VintageBigBlue.org

 

Re: PE according to my ST8. What to do?


Mar 5, 2003

 


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

#14308 Mar 5, 2003

I've been having a tough time getting the autoguider to correct for periodic

error and some frames are ruined because the corrections or error was too

great.

My question to anyone in this group is this: Given the chart (URL provided)

is this a normal amount of error?



The centroid coordinates for this chart was x=16, y=16. X has been aligned

to the RA axis.

My focal length is 1180mm, using a ST8. I'm seeing error in excess of 10

pixels with each pixel = 1.57 arc seconds according to my math. Eyeballing

the chart it seems to be introduced by the worm because it repeats

predictably.

The chart represents 1800 seconds of data.



Second question, what can I do about it? As is, most images have "hooks" on

the stars because of the movement and corrections.



www.geocities.com/jascarden/images/autoguide_log.jpg





Jason



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

#14309 Mar 5, 2003

Jason,



It's not the magnitude of the PE that is causing your trouble.

Rather it is the sudden change.



Do you have the new worm gear that is available from Losmandy?



Regards,





--- In Losmandy_users@yahoogroups.com, "Jason Carden" jcarden@a...>

wrote: > I've been having a tough time getting the autoguider to correct

for periodic > error and some frames are ruined because the corrections or error

was too > great.

> My question to anyone in this group is this: Given the chart (URL

provided) > is this a normal amount of error?

>

> The centroid coordinates for this chart was x=16, y=16. X has

been aligned > to the RA axis.

> My focal length is 1180mm, using a ST8. I'm seeing error in excess

of 10 > pixels with each pixel = 1.57 arc seconds according to my math.

Eyeballing > the chart it seems to be introduced by the worm because it repeats

> predictably.

> The chart represents 1800 seconds of data.

>

> Second question, what can I do about it? As is, most images

have "hooks" on > the stars because of the movement and corrections.

>

> www.geocities.com/jascarden/images/autoguide_log.jpg

>

>

> Jason



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

#14310 Mar 5, 2003

Jason,

Is that with the guider making corrections? Have you trained PEC, and

how (CCD or visual?)





----- Original Message -----

From: Jason Carden jcarden@...>

Date: Wednesday, March 5, 2003 2:10 pm

Subject: [Losmandy_users] PE according to my ST8. What to do?



> span>p>span>p>

>

>

> tt>

> I've been having a tough time getting the autoguider to correct

> for periodic

>

> error and some frames are ruined because the corrections or error

> was too

>

> great.

>

> My question to anyone in this group is this: Given the chart (URL

> provided)

> is this a normal amount of error?

>

>

>

> The centroid coordinates for this chart was x=16, y=16. X has

> been aligned

>

> to the RA axis.

>

> My focal length is 1180mm, using a ST8. I'm seeing error in excess

> of 10

>

> pixels with each pixel = 1.57 arc seconds according to my math.

> Eyeballing

> the chart it seems to be introduced by the worm because it repeats

>

> predictably.

>

> The chart represents 1800 seconds of data.

>

>

>

> Second question, what can I do about it? As is, most images have

> "hooks" on

>

> the stars because of the movement and corrections.

>

>

>

> www.geocities.com/jascarden/images/autoguide_log.jpg

>

>

>

>

>

> Jason

>

>

>

> /tt>

>

>

>

>

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> Service./tt>/br>

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>







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

#14313 Mar 5, 2003

Hi Jason,



Sure looks like you have some fast spikes occuring. That is not the pattern

I would expect to see from normal PE. This log was taken without

corrections being issued by the autoguider, right? What is the rotation

period of your worm?



Marty

----- Original Message -----

From: "Jason Carden" jcarden@...>

To: Losmandy_users@yahoogroups.com>

Sent: Wednesday, March 05, 2003 2:10 PM

Subject: [Losmandy_users] PE according to my ST8. What to do?





> I've been having a tough time getting the autoguider to correct for

periodic

> error and some frames are ruined because the corrections or error was too

> great.

> My question to anyone in this group is this: Given the chart (URL

provided)

> is this a normal amount of error?

