* Astronomy

Members Login
Username 
 
Password 
    Remember Me  
Post Info
TOPIC: (136108) 2003EL61


L

Posts: 131433
Date:
2003 EL61 Paper
Permalink  
 


Photometric Observations Constraining the Size, Shape, and Albedo of 2003 El61, a Rapidly Rotating, Pluto-Sized Object in the Kuiper Belt
Authors: David L. Rabinowitz, Kristina Barkume, Michael E. Brown, Henry Roe, Michael Schwartz, Suzanne Tourtellotte, Chad Trujillo

We present measurements at optical wavelengths of the spectral reflectance, the rotational light curve, and the solar phase curve of 2003 EL61,. With apparent visual magnitude 17.5 at 51 AU from the sun, this newly discovered member of the classical Kuiper Belt is now the third brightest KBO after Pluto and 2005 FY9.
Our observations reveal an unambiguous, double-peaked rotational light curve with period 3.9154 ± 0.0002 hours and peak to peak amplitude 0.28 ± 0.04 mag. This is the fastest rotation period reliably determined for any body in the solar system larger than 100 km.
Assuming the body has relaxed over time to the shape taken by a homogenous fluid body, our observations tightly constrain the shape and density. Given the mass we recently determined for 2003 EL61 from the orbit of a small satellite, we also constrain the size and albedo.
We find a total length of 1960 to 2500 km, a mean density of 2600 to 3340 kg m-3, and a visual albedo greater than 0.6.
We also measure a neutral reflectance at visible wavelengths and a linear phase curve with slope varying from 0.09 mag deg-1 in the B band to 0.13 mag deg-1 in the I band. The absolute V-band magnitude is 0.259 ± - 0.028.

Read More (PDF)

__________________


L

Posts: 131433
Date:
RE: New solar object
Permalink  
 


Jose-Luis Ortiz of the Institute of Astrophysics of Andalusia in Granada the Spanish astronomer has admitted he accessed publicly available internet telescope logs of another astronomer's observations of 2003 EL61 but he say that it was "perfectly legitimate" because the logs were publicly available. And he was just double checking his results.

However, Mike Brown claims that accessing the information was "unethical" and could be construed as scientific fraud.

Browns observatory server records show that access to the online observing logs had come on 26 July 2005 from the institute where Ortiz works. Two days later, a second computer from the same institute accessed those same web pages. The computers' internet addresses matched those used by Ortiz and his student Pablo Santos-Sands to e-mail reports to the MPC.

Ortiz says he found Brown's observing logs when checking a bright transneptunian object that Santos-Sands showed him on July 25, after finding them in images taken in March 2003, and noticed that Brown's abstract for the planetary science meeting, posted online a few days before, described a similar object, identified as K40506A, and googled the web for more information.

"A Google search on K40506A leads to a public web page with what appears to be coordinates of many things" - Jose-Luis Ortiz.

Ortiz announced the discovery on 28 July 2005, (reported here on the 29th)

Brown, however, had kept quiet about his discovery and had been observing the object for months and planned to describe it in September 2005 at the Division of Planetary Science conference in Cambridge, UK.

The incident highlights the pressure that astronomers are under , not to fully confirm their discoveries or to report their discovery before anyone else.
The acceptability of data mining, as well as the withholding of information from the public or scientific community is also brought into question.

Brown, called a press conference on 29 July to quickly claim the discovery of 2003 UB313, which he had also been observing.

__________________


L

Posts: 131433
Date:
2003 EL61
Permalink  
 


Update:
Observations reveal a double-peaked rotational light curve with period of 3.9154 ±0.0002 hours and peak to peak amplitude of about 0.28 ±0.04 magnitudes.



The double peaks indicate an elongated object with large to small axis ratio of 1.4.
Observations also reveal a total length of 1960 - 2500 km, a mean density of 2600 - 3340 kg m-3, and a visual albedo greater than 0.6.
They also measured a neutral reflectance at visible wavelengths and a linear phase curve with slope varying from 0.09 mag deg-1 in the B band to 0.13 mag deg-1 in the I band. The absolute V-band magnitude is 0.259 ±0.028.




__________________


L

Posts: 131433
Date:
Permalink  
 

Photometric observations constraining the size, shape, and albedo of 2003 EL61, a rapidly rotating, Pluto-sized object in the Kuiper Belt.

Read More (PDF)

__________________


L

Posts: 131433
Date:
RE: New solar object
Permalink  
 


Dr. Brown has asked for an investigation of Dr. Ortiz's discovery, alleging a serious breach of scientific ethics. Archival records show that only a day before the discovery was reported, computers traced to Dr. Ortiz and his student Pablo Santos-Sanz visited a Web site containing data on where and when the Caltech group's telescope was pointed.

