Preliminary lon/lat projections of the two PIA19056_hires RC1 images:
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Credit for source images: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA

Rotation around z-axis (47°) should be correct within a few degrees, since otherwise the ellipse doesn't match well.
Rotation around x-axis (10°) is mostly guesswork in this version.

Ceres is turning out to be quite a world of its own. Obviously we have two large impact basins in the southern hemisphere, flanked on both sides by a network of crater-erasing rift valleys, stretching halfway around the globe. One or both impacts may have penetrated and split the (then relatively thin) frozen part of the mantle in the process.

The Piazzi region is bizarre! It's difficult to be certain from a single image and lighting angle, but when I look at those sinuous features, I see snakes and tadpoles with their tails pointing downhill into the large basin from both sides, so they could be vents of some kind. There are also many isolated molehills coming into view as we get closer, that cannot be a product of impacts alone.

The enigmatic bright spot at Region A is equally interesting. Conceivably it might result from an impact by a class E or V (high albedo) asteroid, but serious doubts are raised by the total absence of rays. If it's not an impact, it could be a deposit of salt from a geyser, after the ice has sublimated. The fact the spot is encircled by a dark ring reminiscent of those on Io, may not be a coincidence.

Thanks for the colourised images Ian! This is probably my brain playing tricks but to me it looks almost as if there's an underlying crosss hatching apttern of fine linear features scattered across the surface.

Interesting comment from Marc Rayman about the brightest bright spot (I assume this is the original bright spot):



Still waiting for a more complete RC1 release (allmost all of the really interesting-looking features appear to be out of view in the two frames released).

Here is a composite of the new images reprojected by Gerald and my opnav3 map (with a bit of tweaking to improve the fit), and a comparison with my old HST map. Longitudes start at 0 at the left edge, following the mapping by Li et al. in Icarus in 2006. The match between the two maps is not very good at this stage but it gives an idea of how it should be.

Phil

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A few posts on the Dawn Mission Facebook page suggest a non-detection of orbiting moons.

Looking at the newer images, it looks to me like a mini Moon.
I can see something like cratered highlands (southern hemisphere) / lowland maria regions (northern hemisphere).

"A few posts on the Dawn Mission Facebook page suggest a non-detection of orbiting moons."

It's on Twitter as well, so it must be true.

Phil

During the lull while we await the full video, a question: I gather that a constraint on the lowest orbit targeted for Dawn is that image blur would be problematic due to the lack of maneuvering reserves -- images returned would be blurry below a particular altitude since features would drift over the sensor during the exposure due to the higher relative motion of the spacecraft (both closer to the surface and faster transverse motion). If this is the case (and may be a misconception on my part), then I'm wondering whether deconvolution methods had been contemplated to compensate for the motion blur? It seems like the blur could be highly predictable, and easily invertible.

First, Phil, great composite image! Something I've been struggling with since hours. Hope I can fit the parts seemlessly (unless the complete RC1 sequence is published first), but it's tricky.

@algorimancer: Alternative approaches would be summing up short-exposure images, or to intentionally let Dawn spin with an appropriate angular velocity.
But there are certainly enough science objectives without need to go to the extremes.

I'm seeing all sorts of interesting things on the available images - half of which I'm probably imagining

The next image release will likely illustrate if Ceres is merely a battered lump of rock and ice, or has some more interesting geology.

Can't wait!

The bump at the left limb is just the next column of pixels in the original-resolution image. Remember that the released image has been oversampled 6x, so one original pixel will appear 6 pixels wide. Play around with oversampling circular discs in an image editor and you will see artifacts just like this.

So that tells us the (original) White Spot is still unresolved in RC1. Until it is resolved we will only have lower limits on its albedo.

Phil's latest composite, projected, animated (60 images), 300 pixels version to fit imgur limitations:

If this spot is both half the height and width being assumed, that would put its albedo at 100 per cent. So it really can't be any smaller than that. This means the pictures taken today and on the 25th should resolve it.

WOW ! Thanks a lot Gerald ! (and Phil for the underlying map...)

Great little video Gerald. Your dedication to the cause is greatly appreciated. I am starting to get a good feel for the character of this battered little world now.

Per DSN Now, Dawn's talking with us as I post this. New goodies Monday, presumably?

Unless there is another rogue public holiday coming up, it's a good candidate..

I wonder when we'll see Brightey, the original bright spot, again - in the RC1 or RC2 images? Not that there's any guarantee it will be in the first RC2 images released.

Either way, these latest images should reveal so much previously unseen detail of Ceres' surface that it feels tempting to say that that an unofficial phase 1 of the exploration of Ceres has been successful, once the images have all safely come down to Earth (which should be a matter of hours now, I guess).

No Monday holiday here in the States... looks like sunny weather for DC on Monday so NASA HQ should be open... heres hoping woohoo!

Might not be Monday after all:



https://twitter.com/NASA_Dawn/status/568934417328001024

These three lon/lat maps of processed OpNav3 and the two published RC1 images are made geometrically consistent to a first degree, not quite perfect yet, but may be considered useful:
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Makes me wonder that only two pictures of session RC1 have been released until now...

Wonder if they want to keep the juicy pictures of the Bright Spot for publication because we're now close enough to start estimating its true albedo. Dang politics.

We had more pictures from Rosetta, and sooner

This is still way better than during the Vesta approach; let's not derail into a image release policy comparison thread...

