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The Top of Vera Rubin Ridge Part 2, Site 67-73, sol 1944-2297, 24 Jan 2018-22 Jan 2019
jvandriel
post Jun 21 2018, 09:28 PM
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The Navcam L view on Sol 2087.

Jan van Driel

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jccwrt
post Jun 21 2018, 10:27 PM
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And the drive-direction mosaic:

Vera Rubin Ridge - Curiosity
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fredk
post Jun 22 2018, 12:51 AM
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I'm not sure which sol we hit tau > 8 in Gale, but on 2086 the sun was still visible in MR:
http://mars.jpl.nasa.gov/msl-raw-images/ms...040C00_DXXX.jpg
I'm guessing that frame was without solar ND filter, since several frames around that sol show almost nothing and presumably did use the ND filter. So the sun wasn't very bright, as you'd expect for a roughly e^{-8} ~ 1/3000 attenuation.
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marsophile
post Jun 22 2018, 02:48 AM
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http://redplanet.asu.edu/?p=29635

Plan to use chemcam on the dusty air.
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jccwrt
post Jun 22 2018, 04:21 AM
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QUOTE (fredk @ Jun 21 2018, 06:51 PM) *
I'm not sure which sol we hit tau > 8 in Gale, but on 2086 the sun was still visible in MR:
http://mars.jpl.nasa.gov/msl-raw-images/ms...040C00_DXXX.jpg
I'm guessing that frame was without solar ND filter, since several frames around that sol show almost nothing and presumably did use the ND filter. So the sun wasn't very bright, as you'd expect for a roughly e^{-8} ~ 1/3000 attenuation.


The most recent frame for tau measurement that had been downlinked when that press release came out was on Sol 2079, so either it was estimated from a thumbnail image or the landscape images from sols 2084/2085. You can barely see the sun in the Sol 2085 right MastCam image (I was only able to see the right half of the disk), so I wouldn't be surprised if the tau measurement of 8 was from an earlier sol. It looks closer to Opportunity's last image from Meridiani Planum, but I don't know how the two rovers' ND filters compare to one another.
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jvandriel
post Jun 22 2018, 02:03 PM
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The MASTcam L view on Sol 2084-2087.

Jan van Driel

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jvandriel
post Jun 22 2018, 02:53 PM
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and the Navcam L view on Sol 2086.

Jan van Driel

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jvandriel
post Jun 23 2018, 01:45 PM
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The Navcam L view on Sol 2089.

Jan van Driel

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mcaplinger
post Jun 23 2018, 03:16 PM
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QUOTE (jccwrt @ Jun 21 2018, 08:21 PM) *
I don't know how the two rovers' ND filters compare to one another.

The filters are basically the same (440 nm and 880 nm centers, ND5 neutral density) but obviously the cameras are quite different in their pixel size, f/number, and quantum efficiency.

But without knowing the exposure times of the images (alas, not available until PDS archiving AFAIK) it's tough to figure out the radiometry.


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Disclaimer: This post is based on public information only. Any opinions are my own.
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serpens
post Jun 24 2018, 08:01 AM
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I am having the greatest of difficulty correlating the clarity of the images from Curiosity, having a claimed tau of 8 with images from Opportunity during the 2007 dust storm for a series of images up to tau 4.7. To my old eyes tau 1 to 2 for curiosity would seem more likely.
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Gerald
post Jun 24 2018, 10:04 AM
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The dusty atmosphere may be layered in a different way. The tau measurements on the the basis of images of the sun refer to the whole atmospheric column. Global dust transport may prefer higher atmospheric layers. When talking about clarity, we should consider the distance of the objects we are looking at, as well as the wavelength of the light.

Note also, that directional transmittance and illuminance are only very loosely correlated.
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PaulH51
post Jun 24 2018, 11:21 AM
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I think this may be the left mast camera frame that would normally capture a section of the north wall of the crater rim, that they regularly use to measure the LOS extinction (Line-of-Sight) which combined with other measurements gives the tau value. The large Butte / Mesa in the lower part of the frame may eventually be obscured by worsening levels of dust. Do we know the approximate distance to it from the current location after the drive on sol 2089? I ask as we don't know the exposure times of the images, so images with darker terrain don't necessarily mean more suspended dust etc. May just be a good indication for us to use, as it doesnt look like the MSL team will release tau values as the Oppy team do.
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mcaplinger
post Jun 24 2018, 02:01 PM
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QUOTE (serpens @ Jun 24 2018, 12:01 AM) *
I am having the greatest of difficulty correlating the clarity of the images from Curiosity...

Since I expect these are all autoexposed, you can't really compare them to anything sensibly. The best way to show this would be to show a series of images all taken with the same exposure time, or at least normalized to a single exposure time.

Also, the color processing between the two cameras is significantly different.


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fredk
post Jun 24 2018, 04:20 PM
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Picking up some dust on FLB, visible on 2089:
http://mars.jpl.nasa.gov/msl-raw-images/pr...FHAZ00339M_.JPG
compared with 2082:
http://mars.jpl.nasa.gov/msl-raw-images/pr...FHAZ00337M_.JPG
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djellison
post Jun 24 2018, 05:09 PM
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QUOTE (PaulH51 @ Jun 24 2018, 03:21 AM) *
Do we know the approximate distance to it from the current location after the drive on sol 2089?


See attached - about 1,150 meters.
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