New Moon of Pluto

http://www.cbat.eps.harvard.edu/cbet/cbet002769.txt

Pluto is bigger than Eris

A rare occultation of a star by the Kuiper Belt Object known as Eris was recorded in several stations in Chile and at first glance the data suggest Eris is in fact smaller than Pluto--the albedo of Eris must be higher than predicted.

Sky & Telescope has a good write-up.

Here's a report from one of the observers.

And here's Mike Brown's take on the observation (An observation of the observation).

SDSS conference news

Sloan Digital Sky Survey summary conference this weekend.

The likely press highlight of the Solar System session on the morning of Monday, August 18 will be announcement of the discovery (by SDSS astronomer Andrew Becker) of a remarkable object that is currently about the same distance from Earth as the planet Uranus but whose 27,000-year orbit carries it to more than 70 times that distance. This object is akin to the famous dwarf planet Sedna, but its orbital properties are considerably more extreme, with a much more elongated path that takes it nearly twice as far from the Sun.

Press release

More science on 2003 UB313

A number of 2003 UB313 related news articles has come out in the past week, and Nature will have a paper published tomorrow regarding a size measurement using IR vs. visual albedo. 3000km+-400 diameter , roughly 10% error. It makes the albedo of 2003 UB 313 to be 60%, like Pluto. While many of the big KBOs are bright, not all of them are, and it remains an area of speculation. What's the albedo of crystalline water ice on Quaoar? Why is the bulk albedo of it only 12%? Small areas of fresh ice? Is there a resurfacing going on for the high albedo KBOs?

Meanwhile, ScienceNOW reports that Brown et al made a direct HST measurement of the disk, calling it just a touch over the diameter of Pluto at 2300km.

The naming of the KBO is stuck in international bureaucratic limbo, deep in committees that can't agree on a definition of what a planet is. It depends on what the definition of 'it' is. (I guess).

The satellite so far has only one observation of it published. As soon as a second image is taken and reduced, an accurate determination of the mass of 2003 UB313 can be made.

New Horizons--aka the Pluto and Kuiper Belt mission

The New Horizons spacecraft is nearing a possible launch in mid-January. Despite the moniker its mission is to explore the Pluto/Charon system and any Kuiper Belt objects beyond. We know from looking at their spectrums that Pluto and Charon are different--Pluto is covered in nitrogen ice (brrr) and Charon has water ice. Pluto itself has significant albedo differences, including presumably brighter icier poles and darker warmer equatorial regions (although mixed in everywhere are bright and dark areas--are they cryovolcanoes and geysers or just cratering?). Young, Galdamez, Buie, Binzel, and Tholen used a series of mutual occultations of Pluto and Charon to figure this out in this paper (Link may require a subscription to read).
The Official New Horizons web site

Was this a wasteful governmental project? Nope. It cost less than 1/10 (one-tenth) of a single B-2, or about the same as the Ketchikan, Alaska bridge to nowhere. For the same price we get the first close-up views of the Kuiper Belt.

I have an older animated image I took of Pluto taken from Ryerson here. It shows Pluto appearing to move over an hour and a half, near the center left of the image.
Via http://planetary.org/blog/article/00000334/.

Two new satellites of Pluto/Charon!

http://www.boulder.swri.edu/plutonews/.

Once again, Minor Planet Mailing List has the scoop. Two ~100km bodies orbiting in the same plane as Charon and at 23rd magnitude found via the Hubble Space Telescope. Good thing we haven't dumped it in the ocean yet.

IAU official announcement


This image from Alan Stern (SwRI), Hal Weaver (JHU APL), Max Mutchler (STScI), Andrew Steffl (SwRI), Bill Merline (SwRI), Marc Buie (Lowell Observatory), John Spencer (SwRI), Eliot Young (SwRI), and Leslie Young (SwRI).

LA Times on 2003 UB313

"Ortiz's boss, astronomer Jose Carlos del Toro Iniesta, concedes that those rights will most likely be awarded to Brown.

