[Dennis]

Originally Posted by Tulloch

Excellent work, those little moons sure move quickly.

I'm a little confused by your statement "overlaid with a series of 60 x 1 sec frames ... taken at 60 second intervals", can you explain that a little more please?

I assume the 5 shots of the moons are about 15 minutes apart, did you combine the 60x1 sec frames? Something else?

Thanks, keep posting these excellent images.

>snip

Hi Andrew

I'll write this for a reader who may not have attempted this before, so bear with me for covering ground you that I know you are totally familiar with.

For Mars, I used Firecapture and the ASI1600MM with an ROI of 1024x768 to capture 30 sec duration LRGB SER Files which I processed in Autostakkert!3. As the SER files were exposed for Mars, they did not record the much fainter moons. This gave me a test LRGB series at the start of the session. I followed it up with another LRGB after capturing the fainter moons. I used the later LRGB image in the final composition as Mars was at a greater altitude with slightly better seeing.

I then closed Firecapture and opened up the connection to the ASI1600MM in the Camera Control Add-on in the Sky X Pro and set up an imaging sequence for the much fainter moons. Experimentation led me to choose an exposure of 1 sec, which revealed the moons but did not swamp Phobos with over exposure from the diffraction patterns of the spider vanes.

I took x60 frames, exposure of 1 second with a wait interval of 60 secs between each exposure. That is, I took a 1 sec exposure every 60 secs for 1 hour, thus recording the orbital trails of Phobos and Deimos over the 1 hour interval, which was the “gap” between Phobos clearing the horizontal diffraction spike and then entering the glare for the vertical diffraction spike.

I used Images Plus to Align and Stack the 60 x 1 sec exposures with a setting of Max for Combine and this produced the image of the spider vane diffraction with a blown-out Mars and the fainter trails of Phobos and Deimos. It was nice to see how much quicker (and nearer to) that Phobos orbits Mars as its trail over 60 minutes was longer.

So, I ended up with an LRGB image of Mars and a blown out combined image showing the orbital motion of Phobos and Deimos as trails. I stacked these 2 images as in PS CC and then just used a Layer (with “holes”) to reveal the start, end, middle and 2 intermediate positions of the moons, rather than show their smeared orbital path.

Hope that provides a more clear explanation.

Cheers

Dennis