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Phobos and Deimos Image (Just Barely)

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#1 james7ca

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Posted 15 July 2016 - 10:10 AM

Last night I made an attempt to photograph the two moons of Mars (Phobos and Deimos) using my 9.25" EdgeHD. This proved much more difficult that I would have imagined given that I had previously photographed Saturn's moon Mimus (magnitude = 13.4) and Jupiter's Amalthea (magnitude = 14.8) using a 5" scope. In any case, even though I never saw either Phobos or Deimos on my capture previews I went ahead and recorded 45 frames using my ZWO ASI178MM-Cool with an exposure of 4 seconds. I then aligned the images using PixInsight's FFTRegistration script and stacked the results to produce a total integration time of 3 minutes (45 x 4s).

 

After processing I could just barely see both moons but the image wasn't very sharp and it was pretty hard to see Phobos in the glare of Mars. But, I confirmed the locations based upon scale and position and then overlaided a simulation using NASA's Solar System Simulator. Below is the animated GIF that alternates between my capture and the NASA prediction (shown as black dots, you may need to click on the preview to see the animation). The agreement looks very good, so I'm confident that I captured both moons although the image isn't very good. I suspect that you need both good seeing and very transparent skies to make this work and I don't think I had either during this attempt, but at least I got both moons.

 

Scope: Celestron 9.25" EdgeHD at prime focus

Camera: ZWO ASI178MM-Cool with luminance filter

Phobos magnitude = 13.2, 20 arc seconds from the center of Mars (or approximately 13 arc seconds from the limb of Mars)

Deimos magnitude = 14.3, 41 arc seconds from the center of Mars

Attached Thumbnails

  • Phobos-and-Deimos.gif

Edited by james7ca, 15 July 2016 - 10:52 AM.


#2 wrpspeed16

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Posted 15 July 2016 - 10:16 AM

fantastic catch



#3 james7ca

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Posted 15 July 2016 - 08:05 PM

wrpspeed16, thanks.

 

I've definitely seen better, but whether good or bad these types of shots seem to be fairly rare (there seems to be none on Flickr that show both moons and only a handful on Astrobin). I must say, however, that given my experience in looking at such images (as well as shots of the moons of Saturn and Jupiter) that some of the results seem somewhat suspect, either because of misidentified objects (moons in the wrong location) or because the images are just too "good" (IMO). For the latter, maybe it's just taking more liberties in the processing than I'd considered proper.




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