I did some rough back of an envelope calculations.

At the current distance from New Horizons to Pluto of 101 million kilometers (and counting), an unaided observer (who hypothetically hitched a ride) would see Pluto as a faint magnitude 6 body with an angular diameter of 4.8 seconds, or a disk roughly similar to that of Uranus when observed from Earth. Coincidentally, Uranus has a similar apparent magnitude of 5.9 when observed from Earth (or from New Horizons for that matter).

It sort of puts it in perspective for an amateur astronomer.

No kidding !

for the month of April


the darn thing is ONLY!!!!! 4 px across
LESS!!! than Hubble images of 9 px

see
http://www.planetary.org/blogs/emily-lakda...ns-science.html
this is supposed to be a rather SCIENTIFIC forum
( i tend to be way TOO artistic here and I am the one stating the scientific facts ?????? )

Second that.

It's an odd recent trend to see discussions going on based only on visual impressions of heavily processed images, disregarding the most basic numerical facts.
This is not some fancy maths, we are talking integer numbers here, stuff like 4 pixels < 9 pixels

A small simulated excerpt of what you should consider when trying to interprete pixels and subpixels:
Click to view attachment
Simulated theoretical perfect image, blur by symmetric PSF, blur by asymmetric PSF, pixelation, interpolation, brightness stretch.
I've skipped hot pixels, dark current, CRs, photon noise, possible compression artifacts, etc.

With a sequence of images it's sometimes possible to do some meaningful SR; with a single image you likely run into processing artifacts.

I don’t want to add to the S/N ration. However, I think part of the issue here is it is not clear in this discussion that New Horizons includes two imaging experiments. All of the great tables I have seen that indicate Pluto should currently extend three or four pixels apply to the LORRI experiment. LORRI includes a huge 208mm telescope and has been imaging Pluto since 2006.

The color Image that everyone is chattering over was acquired with the RALPH experiment. RALPH is a wonderful devise that can create images in color whereas LORRI’s products are in monochrome. However, RALPH’s camera has only 60mm lens that would not be able to resolve Pluto at this distance.

Even if Pluto presented a slim crescent or was as oblate as Eros, it would still occupy one pixel in the RALPH image that has been published.

For something different:



https://twitter.com/NewHorizons2015/status/...798138354896896

So I guess from May on the odds are really increasing for discoveries of new moons.

New Horizons is now less than 100 million kilometers away from Pluto.

From http://www.yaohua2000.org website.

Media teleconference coming up tomorrow:



http://www.nasa.gov/press-release/nasa-to-...zons-spacecraft

So I guess we could see some new LORRI images? It would be very cool if we could see some actual contrast from large-scale surface variation rather than PSF artefacts.

Images are out !
Details are visible on deconvolved Pluto !

http://www.nasa.gov/news/media/newsaudio/index.html

Thats impressive at this distance !
Anyone could refer the details to the Hubble images yet ?

Robert

New Horizons has started a "raw" image page for Pluto! http://pluto.jhuapl.edu/soc/Pluto-Encounter/

from the 4th frame of the above gif
2015-4-17 03:45 UT
this is a recreation of pluto
Click to view attachment --- Click to view attachment

it "looks close"
BUT!!!
if anyone could think that they can correlate that with the gif????????
without doing MASSIVE light curve analysis
please see the posts dawn thread about teeny tiny images


wait for 30 to 45 days THEN there will be good EARLY images

It's a polar ice cap! (maybe)

www.nasa.gov/pluto042915

We're gonna have to stock up on popcorn for the summer! Pluto and Ceres, it's more than we deserve!

Oh wow, this is getting real!

Just 4.5 pixels and Pluto is ALREADY juicy! (I smiled when Weaver mentioned "a 10 inch aperture Celestron" in his description of LORRI.)

Brilliant stuff. Good times ahead.

Fantastic images!
BTW, images are already on par with best images from Hubble (what is exactly what follows from laws of physics and ingenuity of New Horizons operators).

This is really impressive, I didn't expect the images to get so detailed so early, even though I knew what Pluto's size in pixels would be when the images were taken. Now we really are almost there...

Is there an archived audio or video of today's press briefing? I can't seem to find one.

