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MEADE LX200 - ACF 16"

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#1 YUKI

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Posted 20 April 2019 - 01:08 AM

I want to shoot ISS at the highest resolution possible.
Is LX200 - ACF 16" able to track ISS?

Edited by YUKI, 20 April 2019 - 02:13 AM.


#2 TomNC

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Posted 20 April 2019 - 05:51 AM

I attended a star party some years ago and viewed the ISS in a Meade LX200 16 inch. (In the daytime, no less. WOW.) (It was someone else's setup, not mine.) It is one of the best things I ever saw in a scope, so I would say now it should certainly be possible to track with the ACF , though I think some special tracking software or device may be necessary. I haven't looked at the Meade forum here @ CN, but suggest you should post your question there. Good Luck!


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#3 junomike

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Posted 20 April 2019 - 06:05 AM

Moved to "Meade Computerized Telescopes".



#4 carolinaskies

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Posted 20 April 2019 - 02:42 PM

There are some tracking programs... check out this one... https://www.heavensc.../telescope.html

 

And another guy has been creating his own... he used an 8" LX200 with it...  https://www.youtube....h?v=sclc5iDyWjE

A more steady video he shot...  https://www.youtube....h?v=Ub4rE6zfS1g
 


Edited by carolinaskies, 20 April 2019 - 02:44 PM.


#5 RedLionNJ

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Posted 21 April 2019 - 12:18 PM

I want to shoot ISS at the highest resolution possible.
Is LX200 - ACF 16" able to track ISS?

Not without considerable effort - and even then not with certainty.

 

For the highest resolution possible, you're going to want an image scale of around 0.2 arcsec/pixel. This is going to limit your frame size with the LX200. Just how much will depend on the particular cam you utilize to do the capturing. Let's say you have a ZWO ASI290MC (as an example). 2.9 micron pixels, frame size 1096 pixels vertically.  That's a field size of around 3,6 arcminutes - three times the size of the ISS during an overhead pass.

 

I don't know of ANY off-the-shelf system (including the LX200) which is capable of tracking a non-geosynchronous satellite like this.

 

An altaz-mounted LX200 is probably more challenged than most, as following any satellite at closest (zenith) approach involves rapidly slewing in azimuth with motors which are not continuously-variable.

 

If you were to put together a guiding (not tracking) system, you could potentially "lock on" with a well-aligned guidescope with an autoguider, but then you would be relying on custom software to issue guiding corrections, using either native commands for the mount, or ASCOM MoveAxis directives. But with an LX200, you would still have the issue of the motors not being continuously-variable.

 

It's an interesting challenge, but I'd have to conclude, for all practical purposes, you will not be able to achieve optimum resolution while tracking the ISS during a close pass, with an LX200.


Edited by RedLionNJ, 21 April 2019 - 12:19 PM.


#6 carolinaskies

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Posted 21 April 2019 - 12:54 PM

RedLion I suggest you read my first post and visit the videos... VERY doable.  



#7 RedLionNJ

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Posted 22 April 2019 - 04:57 PM

The OP asked about tracking, not active guiding.

 

And none of the YouTube videos showed an example at high resolution OR relative closeness to the imager (e.g. above 60 degrees altitude). You can tell that from the lack of apparent rotation in the orientation of the ISS. This was also a requirement of the OP.



#8 OzAndrewJ

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Posted 22 April 2019 - 05:53 PM

Gday RedLion

But with an LX200, you would still have the issue of the motors not being continuously-variable

.As he specifies a 16" ACF model, i assume its an LX200 ASII type and if so,

it is continuously variable up to about 6deg/sec  ( The 14" and smaller can go to 8deg/sec )

The 497 Autostar/Audiostars can only go variable speed up to about 3 deg/sec,

then it has to go to leapfrog mode for higher speeds.

That said, there is a problem of latency in sending commands that can make it tricky

when you have a very narrow FOV

 

Andrew Johansen Melbourne Australia



#9 carolinaskies

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Posted 22 April 2019 - 07:04 PM

The OP asked about tracking, not active guiding.

 

And none of the YouTube videos showed an example at high resolution OR relative closeness to the imager (e.g. above 60 degrees altitude). You can tell that from the lack of apparent rotation in the orientation of the ISS. This was also a requirement of the OP.

I'm not sure what you're issue is but thousands of amateurs have imaged the ISS with various telescopes and cameras around the world, a subset have video'd it successfully.
You really didn't watch the first video through apparently.  You'll see there is rotation to a degree, he wasn't using a wedge just an Alt-Az configuration.  And perspective of rotation really is a matter of where shot and when.  Another video with the 8" ...  https://www.youtube....h?v=MVSRPjU5ZnM

The original post requires 1. Highest resolution possible (as an amateur as this is an amateur board)  2. Is the LX200 able to track it...   
If you want to compare an amateur's 8" LX200 video image to NASA ground cameras... it's pretty **** good.  A 16" will be better than the 8" because it has far better resolution and paired with most planetary cameras this is pretty much a by the book ability to resolve enough of the ISS for it to be quite distinctive. .  

As Andrew indicates the motors are capable of tracking up to 6*/second... more than enough if you are selective of particular passes of the ISS. 

So Red I'm not sure why your being such a naysayer but the videos are clearly evidence it's quite possible.  

 



#10 carolinaskies

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Posted 22 April 2019 - 07:12 PM

Gday RedLion

.As he specifies a 16" ACF model, i assume its an LX200 ASII type and if so,

it is continuously variable up to about 6deg/sec  ( The 14" and smaller can go to 8deg/sec )

The 497 Autostar/Audiostars can only go variable speed up to about 3 deg/sec,

then it has to go to leapfrog mode for higher speeds.

That said, there is a problem of latency in sending commands that can make it tricky

when you have a very narrow FOV

 

Andrew Johansen Melbourne Australia

I'm not sure how the tracker program works to drive the system, but it seems there is adjustability of update rate between the tracking camera and mount directly to the motor control.  Listening to the drive running in the background of the video it's running at a pretty good clip.   It would be an interesting test for an 16" for sure. 



#11 OzAndrewJ

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Posted 22 April 2019 - 08:32 PM

Gday Paul

The problem isnt how fast SatTracker etc can send updates

Its how fast the scope acts upon them

( and many times, it simply lies :-)    )

Basically, a serial command comes in and is processed by the main CPU

The CPU then passes the command to the main PIC on the mainboard

The PIC then slots this into a stack and processes it when it can.

The rs232 to CPU and CPU to PIC is very quick, but PIC to motorcards comms

can take over 1/2 second before getting acted upon,

esp if the PIC is reading an encoder position, ( which can take 300ms or more )

In the meantime, the PICs interrupt just sends back buffered data to the CPU :-)

ie it is reasonably good at keeping up, but sometimes it isnt :-)

 

Andrew Johansen Melbourne Australia




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