Distance between Shaula and Lesath

[Garbz (Chris)]

I've been trying to figure out the optimal spacing between my reducer and my camera to minimise the coma in my pictures, however as I move the camera I change my field of view of the resulting picture. Being unable to actually eliminate the coma I'm trying to determine what setup gives me the greatest field of view.

For that I'm trying to figure out how many arcseconds per pixel I get as a result, sadly the damn images won't plate solve.

So my question is, does anyone have a clue what the distance between Shaula and Lesath is, or how I would go about calculating it? A few of my photos have both stars in the field of view, so with that information I should be able to calculate things manually.

[Robh (Rob)]

35mins53secs of arc or about 35.9 arcmins or 2153 arcsecs

Regards, Rob

Originally Posted by Garbz

I've been trying to figure out the optimal spacing between my reducer and my camera to minimise the coma in my pictures, however as I move the camera I change my field of view of the resulting picture. Being unable to actually eliminate the coma I'm trying to determine what setup gives me the greatest field of view.

For that I'm trying to figure out how many arcseconds per pixel I get as a result, sadly the damn images won't plate solve.

So my question is, does anyone have a clue what the distance between Shaula and Lesath is, or how I would go about calculating it? A few of my photos have both stars in the field of view, so with that information I should be able to calculate things manually.

[mithrandir (Andrew)]

Chris, what program are you using to do the plate solve?

[Barrykgerdes]

I make it 34' 47.8" from Stellarium

Barry

[Robh (Rob)]

Originally Posted by Barrykgerdes

I make it 34' 47.8" from Stellarium

Barry

Hi Barry,

I used the 2012.7 coordinates from SkySafari Pro.
By calculation this gives 35m53s.
However, as a cross-check, I obtained the J2000 coordinates from SIMBAD.
This gave the same result 35m53s.
This is not unexpected as most of the change in coordinates will be due to axial precession and relative star positions will essentially be similar.

Using the coordinates given by Stellarium, the result comes to 35m46s, which I assume is probably due to rounding off errors as arcseconds are given in whole numbers for coordinates (of date).

Regards, Rob

[Barrykgerdes]

Hi Rob

Stellarium is correct. I read it wrong The current distance for 23-9-2012 is 35'53.53" in Stellarium. However Stellarium relies on the pixel count and the error is a function of the FOV and can be nearly 2 arc seconds in a 40 arcminute FOV

I should have zoomed in further and reduced the pixel count error

Barry

[Robh (Rob)]

Originally Posted by Barrykgerdes

Hi Rob

Stellarium is correct. I read it wrong The current distance for 23-9-2012 is 35'53.53" in Stellarium. However Stellarium relies on the pixel count and the error is a function of the FOV and can be nearly 2 arc seconds in a 40 arcminute FOV

I should have zoomed in further and reduced the pixel count error

Barry

Hi Barry,

Interesting technique. Thanks for the feed-back.

Regards, Rob