>

> The centroid coordinates for this chart was x=16, y=16. X has been

aligned

> to the RA axis.

> My focal length is 1180mm, using a ST8. I'm seeing error in excess of 10

> pixels with each pixel = 1.57 arc seconds according to my math.

Eyeballing

> the chart it seems to be introduced by the worm because it repeats

> predictably.

> The chart represents 1800 seconds of data.

>

> Second question, what can I do about it? As is, most images have "hooks"

on

> the stars because of the movement and corrections.

>

> www.geocities.com/jascarden/images/autoguide_log.jpg

>

>

> Jason

>

>

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

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>



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

#14314 Mar 5, 2003

I purchased the G-11 on Dec 22 2002 from Astronomics. I believe

the mount should have the new worm, but its supposition.



I do not have a dataset without corrections yet. The graphed data

is the result set with the autoguider attempting to make corrections.

I have not yet aquired a dataset with corrections turned off.

I tried but didn't have the log turned on. Weather has not

cooperated since.



Jason





--- In Losmandy_users@yahoogroups.com, "cjl023" james.lacey@m...>

wrote: > Jason,

>

> It's not the magnitude of the PE that is causing your trouble.

> Rather it is the sudden change.

>

> Do you have the new worm gear that is available from Losmandy?

>

> Regards,

>

>



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

#14315 Mar 5, 2003

To get some accurate PE measurement, you should run with the guider relays "disabled" in CCDSoft (if you're using it), or simply keep the TIC cable unplugged. I'd run at least 8 minutes for my G-11 (or 2 worm cycles).... Did you train PEC already? You may have a bad PEC run causing some havoc.... Or, some sort of guider error..... Best to keep those things out of the initial measurement. Then, after you get the untrained, unguided data, try to train PEC, averaging at least 2 sets, and re-measure UNGUIDED again.....



I'm interested in your results! I'm hoping that there's another answer other than the mount..... I have yet to measure my new G11 (had about a month)....



Good luck!

Bob ----- Original Message -----

From: jascarden

To: Losmandy_users@yahoogroups.com

Sent: Wednesday, March 05, 2003 5:42 PM

Subject: [Losmandy_users] Re: PE according to my ST8. What to do?





I purchased the G-11 on Dec 22 2002 from Astronomics. I believe

the mount should have the new worm, but its supposition.



I do not have a dataset without corrections yet. The graphed data

is the result set with the autoguider attempting to make corrections.

I have not yet aquired a dataset with corrections turned off.

I tried but didn't have the log turned on. Weather has not

cooperated since.



Jason





--- In Losmandy_users@yahoogroups.com, "cjl023" james.lacey@m...>

wrote:

> Jason,

>

> It's not the magnitude of the PE that is causing your trouble.

> Rather it is the sudden change.

>

> Do you have the new worm gear that is available from Losmandy?

>

> Regards,

>

>







Yahoo! Groups Sponsor

ADVERTISEMENT









To unsubscribe from this group, send an email to:

Losmandy_users-unsubscribe@egroups.com







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[Non-text portions of this message have been removed]



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

#14316 Mar 5, 2003

Jason,



Then you do need to get some "unguided" data to see if maybe you

have a "sudden" change in PE that is causing you trouble.



As another poster said, make sure you have PEC off.



Gemini or stepper by the way?



If stepper what kind of autoguider are you using?



There is a problem with the stepper system not being able to respond

to simultaneous commands issued by some combinations of

autoguider/control software. There is an option to control this in

CCDSoft if that is what you are using.



Regards,





--- In Losmandy_users@yahoogroups.com, "jascarden" jcarden@a...>

wrote: > I purchased the G-11 on Dec 22 2002 from Astronomics. I believe

> the mount should have the new worm, but its supposition.

>

> I do not have a dataset without corrections yet. The graphed data

> is the result set with the autoguider attempting to make

corrections. > I have not yet aquired a dataset with corrections turned off.

> I tried but didn't have the log turned on. Weather has not

> cooperated since.

>

> Jason

>

>

> --- In Losmandy_users@yahoogroups.com, "cjl023" james.lacey@m...>

> wrote:

> > Jason,

> >

> > It's not the magnitude of the PE that is causing your trouble.