"I think there is no longer a debate," he said in an e-mail message to The Times. "Dr. Ortiz acknowledges that Brown's team spotted the object in their archives prior to him.""
http://www.latimes.com/news/local/la-me-planet16oct16,1,3949603,full.story

2003 UB313 has a satellite

Oh boy! Brown using Keck and the adaptive optics there managed to detect an object moving in the same direction as 2003 UB313 and about a half an arcsecond away. When further observations are made and a period found for the satellite, the mass of the parent body will be known! MPML for a forwarded announcement or all the press stories.

The Keck 10m scope can easily beat the resolution of the Hubble Space Telescope when it is using the adaptive optics system, but it only beats Hubble over a very small patch of the sky at a time. It's great for looking at singular near point-source objects.

How does knowing a moon's orbit give you the mass of the parent? Here is what you know: You know the angular distance between the moon and the parent, which gives you the actual distance away from the planet, since you also know the distance to the planet from the Earth. Using Newton's formula of F=G*M₁*M₂/R^{^2}, and that the apparent centripetal force for the moon is F=M₂v^{^2}/R, the two forces are equal, so you get that the velocity is equal to the square root of (G*M₁/R).
The period is equal to 2pi*R/v.

So, the period is equal to 2pi*R/(square root of (G * M₁/R).
Or you can say the Mass of the planet is equal to 4pi * R^{^3}/G * T². I think. Okay, I went back and checked some sites, and my derivation looks correct. This site has a good look at it.

Ortiz response

This was posted on the Minor Planet Mailing List by Ladislav Nemec.

Michael Brown wrote up his page about the issue here.

Reiner Stoss forwarded Brian Marsden's CCNet post about the issue to the MPML as well; it is available here for the moment.


Hello MPML,

Jose Luis Ortiz of Sierra Nevada Observatory asked me
to forward his letter.

-----------------------------------------------------

Hello MPML, I provide you this information which will
go to my webpage in the next days. The detailed timeline
of our find was given to Daniel Green, director of CBAT long
before any controversy. Anyone can ask him and check against
any other timings of events provided by M. Brown. I suppose
that this has been done by the pertinent authorities and
that is why no official request on anything has been sent to
us by the International Astronomical Union (IAU).

Here I will repeat the timeline of events and even expand
some details:

The analysis of most of our 2003 survey images had been
postponed several times because they had a different optical
configuration to the current one and many images had problems,
so only this year did we begin processing them.

On Monday July 25th the object is found in some of our
March 2003 triplet images. We do all possible checks to discard
image artefacts being the cause and to make sure it is not a
false positive. We had had false positives in the past so we
were very careful. We realized that the object was very bright
and could be the same one mentioned in a DPS abstract web page.
A regular google internet search on K40506A leads to a public
internet web page with what appears to be coordinates of many
things. This is no hacking or access to private information nor
spying of any sort. Some of the coordinates shown in those pages
are not very far from ours despite the several years difference
so the object could be the same one but we cannot really tell as
we are not dynamicists and we decided to submit the astrometry
to the Minor Planet Center (MPC) because the MPC is to make such
things.

On Wednesday 27th a report with our 3-day 2003 astrometry is
sent to the MPC with the subject "possible new object" as we
were not sure if it could be new or not. MPC reports have a very
short and specific format and are not regular scientific publications.
Astrometry of known or unknown objects is regularly submitted by
many of us to MPC and as I said they are not peer-reviewed
publications and have no references or bibliography sections,
but even if we had that option there was no possible reference to
give as K40506A was nothing standard and it was not even sure that
it was K40506A.

Apparently this report went unnoticed to the MPC and since we did
not get a response, the next day we seek help of OAM people for
precovery (that is, to try to find the object in publicly available
image archives on the internet) as we had no experience on this.
This requires orbital computations for which we do not have expertise.
R. Stoss was particularly helpful as a reputed person in precoveries.
The description of the process is very technical but I reproduce
it here anyway, quoting parts of his own words to the minor planet
mailing list.

