VintageBigBlue.org

 

Re: PE Errors = Velocity


Nov 10, 2000

 


----------------------------

#932 Nov 10, 2000

To All:

I've been having discussions with Scott L. for months now about PE

and the forthcoming Gemini goto system. The goto portion I can do

without, but, I too thought that maybe the servo motors would provide

better tracking accuracy than the steppers. This is not necessarily

so. The whole tracking thing is a matter of velocity. The steppers

do make discrete steps, but, if you've ever watched them at work,

you'll notice that the worm "seems" at almost a constant rotational

velocity. This in turn, spins the main gear at a very slow, but

pretty much constant velocity. The errors induced by slop in the worm

and main gear account for, by far, the majority of the PE.

The steppers contribution is almost negligible. According to Scott,

the servos in the Gemini would correct for some of the steppers

contribution to PE, but it's already so small....well you get the

idea.

It's easy for us to say that the machining of these parts should

be held to tighter tolerances. When you realistically consider the

number of zeroes behind those decimal points you can see that it's a

lot easier said than done. It's not like Scott's people don't take

pride in their work. If you disassemble a G11, you'll see precision

machining in places that most people never look.

I apologize for the rambling defense of Scott, but I wanted to let

the group know that the Gemini servo motors will not (IMHO) be the

cure-all for the G11.



Regards,

Bruce Inscoe



----------------------------

#933 Nov 10, 2000

Bruce Inscoe wrote:

> I've been having discussions with Scott L. for months now about PE

> and the forthcoming Gemini goto system. The goto portion I can do

> without, but, I too thought that maybe the servo motors would provide

> better tracking accuracy than the steppers. This is not necessarily

> so. The whole tracking thing is a matter of velocity. The steppers

> do make discrete steps, but, if you've ever watched them at work,

> you'll notice that the worm "seems" at almost a constant rotational

> velocity. This in turn, spins the main gear at a very slow, but

> pretty much constant velocity. The errors induced by slop in the worm

> and main gear account for, by far, the majority of the PE.



Bruce,



I agree that the majority of the PE is probably introduced through the worm

gear and worm wheel combo, and plan on replacing the worm gear bearings with

new ones shortly. I already have them (although I just got the grade 5's) as

well as additional needle bearings. I've been waiting for the weather here

(Portland, OR) to clear a bit, since I wanted to take some images before the

modification to measure the results by. I hope to take some comparative

images after the mod, as well as after the Gemini mod, to see what actually

has happened. And since I *do* want the goto cabability, I would be getting

it anyway. The one difference I hope to see is an increase in the torque

available, so that weight won't be of as much a factor (not excessive weight

mind you, just the difference between a 10" SCT and a 4" Tak FS102.)

What I hope to achieve is not 0 PE, but rather a smooth PE curve that might

max out at around 10 - 15 arc seconds. The ST-7 is perfectly cabable of

guiding this out and will achieve nice round stars. The PE on my scope as it

stands now tends to spike rapidly, which can't be guided out.

> It's easy for us to say that the machining of these parts should

> be held to tighter tolerances. When you realistically consider the

> number of zeroes behind those decimal points you can see that it's a

> lot easier said than done.



I agree. When I was much younger, my dad had a tool and die shop, where any

government work they did had to be within a .0001 of an inch. And this was

before CNC machining. It took an incredible amount of skill, not to mention

just a little bit of cash.

> It's not like Scott's people don't take

> pride in their work. If you disassemble a G11, you'll see precision

> machining in places that most people never look.

> I apologize for the rambling defense of Scott, but I wanted to let

> the group know that the Gemini servo motors will not (IMHO) be the

> cure-all for the G11.



No need for apology. Scott does excellent work and given the budget

constraints he's aiming for, the G-11 is an excellent value. I think what I

and some others on this list would like to achieve is the maximum that this

mount is capable of, even if it requires some additional machining or

upgrading of existing parts (at additional $$$). Before this list existed, I

think many of us were just operating in the dark, without much of an idea of

which way to go. The strides that have been made in just a few months is

extremely heartening.







--

Jim Girard

www.teleport.com/~argo



----------------------------

#934 Nov 11, 2000

since I wanted to take some images

before the > modification to measure the results by. I hope to take some

comparative > images after the mod, as well as after the Gemini mod, to see what

actually > has happened.



