Posted on by Fraser Cain

Canyons on Dione

Saturn’s moon Dione taken by Cassini. Image credit: NASA/JPL/SSI. Click to enlarge.
The Cassini spacecraft views the far-off wispy canyons of Saturn’s moon Dione and sees an interesting dichotomy between the bright wisps and the bright south polar region at the bottom.

The view looks toward the trailing hemisphere on Dione. North is up. Dione’s diameter is 1,126 kilometers (700 miles).

The image was taken with the Cassini spacecraft’s narrow-angle camera on Sept. 20, 2005, through a filter combination sensitive to polarized green light. The image was acquired at a distance of approximately 2.1 million kilometers (1.3 million miles) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 64 degrees. Resolution in the original image was 12 kilometers (8 miles) per pixel. The image has been magnified by a factor of two to aid visibility.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA’s Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo.

For more information about the Cassini-Huygens mission visit http://saturn.jpl.nasa.gov . The Cassini imaging team homepage is at http://ciclops.org .

Original Source: NASA/JPL News Release

Posted on by Fraser Cain

Two New Moons for Pluto?

Pluto and its possible new moons. Image credit: Hubble. Click to enlarge.
Using NASA’s Hubble Space Telescope to probe the ninth planet in our solar system, astronomers discovered that Pluto may have not one, but three moons.

If confirmed, the discovery of the two new moons could offer insights into the nature and evolution of the Pluto system, Kuiper Belt Objects with satellite systems, and the early Kuiper Belt. The Kuiper Belt is a vast region of icy, rocky bodies beyond Neptune’s orbit.

“If, as our new Hubble images indicate, Pluto has not one, but two or three moons, it will become the first body in the Kuiper Belt known to have more than one satellite,” said Hal Weaver of the Johns Hopkins Applied Physics Laboratory, Laurel, Md. He is co-leader of the team that made the discovery.

Pluto was discovered in 1930. Charon, Pluto’s only confirmed moon, was discovered by ground-based observers in 1978. The planet resides 3 billion miles from the sun in the heart of the Kuiper Belt.

“Our result suggests that other bodies in the Kuiper Belt may have more than one moon. It also means that planetary scientists will have to take these new moons into account when modeling the formation of the Pluto system,” said Alan Stern of the Southwest Research Institute in Boulder, Colo. Stern is co-leader of the research team.

The candidate moons, provisionally designated S/2005 P1 and S/2005 P2, were observed to be approximately 27,000 miles (44,000 kilometers) away from Pluto. The objects are roughly two to three times as far from Pluto as Charon.

The team plans to make follow-up Hubble observations in February to confirm that the newly discovered objects are truly Pluto’s moons. Only after confirmation will the International Astronomical Union consider names for S/2005 P1 and S/2005 P2.

The Hubble telescope’s Advanced Camera for Surveys observed the two new candidate moons on May 15, 2005. “The new satellite candidates are roughly 5,000 times fainter than Pluto, but they really stood out in these Hubble images,” said Max Mutchler of the Space Telescope Science Institute and the first team member to identify the satellites. Three days later, Hubble looked at Pluto again. The two objects were still there and appeared to be moving in orbit around Pluto.

“A re-examination of Hubble images taken on June 14, 2002 has essentially confirmed the presence of both P1 and P2 near the predicted locations based on the 2005 Hubble observations,” said Marc Buie of Lowell Observatory, Flagstaff, Ariz., another member of the research team.

The team looked long and hard for other potential moons around Pluto. “These Hubble images represent the most sensitive search yet for objects around Pluto,” said team member Andrew Steffl of the Southwest Research Institute, “and it is unlikely that there are any other moons larger than about 10 miles across in the Pluto system.”

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. The Space Telescope Science Institute in Baltimore conducts Hubble science operations. The Institute is operated for NASA by the Association of Universities for Research in Astronomy, Inc., Washington, under contract with Goddard.

The other team members for this observation are: William J. Merline, John R. Spencer, Eliot Y. Young, and Leslie A. Young, Southwest Research Institute.

Original Source: Hubble News Release

Update: Why isn’t Pluto a planet?

Posted on by Mark Mortimer

Book Review: Strange Angel

Jack Parsons, born John Whiteside Parsons, grew up in Pasadena, California. Though his family had substantial assets, the depression hit them hard. His life went from being a sole child in a rich family to being just one more member of a shrinking family with quickly disappearing money. An early fascination with space travel from the likes of Jules Verne gave Parsons a great desire to journey off the planet. In pursuing this quest, Parsons took what was then known of black powder and experimented. He varied constituent ingredients, relative compositions and manufacturing techniques. Yet, seldom did he get far from a glorified firecracker. Nevertheless, through trial and error, he was able to manufacture rockets that convinced the military of their usefulness in assisting take-offs (the JATO’s). Not long after, his group launched the first aeroplane flight powered solely by rockets.

