.
Jan Lamprecht speculates that charged particles from the outer sun are accelerated by circling repeatedly through the inner earth via polar openings some 200 miles across, and suggests that the electrons involved in pulsating auroras originate in the pulsating inner sun and are expelled through the polar holes.
ourworld.compuserve.com /homepages/dp5/inner3.htm   (10275 words)

  
 Polar Alignment using the SBIG STV
Drift alignment is the accepted method of polar alignment by most astrophotographers.
The method presented is similar to using a polar alignment scope, but uses images from the SBIG STV autoguider along with precise x,y locations of alignment stars.
The accuracy achieved is higher than with a polar alignment scope and is within 2 arc minutes of the celestial pole.
home.twcny.rr.com /rkellog1/pol_align.htm   (2494 words)

  
 Interplanetary magnetic field control of polar patch velocity
Polar patch drift speed and direction have been investigated using oxygen 630 nm images recorded by an all-sky imager at Eureka (89° CGM), Canada over an extended period, January and December 1998.
Results from our quantitative study on the IMF control of polar patch speed and drift direction provide constraints for the development of future polar ionospheric convection models.
Index Terms: 2475 Ionosphere: Polar cap ionosphere; 0310 Atmospheric Composition and Structure: Airglow and aurora; 2463 Ionosphere: Plasma convection; 2134 Interplanetary Physics: Interplanetary magnetic fields.
www.agu.org /pubs/crossref/2003/2002JA009742.shtml   (323 words)

  
 Precision Polar Alignment
When rotating the finderscope 180ยบ around the polar axis, the cross hairs will rotate around the point which the polar axis is pointing (indicated by the "X" in Figure B).
Polar finder scopes are useful tools and will get you very close to the mark but imagine having your scope track "dead on" with no declination corrections for 10 to 20 minutes!
Polar alignment by the "star drift" method takes more time than using a polar scope, but a simple procedure using two stars will get your mount RIGHT ON the celestial pole.
www.astro-tom.com /tips_and_advice/precision_polar_alignment.htm   (3136 words)

  
 Techniques
This is the process of aligning the polar axis of an equatorial mount so that it is parallel to the earth's axis.
The drift in RA caused by Periodic Error is much worse than the drift in Dec caused by poor polar alignment.
Drift polar alignment takes time - I usually spend an hour aligning carefully, but pays dividends later in the imaging session.
www.angelfire.com /space2/tgtan/techniques.htm   (1303 words)

  
 JeffPo's Polar Alignment Page
With a polar aligned scope you just look up the coordinates of the object you want to view, "dial" in the correct RA and Declination, and then you'll scope will be pointing in the right direction.
For precise polar alignment, most people agree that the "declination drift method" is the most accurate.
For polar alignment in the southern hemisphere, reverse the NORTH and SOUTH directions (and corresponding adjustments).
www.mindspring.com /~jeffpo/polar.htm   (1515 words)

  
 User talk:Phils - Wikipedia, the free encyclopedia
At the moment polar motion talks about the movement of the rotational axis of the Earth, while polar drift talks about the movement of the magnetic axis - the two seem to be separate phenomena with different causes.
In the literature, they both seem to be referred to as polar motion, the phrase polar drift is not very common.
Rotational polar motion is also complicated, because it can refer either to the motion of the pole due to continental drift, or to the motion that occurs entirely separately from continental drift.
en.wikipedia.org /wiki/User_talk:Phils   (4573 words)

  
 Developing the theory [This Dynamic Earth, USGS]
Continental drift was hotly debated off and on for decades following Wegener's death before it was largely dismissed as being eccentric, preposterous, and improbable.
Alternating stripes of magnetically different rock were laid out in rows on either side of the mid-ocean ridge: one stripe with normal polarity and the adjoining stripe with reversed polarity.
The recognition of such a connection helped confirm the seafloor-spreading hypothesis by pin-pointing the zones where Hess had predicted oceanic crust is being generated (along the ridges) and the zones where oceanic lithosphere sinks back into the mantle (beneath the trenches).
pubs.usgs.gov /publications/text/developing.html   (1866 words)