The information in these observing logs could have been used to help find the object on the Spanish images, taken more than two years ago, or simply to confirm that both groups discovered the same object. Depending on what the Spanish astronomers did, their failure to mention the Caltech observations could be considered scientific dishonesty or even fraud, Dr. Brown suggests.

In comments for his Web site, which includes a detailed timeline of the events surrounding the July announcement, Dr. Brown writes: "It is not clear from the timeline precisely what Ortiz and Santos-Sanz knew and how they used the records that they accessed. They were required by the standards of science, however, to acknowledge their use of our Web-based records"

In an e-mail message to Brian Marsden of the Harvard-Smithsonian Centre for Astrophysics, who is director of International Astronomical Union's Minor Planet Centre, the clearinghouse for such discoveries, Dr. Brown wrote on Aug. 15, "I request that Ortiz et al. be stripped of official discovery status and that the I.A.U. issue a statement condemning their actions"

Dr. Ortiz did not respond to numerous e-mail messages and telephone calls. Last week in an e-mail message to Dr. Brown, Dr. Ortiz neither admitted nor denied looking at the observing logs. Instead he criticized Dr. Brown's failure to report discoveries promptly to the Minor Planet Centre, saying that his penchant for "hiding objects" had alienated other astronomers and harmed science.

"And remember, the only reason why we are now exchanging e-mail is because you did not report your object" - Dr. Ortiz said in the message.

But Jose Carlos del Toro Iniesta, director of the Andalusian institute, said that he intended to investigate Dr. Brown's allegations- "I beg your understanding in separating clearly the institute as a whole from its individual members: the researchers' actions are their sole responsibility" .

The spectacular allegation has flummoxed the International Astronomical Union. Saying that he and his colleagues had never been fooled before, Dr. Marsden admitted that the I.A.U. had no protocol for adjudicating such a dispute.

"I don't think we have a method - other than public tantrums - to resolve these problems" - Dr. Robert Kirshner, Harvard astronomer and the president of the American Astronomical Association.

The imbroglio illustrates the ethical dangers and pitfalls of doing science in the Internet age, where a little clicking can bring you a shocking amount of information about what your colleagues and rivals are up to.
There is a long history of astronomers jealously guarding the coordinates of some celestial phenomenon while they try to figure out what it is, and of others trying to get in on the action. In 1930, when Pluto was discovered, the Lowell Observatory, home of the discoverer Clyde Tombaugh, withheld details of its location because they wanted to be the first to calculate its orbit.
Matthew Holman, a Harvard planetary astronomer, said that in the old days when the logbooks were real books sitting by the telescope, some astronomers would write down fictitious coordinates and objects to cover their tracks.

Since 2002, Dr. Ortiz and his colleagues have been looking for so-called trans-Neptunian objects in the outer solar system with a brace of small telescopes at the Sierra Nevada Observatory, in Granada.
2003 EL61 appears to have been their first big discovery. According to Dr. Ortiz, it was first spotted on July 25 by Mr. Santos-Sanz as a slow-moving object on images taken in March 2003. He e-mailed this news to the Minor Planet Centre on July 27, but it attracted no attention, partly because there was not enough information to tell other observers where to look for it.
The next night Dr. Ortiz reported that his group had been able to trace the object on various old photographs back to 1955, enabling a group at the Astronomical Observatory of Mallorca to observe it.
After checking for themselves that the object was real, Dr. Marsden's team disseminated the details to the rest of the astronomical world on its own Web site and by e-mail.
The new body would have been a prize for any astronomer. At the time it was the brightest and largest object - next to Pluto - yet found in the Kuiper belt, a ring of debris that stretches out beyond Neptune.
Except that it had already been discovered.
Dr. Brown had planned to report the object, which his team had discovered in December 2004 and nicknamed Santa, at a meeting last week. In fact, he had described it in abstracts sent to the American Astronomical Society, abstracts available to anyone with a computer and familiarity with astronomical jargon, only a week before, on July 20.
Dr. Ortiz's report raised eyebrows at the astronomical union because he and his telescopes were relatively unknown and because two years had elapsed since the discovery pictures were taken. Struck by the similarity of the objects and the close timing of Dr. Ortiz's announcement, Dr. Marsden said he had told Dr. Brown that he was worried that a leak might have occurred.
In fact, Dr. Brown himself had inadvertently made such a leak possible.
In the abstracts he referred to "Santa" by a code name, K40506A, which was the same code name his team had used in its observing logs. As a result, as Dr. Brown discovered to his horror the night of Dr. Ortiz's announcement, any astronomer who read the abstracts and typed "K40506A" into an Internet search program would be taken to a Web site containing the observing logs of Smarts, the Small and Moderate Aperture Research Telescope System. It was one of those telescopes, at the Cerro Tololo Inter-American Observatory in Chile, which Dr. Brown and his colleagues were using to track the object.
The telescope is one of four owned by a consortium of universities and operated by two observing assistants at the observatory. The Web site, which is public, does not contain data obtained during observations but does tell where the telescope was pointed.
Shaken by that news that his observations were so accessible, Dr. Brown hastily called a news conference to announce his ace in the hole, a new planet bigger than Pluto, at 7 p.m. on Friday, July 29, "Perhaps the single best time to announce news that you want no one to hear," as he put it on his Web site.
In an e-mail message, he apologized to Dr. Ortiz ahead of time for being about to overshadow him.
Nevertheless questions lingered among minor planet astronomers about whether Dr. Ortiz's group might have helped themselves to Dr. Brown's observing logs, suspicions that Dr. Ortiz found irritating.
But now evidence has been offered that Dr. Ortiz and his group did access the observing logs. Prompted by questions by Dr. Rabinowitz of Yale, one of Dr. Brown's team members, Dr. Pogge, who maintains the Smarts telescope Web site, decided to investigate the traffic on the site.

