These Damm FITS files

[johnb]

So I have been playing around with the Gras Scopes and comets, It outputs both FITS and a preview in JPG format.

The camera is a SBIG ST2000XMC One Shot Color CCD

So the preview jpg file show lots of stars however when I open a FIT file in DSS I see virtually nothing ? and it registered virtually nothing ie 7 stars

If I open the FIT in FITS liberator I see lots, so I then covert to a tiff and DSS registers thousands of stars.

Oh and all im getting is a grey image

Pointers appreciated.

Regards

John B

[Photosbykev]

it sounds like the jpg preview is a stretched image and the Fits file is still in the lnear format and unstretched

[Sp@ce_d]

and will need debayered for colour probably.

[johnb]

Thanks, is there a step by step guide anywhere ?

[ollypenrice]

One shot colour is quite complicated to process.

The FITS are indeed linear, which is just what you want because, that way, you can control the stretch (or stretches) yourself. (Many imagers use different stretches on different parts of the image to give a higher dynamic range to the final result.)

Flats need to be debayered before thay can be used.

I did the stacking and pre-processing in Astro Art.

1) Make a master flat by stacking the flats together using Average/No alignment and then go into Image-Offset and offset by 0.5 pixel on both axes to remove the matrix.

2) Perform the calibration of the files without combining them. So make a new set of lights which have been dark and flat calibrated. These will have a _P.FIT suffix.

3) Run just the calibrated _P.FIT files through again, this time combining them in Sigma, aligning them using Star Pattern, Translation and Rotation and using CCD colour synthesis at default with hot pixel filter set to 30%. (If you get bizarre colour you'll need to experiment with the offset in CCD colour synthesis to ensure that green pixels are assigned to green, red to red, etc.)

4) Save this as a TIFF and export to Pixinsight or Photoshop for post processing.

AA5 is good value and logical to use. No doubt others can explain the alternatives.

Olly