I was looking for a recording too, found one on NASASpaceflight, but instead of using up their bandwidth, I uploaded it to youtube.
https://www.youtube.com/watch?v=5nIiJLON9E4

You'll have to look at the graphics yourself, I didn't synch them up to the audio. http://www.nasa.gov/pluto042915

The MP3 is attached to this forum post, if that is better for you

Someone here knows a lot more about this than I and so I am sure I'll be set straight shortly, but given Pluto's large obliquity, would we really expect polar ice caps at this time? (as opposed to them being closer to equatorial latitudes)

Observations trump theory.

There was certainly one (at least one) cap at Triton. I won't be surprised at a large number of similarities between the two over the next couple of months.


Still hardly believe this is actually happening....

I agree there may be similarities but one difference is that Pluto's albedo is far more contrastive than Triton's -- only Iapetus has a more varied, global-scale albedo. Since Iapetus's albedo contrast can be clearly divided into two hemispheres, you could say Pluto has the most splotchy surface in the solar system (for lack of a better word, hah).

It'll certainly be interesting to discover why that is and what that kind of variation looks like up close. Something different from Triton is going on for sure.

This is my very, very rough attempt to combine all these wonderful new images of Pluto to form a polar-projected view of the polar ice cap (the red line marks the sub-Charon longitude). I've included a tidied and Gaussian blurred version as well as the original stacked frame.

Click to view attachment

Incredible images. I found this excellent article in Nature by Alexandra Witze:

http://www.nature.com/news/pluto-may-have-icy-cap-1.17454

It could be Nitrogen ice.

Echoes of Ceres. Is it a Polar cap or not?

Judging from our experience at Ceres, could it be that the bright areas we are observing now may actually turn out to be rather small upon close approach but appear larger now due to the high contrast?

It's only because most of Ceres is extremely dark that such small white spots are able to contribute significantly to its total reflectance. Pluto is much brighter overall than Ceres.

A bit premature but too hard to resist...

First, a sequence of those images through a rotation:

Click to view attachment

And a crude attempt to map the markings. The prime meridian, facing Charon, is in the middle.

Click to view attachment

Phil

I just calculated that Pluto was only 4.5 arcseconds in diameter when the pictures are shot.
With an 8inch telescope from earth its hard to obtain good images of such a small object (Uranus has about 3.5" or Mars when its far away is around 5")
Okay..NewHorizons has no turbulent atmosphere to conquer - but it has to be hold that stable during the shots !

Extremely impressive results from the New Horizons team !

Robert

I have borrowed a map from here:

http://www.boulder.swri.edu/~buie/pluto/hrcmap.html

(Thanks Mark... I hope it's OK)

And added the one I just posted above. The bright spot at 180 degrees longitude (opposite Charon) is common to all of them - muted in the one below mine because that was made from modelling occultations, which only gave data on the other hemisphere.

Phil

Click to view attachment

And this compares the new map with an average of all five of Buie's. There is a lot of similarity. It doesn't suggest gigantic changes since those maps of the 1990s and 2000s.

Phil

Click to view attachment

Not yet quite sure (with only two processed image quadrupels), could be one of the moons:
Click to view attachment

Pluto likely has a polar ice cap, an equatorial ice cap, a mid-latitude ice cap, and ice on top of the ice that's on top of other ice. Pluto may likely be mainly ice for many kilometers down.

All we see is the surface, and major albedo differences can pertain to thin covering as well as the composition of the crust. As on Callisto or the dark side of Iapetus, which are mainly dark, but small craters surface the ice underneath.

We have yet to know what's causing the color/albedo differences on Pluto, but a good bet is that the major constituent of the crust, everywhere, is ice. And the mantle, as well.

That said, the sunlit pole of Pluto has been sunlit for about 25 years. It's gotten continuous sunlight longer than any other surface we've seen on almost any other world, including the rest of Pluto. Very, very faint sunlight, but more than most of Pluto has gotten.

Perhaps more of a frost cap, being formed more relatively recently.

I tried this exercise with several sets of images (stacking the 5 exposures and aligning on the star field) and I think I can maybe sort of pick out one moon in a few frames but it's really pretty marginal. I decided that this wasn't a very successful exercise. (Click to animate.)