ADMIN: Agreed

I made a composite of Gerald's three latest files.

Phil

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Very nice work Phil.

For visual comparison again:

Where my previous visualisation of Ceres as viewed from Dawn was created entirely within MS Paint, this time I have devised a Python script that generates all of it. The exact visual simulation of the phases is obviously inaccurate (I don't know the formula(s) for a better simulation), but the percentage of pixels not illuminated should be correct (so if you view the black pixels as a liquid, you can squeeze them into the correct crescent shape). All information was gathered from the usual table.

It starts with last week's images (RC2, rightmost) and ends with OpNav 7, which will be taken 15 April.

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(if anything beyond the straight terminators looks strange, let me know )

... colorized with Phil's HST map, and animated (270 pixels version) :

^ Is that true color?

Or close to true color?

There may be some geometric mismatch, so bluish patches may actually belong to the respective bright spot nearby.
But otherwise it's the only and best color information I've available. Hue and saturation is of Phil's Hubble map, brightness from the processed Dawn images.

Fantastic! Any chance of re-posting that in cylindrical format, Gerald?

Don't be looking for true color anywhere! I didn't check, but I expect the HST images include infrared bands which can't be displayed in infrared, so we have to use some visible representation of them. Once you do that, true color is gone. I did see someone -mercifully I think it was somewhere else - insist that Ceres is orange based on the HST images. No, it's not.


EDIT - I checked... the images include UV bands, same basic idea, there's nothing even remotely resembling true color in the HST images. Scientifically, IR and UV tell us much more about composition than visible bands.
Phil

I'd love Ceres to have such beautiful, vivid colors.
But judging from example of Vesta (as Phil & others have mentioned upthread), Hubble pics processed from such low resolutions can introduce some color effects. E.G:



from http://scienceblogs.com/startswithabang/20...-to-asteroid-1/

Here is another version of Habukaz's visualization of upcoming imagery, including RC2.

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Thanks Gerald! I like to plug your projections into Celestia as hi-res textures: I find this to be the most engaging and involving way of viewing them.

Thank you ermar for the map. And it do clearly show what I have had in the back of my head - that we will not have any significant improvement in resolution until mid-April. (Though I am certain that our image processing friends on this forum will do their best to improve on the global map with the information from those crescent images.)

As for the colours, I agree with you stevelu, the colour from the Hubble images should be taken with a lot of caution. The blue areas might simply be the brighter spots that we now have identified, as well as that crater with rays (also mentioned on Max Planck institute page now.)

According to separate comments by Marc Rayman over the past few weeks, the albedo of the Region A spot in OpNav 2 images was about 50% higher than for the average surface (0.135), increasing to 0.25 by the time of the higher-resolution images of RC1. I don't see how it would only increase by a factor of 1.85, when the image scale increased by 2.85 and the spot was still unresolved (limited by the pixel scale). In theory, shouldn't the albedo increase to 0.385 in that case, or is the math not as simple as that?

"we will not have any significant improvement in resolution until mid-April."

Don't worry - what that diagram does not show is that RC2 has twice the resolution of RC1.

Phil

These white spots could have variable shapes and non-uniform brightness, so it is hard to say based on what has been released. We can only pick up hints from comments like Marc Rayman's and then make our own guesses. I'm sure the team already knows a lot more. The rest of us will find out soon enough.

Would be interessting to see which parts of Ceres will be visible during these upcoming image sessions.

We can also use this to see what Dawn's perspective is:

http://dawn.jpl.nasa.gov/mission/live_shots.asp

The old predecessor to Eyes on the Solar System...

'NASA Briefing to Discuss First Spacecraft Arrival at a Dwarf Planet'
http://www.jpl.nasa.gov/news/news.php?feature=4488

Monday March 2nd from noon to 1:00pm EST. Will be shown on NASA TV.

Craig

Maybe they'll still chuck out some teaser images tomorrow for us to gnaw on before they reveal what the bright spot is on Monday (which they probably have a good idea about what is now), and any other exciting features they may have discovered, none of which are visible in some frames.

Yeah, new images coming this week. Tomorrow?

The direct link for Dawn's view of Ceres is http://neo.jpl.nasa.gov/orbits/fullview2.jpg

I've captured 50+ images of that page since February 7, in order to extrapolate distances during imaging sessions. Has anyone recorded distances covering OpNav-3 around Feb 4.4?
The figures on JPL/Horizons are completely in error and evidently based on outdated orbital elements.

I keep referring back to this table in Marc Rayman's January Dawn Journal.

To answer your specific question, it was about 146,000 km or 91,000 miles.


Here is that link again, for future reference:
http://dawnblog.jpl.nasa.gov/2015/01/29/da...nuary-29/#table

Most here will be well aware of Marc's last blog post. Note that OpNav 3 took place a day later than listed there. I'm not after approximate figures - there'd be no point. If I could get distances at two times around Feb 4.4, I could extrapolate them for individual images within 100km and make some measurements; to clear up a discrepancy between the diameter measured by HST and a well-observed occultation -- or we could wait who knows how long for official figures. I already have a figure for the sidereal rotation period over an eleven-year interval!

In sum including today we got only a wretched number of 2 images out of 4 camera activities in 3 weeks so far:
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Makes me wonder how many pics were really taken...