With Parsons leading in such a captivating field, a biography would seem likely to focus primarily on accomplishments. Yet Pendle’s work delivers a much broader perspective. Apparently, as much as Parsons wanted to physically fly into the heavens on a rocket machine, he also wanted to journey mentally into other realms. Pendle provides all the details of how Parsons took over the local chapter of religious group, the Thelemas. Free love was in vogue as was much alcohol and the occasional ritual midnight mass. With their leader’s directive being, ‘Do what thou wilt’, there seemed little to inhibit participants’ actions.

These are the two main venues that appear in this book. Rockets and religion. Pendle steps through Parsons’ life from one main event to another. He describes each step in great detail. Housing architecture, real estate deals, and city officials on the take are all background for Parsons’ first appearance in court as an expert witness. Or there’s the Arroyo Seco range with its dry, still air occasionally broken by the blast from experimental rocket engines, swept clean by a deluge of rain, or enjoyed by youths of the area. By giving such a complete view of events and surroundings, Pendle places the reader directly into the times and moments of Parson’s life.

In keeping with this broad view, Pendle expands upon these background notes. There’s a rendition of the life of the Church of Thelema’s leader, Aleister Crowley. Time and again we get portrayals of the residents and architecture of Orange Grove, the street in Pasadena where Parsons spent much of his life. Pendle also shows a good view of some members of Caltech. Tie-ins with local and national science fiction authors abound. Many came to see Parsons or vice versa. There’s even a perception that L. Ron Hubbard’s definitions of Scientology originally came from Hubbard’s association with Parsons.

Perhaps what does get challenging is that these side issues take up so much of the book. There’s California’s culture, Caltech’s inception and growth, the military’s disfavour with rockets and lists of Crowley’s writings. All of these are interesting, some even fascinating, but it’s not always easy to associate with the biography. Further, though there might have been a tight science fiction community at the time, the description of magazine editors and their many stories and editorials makes one think that Pendle had more information than he knew where to insert. As my interest is in the rocketry aspect, I would have preferred more on this topic and less on the other people marginally involved with Parsons.

As well, the missing element in this writing is the lack of conjecture about Parsons himself. There are allusions to a final suicide, or was it an industrial accident? What was it like always being an outsider of Caltech or Aerojet? Why did magick hold such a spell over Parson? With no formal university training, but an encyclopaedic knowledge of chemistry and explosives, why couldn’t or wouldn’t Parsons integrate into research and development groups? These questions arose in my mind, but I kept having more questions and few answers.

Jack Parsons devoted most of his working life to proving and bettering rocket propulsion. His personal life was equally devoted, but to magick and philosophy. George Pendle in his biography Strange Angel colourfully portrays Parsons’ life and the exciting and mystical events that surrounded him. Some people were just never meant to be normal, and the rocket industry can thank Parsons for being one of those people.

Review by Mark Mortimer

Read more reviews online, or purchase a copy from Amazon.com.

Posted on by Fraser Cain

What’s Up This Week – October 31 – November 6, 2005

The Pleiades. Image credit: David Malin
Monday, October 31 – Happy Halloween! Tonight’s astronomical adventure will be about exploring an ancient and well renowned star cluster associated with this holiday that we’ve kept track of all week — the Pleiades! Easily found from a modestly dark site with the unaided eye, the Pleiades can be spotted well above the north-eastern horizon within a couple of hours of nightfall. To average skies, many of the 7 bright components will resolve easily without the use of optical aid, but to telescopes and binoculars? The M45 is stunning…

First let’s explore a bit of history. The recognition of the Pleiades dates back to antiquity and it’s known by many names in many cultures. The Greeks and Romans referred to them as the “Starry Seven”, the “Net of Stars”, “The Seven Virgins”, “The Daughters of Pleione” and even “The Children of Atlas”. The Egytians referred to them as “The Stars of Athyr”, the Germans as “Siebengestiren” (the Seven Stars), the Russians as “Baba” after Baba Yaga, the witch who flew through the skies on her fiery broom. The Japanese call them “Suburu”, Norsemen saw them as packs of dogs and the Tonganese as “Matarii” (the Little Eyes). American Indians viewed the Pleiades as seven maidens placed high upon a tower to protect them from the claws of giant bears, and even Tolkien immortalized the stargroup in the “Hobbit” as “Remmirath”. The Pleiades have even been mentioned in the Bible! So, you see, no matter where we look in our “starry” history, this cluster of seven bright stars has been part of it.

But let’s have some Halloween fun!