Click to view attachment

If you take the short exposures and stretch them, you can find a few interesting dots that seem to move. I didn't spend a lot of time searching through images but there do seem to be a fair number that don't stretch cleanly at all. I'd be interested to see if anyone else has done this with more frames though.

The animation includes frame lor_0292751773_0x630_sci_9 and lor_0292546843_0x630_sci_6.
Click to view attachment

I'm now almost sure, that at least one moon (besides Charon) can be extracted, after more advanced processing (subtracting background stars), and after adding another two sequences:
Click to view attachment
(follow the red circle)

But I don't know yet, whether it's Nix or Hydra.

Would it not be possible to question the hypothesis of an internal ocean on pluto by simply observing the orbits of Pluto and Charon from this distance ?

The Pluto-Charon system is mutually tidally locked, excentricities are low. Therefore orbital changes due to tidal forces are probably low, with little difference for the long-term orbits between a presence or an absence of oceans.

---------

For system clock 0291115627, I could identify a subtle moon candidate, too:
Click to view attachment
Together with the other four candidates above, here a synopsis of the positions:
Click to view attachment
The first and the last position (at 0292752227) in the synopsis are almost diametrical with respect to the Pluto-Charon barycenter.
The time difference is 0292752227 - 0291115627 = 1636600 s = 18.942 d.
The orbital period of Nix is 24.856 d, that of Hydra is 38.206 d (according to the current Wikipedia values).
This makes the moon candidate most consistent with Hydra.

While there does appear to be a bright albedo feature at the visible rotational pole, it's good to recall that this pole has also been pointing at Sol for, what, decades? Instead of being a cold trap that causes ice deposition, this would be the spot of highest insolation (such as it is, out in Pluto space) on this dwarf planet.

Maybe dark ices absorb more solar heating than higher-albedo ices at this sol-pointing pole and are selectively driven off, to re-accumulate on the shadowed side. Leaving the higher-albedo ices behind, and thus showing what looks like a "polar ice cap," even though it's a net deflational, not depositional, feature.

I don't insist on this interpretation, but it fits the observed facts...

-the other Doug

Possibly tholins account for some of the darker reddish coloration.

http://adsabs.harvard.edu/abs/2005DPS....37.5502O

"Maybe dark ices absorb more solar heating than higher-albedo ices at this sol-pointing pole and are selectively driven off, to re-accumulate on the shadowed side. Leaving the higher-albedo ices behind, and thus showing what looks like a "polar ice cap," even though it's a net deflational, not depositional, feature."


Verily, dvandorn, Sire, thou mayst be correct in thy supposing. Let us call it, not a polar cap, but a polar tonsure!

Phil

Cathy Olkin and Leslie Young have been looking at this problem for a long time, and have determined that Pluto very likely has a permanent north polar cap.

Working a little more systematically:
14 five-image sequences of "OpNav Campaign 3, LORRI 4X4" cleaned and "stacked" by adding up the four most similar corresponding pixel values of each of the five images, and subsequently subtracting 112 to make better use of the available grey values:
Click to view attachment
CRs should be filtered out that way.
Sums larger that 255 are mapped to white, those smaller than 0 (due to the subtraction of 112) to black.

Next intended processing step: accurate registering; I guess, this will take a few days.

Registering of OpNav3 LORRI 4x4 sequence is work in progress, thus far up to about 1 pixel, not yet fully accurate, but sufficient for a tentative identification of a second moon (probably Nix) :

Very nice work Gerald.

Thanks a lot!

Registering of the 14 cleaned and stacked OpNav Campaign 3, LORRI 4x4, quintuples until 2015-05-01 with good accuracy completed.
Pinhole camera model with assumed infinitesimally small fov angle did the job.

Overview:


Animation:


Album of individual images, contained pngs (4-fold magnified) should be of the best quality I can provide thus far.

Next intended processing step is determining starfield and Pluto/Charon(?) background.

Stellar ( + Pluto ) background, median-filtered:

(The "Meridian" in the title of the graphics must be a result of lack of sleep. )

Subtracting this image from the 14 stacked images sequence, and 8-fold brightness-stretching, results in the following preliminary animated gif:


The moons get more distinct, but the images can be improved by some more brightness adjustment...

That is very nice work.