Dust on camera sensor VS Space dust

[spcookiee]

Hi everyone, 

I recently took an image of the Carina nebula with a camera, lens, and a star tracker, and on one part of the image, there is a big dark irregularly shaped shadow. I believe that this is just dust on my sensor because on my other images of the nebula that was taken a month ago, there was no dark spot. PLUS on images from the internet, there is no black spot. But it looks really real because there are stars that are over it. ._. Below is a picture that is autostretched and screenshotted. 

Can someone help reassure me of what it is?

Thanks for reading.

 

 

[wongataa]

Dust on your sensor looks like a circular blob.  I would say that dark spot in the image isn't dust on your sensor.

[david_taurus83]

4 hours ago, wongataa said:

Dust on your sensor looks like a circular blob.  I would say that dark spot in the image isn't dust on your sensor.

Not necessarily, that looks like typical dust/debris on a DSLR light frame. DSLR are harder to keep clean and calibrate due to the shutter movement moving the dust around. I have had similar dust motes move around mid session on my 6D which renders flat frames useless unless you've took some before starting and afterwards as well.