The date of the Pleiades culmination (its highest point in the sky) has been celebrated through its rich history by being marked with various festivals and ancient rites — but there is one particular rite that really fits this occasion! What could be more spooky on this date than to imagination a bunch of Druids celebrating the Pleiades midnight “high” with Black Sabbath? This night of “unholy revelry” is still observed in the modern world as “All Hallow’s Eve” or more commonly as “Halloween”. Although the actual date of the Pleiades midnight culmination is now on November 21 instead of October 31, why break with tradition? Thanks to its nebulous regions the M45 looks wonderfully like a “ghost” haunting the starry skies.

Treat yourself and your loved ones to the “scariest” object in the night. Binoculars give an incredible view of the entire region, revealing far more stars than are visible with the naked eye. Small telescopes at lowest power will enjoy the M45’s rich, icy-blue stars and fog-like nebulae. Larger telescopes and higher power reveal many pairs of double stars buried within its silver folds. No matter what you chose, the Pleiades definitely rocks!

Tuesday, November 1 – On this day in 1977, Charles Kowa made a wild discovery – Charon. This represented the first of a multitude of tiny, icy bodies that lay in the outer reach of our solar system.

While we have your icy body outside on the night of New Moon and “All Souls Day”, let’s try looking for one – asteroid Psyche – the personification of the soul.

While Psyche will not be easy, if you’ve found the Pleiades you are not far. Located around 2 degrees southwest of Zeta Taurii, you’ll find this tiny asteroid moving slowly past star 115 to the south. Don’t let her steal you away….

Wednesday, November 2 – Today celebrates the birth of an astronomy legend – Harlow Shapely. Born in 1885, the American-born Shapley paved the way in determining distances to stars, clusters, and the center of our Milky Way galaxy. Among his many achievements, Shapely was also the Harvard College Observatory director for many years. Today in 1917 also represents the night first light was seen through the Mt. Wilson 100″ telescope.

Although we don’t have that much aperture to study with tonight, we can still get a very satisfactory look at M15 through any size binoculars or telescopes. You can find it easily just about two fingerwidths northwest of red Epsilon Pegasi (Enif). Shining brightly at magnitude 6.4, low power users will find it a delightfully tight ball of stars, but scope users will find it quite unique. As resolution begins, sharp-eyed observers will note the presence of a presence of planetary nebula – Pease 1. This famous X-ray source you have just seen with your eyes may have supernovae remnants buried deep inside…

Thursday, November 3 – On this day in 1955, one of the few documented case of a person being hit by a meteorite occurred. What are the odds on that? Better than average tonight…

1957 the Russian Space Program launched its first “live” astronaut into space – Laika. Carried on board Sputnik 2, our canine hero was the first living creature to reach orbit. The quickly developed Sputnik 2 was designed with sensors to transmit ambient pressure, breathing patterns and heartbeat of its passenger along with a television camera monitor. The craft also monitored ultraviolet and x-ray radiation as well to further study the impact of space flight upon human occupants. Unfortunately, the technology of the time offered no way to return Laika to Earth, so she perished in space. On April 14, 1958, Laika and Sputnik 2 returned to Earth in a fiery re-entry ending after 2,570 orbits.

Laika may be gone, but the cosmos let her a glowing “bone” in space. Tonight turn your telescopes just a breath above Phi Perseii to view planetary nebula – M76. It may be hell in the heavens, because its central star is one of the hottest known. We’ll be back to “dig up” more on this one later.

Friday, November 4 – This morning will be the peak of the Southern Taurid meteor shower. Already making headlines around the world for producing fireballs, the Taurids will be best visible in the early morning hours as soon as the Moon is far west.. The radiant for this shower is, of course, the constellation of Taurus and red giant Aldeberan, but did you know the Taurids are divided into two streams?

It is surmised that the original parent comet shattered as it passed our Sun around 20,000 to 30,000 years ago. The larger “chunk” continued orbiting and is known as periodic comet Encke. The remaining debris field turned into smaller asteroids, meteors and larger fragments that often pass through our atmosphere creating astounding “fireballs” known as bolides. Although the fall rate for this particular shower is rather low at 7 per hour, these slow traveling meteors (27km or 17 miles per second) are usually very bright and appear to almost “trundle” across the sky. With the chances high all week of seeing a bolide, this makes a bit of quiet contemplation under the stars a “frighteningly” good time.

Saturday, November 5 – What dark and creepy night would be complete without the sad tale of Andromeda and Perseus? Tonight let’s have a look at Beta Perseii – the most famous of all eclipsing variable stars. Now, identify Algol and we’ll learn about the “Demon Star”.