I hear you Jim. That's the way to do it. When Scott saw the

difference in the PE shot that I posted, he said, and I agree, that I

should have replaced one set of bearings, taken a shot, then the

needle bearing, another shot, etc. But after removing the OTA,

removing the head from the pier (which is taller than I, so step

ladder needed), putting the head on my workbench,...well in short, I

replaced them all at once, so now I don't know which one made the

bigger difference.

The way to see differences in PE if you have a CCD camera, is to

skew the polar alignment (I unlock and crank the azimuth knob all the

way to one side), then take a four minute shot (one worm cycle)

without any guiding, etc. It's sort of inconvenient, but for accurate

testing, take a shot "before" and "after" each modification. If you

do, please post the results for the rest of us! Thanks.



Regards,

Bruce Inscoe







----------------------------

#938 Nov 11, 2000

>>But if I had my choice,I'd pay a few hundred more to get better tolerances on the shafts/bearing fits,abek7 bearings,and a professional

machinists'steup of the worm to gear fitup.<



Keep in mind, Scott offers three mounts. GM8 at the bottom, the G11 in

the middle and the HGM200, the top of the line. This mount is virtually

never discussed here. How does it compare to the other two?



You do get what you pay for. Therefore, you pay for what you want or

need. If you insert these mounts into the queue of all mounts available,

for all of astronomy, you realize Losmandy makes an excellent mount for

the price.



Take care,

Gregory david Stempel

FIREFRAME



----------------------------

#941 Nov 11, 2000

Greg:

How true! If you look closely at AP, Takahashi, Gemini, Byers,

etc. there is really nothing with the same capacity and accuracy for

anywhere close to the money. The next steps above Losmandy are double

the price for only a small amount of more accuracy.



Regards,

Bruce Inscoe >

> Keep in mind, Scott offers three mounts. GM8 at the bottom, the G11

in > the middle and the HGM200, the top of the line. This mount is

virtually > never discussed here. How does it compare to the other two?

>

> You do get what you pay for. Therefore, you pay for what you want or

> need. If you insert these mounts into the queue of all mounts

available, > for all of astronomy, you realize Losmandy makes an excellent mount

for > the price.

>

> Take care,

> Gregory david Stempel

> FIREFRAME



----------------------------

#956 Nov 12, 2000

I use a GM-200 (got it for about 1 year). I use to have a G11

and would say that the GM-200 is a monster... I can put a 60 pounds

OTA on it without any problem. this mount is about 3x the capacity

of the G11.



Not too difficult to use in the field, certainly heavier but I can

assemble it in about 20 minutes.





PE is about 5 arcsec peak to peak, but there is a drift in RA

causes by a slight error (in my opinion) in the standard speed of

the losmandy computer. I may change the quartz (crystal) in the controler to

correct that.



I have a picture of the scope/mount at



www.astroccd.com/benoit/benoit2.jpg



-- benoit



>From: Gregory David Stempel fyrframe@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: Re: [Losmandy_users] PE Errors = Velocity

>Date: Sat, 11 Nov 2000 09:20:19 -0800

>

> >>>But if I had my choice,I'd pay a few hundred more to get better

>tolerances on the shafts/bearing fits,abek7 bearings,and a professional

>machinists'steup of the worm to gear fitup.<

>

>Keep in mind, Scott offers three mounts. GM8 at the bottom, the G11 in

>the middle and the HGM200, the top of the line. This mount is virtually

>never discussed here. How does it compare to the other two?

>

>You do get what you pay for. Therefore, you pay for what you want or

>need. If you insert these mounts into the queue of all mounts available,

>for all of astronomy, you realize Losmandy makes an excellent mount for

>the price.

>

>Take care,

>Gregory david Stempel

>FIREFRAME



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----------------------------

#960 Nov 13, 2000

> PE is about 5 arcsec peak to peak, but there is a drift in RA

> causes by a slight error (in my opinion) in the standard speed of

> the losmandy computer. I may change the quartz (crystal) in the controler to

> correct that.



Benoit,

I have noticed the same thing on my G-11. It is about 1

arc-second/minute, slow enough to guide out, but not at all what I

expected. Let me know if changing the crystal has an effect. It would

be strange if it was bad, they are pretty accurate and tend not to

change all that much over time.



Thanks

Tom Carrico

www.proaxis.com/~carrico



----------------------------

#966 Nov 13, 2000

I think that there is a minor error in the code of the controller

which causes the speed not to be exactly right.



Since everything is timed based on the CPU clock, if I change the

crystal everything should scale.



Crystal can be obtained with accuracy of better than 0.01 % !



