Astroart Forum

Hi,

I'm trying to combine a set of images of M27 using AA5 and drizzle. I have flats, darks and darkflats. Combining them using sigma average (1.8), "fractional alignment" and "normalize background" enabled and "auto aligmment->star pattern->translation + rotation" but not using drizzle I got a fine image well aligned. Now I'd like to try drizzling (the images were taken with another software enabling dithering) so I just enabled the Resize and Drizzle 200% checkboxes and run a new processing but now the final image is completely unaligned. I mean the averaging seems done without aligning the images.

In the past I did the same process using a set of imges for M57, but the drizzle didn't improve the quality. I though the problem was the lack of dithering but in any case AA was able to align the frames.

Where am I wrong? Can you give me some advice to try drizzling? Is there any missed step in the process?

Thank you and Regards
Max

Hi, you're not wrong, you just discovered a bug which will be corrected in the Service Pack, available next week!
Thanks,
Fabio.

Hi,
Sorry, I have a question a little OT,
with drizzle, is allowed translation and rotation, or only translation ?
Thanks,
Michel

Hi, only translation.
Also, drizzle is useful only if the image is undersampled, here is an example:
Undersampled images are the result of short focal instruments with low-res cameras, stars are usually 1-2 pixels wide.

I have been testing AA8 but.. no rotational drizzle yet?
Any way of doing it via script interface?
That's the only thing holding me from the upgrade.
Thanks

Hi, drizzle for rotated images will be added in Astroart 8 SP1, available in March.
Clear skies,
Fabio.

Thanks! Looking foward to it..