> > Rather it is the sudden change.

> >

> > Do you have the new worm gear that is available from Losmandy?

> >

> > Regards,

> >

> >







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

#14317 Mar 5, 2003

I've the Gemini Goto setup. I haven't train the PEC, I was attempting to

see if I could guide out any errors first.

I'll get some unguided data the next time there's a hole in the clouds. I'm

just looked outside and it doesn't look like it will be tonight. It figures,

I just installed the Level 3 chip this past Saturday and really want to try

it out.



Jason





-----Original Message-----

From: cjl023 [mailto:james.lacey@...]

Sent: Wednesday, March 05, 2003 6:19 PM

To: Losmandy_users@yahoogroups.com

Subject: [Losmandy_users] Re: PE according to my ST8. What to do?





Jason,



Then you do need to get some "unguided" data to see if maybe you

have a "sudden" change in PE that is causing you trouble.



As another poster said, make sure you have PEC off.



Gemini or stepper by the way?



If stepper what kind of autoguider are you using?



There is a problem with the stepper system not being able to respond

to simultaneous commands issued by some combinations of

autoguider/control software. There is an option to control this in

CCDSoft if that is what you are using.



Regards,





--- In Losmandy_users@yahoogroups.com, "jascarden" jcarden@a...>

wrote: > I purchased the G-11 on Dec 22 2002 from Astronomics. I believe

> the mount should have the new worm, but its supposition.

>

> I do not have a dataset without corrections yet. The graphed data

> is the result set with the autoguider attempting to make

corrections. > I have not yet aquired a dataset with corrections turned off.

> I tried but didn't have the log turned on. Weather has not

> cooperated since.

>

> Jason

>

>

> --- In Losmandy_users@yahoogroups.com, "cjl023" james.lacey@m...>

> wrote:

> > Jason,

> >

> > It's not the magnitude of the PE that is causing your trouble.

> > Rather it is the sudden change.

> >

> > Do you have the new worm gear that is available from Losmandy?

> >

> > Regards,

> >

> >





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ADVERTISEMENT









To unsubscribe from this group, send an email to:

Losmandy_users-unsubscribe@egroups.com







Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.





[Non-text portions of this message have been removed]



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

#14319 Mar 5, 2003

Jason,



Your results are really weird then.



Make sure have TVC turned off too and that you the handcontroller

mode is set to photographic mode also.



Take Care,





--- In Losmandy_users@yahoogroups.com, "Jason Carden" jcarden@a...>

wrote: > I've the Gemini Goto setup. I haven't train the PEC, I was

attempting to > see if I could guide out any errors first.

> I'll get some unguided data the next time there's a hole in the

clouds. I'm > just looked outside and it doesn't look like it will be tonight.

It figures, > I just installed the Level 3 chip this past Saturday and really

want to try > it out.

>

> Jason

>

>

> -----Original Message-----

> From: cjl023 [mailto:james.lacey@m...]

> Sent: Wednesday, March 05, 2003 6:19 PM

> To: Losmandy_users@yahoogroups.com

> Subject: [Losmandy_users] Re: PE according to my ST8. What to do?

>

>

> Jason,

>

> Then you do need to get some "unguided" data to see if maybe you

> have a "sudden" change in PE that is causing you trouble.

>

> As another poster said, make sure you have PEC off.

>

> Gemini or stepper by the way?

>

> If stepper what kind of autoguider are you using?

>

> There is a problem with the stepper system not being able to

respond > to simultaneous commands issued by some combinations of

> autoguider/control software. There is an option to control this

in > CCDSoft if that is what you are using.

>

> Regards,

>

>

> --- In Losmandy_users@yahoogroups.com, "jascarden" jcarden@a...>

> wrote:

> > I purchased the G-11 on Dec 22 2002 from Astronomics. I

believe > > the mount should have the new worm, but its supposition.

> >

> > I do not have a dataset without corrections yet. The graphed

data > > is the result set with the autoguider attempting to make

> corrections.

> > I have not yet aquired a dataset with corrections turned off.

