From: Mark Gaffney <markgaffney@me.com>

Date: June 5, 2010 12:40:02 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Plate solving

Thanks Milton, 

I`ll look into whether images taken from my DSLR & converted to TIFF will work with Elbrus..(or what the story is there?)

I had a reasonable PA done recently with All Star such that stars slewed to with the HC were just a little off centre in the DSLR`s FOV after hibernating the mount & waking it a couple of nights later. 

After a week of sleep however, the Tarantula nebula had migrated to the outside of the frame of the DSLR. 

I was intending to use the preserved alignment (which included a 3 star done before the All star) & do the All Star again next time centring the star more precisely with the reticle of my illuminated reticle EP (I stretched the spring on it`s LED & it now will stay on permanently)

Since then it`s rained heavily & consistently for several days & I brought the scope inside so have to begin again anyway..

I have marks on my bricks at the base for the tripod legs but putting the OTA & weights back is always a little different to last time I`ve found...

Basically Hibernating should be OK anyway & I`d possibly only resort to plate solving if I lost this saved alignment somehow...

Mark.

On 05/06/2010, at 3:42 PM, Milton Aupperle wrote:

Hi Mark;

On 4-Jun-10, at 10:39 PM, Mark Gaffney wrote:

Hi Milton,

When taking a FITS image with one of my Astro IIDC cameras are the  

telescope's co- ordinates written into this FITS file?

No. Astro IIDC doesn't know where the scope is pointed too.

At a bare minimum you would need to have a GotTo scope that is polar aligned and then a star alignment done so the mount knows where it's pointing. Then you'd have to have a Serial to USB adapter connected, then tell Astro IIDC what mount type it's talking to (huge differences between LX200 types Celestron mounts in protocols). At that point Astro IIDC would know where the mount "thinks" it's pointing too. You also have to make sure that the camera is pointing at the center of the object too.

But I don't really have much interest in implementing all of this, just to get the location for FITS files.

I know I'm talking about using this file with free Windows plate  

solver Elbrus & this may cause problems but I understand this can be  

an easy way of aligning.

I can not see how this will help. If the mount isn't polar aligned, then the accuracy of where your point to isn't accurate either, so this becomes a catch 22 situation as your using the incorrect location for plate solving.

An easy way of aligning is drift align. I get within a few arc seconds of polar alignment in about an hour to hour and a half. It usually takes me about 5 to 15 minutes to get each orientation (South and then east) reasonably close and then about  a 10 minutes of running to make sure it's correct. After that I do 30 minute runs to make sure it's all dialed in for the long exposures (each object is 2 to 3 hours sequences of LRGB images). With a larger FOV like a 1280x1036 Grasshopper, it's a lot easier, but even a 640x480 TIS camera works just fine as long as your careful in how fast you crank the Ra/ Dec axis.

 As long as PA is accurate to within 2 degrees I understand with  

Maxim at least this can take just 30 seconds.

Except that you have horrendous field rotation in each frame. That is a major PITA to deal with when you start aligning LRGB images.

HTH..

Milton J. Aupperle