Ancient history has given this star many names. Associated with the mythological figure, Perseus, Beta was considered to be the head of Medusa the Gorgon, and was known to the Hebrews as Rosh ha Satan or “Satan’s Head”. 17th century maps labeled Beta as Caput Larvae, or the “Spectre’s Head”, but it is from the Arabic culture that the star was formally named. They knew it as Al Ra’s al Ghul, or the “Demon’s Head”, and we know it as Algol. Because these medieval astronomers and astrologers associated Algol with danger and misfortune, we are led to believe that Beta’s strange visual variable properties were noted throughout history.

Italian astronomer Geminiano Montanari was the first to note that Algol occasionally “faded” and its methodical timing was cataloged by John Goodricke in 1782, who surmised that it was being partially eclipsed by a dark companion orbiting it. Thus was born the theory of the “eclipsing binary” and it was proved spectroscopically in 1889 by H.C. Vogel. At 93 light years away, Algol is the nearest eclipsing binary of its kind and is treasured by the amateur astronomer for it requires no special equipment to easily follow its stages. Normally Beta Persii holds a magnitude of 2.1, but approximately every three days it dims to magnitude 3.4 and gradually brightens again. The entire eclipse only lasts about 10 hours!

Although Algol is known to have two additional spectroscopic companions, the true beauty of watching this variable star is not telescopic – but visual. The constellation of Perseus is well placed this month for most observers and appears like a glittering chain of stars that lay between Cassiopeia and Andromeda. To help further assist you, locate Gamma Andromedae (Almach) east of Algol. Almach’s visual brightness is about the same as Algol’s at maxima.

Sunday, November 6 – On this night in 1572, the incomparable Tycho Brahe set to record a bright new star. Today we realize he was looking at a supernova! “Visible” now as a supernova event only at very long wavelengths in the constellation of Cassiopeia, if you are good with your finderscope under such bright conditions, you can still view it as a 7th magnitude star. Using Gamma, Alpha and Beta as your visual starting point, use binoculars to locate Kappa just north of this trio. Small Kappa will also be part of a configuration of stars which will look much like our starting point, only much dimmer. From Kappa, you will see a line of stars heading northwest. The very first in this series of 7th magnitude stars is SN1572.

Tomorrow Mars reaches opposition, but why wait to take on the “God of War”? The planet’s bloody red color, swift movement and changing brightness made the ancients fear it. For them, these times of changes in the sky spelled disaster for mortal man, but you’ll find this natural phenomena rather enlightening! Even if you do not use a telescope, look at how close it is to the Pleiades. Double disaster? Or double the pleasure.

Until next week? May all your journeys be at light speed… ~Tammy Plotner

Posted on by Fraser Cain

Power Problem with SSETI Express

SSETI Express in construction. Image credit: ESA. Click to enlarge.
Since Friday morning, the ground control station in Aalborg has not had any contact with SSETI Express. Thorough analysis over the weekend indicates that a failure in the electrical power system on board the spacecraft is preventing the batteries from charging, resulting in a shutdown of the satellite. There is a small but significant possibility of recovery, the likelihood of which is being ascertained by ongoing testing.

“Naturally, the SSETI teams are disappointed that we lost contact, but the mission has still been a success from both an educational and a technical standpoint”, says Project Manager Neil Melville. “The main goal of the mission was to educate students by having them involved hands-on in all the different aspects of a space mission, and now we really have experienced everything”.

On top of the educational purpose, several of the operational goals were met in the time the satellite operated. All evidence suggests that the three CubeSat passengers were successfully deployed into orbit by SSETI Express, and were hence able to begin their own independent missions.

The CubeSats Xi-V and UWE-1 are alive and well, the status of NCube-2 has yet to be confirmed. Stable two-way communications between the groundstation and SSETI Express was established and both the Aalborg University as well as many radio amateurs all over the world downloaded a significant amount of housekeeping data.

Currently, the student teams continue to investigate the situation and assess the chances of recovery. “Even if we don’t recover contact with SSETI Express, it was still a very worthwhile mission for everyone. We will take many lessons learned on to our next educational satellite project, SSETI ESEO”, says Roger Elaerts, ESA’s Head of Education Department.

Original Source: ESA News Release

Posted on by Fraser Cain

Anything That Can Go Wrong, Will… on Mars

Mars. Image credit: NASA/JPL.
The spacecraft door has just clanged shut behind you, locking you and your fellow astronauts into the small cabin that will be your home for the next half-year’s journey through interplanetary space–at the end of which you personally will be the first human to set foot on Mars.

As the countdown echoes in your ears and as you feel the boosters rumbling beneath you, you wonder … Are we ready?

According to Murphy’s Law, whatever can go wrong, will go wrong, and presumably this applies on Mars as well as Earth. So if things go wrong on Mars, are we ready for them? What do we need to know about Mars before we send people there?