1 arcsec/min is about 0.1% accurate which is in the range advertized

by Losmandy, but one could do better.



-- benoit



>From: Julie and Tom Carrico carrico@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: Re: [Losmandy_users] PE Errors = Velocity

>Date: Mon, 13 Nov 2000 07:40:12 -0800

>

>

> >

> > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > causes by a slight error (in my opinion) in the standard speed of

> > the losmandy computer. I may change the quartz (crystal) in the

>controler to

> > correct that.

>

>Benoit,

>I have noticed the same thing on my G-11. It is about 1

>arc-second/minute, slow enough to guide out, but not at all what I

>expected. Let me know if changing the crystal has an effect. It would

>be strange if it was bad, they are pretty accurate and tend not to

>change all that much over time.

>

>Thanks

>Tom Carrico

>www.proaxis.com/~carrico



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----------------------------

#968 Nov 13, 2000

Do you mean the G-11 has drift due to error in the computer speed or is that for

the GM-200?



benoit schillings wrote:

> I use a GM-200 (got it for about 1 year). I use to have a G11

> and would say that the GM-200 is a monster... I can put a 60 pounds

> OTA on it without any problem. this mount is about 3x the capacity

> of the G11.

>

> Not too difficult to use in the field, certainly heavier but I can

> assemble it in about 20 minutes.

>

> PE is about 5 arcsec peak to peak, but there is a drift in RA

> causes by a slight error (in my opinion) in the standard speed of

> the losmandy computer. I may change the quartz (crystal) in the controler to

> correct that.

>

> I have a picture of the scope/mount at

>

> www.astroccd.com/benoit/benoit2.jpg

>

> -- benoit

>

> >From: Gregory David Stempel fyrframe@...>

> >Reply-To: Losmandy_users@egroups.com

> >To: Losmandy_users@egroups.com

> >Subject: Re: [Losmandy_users] PE Errors = Velocity

> >Date: Sat, 11 Nov 2000 09:20:19 -0800

> >

> > >>>But if I had my choice,I'd pay a few hundred more to get better

> >tolerances on the shafts/bearing fits,abek7 bearings,and a professional

> >machinists'steup of the worm to gear fitup.<

> >

> >Keep in mind, Scott offers three mounts. GM8 at the bottom, the G11 in

> >the middle and the HGM200, the top of the line. This mount is virtually

> >never discussed here. How does it compare to the other two?

> >

> >You do get what you pay for. Therefore, you pay for what you want or

> >need. If you insert these mounts into the queue of all mounts available,

> >for all of astronomy, you realize Losmandy makes an excellent mount for

> >the price.

> >

> >Take care,

> >Gregory david Stempel

> >FIREFRAME

>

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>

> To unsubscribe from this group, send an email to:

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--

Rob Watson

home.pacbell.net/watsonrm/



----------------------------

#986 Nov 14, 2000

I cannot say for certain for the G11 but I would not be

surprised.



Keep in mind that you need to have an extremely good polar

alignement before judging that since small error in elevation

will offset the rate by (sin(dec)/sin(dec+error))



-- benoit



>From: Rob Watson watsonrm@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: Re: [Losmandy_users] PE Errors = Velocity

>Date: Mon, 13 Nov 2000 19:39:20 -0800

>

>Do you mean the G-11 has drift due to error in the computer speed or is

>that for

>the GM-200?

>

>benoit schillings wrote:

>

> > I use a GM-200 (got it for about 1 year). I use to have a G11

> > and would say that the GM-200 is a monster... I can put a 60 pounds

> > OTA on it without any problem. this mount is about 3x the capacity

> > of the G11.

> >

> > Not too difficult to use in the field, certainly heavier but I can

> > assemble it in about 20 minutes.

> >

> > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > causes by a slight error (in my opinion) in the standard speed of

> > the losmandy computer. I may change the quartz (crystal) in the

>controler to

> > correct that.

> >

> > I have a picture of the scope/mount at

> >

> > www.astroccd.com/benoit/benoit2.jpg

> >

> > -- benoit

> >

> > >From: Gregory David Stempel fyrframe@...>

> > >Reply-To: Losmandy_users@egroups.com

> > >To: Losmandy_users@egroups.com

> > >Subject: Re: [Losmandy_users] PE Errors = Velocity

> > >Date: Sat, 11 Nov 2000 09:20:19 -0800

> > >

> > > >>>But if I had my choice,I'd pay a few hundred more to get better

> > >tolerances on the shafts/bearing fits,abek7 bearings,and a professional

> > >machinists'steup of the worm to gear fitup.<

> > >

> > >Keep in mind, Scott offers three mounts. GM8 at the bottom, the G11 in

> > >the middle and the HGM200, the top of the line. This mount is virtually

> > >never discussed here. How does it compare to the other two?

