Re: [ap-gto] Re: 900 gto settings in maxim


Sep 28, 2004

 


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#10828 Sep 28, 2004

Hello Roland



A while back i contacted you regarding autoguiding problems on my 900gto.

A few nights back i let it run for 8 minutes in maxim ccd auto guiding

through the fs 60c and no barlows ect. I was imaging through the Tak TOA 130 focal

length 1000mm. Out of three images one was perfect round stars the other two

were small ovals?



What settings should i set in maxim ccd for a similar setup like mine. I

have given up with the starlight xpress software for autoguiding for now.

Hopefully you or anyone will help with the parameters for the maxim ccd software.

PS i did train at 1x and used this.

Richard





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



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#10829 Sep 28, 2004

Richard....



I would just use the defaults to begin with. You could also use tracking

with the cables disconnected to get a good idea of what the seeing and

mount are like...



Adrian







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

From: rvbest123321@... [mailto:rvbest123321@...]

Sent: 28 September 2004 18:54

To: ap-gto@yahoogroups.com

Subject: [ap-gto] Re: 900 gto settings in maxim



Hello Roland



A while back i contacted you regarding autoguiding problems on my

900gto.

A few nights back i let it run for 8 minutes in maxim ccd auto guiding

through the fs 60c and no barlows ect. I was imaging through the Tak TOA

130 focal

length 1000mm. Out of three images one was perfect round stars the other

two

were small ovals?



What settings should i set in maxim ccd for a similar setup like mine.

I

have given up with the starlight xpress software for autoguiding for

now.

Hopefully you or anyone will help with the parameters for the maxim ccd

software.

PS i did train at 1x and used this.

Richard





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







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#10830 Sep 28, 2004

In a message dated 9/28/2004 1:15:30 PM Central Daylight Time,

rvbest123321@... writes:



> A while back i contacted you regarding autoguiding problems on my 900gto.

> A few nights back i let it run for 8 minutes in maxim ccd auto guiding

> through the fs 60c and no barlows ect. I was imaging through the Tak TOA 130

> focal

> length 1000mm. Out of three images one was perfect round stars the other

> two

> were small ovals?

>



There are many reasons that you might be getting oval stars. Guiding errors

is just one of them.



If you are using a second scope for guiding, you may be having flexure

problems between the two mounting rings. This would be especially true if you used

some kind of dovetail system. Also, please be aware that if you image low in

the sky, you will definitely get oval stars, even in a 1 second exposure.

Atmospheric refraction will spread the Luminance image into an oval.



Roland Christen





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



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#10831 Sep 28, 2004

Thanks Roland and Adrian



What do myou mean by disconnecting the cables Adrian? How and in what method?



Rich





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



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#10832 Sep 28, 2004

Richard...



Just disconnect the guiding cable from the mount or you could turn off

the guiding corrections in Maxim. I find it useful to see the raw

tracking without corrections as it gives an idea of the PE of the mount

and also the smoothness of PE and finally you can see the random motion

of seeing. Then when you re-connect the guider cable you can get a much

better idea of tracking behaviour, understanding what might be seeing,

mount behaviour etc. Then you might have an idea about the cause of oval

stars and you can start to experiment with Maxim settings adjusting one

at a time then assessing guiding accuracy..



I agree with Roland that you shouldn't image near the horizon, as

atmospheric diffraction will cause elongated stars in a DEC direction,

although you can improve this by using narrower band filters.



Adrian









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

From: rvbest123321@... [mailto:rvbest123321@...]

Sent: 28 September 2004 20:06

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] Re: 900 gto settings in maxim



Thanks Roland and Adrian



What do myou mean by disconnecting the cables Adrian? How and in what

method?



Rich





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#10836 Sep 29, 2004

Hello Adrian



i will try that next clear night we get. How long would you run unguided to

get an idea and also how do you make sure its not a slight bit of drift due to

polar alingment versus tracking problems. I understand Rolands sujjestion

that imaging low down causes oval stars but surely that would be in all images

not 2 out of three.

Anyway i will explore this further maybe trying guiding with the dec cable

disconnected and the the ra cable. My feeling it is periodic error but well

see.



Richard





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







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#10837 Sep 29, 2004

Richard....



I would run for 2 cycles of periodic error which I think is 8 x 2 mins

for the AP900.



Any drift due to mis-polar alignment will be constant and in one

direction. It is most likely you will some after 16 mins even if a few

pixels.



Periodic error will be a repeatable and sinusoidal curve of around 5-10

arc secs for an AP900.



The small rapid and random fluctuations will be seeing effects, usually

less than 1 pixel but dependant on your focal length.



Now mix all that up and try and decipher what is what, actually with

that knowledge it is fairly simple~! I think there might be some

examples in the files section, but often people run a best fit curve

through the track log.



Adrian









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

From: rvbest123321@... [mailto:rvbest123321@...]