That question is what NASA’s Mars Exploration Program Analysis Group (MEPAG for short) addressed in its report dated June 2, 2005, which bears the long mouthful of a title An Analysis of the Precursor Measurements of Mars Needed to Reduce the Risk of the First Human Mission to Mars.

The heart of MEPAG’s June report is a full-page table on p. 11 that lists 20 risks, “any one of which could take out a mission,” says David Beaty, Mars Program Science Manager at the Jet Propulsion Laboratory, and the report’s lead author.

Top among those risks:
* Martian dust–its corrosiveness, its grittiness, its effect on electrical systems such as computer boards;
* possible Martian “replicating biohazards”–organisms dangerous either to the astronauts or for return to Earth;
* the dynamics of the Martian atmosphere, including dust storms, that might affect landing and takeoff;
* potential sources of water, especially crucial if the first astronauts were to stay on the surface longer than a month.

The group asked itself, “What would we need to learn by sending robotic missions to Mars to reduce each risk? And how much would that information lower the risk [e.g., if engineers could design the spacecraft differently to protect astronauts]?”

Loud and clear from the MEPAG report is that “Martian dust is a #1 risk,” says Jim Garvin, NASA chief scientist at the Goddard Space Flight Center. “We need to understand the dust in designing power systems, space suits and filtration systems. We need to mitigate it, keep it out, figure out how to live with it.”

According to MEPAG, a mission to gather and return samples of Martian soil and dust to Earth is crucial.

“Most scientists believe it’s not possible to evaluate biohazards without a sample return,” notes Beaty. In addition, a sample return could resolve controversies about just how gritty or how chemically toxic the Martian soil may be. Even though lunar dust proved to be a major problem for the Apollo astronauts, “lunar dust does not equal Martian dust,” Garvin cautions. Scientists and engineers simply need to get their hands on real Martian dirt. The significance of a sample even as small as 1 kilogram “should not be underestimated” for both its scientific and engineering value, Beaty adds.

The MEPAG report also gave high rank to measurements involving the release of probes with parachutes and balloons into the Martian atmosphere. “We could observe Martian wind speeds at different altitudes, which is vital both for targeting accuracy when a mission lands, and for reaching the right orbit when the mission departs,” Beaty says.

And then there’s water: MEPAG assigns high priority to robotic expeditions that could definitively find water, either as water ice or as deposits of hydrous minerals. Two versions of a first human expedition are being debated: a short stay of about a month, and a long stay of about a year and a half. While a short-stay mission might be able to carry all the water it needed with it–relying on closed-loop life-support systems to recycle waste-water–a long-stay mission would need to excavate fresh water and manufacture breathable oxygen from ice-filled Martian soils.

These are but a few of MEPAG’s recommendations. The full report may be read here.

MEPAG itself is something new.

“NASA is reinventing how it formally acquires advice,” explains Garvin. Until the last few years, NASA has relied either on commissioning formal recommendations from the National Academy of Sciences, or on constituting ad hoc working groups. But both “would go quiet” after completing a single report, so there was no mechanism for evaluating how such high-level recommendations translated into concrete specifications for engineering hardware, scientific experiments, and actual measurements.

In contrast, MEPAG is a permanent body of scientists and engineers, working rather like the former U.S. Congressional Office of Technology Assessment. Its sole purpose is to figure out how big-picture goals translate into specific design options for exploration.

“It’s worked so well that we’re seeking to use the MEPAG model to form similar groups devoted to analyzing mission approaches to the Moon, Venus, and the outer planets,” Garvin says.

Are we ready? Ask MEPAG.

Original Source: Science@NASA Story

Posted on by Fraser Cain

Spitzer Presents Black Widow Nebula for Halloween

Black widow nebula. Image credit: NASA/Spitzer. Click to enlarge.
Unsuspecting prey be warned! Hiding in the darkest corner of the constellation Circinus is a gigantic black widow spider waiting for its next meal. For decades, this galactic creepy crawler has remained largely invisible, cunningly escaping visible-light detection. At last, it has finally been caught by NASA’s Spitzer Space Telescope’s dust-piercing, infrared eyes.

The spider is actually a star-forming cloud of gas and dust. In this Halloween interactive image comparison, an hourglass-shaped insignia, typically found on the underbelly of a black widow spider, can be seen faintly in the visible-light image from Digital Sky Survey (DSS). As Spitzer’s infrared image fades in, the veil of galactic dust shrouding the rest of the spider is lifted to reveal a poisonous widow.

In the Spitzer image, the two opposing bubbles that make up the black widow’s body are being formed in opposite directions by the powerful outflows from massive groups of forming stars. The baby stars can be seen inside the widow’s “stomach” where the two bubbles meet.