He found that computers from an unfamiliar address had visited the Web site eight times from July 26 to 28, when the Spanish group was making its announcement. Each time the computers went straight to pages deep within the site that described the Brown group's observations of K40506A.
The first three visits happened a few minutes apart early on July 26, a day and a half before the Ortiz group made its announcement. Another cluster of hits came on the morning of the July 28 before the object was observed in Mallorca and Dr. Ortiz made his more complete report to the astronomical union.
Dr. Pogge was able to trace the computers through the so-called IPP numbers, which the Internet assigns to each computer on it. Those numbers eventually led him to the Web site of the Andalusian Institute. Dr. Pogge said he gasped out loud when it popped up.

"I remember saying, 'Oh no, oh no, oh no,' over and over again".

Moreover, the IPP numbers of the intruders match the numbers on the e-mail messages Mr. Santos-Sanz and Dr. Ortiz sent to the Minor Planet office, according to Dr. Marsden. Dr. Pogge called Dr. Brown on Aug. 8. Dr. Brown in turn sent an e-mail message to Dr. Ortiz asking for an explanation, but by then all of Spain seemed to be on vacation.
It was not until early this month that Dr. Iniesta and Dr. Ortiz wrote back, the latter to say that he was still on vacation and saw no need to respond further until Sept. 15.
In the absence of further information, exactly what Dr. Ortiz did with the observing logs is likely to remain a mystery. Were he and his colleagues only checking to see if Dr. Brown's object was the same as theirs to confirm their own discovery? Or did they use the information to find the object and beat the Caltech team?
Both actions would violate scientific ethics but with varying degrees of seriousness, astronomers said.
John Huchra, an astronomer and the vice provost for research policy at Harvard, said that at some level it is all right to use knowledge of what a rival group is doing.
"If you hear them give a talk at a conference, it's fair game. But if you found it in the trash bin or the copier, that's not kosher".

If you used tainted information to beat out the other group, he said, the director of the observatory (the only authority in this system) could forbid publication and banish you from the telescope. "If they were just confirming. there's still a tinge here. It's not kosher to point your telescope at somebody else's object, unless you ask"

Ben Oppenheimer, an astronomer and extrasolar planet hunter at the American Museum of Natural History, said that he thought it was unethical to use tainted information in any way, but added: "It's a borderline case, though, because the logs were public. I don't know why that information was so freely available"
One complicating factor is that professionals like Dr. Brown tend to nurse their work along in private until they are ready to publish a major scientific paper. This practice has sometimes created tension among the minor planet observers, including a large number of amateurs who take pride in spotting comets, uncharted asteroids and other objects before the professionals. In his response to Dr. Brown, Dr. Ortiz offered to collaborate with him on the naming of 2003 EL61 if Dr. Brown would change his secretive ways.

Dr. Brown called Dr. Ortiz's e-mail message "astonishing."

Regarding the practice of guarding his data, he said, "This is what every single scientist does every day of their lives"

Dr. Marsden pointed out that Dr. Brown had advanced science while he was keeping his "Santa" object under observation. He discovered that it has a moon, nicknamed Rudolph, allowing him to calculate the object's mass - about one-third that of Pluto.
Moreover, he did report it, said Dr. Marsden, citing the abstracts.

"I don't blame him for wanting to finish the job. You do the whole thing. That is how astronomy is done, or used to be done"

Dr. Marsden, who is secretary of astronomical union's committee for naming small bodies, said that he would suggest to Dr. Brown that he propose names for both 2003 EL61 and its satellite.

