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Cape York - Northern Havens, Sol 2780 - 2947
Matt Lenda
post Jan 30 2012, 02:09 AM
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QUOTE (fredk @ Jan 29 2012, 01:44 PM) *
More late afternoon frames coming down. In this one, we might be seeing the shadow of Oppy, or perhaps the outcrop she's on, arrowed here:
[attachment=26336:1P380945...y_shadow.jpg]
What suggests this to me is that, if you look closely, you can see what seems to be an "opposition surge" or "Heiligenschein" centred around what could be Oppy. I'd need to check the geometry to be sure.

Wow!

I'll ask the folks tomorrow if that could possibly be our shadow. Do you know what sequence ID(s) this image got captured with? This will narrow it down for me.

-m

edit

QUOTE (jamescanvin @ Jan 28 2012, 01:32 PM) *
I've only just started working on my version of the Greeley Pan, but to join the party I thought I'd share an initial low res image straight from my automated process before I've done any fiddling.

James

See the HGA? It's moved! I wonder how the Pancam folks will stitch that out...

-m
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djellison
post Jan 30 2012, 02:25 AM
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QUOTE (Matt Lenda @ Jan 29 2012, 06:09 PM) *
Do you know what sequence ID(s) this image got captured with? This will narrow it down for me.


P2445

I've got a lunch in the 167 cafeteria that says it's our shadow tongue.gif
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Deimos
post Jan 30 2012, 02:56 AM
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QUOTE (walfy @ Jan 29 2012, 10:57 PM) *
Wonderful! By the way, in upper right of the sequence one of Mars' moon is tracking across the sky. Or a star?


That's Phobos. It is anti-Sun-ish (E). A star would be rising, Phobos is setting. It has no right to be visible in the image, but there you go.

Edit: The image azimuth is 66; Phobos is at 86-87. The elevation is about 52 (sinking by 3/4 deg/minute).
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Deimos
post Jan 30 2012, 03:20 AM
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Umm, yes, seems to be the right shadow. Using the automated image navigation, the anti-solar point is just below and to the left of the notch. The elevation is off (tilt uncertainty), but I referenced my guess of the horizon.
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fredk
post Jan 30 2012, 05:12 AM
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QUOTE (PDP8E @ Jan 30 2012, 12:52 AM) *
fred: I think that shadow down range is the sundial, the mast shadow is just coming into view on the far right.

That shadow is so far away into Endeavour that we'd never be able to resolve anything on Oppy. At best she'd be a blurry speck. At worst the blurry speck is the whole outcrop she's on.

Thanks a lot for the info, Deimos. Remarkable to sight Phobos like this. I guess being anti-Sun helps - Phobos would be close to "full". Can anyone estimate a magnitude for a full Phobos as seen from the surface of Mars? I wonder if a search of old navcams would reveal any other sightings.
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Astro0
post Jan 30 2012, 05:57 AM
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Just to clarify, the bump is either Opportunity or the outcrop that was identified (circled) in the image.
The rest of the shadow is part of the ridge of Cape York marked in yellow.
Attached Image


Can any of our image experts give a best guess for the distance of that shadow?
FredK - any chance of some 'waving men' put in place for scale?
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James Sorenson
post Jan 30 2012, 06:23 AM
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Very nice pictures you guys! smile.gif

Here is my preview version of the Greeley Panorama sofar. I still have some color correction to do in between some images, plus there was some stitching error's that I need to address, but figured I'd show you what I got.

Attached Image
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Ant103
post Jan 30 2012, 01:24 PM
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Fantastic James ! smile.gif

My version of the "shadow pan" of Sol 2846 :


--------------------
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Deimos
post Jan 30 2012, 01:33 PM
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Starry Night gives Mv=-8.5. It appears to account for distance and phase.

Geometrically, Deimos should be in close to 1/8 of the p1587s, although at the edge. Phobos should be in a smaller number, maybe 5-10%. It could be in other sequences that have the sky near 85-90 and 270-275 azimuth. It would not be recognized without either the movie or stereo. It won't be in the stereo ones, as they are small swaths of sky near the horizon, through much more dust. We've deliberately had Phobos in Navcam before, at low elevations and moderate tau, without being able to see it (with no downsampling). Most of the time, p1587s are run with a much higher Sun (11 AM - noon); this time of day was opportunistic (no pun intended)--and the presence of Phobos was of course serendipitous.
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rickyjames
post Jan 30 2012, 03:07 PM
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QUOTE (Deimos @ Jan 29 2012, 08:56 PM) *
That's Phobos. It is anti-Sun-ish (E). A star would be rising, Phobos is setting. It has no right to be visible in the image, but there you go.

Edit The image azimuth is 66; Phobos is at 86-87. The elevation is about 52 (sinking by 3/4 deg/minute).


