Astroart Forum

Good Morning,
I've been using AA since AA4 first came out so I'm OK with the interface. I'm now using AA5 and thought I'd try my hand at plate solving. I tried the tutorial and it worked OK, but in the field I could not get it to work. Using my old but trusty SXV M5C in 1 x 2 (not 2x2) binning and setting the Horiz field arcmin to 20, +-20%as I'm using 10" Meade SCT with 0.33 reducer and aspect ratio of 1.56 (CCD spec; Pix X 9.8, pix Y 6.3, CCD size 4.9 x 3.65) and Size in deg 4 x 3 I get "Cannot find coordinates". (with or without vertical flip) I also tried setting the aspect ratio to 0.78 which equates to a pixel size of 9.8 x 12.6 to allow for 2 x binning on Y pixels, but still no luck.
Next clear night I'll try no binning 1 x 1 and see what happens. Have I missed something? I've attached the settings page. My rig is permanently fixed on a pier and wedge in a Pod. Go too's with a.33 reducer are usually very good so plate solving is not usually required. In the past on AA4 I'd use pulse centre as indeed I tend to use now.
Rich

Screenshot:

Good Morning,
in binning 2x1 the equivalent pixel is 9.8x12.6, so the pixel ratio should be 0.778

The horizontal field of view seems to me 25 arcminutes (667 focal - 4.9 size) so 20.4+-20% won't suffice. Start with an error tolerance of +- 50% then refine it later with the Statistics window. If it still does not work, post a jpeg image of the star field.

i Facavi,
Thanks for the very prompt attention. I tried all your suggestions with my existing raw M 51 image (not resized to account for non-square pixels), but no luck.
Here are my calculations for Meade LX200GPS, 254mm Aperture + 3.3 reducer+SXVM5C camera 1 x 2 binning ;
Horizontal FoV; Pixel size 9.8 x 6.3, Focal Length with 3.3 reducer 825mm (I think your suggested F/L was for a 200mm ‘scope, I did try it though)=20.42 arcmin
Aspect Ratio; 9.8/12.6=0.778
Search Region M 51, RA 13 29 52.4 DEC +47 11 44. (Also tried using Current Image).
I've attached a jpg of my capture of M 51 as requested, this has not been resized to account for non-square pixels and also some additional info.

Hi,
the good news is that 0.78 is indeed the right aspect ratio.
The field of view is 16x11.

That image has a strong dithering, after removing it I was able to plate solve this:
With the following parameters: M 51 , 15 +- 20% arcminutes , 30° , 0.78 , 5 stars

By the way, I suggest to tune your plate solve with another image. When a wide galaxy (say the 10 biggest of the sky) is (almost) yet in the middle of the image, and the CCD FOV is small (so there is no much empty space around it), plate solve suffers, because that galaxy was saturated in the original plates from where the patterns were calculated.

Good Afternoon Facavi,
Thank you so much for your help.

Thanks to you I now understand where I went wrong. I've tried plate solving using 'scope simulators on some of my other pictures from my Mintron MTV-12V6HE-EX camera and they solve without error.