  
 Polar Alignment   (Site not responding. Last check: 2007-11-01)
Before attempting to correct polar alignment, ensure that the finderscope is properly aligned with the telescope axis.
If the telescope polar axis is tilted eastward of the true NCP, then the telescope will follow a path taking it north of the equator (and of the star).
If the telescope polar axis is higher than the NCP, then the telescope will follow a path taking it south of the equator (and of the star).
www.beloit.edu /~physics/observatory/manuals/polar.html   (540 words)

  
 Polar Drift Alignment
This means that if the polar axis is aligned to within 1 arcminute of the true pole, then a star will drift in declination by 0.262 arcseconds per minute or less.
We can calculate the time for a star to drift 1 arcsecond by simply inverting the drift rate.So, if the drift rate is 0.262 arcseconds per minute and we wait for 3.8 minutes, it will move by 1 arcsecond.
If we are trying to detect drift rates of 1 or 2 arcseconds per minute, this is a bit coarse but for many applications such as CCD imaging using short exposures where polar alignment is not so critical, this may be adequate.
home.comcast.net /~astrophoto/Articles/Polar_Align.htm   (1372 words)

  
 Cosmic Voyage-The Online Resource for Amateur Astronomers   (Site not responding. Last check: 2007-11-01)
The declination drift method allows you to perfect the polar alignment of your telescope.
This method allows you eliminate declination drift, leaving only periodic error and the resulting right ascension drift to correct during exposures.
Any remaining north-south drift should be eliminated after completing both steps of this procedure a second time.
hometown.aol.com /billferris/decdrift.html   (398 words)

  
 'Drift Alignment' made simple
Polar alignment is the act of setting up your telescope in such a way that the North end of its polar axis points toward the North Celestial Pole and its South polar axis points toward the South Celestial Pole.
To be sure, once you see a direction drift, just gently nudge the bottom of the optical tube UP a little, and see if that makes the star move 'South' according to your interpretation.
Instead of using an eyepiece for determining the drift of a star, I simply select the star, begin to 'self guide'; with the Dec corrections turned off, and assure myself that after 15 minutes or so, there has been no more than approximately 1.5 arc seconds of drift in Dec. That's usually good enough.........
members.aol.com /ccdastro/drift-align.htm   (3685 words)

  
 Polar Alignment
A mount is said to be "equatorial" if one of its two axes can be made parallel with the Earth’s axis of rotation, and "polar aligned" if one axis IS parallel with the Earth’s axis of rotation.
Aligning the telescope to the Earth's axis can be a simple or rather involved procedure depending on the level of precision you want to achieve.
The polar alignment procedure works on one simple principle: The polar axis of the telescope must be made parallel to the Earth’s axis of rotation.
www.utahskies.org /tips/polar.htm   (1227 words)

  
 [No title]   (Site not responding. Last check: 2007-11-01)
Roughly polar align with a polar alignment scope or by sight and start your clock drive.
If the new drift is in the same direction, but worse, you corrected in the wrong direction.
If the new drift is in the opposite direction, you've overcorrected, but you're on the right track.
www.cvilleastro.org /casu/polar_align_files/polaraligndrift.html   (284 words)

  
 Polar Alignment
The drift alignment requires that you let the telescope track on two different stars are specific locations in the sky.
Watching how the stars drift relative to the reticle in the crosshair eyepiece tells how far the mount is offset from true celestial north and in which direction.
If the star drifts down, use the mount's azimuth adjustment knobs to move the mount so that the star appears to move left in the field of view.
www.darkskyimages.com /gpolar.html   (1022 words)