When individual stars form from molecular clouds of gas and dust they produce intense radiation and very strong particle winds. Both the radiation and the stellar winds blow the dust outward from the star creating a cavity or, bubble.

In the case of the Black Widow Nebula, astronomers suspect that a large cloud of gas and dust condensed to create multiple clusters of massive star formation. The combined winds from these large stars probably blew out bubbles into the direction of least resistance, forming a double-bubble.

Original Source: Spitzer News Release

Posted on by Fraser Cain

Amateur Observers Are Seeing Double

Image credit: Derek Breit. Click to enlarge.
Findings of this nature are one of the many reasons why International Occultation Timing Association (IOTA) members pursue their craft. One of the notable and historic discoveries on a standard star by occultation means happened in 1819 when Antares’ companion star was observed. However, the name of the astronomy game is confirmation – and also filming and timing the northern limit event at differing locations were Walt Morgan and Ed Morana.

Contacting IOTA’s Dr. David Dunham, Breit forwarded his findings, contacted team members and started seeking an answer for two unusual seconds of video. According to Dunham’s response, “Almost 2 seconds with a distance of much more than a km; it’s unlikely that the Moon would be that smooth, it would have to be within about 5m or less for the brightness to remain faint and constant at that level so long. Especially since this apparently occurred at nearly every event, a faint, close companion, only 0.01″ to 0.02″ north of the primary, seems likely.”

And Morgan clarifies, “The disappearances and reappearances by upsilon Geminorum as it passed lunar peaks were usually slow transitions, that is, the star appeared to fade (or brighten) over a matter of several video frames. That was not considered unusual because of the fairly large angular diameter of the star. However, in some instances the magnitude 4.1 star did not seem to completely disappear on Breit’s record: a very faint point of light remained visible right at the lunar limb.”

But confirmation of such importance to the scientific community doesn’t stop there. Breit’s findings went out to all IOTA observers and the critical timing information provided them with the clues they needed. Also recording the event was Dr. Richard Nolthenius, whose answer was, “Derek’s right! I’ve just reduced my upsilon Gem graze video recording from last Friday. I used a PC164c on an 8″ f/10 operating at f/6.3, recorded on my Canon ZR45mc. And the conclusion is…. Derek’s camcorder is not going crazy! I fully confirm his observations and conclusions – this star is a very close double star.”

As they continue to work through the geometry and astrometric angles, Dr. Nolthenius offers the following information from his own recordings: “The second and 3rd D’s look especially like there is an 11th magnitude companion, and the final D most dramatic of all, with the initial fade happening in just 3 frames, followed by a definite but very faint 11th magnitude star left over for fully 1 second before finally disappearing.”

Although it might seem that in a sky filled with innumerable double stars that a revelation of this type would be of little significance, IOTA member – Dr. Michael Richmond – knew better: “I did a little searching to see if there was any other indication that upsilon Geminorum might be double. The Hipparcos observations indicate that it is slightly variable, with an amplitude of about 0.08 mag, but there is no indication of a period. The Astrophysics Data Service has a number of references which mention upsilon Geminorum. This star has been chosen to be a calibrator for optical interferometers; that is, people have decided that it’s a good star to use as a reference when doing high angular resolution measurements. There are two recent papers which list measurements of its angular size: Borde et al. (A&A 393, 183, 2002), which finds an angular diameter of 5.00 +/- 0.051 mas, and Richichi and Percheron (A&A 386, 492, 2002), which lists angular diameter of 5.23 +/- 0.31 mas. Given the Hipparcos parallax of 13.57 mas, this means that the star’s diameter is roughly 0.37 AU. The main star has spectral type listed as late K or early M giant, with V-band mag 4.08 and K-band mag 0.24. If this is a double star, with a companion of roughly mag 11, then it would be important to let other astronomers know: it would no longer be a really good calibration star.”

But, Dr. Richmond did not let his findings rest there and he continued to look for more precise information. Says Richmond, “I found that both of the catalogue entries were NOT based on direct measurements of angular size; instead, they were simply estimates, based on the observed brightness and the shape of the spectrum. In other words, they were basically fits to a blackbody with a given temperature. I was surprised to find such indirect evidence appearing in catalogues of angular size, for use as a calibrator for interferometers.”

Recognizing the importance of such a finding as opposed to known data definitely changes the way we perceive information. Astronomy is a continually upgrading science as Dr. Nolthenius notes: “For some 9th magnitude star, finding yet another double is one thing, but for such a bright star, being a standard for certain measurements should be checked, as you did. The star is apparently in that fall-through-the-cracks area of parameter space: a wide enough double to not make for noticeable periodicity in the radial velocity on a time scale of a few years – the period is likely in the 100+ year range, (although this is something I will calculate later) and yet impossibly difficult as a visual binary without using interferometry or lunar occultations.”