> > I tried but didn't have the log turned on. Weather has not

> > cooperated since.

> >

> > Jason

> >

> >

> > --- In Losmandy_users@yahoogroups.com, "cjl023"

james.lacey@m...> > > wrote:

> > > Jason,

> > >

> > > It's not the magnitude of the PE that is causing your

trouble. > > > Rather it is the sudden change.

> > >

> > > Do you have the new worm gear that is available from

Losmandy? > > >

> > > Regards,

> > >

> > >

>

>

> Yahoo! Groups Sponsor

> ADVERTISEMENT

>

>

>

>

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

> Losmandy_users-unsubscribe@egroups.com

>

>

>

> Your use of Yahoo! Groups is subject to the Yahoo! Terms of

Service. >

>

> [Non-text portions of this message have been removed]







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

#14327 Mar 6, 2003

Hi Jason,



First, as you know, you need to gather a data set without the guider.

That'll give you hard facts about how your worm/gear combination

performs.



From the chart it certainly does not look like a normal PE behavior.

The guider appears to be overreacting and making too large of a

correction: each large spike is preceded by a smaller spike in the

opposite direction.



Here are some things you may want to try:



- Turn off TVC (set it to 0)

- Reduce the guiding speed of the mount to 0.5 or less of the sidereal

- Reduce guider aggressiveness (assuming your software allows you to)

- Carefully balance the weight to be a bit overweight on the east

side and heavier on the camera side.

- Check for backlash in RA. If the mount has a lot of play in RA,

slight wind or weight shift will cause large errors

- Try guiding with the DEC cable disconnected to see if the DEC

corrections are causing the errors

- If you find that the RA worm has large PE spikes, swap it with the

DEC worm, and see if you get an improvement.



Regards,



-Paul



--- In Losmandy_users@yahoogroups.com, "Jason Carden" jcarden@a...>

wrote: > I've been having a tough time getting the autoguider to correct for

periodic > error and some frames are ruined because the corrections or error

was too > great.

> My question to anyone in this group is this: Given the chart (URL

provided) > is this a normal amount of error?

>

> The centroid coordinates for this chart was x=16, y=16. X has been

aligned > to the RA axis.

> My focal length is 1180mm, using a ST8. I'm seeing error in excess

of 10 > pixels with each pixel = 1.57 arc seconds according to my math.

Eyeballing > the chart it seems to be introduced by the worm because it repeats

> predictably.

> The chart represents 1800 seconds of data.

>

> Second question, what can I do about it? As is, most images

have "hooks" on > the stars because of the movement and corrections.

>

> www.geocities.com/jascarden/images/autoguide_log.jpg

>

>

> Jason



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

#14329 Mar 6, 2003

I agree with others, check the mount out first all by itself.



Kevin

--- In Losmandy_users@yahoogroups.com, "Paul K" pkane@h...> wrote:

> Hi Jason,

>

> First, as you know, you need to gather a data set without the

guider.

> That'll give you hard facts about how your worm/gear combination

> performs.

>

> From the chart it certainly does not look like a normal PE

behavior.

> The guider appears to be overreacting and making too large of a

> correction: each large spike is preceded by a smaller spike in the

> opposite direction.

>

> Here are some things you may want to try:

>

> - Turn off TVC (set it to 0)

> - Reduce the guiding speed of the mount to 0.5 or less of the

sidereal

> - Reduce guider aggressiveness (assuming your software allows you

to)

> - Carefully balance the weight to be a bit overweight on the east

> side and heavier on the camera side.

> - Check for backlash in RA. If the mount has a lot of play in RA,

> slight wind or weight shift will cause large errors

> - Try guiding with the DEC cable disconnected to see if the DEC

> corrections are causing the errors

> - If you find that the RA worm has large PE spikes, swap it with

the

> DEC worm, and see if you get an improvement.

>

> Regards,

>

> -Paul

>

> --- In Losmandy_users@yahoogroups.com, "Jason Carden"

jcarden@a...>

> wrote:

> > I've been having a tough time getting the autoguider to correct

for

> periodic

> > error and some frames are ruined because the corrections or

error

> was too

> > great.

