PS1SC blog

We are on APOD!

2012-10-12T18:50:25Z

Today’s Astronomy Picture of the Day is a spectacular Pan-STARRS picture of the Triffid and Lagoon nebulae. Here’s the lower resolution version.

The Triffid and Lagoon Nebulae. Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

APOD also has a higher (1/10) resolution version, but you can explore the image at 3 times the resolution using this interactive version. Have fun exploring, maybe while looking around you could spot this,

The globular cluster NGC 6544 Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

It’s the globular cluster NGC 6544, discovered in 1784 by William Herschel. This lies about 3kpc from the Sun. Globular clusters are found in the halo of our galaxy and are much older and denser that open clusters such as Messier 21 (more of which later).

To make the image, 12 dithered 40sec exposures were stacked in each of three different coloured filters, so the total exposure was only about 8mins per filter. The dithering is necessary as the Pan-STARRS gigapixel camera is made of many individual CCD detectors bonded to the same piece of silicon, and there are unavoidable gaps at the joins where no light is captured. By moving where the camera is pointing slightly between exposures we can ensure that every bit of sky is seen at some stage. As, for scientific purposes, the Pan-STARRS data normally has any background light removed, special software techniques were employed to ensure the nebulae did not dissappear!

The resulting three greyscale images were then aligned and combined using the GIMP photo processing package into an RGB colour picture, a technique quite familar to amateur astrophotographers. To make the colours, the g filter was mapped to the blue channel, the r filter to green and the i filter (which is near infra-red, and would be invisible to the eye) to red. This combination is necessary as Pan-STARRS does not have a Visual filter, which would normally mapped to green. It does have the unusual consequence that hydrogen alpha emission, which at a wavelength of 656nm would look red to the naked eye, comes out looking green on the picture!

The idea for taking images of these particular nebulae came from PS1 scientist Nigel Metcalfe after taking a picture of them with his 4 inch refractor while on holiday in Wales.

Messier 20 is the famous Triffid Nebula. This is actually a star forming nursery, with three objects for the price of one: a cluster of young stars, an emission nebula, seen here glowing green due to hot hydrogen gas, and a blue reflection neubula, where starlight (from the cluster) is reflected off dust grains.

M20, the Triffid Nebula. Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

Messier 8, otherwise known as the Lagoon nebula, is a giant interstellar cloud and stellary nursary. It contains several Bok globules which are dark clouds of dense material in the process of collapsing to form stars, see if you can find a few.

M8, the Lagoon Nebula. Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

The Planetary Nebula M1-40. Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

The open cluster Messier 21. Credits: Eugine Magnier (UH IfA), Peter Draper & Nigel Metcalfe (Durham University), ©PS1 Consortium

There’s also other things to look out for in the image. For example M1-40 (left), a planetary nebula lying 2.8kpc from the Sun. Despite the name, these are really stars which have shed their outer layers. It is this hot hydrogen gas which we see glowing brightly.

And then there’s also Messier 21 (right) a relatively young open cluster of stars, believed to be only 4.6 million years old, lying 1.3kpc from the Sun. An open cluster is a group of up to a few thousand stars inside our galaxy that were formed at roughly the same time from the same gas cloud.

German school students hunt for unknown asteroids

2012-04-18T19:59:47Z

It’s March 15th 2012, the official start date of the fourth Pan-STARRS Asteroid Search Campaign of the International Astronomical Search Collaboration. Students from 40 schools - most of them from the United States and Germany, but also from Brazil, Bulgaria, England, India, Poland, and Taiwan - are ready to go. During the last few weeks, they practiced how to search for asteroids in astronomical images. Now they will have the opportunity to work with data from the Pan-STARRS PS1 telescope - and to discover several previously unknown objects in our solar system for the next five weeks.

The International Astronomical Search Collaboration (IASC) is a cooperation of American universities, international observatories, and educational partners with the aim to give students worldwide access to astronomical research data. Since October 2010, the Pan-STARRS PS1 Science Consortium semi-annually provides sets of images from the PS1 telescope to IASC. These data are full of so far unknown asteroids yet to be discovered - a job that is assigned to the schools that - partnered in teams - participate in IASC’s asteroid search campaigns. For the students, this project is a unique experience. They have exclusive access to the newest data from a professional telescope, and they can use it to learn how to apply scientifc methods. Finally, they have the chance to be the first to spot a celestial body no one else has ever seen before.