> > >

> > >You do get what you pay for. Therefore, you pay for what you want or

> > >need. If you insert these mounts into the queue of all mounts

>available,

> > >for all of astronomy, you realize Losmandy makes an excellent mount for

> > >the price.

> > >

> > >Take care,

> > >Gregory david Stempel

> > >FIREFRAME

> >

> >

---------------

> > Get Your Private, Free E-mail from MSN Hotmail at

>www.hotmail.com

> >

> > Share information about yourself, create your own public profile at

> > profiles.msn.com

> >

> >

> > To unsubscribe from this group, send an email to:

> > Losmandy_users-unsubscribe@egroups.com

>

>--

>Rob Watson

>home.pacbell.net/watsonrm/

>

>



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----------------------------

#1045 Nov 18, 2000

Benoit,

>>>I use a GM-200 (got it for about 1 year). I use to have a G11

and would say that the GM-200 is a monster... I can put a 60 pounds

OTA on it without any problem. this mount is about 3x the capacity

of the G11<



Wow! A nice setup. Is the scope hand made or kit form?



I appreciate the feedback on the HGM200, this mount has always

interested me and may be my next upgrade.

>>>I may change the quartz (crystal) in the controler to

correct that.<



Is this an easy upgrade? What are your sources of the quartz controller?



Thanks Bennoit, take care out there.

Gregory david Stempel

FIREFRAME



----------------------------

#1067 Nov 20, 2000

The scope is mostly home made... still in constant improvement.



For the quartz, I've found a while back a few companies which will

make a quartz for a given frequency for $50 or so... still need to

try that.



-- benoit



>From: Gregory David Stempel fyrframe@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: Re: [Losmandy_users] PE Errors = Velocity

>Date: Sat, 18 Nov 2000 08:08:54 -0800

>

>Benoit,

>

> >>>I use a GM-200 (got it for about 1 year). I use to have a G11

>and would say that the GM-200 is a monster... I can put a 60 pounds

>OTA on it without any problem. this mount is about 3x the capacity

>of the G11<

>

>Wow! A nice setup. Is the scope hand made or kit form?

>

>I appreciate the feedback on the HGM200, this mount has always

>interested me and may be my next upgrade.

>

> >>>I may change the quartz (crystal) in the controler to

>correct that.<

>

>Is this an easy upgrade? What are your sources of the quartz controller?

>

>Thanks Bennoit, take care out there.

>Gregory david Stempel

>FIREFRAME



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----------------------------

#1082 Nov 23, 2000

Benoit,

>>>make a quartz for a given frequency for $50 or so... still need to

try that.<



It seems then, there is the problem of inserting the new quartz control

into the existing electrial system.



I like the idea.



Take care,

Gregory david Stempel

FIREFRAME



----------------------------

#1085 Nov 23, 2000

Well, it seems to me to be a simple job of desoldering it and

puting the new one in place.



I have two things which holds me for now to do it (other than time ;-))



- There are different types of crystal and I need to be certain I order

the proper one.



- I want to be certain that I measured the rate error accuratly, this

can only be done if the polar alignement is nearly perfect which is

not a trivial task.



I will keep the list informed.



-- benoit



>From: Gregory David Stempel fyrframe@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: Re: [Losmandy_users] PE Errors = Velocity

>Date: Thu, 23 Nov 2000 10:38:35 -0800

>

>Benoit,

>

> >>>make a quartz for a given frequency for $50 or so... still need to

>try that.<

>

>It seems then, there is the problem of inserting the new quartz control

>into the existing electrial system.

>

>I like the idea.

>

>Take care,

>Gregory david Stempel

>FIREFRAME



---------------

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----------------------------

#1088 Nov 24, 2000

Benoit,

>>>only be done if the polar alignement is nearly perfect which is

not a trivial task.<



So true.



I assumed the crystal would be in some kind of housing specifically

designed for the shape.



Thanks for your feedback, it will be interesting to hear your results.



Take care,

Gregory david Stempel

FIREFRAME



----------------------------

#1107 Nov 26, 2000

If you are not perfectly aligned, then the proper RA rpd will

always be too small. Its a case of a projection of any vector into

any other direction will always be too small



--- In Losmandy_users@egroups.com, Julie and Tom Carrico

carrico@p...> wrote: >

> >

> > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > causes by a slight error (in my opinion) in the standard speed of

> > the losmandy computer. I may change the quartz (crystal) in the

controler to > > correct that.

