DMouse

Hi all, here is another scope test. This time M51. I am getting closer to getting clean flats so feeling happier with the scope as I get used to its foibles. This is 16x 300sec with the Luminance filter. Camera ATIK 383L_ mono. 

Scope: Skywatcher Quattro 300s

Mount: Paramount MX+

Software : TheSkyX pro, CCDAP and Pixinsight

There are a couple of dust moats that the flats aren't removing so I have cleaned the CCD. Next session will clear that up hopefully.

9 hours ago, wimvb said:

It seems to me that your flats are doing a decent job, but not perfect. Most dust motes are taken care of. But it looks like there are some residuals left of the strongest motes in the upper left corner, near the upper right corner/edge, and one going from the left galaxy to the left edge. To see if the calibration process works, you can calibrate single flat exposures with the master flat. (I would take the first, middle, and last flat exposures.) This should give perfectly calibrated "flat" images. If you still see residuals, your calibration process isn't doing its job.

Thanks for the idea. Just tried calibrating some of the Flats subs  with the Master Flat. This worked really well. Maybe a hint of a left right gradient, but only if I really stretch the image. The dust motes and halo are not evident.

No, The canon was to see if the halo was visible with this camera as well and therefore ruling out that it was a problem with the ATIK camera. I'm not quite that new to this hobby  The flats for the ATIK and the Canon both show the halo.

On 30/04/2019 at 15:56, fwm891 said:

Is it your flat's causing the problem, as usually they would have removed any unevenness in illumination provided you didn't alter anything between taking the lights and doing the flats. Bias and darks can be done 'off scope'?

The central halo is a lot worse without the flats. I have contacted skywatcher and they are looking into it. I took some more flats as a test today with my Canon T2i, and the halo is still there, so it's not the ATIK camera and filter wheel. I have a feeling its either the coma corrector(Skywatcher f4 version) or a reflection off the secondary mirror. It comes with black sides and back so I didn't check it for any other issues. 

Hi, here is last nights shot at M101. This is a luminance run only and was to test to see if the central Halo was still there, and it is, grrrr. I have a sneaky suspicion it is coming from the edge of the secondary mirror. I have pretty much painted everything else matt black, so far. Anyway, Here is the Luminance run.

Subs: 10x 300sec, 5x 420sec

Processed in Pixinsight. BIAS, DARKS and FLATS applied.

Cheers

Paul