At the Haus der Astronomie in Heidelberg, I coordinate a growing network of German teachers who participate in the IASC campaigns with their students. We set up a Yahoo group where teachers and students can discuss problems or their findings with the other German-speaking groups. I also created German versions of the IASC manuals, and the Haus der Astronomie provides supplementary German-language educational material that the teachers can use in class to complement the asteroid search campaigns.

March 19th. Images taken on March 16th by the PS1 telescope are finally processed for the schools. The students download them, and, using the software Astrometrica, they search for moving objects and measure their positions on the sky. They report their findings to IASC, where the data is cross-checked with the results of Pan-STARRS’ automated search. And they are quite successful: The eight German schools supported by the Haus der Astronomie alone spotted a total number of 44 new asteroids. But for some of the students, just having discovery candidates is not enough. They want to do their own follow-up observations, in order to recover as many of their findings as possible.

Asteroid 2011 WC1 re-observed with Faulkes Telescopes after it was discovered by LGL student Julia Schnepf during the fall 2011 IASC Pan-STARRS asteroid search campaign.

The discovery of an asteroid is a three-step process: An initial candidate must be confirmed by further observations in order to get designated by the Minor Planet Center (MPC). The asteroid will finally be numbered when it can be monitored for several oppositions, a procedure that typically takes several years. And not till then, the discoverers are officially credited and are allowed to name it. Especially for the second step, follow-up observations are essential. This work is usually done by IASC astronomers, but my aim is to widen the project and to involve the students themselves in this process.

One of the German schools participating in the Pan-STARRS asteroid search campaigns is the Lessing-Gymnasium Lampertheim (LGL), which has a focus on natural sciences and is a member of the German STEM network MINT-EC. Since 2010, the LGL participates in a pilot project with the Faulkes Telescope Project (FT)in Germany, which started in 2004 with the focus on the coordination of asteroid observations. 650 positions of 115 asteroids have been measured and reported to the MPC until 2005; three asteroids have been discovered and designated, two of them have been numbered and named by students. Additional activities include photometry of the eclipsing binary asteroid (4492) Debussy. In the framework of this project, the LGL has access to the 2-meter telescopes of FT, which are perfectly suited for follow-up observations of the Pan-STARRS asteroids, which are typically fainter than magnitude 20. During the October 2011 IASC Pan-STARRS campaign, I therefore initiated a project together with teacher Martin Metzendorf and Lothar Kurtze from the German FT team, where students aged 12 to 17 plan and perform follow-up observations of the asteroids discovered during the Pan-STARRS campaign within regular physics classes or at the astronomy club of the LGL.

Doing their own observations provides the ultimate hands-on experience for the students. Telescope time at FT is booked in advance, but for reasonable follow-up observations, their candidates must be caught within the next few days after their initial discovery. So first of all, the students learn how important it is to be as fast as possible with the analysis of their Pan-STARRS data. They can use the position measurements of their own Pan-STARRS discoveries or data from the other groups to calculate a preliminary ephemeris of these asteroids with MPC tools. This way, coordinates where the telescope should be pointed at for recovery can be predicted. Additionally, observing with FT means that the students themselves are responsible for controlling the telescope and its camera. Subsequently, they analyse the obtained images like they did for the Pan-STARRS data. Finally, the positions they measure for the recovered asteroids are checked by the FT team and sent to the MPC.

Something else happens on March 19th. The PS1 telescope itself points at the same region of the sky it did three nights ago, thus matching the images the students got. As a result, the schools supported by the Haus der Astronomie can celebrate the confirmation of 12 of their candidates already during the first week of the Pan-STARRS campaign - what an outstanding start.

Nevertheless, the LGL students are well-prepared. On April 3rd they started their follow-up observations with FT during this campaign, and already during their first run, they were able to recover two candidates. Additionally, they plan to monitor the designated asteroids discovered by German schools during previous campaigns in order to get them numbered.

