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Polar Alignment
Newbie question, I cannot quite see Polaris from where i would like to
use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. |
#2
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While it is possible to align without seeing polaris it certainly is not as simple.
The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA |
#3
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While it is possible to align without seeing polaris it certainly is not as simple.
The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA |
#4
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Thanks (I changed my name/address as it is probably coincidence but I
already seem to be getting more spam). Do you use a wedge on your Meade? Or do you align it using it in Alt-Az mode? Is it really possible to polar align without seeing Polaris? I plan on doing astrophotog at some point but certainly not most of the time. In article , Gregory Phillips wrote: While it is possible to align without seeing polaris it certainly is not as simple. The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA |
#5
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Thanks (I changed my name/address as it is probably coincidence but I
already seem to be getting more spam). Do you use a wedge on your Meade? Or do you align it using it in Alt-Az mode? Is it really possible to polar align without seeing Polaris? I plan on doing astrophotog at some point but certainly not most of the time. In article , Gregory Phillips wrote: While it is possible to align without seeing polaris it certainly is not as simple. The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA |
#6
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I use a wedge (a Meade "super wedge"). A wedge is definitely the way to
go, it allows aligning one of the mount axis with earths spin axis. Therefore to track a star only one motor needs to run (the other motor is only used when moving to a different object). This means the various errors introduced by non-perfect drive components are only introduced once instead of for each motor. Note that with a wedge all that is needed for alignment is to adjust the wedge tilt to the latitude and to aim the wedge axis at true north. Once well adjusted all that is needed to re-position the tripod correctly each night is a good level and a good compass. All that said, you will want access to most of the sky at some point to look at whatever object you have decided to track down. So maybe you should think about how you could gain access to a larger area of the sky instead of how to align without polaris. On Sun, 26 Oct 2003 13:59:50 -0800, hacky wrote: Thanks (I changed my name/address as it is probably coincidence but I already seem to be getting more spam). Do you use a wedge on your Meade? Or do you align it using it in Alt-Az mode? Is it really possible to polar align without seeing Polaris? I plan on doing astrophotog at some point but certainly not most of the time. In article , Gregory Phillips wrote: While it is possible to align without seeing polaris it certainly is not as simple. The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA --- Gregory Phillips Seattle, Washington, USA |
#7
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I use a wedge (a Meade "super wedge"). A wedge is definitely the way to
go, it allows aligning one of the mount axis with earths spin axis. Therefore to track a star only one motor needs to run (the other motor is only used when moving to a different object). This means the various errors introduced by non-perfect drive components are only introduced once instead of for each motor. Note that with a wedge all that is needed for alignment is to adjust the wedge tilt to the latitude and to aim the wedge axis at true north. Once well adjusted all that is needed to re-position the tripod correctly each night is a good level and a good compass. All that said, you will want access to most of the sky at some point to look at whatever object you have decided to track down. So maybe you should think about how you could gain access to a larger area of the sky instead of how to align without polaris. On Sun, 26 Oct 2003 13:59:50 -0800, hacky wrote: Thanks (I changed my name/address as it is probably coincidence but I already seem to be getting more spam). Do you use a wedge on your Meade? Or do you align it using it in Alt-Az mode? Is it really possible to polar align without seeing Polaris? I plan on doing astrophotog at some point but certainly not most of the time. In article , Gregory Phillips wrote: While it is possible to align without seeing polaris it certainly is not as simple. The "drift method" is tricky and takes quite a while (each check takes a few minutes and many adjustments and checks are needed). The good news is great alignment is not needed for anything but long exposure photographic work. I own a 10" Meade LX-200 f6.3 and need to roll it out and re-align it each time I use it. I replaced the cheap bubble level that came on the mount with a higher quality pair of 3" carpenter levels and pay close attention to setting the magnetic compass to corrected north. Once it is dark and I actually turn the scop on it is usually very close to aligned from the start, and "synching" on the first bright star makes it exact for any star in the same quadrant of the sky as the sync star. If I slew all the way across the sky it may end up off by about 1/2 a field of view (with a 26mm eyepiece) but is very easy to center the new target and press sync again. I use to spend about 30 minutes getting a "perfect" alignment at the start of each night but once I got the mount dialed in (latitude and true north) I found that a detailed alignment was not really needed for regular observing. What IS needed is learning the sky well enough to be able to pick out a few bright stars by name so you can check the alignment against them and re-sync if necessary. By the way, watch out for daylight savings time, for the first year I owned the scope I was baffled every 6 months when I suddenly could not seem to align correctly (I use a laptop, The Sky Software, and a serial link). Of course after a while I would remember to correct the relevant clocks so the correct sidereal time was displayed and everything would make sense again. On Fri, 24 Oct 2003 20:38:44 -0700, chansky wrote: Newbie question, I cannot quite see Polaris from where i would like to use my (future) scope. Can see clear to the east and NW and south but not north due to trees (can see about 50 deg and up). Is there some way to align a scope on a GEM with GOTO and GPS without seeing Polaris? It seems like it should be relatively simple to get close given GPS and ability to align with other known stars and then use drift method to come even closer. --- Gregory Phillips Seattle, Washington, USA --- Gregory Phillips Seattle, Washington, USA |
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