Remote imaging - iTelecope.net

[RichardL]

Good evening all!

Has anyone any experience of using remote imaging services such as iTelescope.net?

I subscribed yesterday, and scheduled a plan last night to photograph the Iris Nebula - fairly basic, I used their "beginners" telescope "T3" 150mm APO Refractor, and requested 10 180 second exposures. Having only owned a iOptron SkyTracker, whilst I'm fairly confident on processing stacked images, my knowledge of telescope imaging (resultant files) and filters etc is fairly non-existent...

Following the imaging session output files included:

10x calibrated  (approx. 8mb each)
10x calibrated-colour (approx. 24mb each)
10 x Bin (approx. 8mb each)

From what I can ascertain, whilst you are able to download darks, flats and bias files, the images are automatically calibrated...

With this in mind, is anyone aware of whether I only need to stack the calibrated-colour files? I did download the darks etc., and sought to create master files, however DSS returned incompatibility issues, perhaps down to the calibrated-colour files being RGB and the darks etc being grey scale...

I did try stacking just the calibrated-colour however there are still "hot" pixels (red, blue) evident, and also a vertical line - the former I thought would be removed through the auto-calibration, the later I understand is quite common in CCD cameras - I use PixInsight, and understand there is a function to remove these issues, however from what I understand it should be used in the calibration phase rather than after stacking - plus the technique is more advanced to what I'm used to! Is anyone aware of a setting in DSS that will remove both of these defects?

On the plus side its opened up a whole new horizon for me, and the image itself (even though I photographed under last nights moon) is pretty impressive! The focal length (1095mm) alone, tops my 500mm I get with my camera!

Thanks in advance!
Richard 

[RichardL]

After playing around, I can stack either the bin or calibrated images with darks, flats and bias - though the vertical line is still evident, as are some of the hot pixels... though still no clearer on what the bin or calibrated images are!

Does anyone know of a good tutorial online for CCD image processing, using DSS and or PixInsight?

Thanks
Richard

[Carole]

Sorry I only use Photoshop for processing. 

It's unusual for images which still need to be stacked to already be calibrated, so then why offer the option of the calibration files.

Is it possible to ask them exactly what you have?

Carole

[RichardL]

Hi All,

After a rather late night researching, they provide the raw files, calibrated (such that once an exposure is finished its has matching Bias, Darks and Flats applied to it), and colour calibrated. The latter two can be stacked in DSS without additional bias, darks and flats. Alternatively, you can download Bias, Dark and Flat files to stack with the raw ones.

I suspect the hot pixels post stacking in DSS are due to me not selecting dithering in my capture plan - possibly by selecting it, it may also remove the vertical column defect, though not holding out! I've another run scheduled for tonight (discounts for when the moon is out!). There are scripts within PixInsight to remove it during the calibration process, so I may have to result to this, though doesn't seem as intuitive as DSS!

How do others deal with vertical column defects from CCD imaging?

Thanks
Richard

[Carole]

I don't normally get any but choosing sigma clipping stacking normally gets rid of that sort of thing.

Hopefully one of the more technical people, especially those who use Pixinsight will be able to answer this.

Carole

[RichardL]

Thanks Carole