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New Meteor ?, Astronomy
vikingmars
post Oct 25 2005, 02:44 PM
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smile.gif Here is a picture just downloaded from Pancam sol 643 at 22:03 LLT
Does anyone knows is Mars is going now throu
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gh a swarm of meteors ?
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Tesheiner
post Oct 25 2005, 02:52 PM
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I would say yes because this meteor search is intentional.
I correlated that image to the following planned sequence:

643 p2734.03 18 0 0 18 2 38 pancam_meteor_search_L1R2

And there is another one planned for sol 644:

644 p2737.03 18 0 0 18 2 38 pancam_meteor_search_L1R2
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Guest_Richard Trigaux_*
post Oct 25 2005, 02:56 PM
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Eventually meteors on Mars may be more numerous and brighter, as the layer where they appear is closer to the ground. This of course is independent of the real number of objects which disintegrate in the atmosphere, which may be roughly the same than on Earth.
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fredk
post Oct 25 2005, 06:36 PM
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I'm sceptical these are meteors, as I explained in the Spirit The Astrophotographer thread. Even this latest long streak would've been an incredibly bright fireball. Even though they call them "meteor searches" in the planning sequences, at the very bottom of this press release image page it says

"Bright streaks in some parts of the images aren't stars or meteors or unidentified flying objects, but are caused by solar and galactic cosmic rays striking the camera's detector."

And earlier

"Scientists use the images to assess the cameras' sensitivity and to search for evidence of nighttime clouds or haze."

But on the evening of sol 643, Spirit took an extremely interesting series of pancam images, eerily reminiscent of my "suggestion" in the first post of the Spirit The Astrophotographer thread. There are five sequential images of the same region of sky. In the attached image I tried to sum these images, but I'm sure the experts could do a better job. The result clearly shows the trails as arcs around what must be the south Martian celestial pole off to the left, though I haven't ID'd the stars yet. It's a spectacular shot!
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akuo
post Oct 25 2005, 07:13 PM
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This sure does look like a meteor (some of the ones in earlier night time pics did too), though there are a lot of cosmic rays too. I think it would be pretty unlikely for a cosmic ray to make such a long mark without being deflected.

About the brightness: you have to remember that the pancam is a pretty long telephoto lens and with that sort of magnification you see quite dim objects. Also CCDs are quite sensitive instruments. The field of view of the pancam is also quite small and you see a lot of stars there, meaning that the dimmest are quite dim (longer exposures don't help that much, as the stars aren't tracked). They probably are dimmer that we would see with naked eye, maybe 7-8 mag. Therefore that meteor doesn't really need to be that bright, probably dimmer than 0 mag, so not in the fireball range.

antti


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Tman
post Oct 26 2005, 06:52 AM
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Wow that's a great sequence from Spirit. And only ten shots to capture a meteor in such small field smile.gif

I think too that's a typical meteor track. Maybe they tried it because there's a.t.m. a well-known stream near Mars.

Fred's image was first a secret to me how he's processed it blink.gif but then it works too. Tried to get more darkness in the lower part: http://www.greuti.ch/spirit/Spirit_pancamL1_M1.jpg


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vikingmars
post Oct 26 2005, 08:03 AM
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biggrin.gif CONGRATULATIONS, Fredk !
So far, this is the 1st astronomical sky rotation picture ever seen from Mars !


QUOTE (fredk @ Oct 25 2005, 06:36 PM)
I'm sceptical these are meteors, as I explained in the Spirit The Astrophotographer thread.  Even this latest long streak would've been an incredibly bright fireball.  Even though they call them "meteor searches" in the planning sequences, at the very bottom of this press release image page it says

"Bright streaks in some parts of the images aren't stars or meteors or unidentified flying objects, but are caused by solar and galactic cosmic rays striking the camera's detector."

And earlier

"Scientists use the images to assess the cameras' sensitivity and to search for evidence of nighttime clouds or haze."

But on the evening of sol 643, Spirit took an extremely interesting series of pancam images, eerily reminiscent of my "suggestion" in the first post of the Spirit The Astrophotographer thread.  There are five sequential images of the same region of sky.  In the attached image I tried to sum these images, but I'm sure the experts could do a better job.  The result clearly shows the trails as arcs around what  must be the south Martian celestial pole off to the left, though I haven't ID'd the stars yet.  It's a spectacular shot!
*
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AndyG
post Oct 26 2005, 09:35 AM
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QUOTE (fredk @ Oct 25 2005, 06:36 PM)
...The result clearly shows the trails as arcs around what  must be the south Martian celestial pole off to the left, though I haven't ID'd the stars yet.  It's a spectacular shot!
*

It's lovely!

I've made a stab at placing the Mars' South Pole location relative to the map, but I'm away from any useful starcharts at the moment. Anyone like to hazard a guess of where we are, from the annotated image?

Regards,

Andy G
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Joffan
post Oct 26 2005, 12:16 PM
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I agree, what great images! biggrin.gif

QUOTE (AndyG @ Oct 26 2005, 03:35 AM)
Anyone like to hazard a guess of where we are, from the annotated image?
*

We also need camera angle to horizontal (not to rover) at least I think. Given that we have vertical trails centred in the view and that the horizon brightening looks square to the picture (=no camera tilt), the camera elevation will be a close approximation of the S latitude.

Actually I look at the image again and the vertical trails are 1/3 down the frame, so camera elevation will underestimate latitude by a few degrees. Anyone know the angular FoV for this shot?
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Tman
post Oct 26 2005, 12:32 PM
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The field of view of these Pancam shots is a square of 16,8 x 16,8 degrees.


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SigurRosFan
post Oct 26 2005, 12:53 PM
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Is the bright star Achernar? Exactly separation of 56.

http://xs52.xs.to/pics/05433/Spirit_Meteor.jpg (178 KB)


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Bill Harris
post Oct 26 2005, 01:34 PM
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QUOTE
so camera elevation will underestimate latitude by a few degrees.


The latitude of the site is known: 14.6* S. Using that and other info the altitude, azimuth, etc can be calculated and the approximate RA and DEC of the photo can be determined, which would narrow down the search.

Or wait a couple of weeks and they'll tell us at the JPL/MER site... biggrin.gif

--Bill


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Tman
post Oct 26 2005, 04:26 PM
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smile.gif still more frames came down: http://www.greuti.ch/spirit/Spirit_pancamL1_M2.jpg

One of the R1 captured another one (I guess): http://marsrovers.jpl.nasa.gov/gallery/all...8P2734R2M1.HTML


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fredk
post Oct 26 2005, 06:16 PM
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I was too slow with the nine frame image - as soon as I finished compiling it I see Tman's!

Nice job darkening the bottom part, Tman! My "secret" was to apply 1 pixel gaussian blur, followed by a simple levels adjust to remove most of the faint noise before summing the frames. I knew you experts could improve it!
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Tman
post Oct 26 2005, 06:50 PM
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Hi Fred, first I thought to doing some work with the eraser between the star tracks in the second image, but too much to tinker with it.

The method I found was to copy all white structures in a new image (layer) with the "magic wand", of course first with a lot of noises too (the "white" color still to boost helps, also some "auto color changing" on small noises). Then soft-focus effects too. The background got a simulated black.

I guess there are still smarter methods.


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