Tweeting NEOs

2012-02-03T16:21:47Z

The new @PS1NEOwatch feed tweets when PS1 finds a new Near Earth Object

From today onwards you can see tweets of new Near Earth Objects identified by Pan-STARRS1. Follow @PS1NEOwatch for updates of new PS1 NEOs. If you want to know more about how PS1 finds asteroids then why not check out the following blog posts.

MOPS: Finding things that go bump in the night where Larry describes how advanced software helps Pan-STARRS identify rocks that could come very close to the Earth.

School students find hundreds of potential new asteroids with PS1 where Will Burgett outlines work being done by school students across the globe to identify new asteroids.

A trip to the telescope

2012-02-03T10:56:21Z

As part of last month’s consortium meeting in Hawai`i, astronomers got the chance to visit the telescope that’s been keeping them busy over the last few years. Here’s what they saw on the trip….

The Pan-STARRS1 Telescope (right). The left-hand dome is currently being cleared for the construction of a second Pan-STARRS telescope. Credit: Douglas Finkbeiner

The power behind Pan-STARRS - world's largest digital camera. Credit: Douglas Finkbeiner

No this isn't a trampoline used by astronomers when the weather is bad. This screen is used to calibrate the PS1 telescope. Credit: Douglas Finkbeiner

The primary mirror of the PS1 telescope. Credit: Douglas Finkbeiner

Some Belfast supernova-hunters pose inside the dome. Credit: Douglas Finkbeiner

Telescope Manager Jeff points out the small telescope attached to PS1 that's used to monitor the transparency of the night sky. Credit: Douglas Finkbeiner

In the Telescope control room at IfA Maui the visting astronomers where shown how PS1 observations are scheduled and carried out. Credit:Douglas Finkbeiner

And here's the happy (and slightly windswept) group. Credit: Laura Fiorentino

Pan-STARRS Image of the Month – October

2012-02-01T22:58:38Z

Stephan's Quintet, a beautiful group of galaxies in Pegasus. Credit: Nigel Metcalfe/PS1SC

This month we are in the constellation of Pegasus looking at one of the most famous groups of galaxies in the sky. Stephan’s Quintet is an arrangement of five spectacular galaxies. Four of these are a physically associated group while one (the largest in the image NGC 7320) actually lies much closer. Note the galaxy with too nuclei, this is actually two galaxies in the process of colliding.

Extemely Luminous, Distant, and Mysterious Explosions Discovered by Pan-STARRS1

2012-02-01T23:25:23Z

Recently, astronomers have discovered a new class of very bright—and very mysterious—stellar explosions. These events rank as the most luminous supernovae known, more than ten times brighter than the normal supernova explosions which mark the deaths of massive stars. Curiously, these explosions show no evidence for the two most common elements in the universe: hydrogen or helium. Instead, their spectra show the much rarer elements (in the universe on average—although not on earth) of carbon, oxygen, and magnesium. In addition, the colors of these supernovae are very blue, peaking at ultraviolet wavelengths where our eyes are not sensitive and the Earth’s atmosphere blocks radiation.

Images taken before (left) and after (right) explosion, for the two ultra-luminous SNe recently discovered by Pan-STARRS1, PS1-10ky and PS1-10awh.

While this class of explosions was first recognized in the local universe by the Palomar Transient Factory, Pan-STARRS1 has been identifying them at significant cosmological distances and redshifts. We just completed a study of two of these “ultra-luminous” supernovae at a redshift of ~1, which means that these supernovae exploded when the universe was just half the age it is today. It also means they are very far away—you can imagine that they must be very luminous explosions indeed, if we can detect the death of a single star at distances of 18 billion light years! Conveniently, when we observe these sources at such large distances, their spectra get shifted towards redder wavelengths by the cosmological expansion of the universe, so that the ultraviolet peak of their spectra is shifted to visible wavelengths that are visible through the atmosphere. This helps us discover them at these great distances, and also allows us to study the part of their spectra where most of the energy comes out. Pan-STARRS1 is continuing to find approximately one of these rare explosions each month, greatly expanding the number known and allowing us to trace how this class of extremely bright explosions evolves over cosmic time. We note that most of these ultra-luminous supernovae discovered by Pan-STARRS1 have been “orphans”, without a clear host galaxy; targeting orphaned supernovae often turns up particularly interesting transients, as described in this other blog post.