> > My question to anyone in this group is this: Given the chart

(URL

> provided)

> > is this a normal amount of error?

> >

> > The centroid coordinates for this chart was x=16, y=16. X has

been

> aligned

> > to the RA axis.

> > My focal length is 1180mm, using a ST8. I'm seeing error in

excess

> of 10

> > pixels with each pixel = 1.57 arc seconds according to my math.

> Eyeballing

> > the chart it seems to be introduced by the worm because it

repeats

> > predictably.

> > The chart represents 1800 seconds of data.

> >

> > Second question, what can I do about it? As is, most images

> have "hooks" on

> > the stars because of the movement and corrections.

> >

> > www.geocities.com/jascarden/images/autoguide_log.jpg

> >

> >

> > Jason



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

#14331 Mar 7, 2003

Thanks to all that have responded.



Last night I was able to collect a bit more data.

I didn't have much time so I did a rough polar alignment and setup the

camera, let it start logging, and went back in the house to feed the baby.

The data looks much better with the autoguider disconnected. The guide

star eventually drifted of the chip but the chart doesn't show any fast

sudden spikes.



I later went back out and plugged the guider back in and collected some more

data with it plugged in. Also a few 5 minute light exposures with the guider

turned on.



Each chart represents about 8 minutes of data.

Here's the chart with the guider unplugged:

www.geocities.com/jascarden/images/guider_on.jpg

Here's the chart with the guider plugged in:

www.geocities.com/jascarden/images/guider_off.jpg

and the image I took: www.geocities.com/jascarden/images/flame_l.jpg



Jason









-----Original Message-----

From: kevinbm13 [mailto:_kevin1231@...]

Sent: Thursday, March 06, 2003 9:36 PM

To: Losmandy_users@yahoogroups.com

Subject: [Losmandy_users] Re: PE according to my ST8. What to do?





I agree with others, check the mount out first all by itself.



Kevin

--- In Losmandy_users@yahoogroups.com, "Paul K" pkane@h...> wrote:

> Hi Jason,

>

> First, as you know, you need to gather a data set without the

guider.

> That'll give you hard facts about how your worm/gear combination

> performs.

>

> From the chart it certainly does not look like a normal PE

behavior.

> The guider appears to be overreacting and making too large of a

> correction: each large spike is preceded by a smaller spike in the

> opposite direction.

>

> Here are some things you may want to try:

>

> - Turn off TVC (set it to 0)

> - Reduce the guiding speed of the mount to 0.5 or less of the

sidereal

> - Reduce guider aggressiveness (assuming your software allows you

to)

> - Carefully balance the weight to be a bit overweight on the east

> side and heavier on the camera side.

> - Check for backlash in RA. If the mount has a lot of play in RA,

> slight wind or weight shift will cause large errors

> - Try guiding with the DEC cable disconnected to see if the DEC

> corrections are causing the errors

> - If you find that the RA worm has large PE spikes, swap it with

the

> DEC worm, and see if you get an improvement.

>

> Regards,

>

> -Paul

>

> --- In Losmandy_users@yahoogroups.com, "Jason Carden"

jcarden@a...>

> wrote:

> > I've been having a tough time getting the autoguider to correct

for

> periodic

> > error and some frames are ruined because the corrections or

error

> was too

> > great.

> > My question to anyone in this group is this: Given the chart

(URL

> provided)

> > is this a normal amount of error?

> >

> > The centroid coordinates for this chart was x=16, y=16. X has

been

> aligned

> > to the RA axis.

> > My focal length is 1180mm, using a ST8. I'm seeing error in

excess

> of 10

> > pixels with each pixel = 1.57 arc seconds according to my math.

> Eyeballing

> > the chart it seems to be introduced by the worm because it

repeats

> > predictably.

> > The chart represents 1800 seconds of data.

> >

> > Second question, what can I do about it? As is, most images

> have "hooks" on

> > the stars because of the movement and corrections.

> >

> > www.geocities.com/jascarden/images/autoguide_log.jpg

> >

> >

> > Jason





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To unsubscribe from this group, send an email to:

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Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.





[Non-text portions of this message have been removed]







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