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New Horizons: Approach Phase, OpsNav - 25 January 15 to 28 June 15
Bjorn Jonsson
post May 26 2015, 11:09 PM
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A few days from now New Horizons will obtain unbinned images that will have almost two times better resolution than the images released in April. In these images Pluto will be a whopping 8 pixels or so across - I may never have been looking as much forward to seeing such tiny images as I'm doing now. These images might even start revealing something on Charon if it has large scale markings.

I decided to assemble a quick montage comparing the best released NH Pluto images so far to several outer planet satellites at low resolution. For the satellites I used Voyager images except at Saturn where I used Cassini images. I used two images of each body. In the best NH images so far Pluto is roughly 8 pixels across following stacking and extensive processing (in the original images it is 4-5 pixels). I decided to make the satellites bigger, about 12 pixels across, mainly because soon we'll be seeing better NH images than the ones released last month. In all of these images where possible the phase angle is comparable to the phase angle in the NH images. I made no attempts to correct the image orientation (i.e. make north up).

This is the result:

Attached Image


Pluto is known to be a high-contrast body. It is obvious from this (with lots of caveats since I don't know the details of the Pluto image processing) that the contrast is rather big but not nearly as big as on Iapetus. The best satellite analogs in terms of contrast seem to be Dione, Ganymede, Io and maybe Ariel. Triton exhibits far less contrast than Pluto. It's interesting to note that Ganymede has polar caps that are brighter than the equatorial regions.

It's going to be really exciting to see the true nature of Pluto's bright/dark markings revealed over the next several weeks.
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Bjorn Jonsson
post May 27 2015, 12:08 AM
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And here is a version of the above image where I have attempeted to correct for the albedo of the bodies. This is only approximate and should be taken with a grain of salt.

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Gerald
post May 27 2015, 05:38 PM
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QUOTE (Bjorn Jonsson @ May 27 2015, 01:09 AM) *
I made no attempts to correct the image orientation (i.e. make north up).

In my latest "OpNav Campaign 3, LORRI 4X4" series I've chosen south up (Astrometry.net) (within 0.1 degrees accuracy, most likely according to the J2000.0 system) to stay compatible with google sky, and to simplify comparison with a generally accepted frame of reference.

Regarding FOV: The new-image.fits (link on Astrometry.net site) image header says 1.02179 arcsec/pix (using the ESA/ESO/NASA FITS Liberator 3), that's 1024 x 1.02179'' / 3600(''/°) = 0.29064° fov for 1024 pixels.
(I've submitted an average image, obtained from the 21 cleaned, 4-fold magnified, stacked and registered 4x4 binned LORRI images; the pixel scale is hence for the 1x1 binned images.)
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Ian R
post May 27 2015, 07:32 PM
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New images from early May have been released!

http://pluto.jhuapl.edu/News-Center/News-A...p?page=20150527


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Habukaz
post May 27 2015, 07:41 PM
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Wowzers at the latest images! I made a quick animation with the images closer to native resolution.

Attached Image


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epoca
post May 27 2015, 07:45 PM
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Does anyone have the specs of the Pluto and Charon occultations that NH will use to study their atmospheres? Not really sure if this is the correct place to ask it, please excuse me and feel free to move them somewhere else if necessary.
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pitcapuozzo
post May 27 2015, 07:48 PM
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QUOTE (epoca @ May 27 2015, 09:45 PM) *
Does anyone have the specs of the Pluto and Charon occultations that NH will use to study their atmospheres? Not really sure if this is the correct place to ask it, please excuse me and feel free to move them somewhere else if necessary.


Sure.

For both ingress and egress, far-ultraviolet solar occultations will be observed with the Alice instrument (wavelength bandpass: 52-187 nm) and uplink radio occultations will be observed with the REX instrument (X band wavelength: 4.2 cm), for both Pluto and Charon. The solar and radio occultations mostly overlap in time (since the Earth and Sun are very close together as seen from Pluto); the Pluto occultations are about an hour after closest approach (e.g., NH will observe the solar ingress at Pluto from 12:16-12:49 UT on July 14th, and the Sun is expected to set at about 12:47 UT; closest approach to Pluto is expected at 11:50 UT). The Charon occultations occur about an hour after the Pluto occultations.

Besides all these occultations (NH will also observe the occultation by Pluto of a bright UV star with Alice, starting about 4 hours after closest approach), NH will use the Alice instrument to look for “airglow” (a faint glow at certain UV wavelengths, mostly due to processes related to UV sunlight; e.g., a UV photon from the Sun ionizes an N2 molecule, the emitted electron may be energetic enough so that when it hits another N2 molecule it breaks it apart and excites one of the N fragments to emit a photon at 134 nm). The particle instruments will indirectly study atmospheric escape by measuring ions formed when solar wind protons collide with escaping N2 molecules and steal an electron – the N2+ ions are swept up into the solar wind and are called “pickup ions”. NH will also use the LORRI and MVIC imagers to look for clouds and hazes, or even plumes (as were seen at Triton, a near twin of Pluto).

Source: a conversation I had with Randy Gladstone, who leads the atmospheric studies for the New Horizons mission team.
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scalbers
post May 27 2015, 08:59 PM
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Very nice Pluto images - hard to believe. In comparing the contrast to other satellites Earth's moon comes to mind.


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ngunn
post May 27 2015, 09:20 PM
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QUOTE (pitcapuozzo @ May 27 2015, 08:48 PM) *
a conversation I had with Randy Gladstone, who leads the atmospheric studies for the New Horizons mission team.


Randy Gladstone, 'Gladstoner' - any relation? I always had the latter down as a geologist.
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Phil Stooke
post May 27 2015, 11:06 PM
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Here are the three images side by side. Looks mappable!

Phil


Attached Image


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... because the Solar System ain't gonna map itself.
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Aldebaran
post May 27 2015, 11:34 PM
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It's good to see the surface features of Pluto gradually taking shape.

Hang on. Is it me, or just pareidoglia ?
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Bjorn Jonsson
post May 27 2015, 11:47 PM
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Incredible new images. I mentioned new images in my montage post above but the images I had in mind were images that will be obtained at the end of this month. I was expecting them to look similar to these new images so now I'm getting even more interested in seeing them.

Looking at the three images posted above by Phil it's starting to look as if there might be fairly strong longitudinal contrast variations. There seems to be considerably stronger contrast in the leftmost image but this may be a processing artifact. Anyway I'm now getting seriously interested in knowing which of the features (or which hemisphere) visible in the new images are going to be imaged at really high resolution near closest approach.
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jgoldader
post May 28 2015, 02:38 AM
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Had to do this...
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SFJCody
post May 28 2015, 03:49 AM
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Those albedo differences! Seriously exciting.
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0101Morpheus
post May 28 2015, 09:21 AM
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QUOTE (Phil Stooke @ May 27 2015, 07:06 PM) *
Here are the three images side by side. Looks mappable!

Phil


Attached Image


Pluto looks less spherical than I expected.
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