Adapted from Source

__________________


L

Posts: 131433
Date:
2003EL61
Permalink  
 


Using the V=17.5 minor planet as the tip-tilt reference, the Keck observatories LGSAO system delivered images with a typical resolution of 0.06 arcseconds at 2.1 microns wavelength.
Observations made during 5 commissioning nights between 26 January and 30 June 2005 allow Mike Browns team to derive the following orbital solution for the delta K=3.8 magnitude satellite with respect to the primary:

a=49100 ±400 km
P=49.05 ±0.03 days
e=0.048 ±0.002.

This implies a total mass of the system of 3.9 ±0.1 x 1021 kg, or 30.2 ±0.8% the mass of Pluto.

"All three objects are nearly Pluto-sized or larger, and all are in elliptical orbits tilted out of the plane of the solar system. We think that these orbital characteristics may mean that they were all formed closer to the sun, and then were tossed around by the giant planets before they ended up with the odd orbits they currently have" - Mike Brown.

__________________


L

Posts: 131433
Date:
2003 EL61
Permalink  
 


Astronomers have discovered the fastest rotating object for its size in the Solar System.
The Kuiper Belt Object 2003 EL61, discovered in July, rotates once every 3.9 hours.
Rather than being spherical like Pluto, the object has a shape much like a squashed rugby ball.

Read More

__________________


L

Posts: 131433
Date:
RE: 2003EL61
Permalink  
 


This discovery shows nicely the potential of treasure-hunting in old astronomical image archives.
Because it was relatively bright, the chances are that it was captured in even modest 8 inch telescopes.
For example, 2003 EL61 passed within 15'-20' from the centre of the Black Eye galaxy (M64) several times during the period 1996-1998.

Here is the Daily Ephemeris from 1994/01/01 to 2005/07/31



__________________


L

Posts: 131433
Date:
RE: New solar object
Permalink  
 


It seems that 2003 EL61 has a diameter of around 1500 Km, about 70% of Pluto's diameter, and only 32% its mass, which places it roughly on par with Sedna.
The object is about 51 Astronomical Units from the Sun, though its orbit brings it as close to the Sun as 35 AU. The orbital plane is tilted by 28° with respect to the orbital planes of most the planets.
The new Kuiper Belt Object (KBO) was initially named K40506A.

Quaoar, Orcus and Sedna have H values of 2.6, 2.3 and 1.6, respectively.
2003 EL61 with a heliocentric distance of 51 AU and a visual magnitude of 17.5, gives it an H value of about 0.4.
Therefore, it is the brightest apparent magnitude KBO and the brightest absolute magnitude minor planet so far.

Low and medium resolution 1.0 to 2.5 micron near-infrared reflectance spectra of the surface of K40506A, obtained at the Gemini 8-m and Keck 10-m telescopes on Mauna Kea show clear signs of water ice.

And it has a moon!

The moon around 2003 EL61 is tiny, making up only about 1 percent of the mass of the two-body system.


The satellite on the night of 30 June 2005.
2003 EL 61 is the bright object in the centre and the satellite appears directly below about 0.5 arcseconds. To the south of 2003 EL61 you can also see a faint background star.


2003 EL61s moon was discovered on January 28th 2005 using the Keck Observatory. The satellite is on a long period orbit, circling 2003 EL61 every 49 days. Seen from the Earth the satellite reaches a maximum distance from 2003 EL61 of about 1.5 arcseconds.


The orbit of the satellite from five observations.

__________________


L

Posts: 131433
Date:
RE: 2003EL61
Permalink  
 


The icy object, designated 2003 EL61, is at least 1,500km (930 miles) across, though it may be larger than Pluto, which is 2,274km across. It orbits just beyond the orbit of Pluto, never coming closer to the Sun than the orbit of Neptune.
The uncertainty in its size is due to errors in its albedo.
It might be a large, dim object, or a smaller, brighter object. Whatever it is, astronomers consider it a major discovery.



In 2004 scientists discovered Sedna, a remote world that is 1,700 km across.
It was picked up by astronomers of the Institute of Astrophysics in Andalusia as part of a survey of the outer solar system for new objects that they have been carrying out since 2002.

"We found a bright, slow moving object while checking some older images of our survey for Trans-Neptunian Objects" Jose-Luis Ortiz, one of the objects co-discoverers.

However, American astronomers also appear to have detected it.
The same team found Sedna (K40506A) after it was picked up by the Gemini telescope and one of the twin Keck telescopes in Hawaii.

They are due to present their findings at a conference in Cambridge in September.
Because the object is relatively bright, astronomers are frantically checking other observations that may have picked it up, particularly robotic sky surveys.

__________________
«First  <  14 5 6 7  >  Last»  | Page of 7  sorted by
Quick Reply

Please log in to post quick replies.



Create your own FREE Forum
Report Abuse
Powered by ActiveBoard