Um, if Phobos is the dot in the upper right corner that appears in all four frames, what's the dot in the last two frames that tracks in a horizontal line just above the midline of the photo? In the third frame it is two-thirds of the picture over from the left edge, in the last frame is about one-sixth of the way from the left edge. What's the time between these two shots? Is this a deliberate attempt to photograph an overhead pass of one of the orbiters from Earth, possibly one used as a comm relay? Or OMG - maybe Mariner 9 or Viking 1 or 2?
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fredk
post Jan 30 2012, 03:49 PM
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Those two specks look like garden-variety cosmic ray hits. They don't have the clean "point spread functiony" look of Phobos. Remember that you can connect a line between any two points. When you get 4 in a line, with the right spacing between them, like with Phobos, then you know you've got something.
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john_s
post Jan 30 2012, 03:50 PM
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Nah- consider the size of Phobos relative to the size of any of our spacecraft. The spacecraft might be closer, but not enough closer to compensate for Phobos being 20 km diameter and the spacecraft being a few meters across.

John
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remcook
post Jan 30 2012, 03:50 PM
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"My version of the "shadow pan" of Sol 2846 :"
Holy cow! One of the most stunning MER images I've seen in ages ohmy.gif
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rickyjames
post Jan 30 2012, 07:27 PM
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QUOTE (fredk @ Jan 30 2012, 09:49 AM) *
Those two specks look like garden-variety cosmic ray hits. They don't have the clean "point spread functiony" look of Phobos. Remember that you can connect a line between any two points. When you get 4 in a line, with the right spacing between them, like with Phobos, then you know you've got something.


I still wonder if I've got something here.

Consider what is being said about this sequence of four cloud images which have six dots of light in them, four of which are identified as Phobos. Each frame of the four frame sequence is 512 by 512 pixels in size. Denote the lower left pixel as being at X=1, y=1 to define a standard Cartesian coordinate plane. Shooting the sequence at an azimuth of 66 degrees implies that the 66 degree heading is aligned along the vertical column of pixels in column 256. Look at the four dots of light visible in the upper right corner of the sequence. This is said to be Phobos descending nearly vertically in pixel column 448 at an azimuth or heading of 87 degrees. That’s a heading difference of 87-66=21 degrees in 448-256= 192 pixels for a scaling factor of around 0.109 degrees per pixel. Between frames 3 and 4 Phobos moves down about 14 pixels which would correspond to 14 * 0.109 = 1.5 degrees in the sky. If Phobos is sinking at 3 / 4 or 0.75 degrees per minute as specified in the forum discussion then these last two frames in the cloud sequence were taken two minutes apart.

Now look at the two mystery dots that appear to be “flying” from right to left in frames 3 and 4. Assume for a moment they are two images of the same object instead of two random cosmic ray pixel glitches. Note that if Phobos is descending anti-sunward in the east in the images, then the right-to-left motion of our mystery object means it is moving from south to north, over the poles –a reasonable path of motion for a science orbiter from Earth like, say, Mars Odyssey with its inclination of 93.2 degrees.

Also, the “mystery object” changes its position by around 230 pixel units or 25 degrees in the field of view using the scaling factor defined above, and it does so in the two minute interval between frames. Horizon-to-horizon is 180 degrees, so at constant speed this mystery object would have appeared to go from horizon to horizon in (180/25)*2 = 14.4 minutes.

Huh, Mars Odyssey is used for 15 minute communication passes with the MER landers. See Step 18 at this NASA website:

http://marsrover.nasa.gov/mission/tl_entry1.html

So if the two mystery dots in this image sequence ARE cosmic ray glitches, they are glitches that ACCIDENTALLY mimic BOTH the expected direction AND expected speed of an orbital communications satellite that we know is being used by the rover.

Another point: are there statistics showing that two cosmic ray pixel glitches of this magnitude per every four images is routine? If not, then these are REALLY amazingly coincidental cosmic rays.

As for the “it would never be visible” argument, remember that Mars Odyssey or a Mars polar orbiter like her have got something Phobos doesn’t – solar cells that can reflect solar glint. That’s why we can see the Space Station from Earth on the ground as a bright star (usually right at sunset when the observer is in just entering darkness and the station is in still sunlight) as well as the infamous” Iridium flares” that can make a satellite in earth orbit appear as an incredibly bright -8 magnitude object in the sky.

http://en.wikipedia.org/wiki/Satellite_flare

So I still wonder - are the two mystery dots an orbiter from Earth?
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PDP8E
post Jan 30 2012, 09:56 PM
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the NAV cloud shots were taken at:
17:23:57
17:25:01 +64secs
17:26:21 +80secs
17:27:48 +86secs


--------------------
CLA CLL
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