Artist’s impression of a supernova powered by an extra “engine”—perhaps a magnetar (Courtesy of NASA/D. Berry).

Typically in a supernova explosion, only ~10% of the energy of the explosion is transformed into light. The rest of the energy goes into heat and the motion of expansion. We think it’s possible to get ten times more light out of a supernova in two ways: either all of the explosion’s energy is transformed into light, or there is an extra source of energy that boosts the total explosion energy of the supernova. The first popular explanation for these ultra-luminous explosions touches on point (a): the supernova blast interacts with a dense envelope of material that surrounds the exploding star, and this strong interaction makes the blast wave dump all of its energy into radiation in one relatively rapid burst. The second popular explanation exploits possibility (b): when the star explodes, it leaves behind a rapidly-spinning, highly-magnetic remnant called a magnetar. This magnetar then rapidly spins down, and transfers the rotational energy that it is losing to the supernova explosion. In this way, the magnetar is an “engine” that gives the supernova extra power. As of today, both of these explanations have strengths, and both have weakneses. In the months to come, as we discover more of thse powerful explosions, we will better understand which, if either, of these explanations is most likely—or additional possible explanations will surface. However, for the moment, the cause of thse extremeley energetic explosions remains a mystery.

There’s something icy in the Asteroid belt

2012-02-01T23:28:29Z

Comets and asteroids have classically been considered to be two distinctly different types of objects. Both are considered “small solar system bodies”, too small to be considered planets, but large enough to be tracked individually as they travel through the solar system. Asteroids are typically thought of as inert chunks of rock or metal that are mostly found on roughly circular, flat orbits (compared to those of the major planets) in the main asteroid belt between the orbits of Mars and Jupiter, where we believed they formed (and where we therefore believe they’ve been since the formation of the solar system). Comets, on the other hand, are thought of as “dirty snowballs” that travel along often highly elongated orbits that take them from the cold, distant outer solar system to the warm inner solar system where we usually observe them. They are believed to originate in the one of two distant reservoirs of frozen, icy bodies: the Kuiper Belt just outside the orbit of Neptune, and the far more distant Oort Cloud. Occasionally, a collision or the slight gravitational tug of a passing star sends one of these bodies Sun-ward into the inner solar system, where the object’s ice heats up and sublimates (turns from solid to gas), ejecting gas and dust which we observe as the familiar fuzzy haze that
surrounds the core, or nucleus, of the comet, and often also in the form of a cometary tail.

Comets have been able to preserve their icy content over the 4.6 billion year life of the solar system because they have spent most of their lives stored in the cold outer solar system beyond the orbit of Neptune. Meanwhile, if asteroids ever contained ice (and there is evidence that indicates some did once contain ice, albeit in the distant past), they are believed to be mostly baked dry by now by the much higher temperatures in the main asteroid belt. Recent research has been challenging this traditionally-held picture though.

The first main-belt comet, an object that had an orbit like a main-belt asteroid but had the appearance of a comet, was discovered in 1996. The thought that an object orbiting so close to the Sun could still have enough surviving ice to power cometary activity, however, was initially so disturbing to astronomers that many believed that what they had witnessed was the result of an impact tossing dust up into space. Observations six years later, however, showed that cometary activity had returned. This discovery all but ruled out the impact hypothesis for driving the activity since two random impacts on the same asteroid would be required in an
extraordinarily short period of time. Comets, however, routinely exhibit recurrent activity, as temperature changes as their orbits take them closer to and then farther away from the Sun make them warmer and then colder, turning sublimation on and off in predictable ways. Main-belt comets have much more circular orbits and as such do not go through temperature swings as severe as other comets, and so we suspect that their activity may be instead be controlled by seasonal effects caused by the tilt of their rotational poles (as compared to their orbits) in the exact same way that seasons with widely varying temperatures are caused on Earth.