>

> Benoit,

> I have noticed the same thing on my G-11. It is about 1

> arc-second/minute, slow enough to guide out, but not at all what I

> expected. Let me know if changing the crystal has an effect. It

would > be strange if it was bad, they are pretty accurate and tend not to

> change all that much over time.

>

> Thanks

> Tom Carrico

> www.proaxis.com/~carrico







----------------------------

#1153 Nov 29, 2000

mmm... if your polar axis is pointing too low and

if you are imaging near the meridian at a positive dec,

it seems to me that the tracking would be fast ? do I miss

something ?



-- benoit



>From: havriliak@...

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: [Losmandy_users] Re: PE Errors = Velocity

>Date: Mon, 27 Nov 2000 00:45:50 -0000

>

> If you are not perfectly aligned, then the proper RA rpd will

>always be too small. Its a case of a projection of any vector into

>any other direction will always be too small

>

>--- In Losmandy_users@egroups.com, Julie and Tom Carrico

>carrico@p...> wrote:

> >

> > >

> > > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > > causes by a slight error (in my opinion) in the standard speed of

> > > the losmandy computer. I may change the quartz (crystal) in the

>controler to

> > > correct that.

> >

> > Benoit,

> > I have noticed the same thing on my G-11. It is about 1

> > arc-second/minute, slow enough to guide out, but not at all what I

> > expected. Let me know if changing the crystal has an effect. It

>would

> > be strange if it was bad, they are pretty accurate and tend not to

> > change all that much over time.

> >

> > Thanks

> > Tom Carrico

> > www.proaxis.com/~carrico

>



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----------------------------

#1164 Nov 29, 2000

As I see it velocity is a vector and the correct RA velocity is

also a vector. Projection of the former onto the latter is related

to the cosine of the angel between them. Cosine of any vector will

always be small that the original vector.



--- In Losmandy_users@egroups.com, "benoit schillings"

benoit_schillings@h...> wrote: > mmm... if your polar axis is pointing too low and

> if you are imaging near the meridian at a positive dec,

> it seems to me that the tracking would be fast ? do I miss

> something ?

>

> -- benoit

>

>

> >From: havriliak@a...

> >Reply-To: Losmandy_users@egroups.com

> >To: Losmandy_users@egroups.com

> >Subject: [Losmandy_users] Re: PE Errors = Velocity

> >Date: Mon, 27 Nov 2000 00:45:50 -0000

> >

> > If you are not perfectly aligned, then the proper RA rpd will

> >always be too small. Its a case of a projection of any vector into

> >any other direction will always be too small

> >

> >--- In Losmandy_users@egroups.com, Julie and Tom Carrico

> >carrico@p...> wrote:

> > >

> > > >

> > > > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > > > causes by a slight error (in my opinion) in the standard

speed of > > > > the losmandy computer. I may change the quartz (crystal) in

the > >controler to

> > > > correct that.

> > >

> > > Benoit,

> > > I have noticed the same thing on my G-11. It is about 1

> > > arc-second/minute, slow enough to guide out, but not at all

what I > > > expected. Let me know if changing the crystal has an effect. It

> >would

> > > be strange if it was bad, they are pretty accurate and tend not

to > > > change all that much over time.

> > >

> > > Thanks

> > > Tom Carrico

> > > www.proaxis.com/~carrico

> >

>

>

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----------------------------

#1169 Nov 29, 2000

mmm... take the trivial case :



Tracking an object at the meridian and at +89.9 dec



If the elevation of the polar axis is too low, the actual

tracking speed projected on the sky will be larger than

what is required in azimuth for that elevation.





-- benoit



>From: havriliak@...

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: [Losmandy_users] Re: PE Errors = Velocity

>Date: Wed, 29 Nov 2000 23:08:00 -0000

>

> As I see it velocity is a vector and the correct RA velocity is

>also a vector. Projection of the former onto the latter is related

>to the cosine of the angel between them. Cosine of any vector will

>always be small that the original vector.

>

>--- In Losmandy_users@egroups.com, "benoit schillings"

>benoit_schillings@h...> wrote:

> > mmm... if your polar axis is pointing too low and

> > if you are imaging near the meridian at a positive dec,

> > it seems to me that the tracking would be fast ? do I miss

> > something ?