Of course, there is far more to this picture than just the discovery of undisclosed double star. By recording, timing, and observing both grazing and occultation events, IOTA is able to help determine proper movement, orbit and lunar limb features as well. As Dr. Nolthenius explains, “The absolute UT’s of the events will help in assessing the slope of the moon at the event points. However, the most convincing case for duplicity will be identifying significant periods of time of constant brightness at the very faint levels.” The diffraction of large stars aids astronomers in making more accurate calculations, “Perhaps there is a secondary that is of order 1 radius or less above the surface of upsilon Geminorum.” hypothesizes Nolthenius, “If such extended periods of very faint levels might be consistent with limb darkening which is very extended. As a K giant, I would not expect the limb darkening to be so extreme – normally limb darkening is more extreme the cooler the star, and late K is not all that cool.”

More confirmation was needed and the findings were sent to Dr. Mitsuru Soma of the National Astronomical Observatory of Japan. Says Soma, “From the comparison of your faint flash mentioned above and the short duration (0.7s) from R to D of the primary of Walter Morgan the companion’s separation from the primary is estimated to be about 0.04 arcsec, and this is consistent with the duration of your gradual R’s at 4:39:07 and at 4:40:21 (UT). The spectral type of ups Gem is K5III which is the same as Aldebaran according to the Hipparcos catalogue, so I assume that the actual radius of ups Gem is almost the same as Aldebaran. The angular radius of Aldebaran was estimated to be about 0.010 arcsec from lunar occultations.”

But confirmation means being very sure that there is no chance of this being a diffraction effect. As Dr. Soma explains, “The distance to ups Gem is 3.6 times the distance to Aldebaran (ups Gem’s parallax is 0.014 arcsec and Aldebaran’s parallax is 0.050 arcsec) so the angular radius of ups Gem should be about 0.003 arcsec, which is small so that I think the error arisen from the assumption that the star is a point source is almost negligible when we estimate the diffraction effects. Referring to this fact I think 0.04 arcsec I mentioned above is too large to be attributed to the diffraction effects.”

Confirmation continues on a deeper level when Dr. Michael Richmond plots the photometry of all three tapes of the Upsilon Geminorum event: “The thing I find very interesting and encouraging is that I see an asymmetry in these light curves.” says Richmond, “If this is true, then I think we can make a good case that there may be a faint companion to the primary star. The companion must be “ahead” of the primary, so that the moving limb of the moon first blocks (or reveals) the companion, before it blocks (or reveals) the primary.”

Dr. Mitusuru Soma also continued with his analysis and presented the papers at the Journees 2005 meeting in Warsaw on 2005 September 19-21. Based on available information says, “My conclusion about the position of the secondary of upsilon Geminorum relative to the primary is 0″.04 +/- 0″.01 in separation and 70deg +/- 20deg in PA.” Although these findings are preliminary, Soma will continue to review the data and clarify the results of all accumulative information.

Seeing double? The answer is quite probable. In the mean time IOTA members will continue to review of the data and further research the duplicity of upsilon Geminorum. There’s a whole big wide sky out there, and each time an observation of this type is made it adds more to our understanding. While speckle interferometry is cutting edge of double star detection – the occultation method can reveal far more. Contributions from dedicated members are what makes the International Occultation and Timing Association play an important role in today’s astronomy.

Says Breit, “It was a pretty darn good feeling when Dr Nolthenius wrote “Derek’s RIGHT!” When four PhD’s say I have found something special doing a hobby I taught myself from the age of six, that’s pretty good. Something to tell the grandkids… But my real thought was that I finally have a great video to show others and hopefully get them interested in observing these very dynamic and temporal events!” So what are the chances of IOTA members Derek Breit, Walt Morgan, Ed Morana and Michael Richmond making a contribution to the scientific community?

I’d say double.

Written by Tammy Plotner.

Posted on by Fraser Cain

First Mirror Cast for the Giant Magellan Telescope

Computer illustration of the GMT’s 7 giant mirrors. Image credit: GMT. Click to enlarge.
The University of Arizona Steward Observatory Mirror Lab’s casting of the first mirror for the Giant Magellan Telescope (GMT) “appears to be essentially perfect,” UA Steward Observatory director Peter Strittmatter said after astronomers got their first look at the glass last Friday.

“We’re very happy to see this one come out looking so gorgeous,” Mirror Lab Technical Director J. Roger Angel said. “We’ll see more once the mold is removed, but so far, looking through the front surface, it looks great.”