------
The initial orbit based on the three positions from 2003 was a
crap, even retrograde if I remember well, but it was good enough
to find it on NEAT data from few days later. This way the orbit
was improved iteratively, the prediction improved, new frames
found etc. until the NEAT archive was plundered. The next step
then is to go to DSS, until back to POSS I. From all the 1-opp
TNO precoveries I had done so far, this one was a no-brainer.
The object was very bright and the "stepstones" were perfect,
i.e. the frames and plates were perfectly "timed". Thus DSS2
and 1 were plundered and some POSS I non-DSS plates as well and
both NEAT and DSS data submitted.

Additionally, as it was getting dark in Spain and weather was
clear in Mallorca, I opened over internet the 30-cm scope and
started to prepare it for the night, looking We had to start
before the end of nautical twilight because the object would set
behind the shelter soon. We did 30 images of 30s each and stacked
with Astrometrica in sets of 10 images to get three measurements.
Motion could not be seen visually but the numbers showed it moving
and in the right direction. So I decided we should report these
three data points instead of stacking all 30 images to get one
data point. One data point would have been better (better SNR etc.)
but I know the MPC folks and their pretentions
------

As a result of all of this the provisional designation of the
object was assigned to our 2003 images, but Brown's group received
credit through several means. It is evident that they spotted it
first, but did not report it to the MPC so the provisional
designation came to our images.

We have been studying physical properties of large Trans Neptunian
Objects for several years and have published more than 10 scientific
peer-reviewed papers on them, so we are driven by purely scientific
goals here. We conduct also our own survey since late 2002 in order
to find a few very large TNOs and report them to the astronomical
community as soon as we find and confirm them because we believe that
international scientists working together, collaborating and sharing
resources can boost science progress and do the best possible job.
In other words, our survey is not only to feed our work, but also to
provide the scientific community with objects that can soon be
studied by the international community with all its man and
technology power.

Jose L. Ortiz

Trouble a brewin' on 2003 EL61

http://www.nytimes.com/2005/09/13/science/space/13plan.html

2003UB313

Brown, Trujillo and Rabinowitz have submitted a paper to ApJ Letters for it:
http://www.gps.caltech.edu/%7Embrown/papers/ps/xena.pdf

2003 EL61: bulgy or salt and pepper?

The TNO object first reported by the Ortiz et al now has a light curve that either has it spinning every fast and non-spherical or covered in spots a la Pluto.

New Scientist has the press release.

Division for Planetary Sciences meeting

The DPS of the American Astronomical Society is meeting with the Royal Astronomical Society (alas, not that RAS) in Cambridge this week. This is the meeting where Michael Brown, Trujillo, et al at Keck are announcing their big TNOs. Will we find out the proposed name for 2003 UB313 and 2003 EL61 and it's satellite?

Bad time to be away

Brown's team, afraid of being upstaged by someone else, dropped the bomb in announcing 2003 UB313 -- and finally found the big one. Bigger than Pluto. It had to happen.

And it has a satellite

The total system mass is 30% of Pluto's.
http://www.aas.org/publications/baas/v37n3/dps2005/786.htm

Huge new Kuiper Belt Object / Transneptunian Object?

2003 EL61. A Spanish survey claims to have found a mid 17th magnitude object with a proper motion consistent with a TNO at 51 AU distance, and have images of it from 2002 and 2003.

Their web site

According to our best orbit fit and using regular assumptions on phase angle
correction, the H value es around 0.3. Unfortunately we do not know the
geometric albedo but if below 0.25 (which is the case of all TNOs for which an
albedo has been measured except Pluto), the object would be larger than Pluto.
However, it may well happen that this object is abnormally bright (with a very
high albedo), like Pluto. So, depending on the albedo, this object might be sort
of a Pluto's brother or Pluto's father...

This object is beyond Pluto and almost reachable by most amateurs, which is the
reason why we write here!. It is observable right after sunset for a while at a
reasonable elevation. Maybe some decent science can still come out of your
observations.

Time will tell if it is a legitimate huge find. The size/population numbers have always indicated that there should probably be at least one more Pluto-size object out there, and I always believed someone would find it. Early KBO papers after the discovery by Jewitt and Luu of 1992 QB1 discussed the size distribution with Pluto at the top and kept the option open of other big ones.