> >

> > -- benoit

> >

> >

> > >From: havriliak@a...

> > >Reply-To: Losmandy_users@egroups.com

> > >To: Losmandy_users@egroups.com

> > >Subject: [Losmandy_users] Re: PE Errors = Velocity

> > >Date: Mon, 27 Nov 2000 00:45:50 -0000

> > >

> > > If you are not perfectly aligned, then the proper RA rpd will

> > >always be too small. Its a case of a projection of any vector into

> > >any other direction will always be too small

> > >

> > >--- In Losmandy_users@egroups.com, Julie and Tom Carrico

> > >carrico@p...> wrote:

> > > >

> > > > >

> > > > > PE is about 5 arcsec peak to peak, but there is a drift in RA

> > > > > causes by a slight error (in my opinion) in the standard

>speed of

> > > > > the losmandy computer. I may change the quartz (crystal) in

>the

> > >controler to

> > > > > correct that.

> > > >

> > > > Benoit,

> > > > I have noticed the same thing on my G-11. It is about 1

> > > > arc-second/minute, slow enough to guide out, but not at all

>what I

> > > > expected. Let me know if changing the crystal has an effect. It

> > >would

> > > > be strange if it was bad, they are pretty accurate and tend not

>to

> > > > change all that much over time.

> > > >

> > > > Thanks

> > > > Tom Carrico

> > > > www.proaxis.com/~carrico

> > >

> >

> >

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>_______________

> > Get more from the Web. FREE MSN Explorer download :

>explorer.msn.com

>



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#1173 Nov 29, 2000

The tracking speed should be cast in terms of rev./day





--- In Losmandy_users@egroups.com, "benoit schillings"

benoit_schillings@h...> wrote: > mmm... take the trivial case :

>

> Tracking an object at the meridian and at +89.9 dec

>

> If the elevation of the polar axis is too low, the actual

> tracking speed projected on the sky will be larger than

> what is required in azimuth for that elevation.

>

>

> -- benoit

>

>

> >From: havriliak@a...

> >Reply-To: Losmandy_users@egroups.com

> >To: Losmandy_users@egroups.com

> >Subject: [Losmandy_users] Re: PE Errors = Velocity

> >Date: Wed, 29 Nov 2000 23:08:00 -0000

> >

> > As I see it velocity is a vector and the correct RA velocity

is > >also a vector. Projection of the former onto the latter is related

> >to the cosine of the angel between them. Cosine of any vector will

> >always be small that the original vector.

> >

> >--- In Losmandy_users@egroups.com, "benoit schillings"

> >benoit_schillings@h...> wrote:

> > > mmm... if your polar axis is pointing too low and

> > > if you are imaging near the meridian at a positive dec,

> > > it seems to me that the tracking would be fast ? do I miss

> > > something ?

> > >

> > > -- benoit

> > >

> > >

> > > >From: havriliak@a...

> > > >Reply-To: Losmandy_users@egroups.com

> > > >To: Losmandy_users@egroups.com

> > > >Subject: [Losmandy_users] Re: PE Errors = Velocity

> > > >Date: Mon, 27 Nov 2000 00:45:50 -0000

> > > >

> > > > If you are not perfectly aligned, then the proper RA rpd

will > > > >always be too small. Its a case of a projection of any vector

into > > > >any other direction will always be too small

> > > >

> > > >--- In Losmandy_users@egroups.com, Julie and Tom Carrico

> > > >carrico@p...> wrote:

> > > > >

> > > > > >

> > > > > > PE is about 5 arcsec peak to peak, but there is a drift

in RA > > > > > > causes by a slight error (in my opinion) in the standard

> >speed of

> > > > > > the losmandy computer. I may change the quartz (crystal)

in > >the

> > > >controler to

> > > > > > correct that.

> > > > >

> > > > > Benoit,

> > > > > I have noticed the same thing on my G-11. It is about 1

> > > > > arc-second/minute, slow enough to guide out, but not at all

> >what I

> > > > > expected. Let me know if changing the crystal has an

effect. It > > > >would

> > > > > be strange if it was bad, they are pretty accurate and tend

not > >to

> > > > > change all that much over time.

> > > > >

> > > > > Thanks

> > > > > Tom Carrico

> > > > > www.proaxis.com/~carrico

> > > >

> > >

> > >

>

---------------

_ > >_______________

> > > Get more from the Web. FREE MSN Explorer download :

> >explorer.msn.com

> >

>

>

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