  
 Viewzone: Polar Shift Theories   (Site not responding. Last check: 2007-11-01)
Hapgood, while credited with plotting the positions of past polar coordinates, was forced to adhere to a much slower transition of the poles, accepting the paradigm of continental drift and plate tectonics to maintain the support of the scientific community.
"Polar wandering is based on the idea that the outer shell of the earth shifts about from time to time, moving some continents toward and other continents away from the poles.
Continental drift is based on the idea that the continents move individually...
www.viewzone.com /changingpoles22.html   (1366 words)

  
 ccdpolaralign
If you drifted over five pixels very quickly, your alignment is way off and you'll have to move the mount a fair amount so you may as well prematurely terminate the routine.
Once you you have achieved zero declination drift, you can test for up to 20 minutes for further drift if you wish, but if you were way off in East-West alignment, you're going to be doing this again so don't bother.
I was surprised that the polar alignment scope wasn't as accurate as I had hoped.
www.highenergyastro.homestead.com /ccdpolaralign.html   (1805 words)

  
 12-08-05 Movement of Earth's North Magnetic Pole Accelerating Rapidly
Because of that field, a compass reading of north in Oregon will be approximately 17 degrees east from "true geographic north." In Florida, farther away and more in line with the poles, the declination is only 4-5 degrees west.
The Northern Lights, which are triggered by the sun and fixed in position by the magnetic field, drift with the movement of the North Magnetic Pole and may soon be visible in more southerly parts of Siberia and Europe - and less so in northern Canada and Alaska.
In their research, funded by the National Science Foundation, Stoner and his colleagues took core samples from several lakes, but focused on Sawtooth Lake and Murray Lake on Ellesmere Island in the Canadian Arctic.
oregonstate.edu /dept/ncs/newsarch/2005/Dec05/magneticnorth.htm   (789 words)

  
 Astronomical Leage - Astro Note 15: Accurate Polar Alignment
Both methods are more involved than those presented in Astro Note 1, Polar Alignment in the Field, and you may spend several hours completing the alignment, depending on the precision you desire.
Select three bright stars that are easily located: one near or a little east of the meridian, one well to the east and one well to the west.
The movement of the polar axis refers to the top end of the axis and can be done by means of shims or adjusting screws, depending on your particular mounting.
www.astroleague.org /al/astrnote/astnot15.html   (535 words)

  
 Polar Alignment
Although residents of the northern hemisphere are convenienced with a bright star (Polaris) less than a degree from Earth's rotational axis, the NCP can still be a somewhat elusive place to locate.
Most telescopes have a latitude scale on the side of the mount that tells you how far to angle the mount for a given latitude (see your telescope owner's manual for instructions on how to make this adjustment).
This calculation can be approximated for any finderscope with a known field of view.
telescopes.com /faq/Polar-Alignment.html   (2397 words)

  
 am_astro   (Site not responding. Last check: 2007-11-01)
Our goal is to achieve precise polar alignment by mechanically adjusting the azimuth and declination controls so that 7-10 minutes of no discernable drift occurs in either northward or southward direction for both azimuth and declination adjustments as described below.
If the drift is south, then your polar axis is too far east, so move it a bit westward.
If the drift is north, then your polar axis is too far west, so move it a bit eastward.
home.earthlink.net /~mtnviews/just_astro.html   (5013 words)

  
 IERS/GGFC/SB Mantle: Co-seismic Excitation of Earth Rotational and Gravitational Changes
E, roughly opposite to that of the observed polar drift.
However, the speed of this earthquake-induced polar drift in the last two decades is two orders of magnitude smaller than that observed.
The polar motion excitation function derived from these observations shows a generally broad-band structure, but with certain prominent signals superimposed: a more-or-less secular drift largely attributed to the present-day post-glacial rebound, a 30-year Markowitz wobble whose origin remains mysterious, and the very notable annual wobble of obvious meteorological origin.
bowie.gsfc.nasa.gov /ggfc/sbm_cos.html   (2004 words)

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