Sent: 29 September 2004 16:18

To: ap-gto@yahoogroups.com

Subject: Re: [ap-gto] Re: 900 gto settings in maxim



Hello Adrian



i will try that next clear night we get. How long would you run unguided

to

get an idea and also how do you make sure its not a slight bit of drift

due to

polar alingment versus tracking problems. I understand Rolands

sujjestion

that imaging low down causes oval stars but surely that would be in all

images

not 2 out of three.

Anyway i will explore this further maybe trying guiding with the dec

cable

disconnected and the the ra cable. My feeling it is periodic error but

well

see.



Richard





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







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see groups.yahoo.com/group/ap-gto

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

#10839 Sep 29, 2004

Richard,



As far as setting up Maxim DL for guiding goes... I aim for the

minimum required aggressiveness on each axis, and as short

a 'minimum' guide time as possible.



There is a very good document on the net we talked about at Kelling.

I'll dig it out and email it to your home address. It gives some very

good tips.



How long are your guide integrations? I aim for between 5 and 10secs.

Anything less and you are just chasing the bad UK seeing.



Also, be aware, if you're using Maxim DL ver 4, on the screen showing

guide errors and the graph, the axes are transposed, ie. the graph

for X is shown in the box for Y error and vice versa. You can end up

tweaking one axis and making it worse - when you should be doing the

other!



Cheers, Rob.



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#10840 Sep 30, 2004

Hi Richard



I recently had major guiding problems with a similar setup (TMB 5"

F6 and FS60) whilst imaging near the zenith. I ended up with an

oscillation where the guide movements kept moving between a positive

and a negative amount.



This was partly caused by a balance problem (which I have not

entirely eliminated) but I have since discovered the major problem

was probably UK SEEING. At that particular time I was getting guide

movements of +/- 1-2 pixels.



Last week, the seeing was particularly good, and with no changes to

my mount/scope configuration, the guiding kept within +/- 0.2 pixels

throughout the night.



I would suggest you have another try when the seeing is good (a

rarity these days in SE England I must admit, but it does settle

down at times) and see what results you get then.



I have also found that when the seeing is not particularly good, it

can help a lot to turn off guide adjustments in dec (so long as you

have good polar alignment). I have done this successfully with 10

minute exposures at the same focal length you are using.



Hope this helps



Eddie Guscott



(PS. Nice to meet you at Kelling)





--- In ap-gto@yahoogroups.com, rvbest123321@a... wrote:

> Hello Roland

>

> A while back i contacted you regarding autoguiding problems on my

900gto.

> A few nights back i let it run for 8 minutes in maxim ccd auto

guiding

> through the fs 60c and no barlows ect. I was imaging through the

Tak TOA 130 focal

> length 1000mm. Out of three images one was perfect round stars the

other two

> were small ovals?

>

> What settings should i set in maxim ccd for a similar setup like

mine. I

> have given up with the starlight xpress software for autoguiding

for now.

> Hopefully you or anyone will help with the parameters for the

maxim ccd software.

> PS i did train at 1x and used this.

> Richard

>

>

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



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#10841 Sep 30, 2004

Hello Eddie



Thanks for that advice i will try all you sujjest. Also interesting to note

the turning off of dec, how exactly is this done?

Incidently are you aware if Nick Hudson is away i have tried calling a few

times but just get an answer machine?



Where abouts in the UK are you?



Rich





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







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#10842 Sep 30, 2004

In a message dated 9/30/2004 1:08:46 PM Central Daylight Time,

rvbest123321@... writes:



> Thanks for that advice i will try all you sujjest. Also interesting to note

>

> the turning off of dec, how exactly is this done?

>



In the Maxim parameters you can turn off x or y tracking. Be sure to pick the

right one because they have it backwards in the software. Turning off x

actually turns off y tracking and vise versa.



Roland Christen





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



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#10849 Oct 2, 2004

As Roland stated - be careful which correction axis you turn off. If

in doubt, try one after the other and see the results. You can

access these from the options button under guide settings.



I should point out that all of the problems I have had with guiding,

appear to be software or seeing related (apart from my equipment

balance problems).



When I manage to get these all working together, the mount tracks

superbly. (In fact I get good unguided results - something I have to

investigate more fully with a more precise polar alignment)



I still think that there is some "dark magic" involved with

autoguiding.





Eddie Guscott



--- In ap-gto@yahoogroups.com, rvbest123321@a... wrote:

> Hello Eddie

>

> Thanks for that advice i will try all you sujjest. Also

interesting to note

> the turning off of dec, how exactly is this done?

> Incidently are you aware if Nick Hudson is away i have tried

calling a few

> times but just get an answer machine?

>

> Where abouts in the UK are you?

>

> Rich

>

>

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



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#10850 Oct 3, 2004

OK Eddie



I'll remeber this. Looks like here in England were set for a few days rain.





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



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