The mirror is the first of seven 8.4-meter (27-foot) mirrors that the Mirror Lab is making for the Giant Magellan Telescope. The GMT is the world’s first extremely large ground-based telescope to start construction.

The colossal telescope will feature six giant off-axis mirrors around a seventh on-axis mirror. This arrangement will give it a 22-meter (72-foot) aperture, or 4.5 times the collecting area of any current optical telescope. It will have the resolving power of a 24.5-meter (80-foot) diameter telescope, or 10 times the resolution of the Hubble Space Telescope. The GMT is slated for completion in 2016 at a site in northern Chile.

Randy Lutz and the Mirror Lab casting team knew they had a superb first GMT mirror blank when they removed the casting furnace lid Oct. 21. But they aren’t standing around to admire their handiwork. They’re racing to remove furnace walls and ready the mirror blank for moving off the furnace hearth.

“We’re very eager to get on to the critical part of why we made this mirror — to the polishing and the testing, which are really the new ground-breaking steps in making this mirror because its shape is so different,” Angel said. “We’re moving fast because we want to get on with casting the next mirror, a 3.7-meter mirror that will be needed to measure the shape of the GMT primary mirrors.”

Mirror Lab workers are about to disassemble their facility’s 7.5-story test tower (that’s 27 meters, or 88 feet) and construct a higher tower that will hold the 3.7-meter (12-foot) mirror for measuring the off-axis GMT mirrors. The test mirror is crucial for making measurements needed for shaping all the primary mirrors so they gather and focus light as a single gargantuan primary mirror.

Meanwhile, Steward Observatory Mirror Lab scientists Buddy Martin and Jim Burge are already polishing a one-fifth scale prototype of the GMT primary. Polishing the full size off-axis mirror will be a huge step forward in the GMT project, Angel said.

For the casting last July, Mirror Lab workers used 40,000 pounds of Ohara E-6 borosilicate glass. The furnace hit peak temperature, 2,150 degrees Fahrenheit (1,178 Celsius) on July 23. As the furnace rotated at 5 revolutions per minute, glass melted around the 1,681 hexagonal cores in the mold. This created a ‘honeycomb’ mirror blank with a faceplate of the desired curvature. The honeycomb mirror weighs only a fifth as much as would a solid mirror of the same size.

The first GMT primary is the third 8.4-meter mirror cast at the Steward Observatory Mirror Lab. The GMT builds on the very successful 6.5-meter (21-foot) Magellan telescopes which many of the same GMT partners operate in Chile.

Eight institutions are partners in the GMT. They are the Carnegie Observatories, Harvard University, Smithsonian Astrophysical Observatory, University of Arizona, University of Michigan, Massachusetts Institute of Technology, University of Texas at Austin, and Texas A & M University.

The two other 8.4-meter mirrors cast at the Mirror Lab are at the Large Binocular Telescope (LBT) on Mount Graham, Ariz. U.S., Italian and German partners in the LBT released ‘first light’ images obtained with the first of the LBT’s primary mirrors yesterday (Oct. 26). The LBT, the forerunner of the GMT, will be the world’s most powerful single telescope when its two primary mirrors, mounted side-by-side, become operational in 2006.

Original Source: UA News Release

Posted on by Fraser Cain

Bright Mars This Weekend

Hubble image of Mars. Image credit: Hubble. Click to enlarge.
Look east in the next few evenings and you may see a big, reddish-yellow ‘star’, shining much brighter than any other. This is the planet Mars, and it is passing unusually close to Earth during late October and early November 2005.

Anyone should be able to see it, no matter how little you know about the stars or how badly light-polluted your sky may be.

During mid- to late October, Mars will be low in the east after sunset. Later in November evenings, Mars climbs higher into better view and shifts over to the south-east. Mars is at opposition (opposite the Sun in our sky) on 7 November. This means it rises at sunset, is up all night, and sets at sunrise.

Mars will be closest to Earth on the night of 29 October, passing by our planet at 69.4 million kilometres distance. However, Mars will look just about as big and brilliant for a couple of weeks before and after this date.

This is the nearest that Mars has come since its record-breaking close approach in August 2003 just after ESA’s Mars Express spacecraft was launched and sent to the Red Planet. At that time it passed by at a distance of only 55.8 million kilometres, the closest it had come in nearly 60 000 years.

In fact, not until summer 2018 will Mars again come as close to Earth as it is now. But this year, skywatchers at North American and European latitudes have a big advantage they did not have in 2003.

That year Mars was far south in the sky and never rose high enough for telescope users at mid-northern latitudes. But this time Mars is farther north and rises higher during the night, giving a sharper, cleaner view with a telescope through Earth’s blurring atmosphere.

Original Source: ESA News Release