Main-belt comets have much to tell us about the true composition of the asteroid belt, which in turn will help us to understand the formation of our own solar system, and therefore the conditions that might need to be present for similar solar systems to form around other stars. In the case of Earth in particular, main-belt comets may be the key to understanding a particularly vexing problem, that of discovering the origin of our water. Due to its close proximity to the Sun, the Earth is thought to have been too warm to be able to accumulate much water as it was forming, and likely accumulated most of its water from impacts from objects from colder parts of the solar system. Comets from the outer solar system were once considered good candidates for playing this role as water deliverers, but recent studies have suggested that main-belt objects may have played a much larger role than previously thought. The discovery that ice still remains in the asteroid belt in main-belt comets gives us a present-day opportunity to probe this potential ancient water source, and as such, is of great interest to astronomer.

The Main Belt Comet La Sagra imaged with PS1. studying the origin of water, and therefore of life, on Earth.

The extremely recent discovery of the main-belt comets (first discovered in 1996, but not recognized as a new class of objects until 2006 when the discoveries of two
more were announced) means that we still have much to learn about them. At the moment, just five such objects are known, meaning that at the moment, a high priority
is to discover more so that we can begin to understand the extent and diversity of the population of these strange objects. How many are there in total? Are they
confined to particular parts of the asteroid belt? Luckily for astronomers interested in these questions, this is one area where Pan-STARRS is expected to help. By
surveying the sky repeatedly and being able to detect fainter objects than previous surveys, we expect that Pan-STARRS should be able to discover many more main-belt comets. To do so, we require sophisticated techniques to sift through the mountains of Pan-STARRS data generated each night to automatically select potential comets for further inspection by humans. Since the start of the Pan-STARRS survey, these techniques have been undergoing refinements to optimize their comet-finding effectiveness and have now reached the point where Pan-STARRS has been credited with the discovery of four comets this year (three of them just in the last 2 months including C/2011 L4 (PANSTARRS) ). None of these have so far turned out to be main-belt comets, but as comet discoveries start to become more routine, we hope it’s just a matter of time!

Even before Pan-STARRS makes its first main-belt comet discovery, it is already assisting research on known main-belt comets. A new paper submitted to the Astronomical Journal earlier this week describes a worldwide observational campaign to study the most recently discovered main-belt comet named P/2010 R2 (La Sagra), or P/La Sagra for short. Pan-STARRS actually recorded the first known observations of this object, about a month before its official discovery, but unfortunately, it escaped our detection software at the time and was not found in our data until after it was discovered by others. Nonetheless, early Pan-STARRS observations of the comet played a key role in the monitoring of its activity over the year-long series of observations that we present in this new paper. In particular, these observations show the comet becoming steadily brighter over a period of months, strong evidence for ongoing dust emission, a characteristic signature of cometary activity, and confirmation that this object is indeed a true main-belt comet.

While an exciting start, we of course hope that this paper will not be the last that Pan-STARRS has to say about main-belt comets. Stay tuned…

Pan-STARRS Image of the Month – September

2012-02-01T23:00:08Z

The globar cluster M2. Credit PS1SC/Nigel Metcalfe

This month our image comes from the constellation of Aquarius. It’s M2, a globular cluster situated 37,000 light-years away. Globular cluster such as these are dense groups of some of the oldest stars known in our Galaxy.

Pan-STARRS Image of the Month – August

2012-02-01T23:02:52Z

The Ring Nebula, M57. Credit:PS1SC/Nigel Metcalfe

This month’s Pan-STARRS image of the Month is M57, the Ring Nebula. This is a planetary nebula, remains of the death-throws of a star of about the same mass as the Sun. The colour variations are caused by excited low density gas. Different colours indicate different elements or different levels of excitation. The dot in the centre is a white dwarf, the remnant of the now dead star which created the nebula.

MOPS: Finding things that go bump in the night

2012-02-03T10:50:24Z

You’ve seen the Hollywood movie version, an astronomer looks through the eyepiece of a telescope (it’s always got an eyepiece), scribbles some calculations on a piece of paper and, with a look of horror flashing across his face, realizes that this is the one, the deadly asteroid that’s going to hit the Earth. In reality discovering asteroids that may threaten the Earth is nowhere near as sensational. But it is somewhat more complicated than and equally as fascinating as the movie version.

Pan-STARRS1’s 7.0 square degree field of view makes it an excellent tool for finding objects moving around our own solar system. Part of PS1’s mission is to discover and catalog these hazardous near-Earth objects (NEOs) and their even more dangerous cousins, potentially-hazardous objects (PHOs). NEOs have orbits that bring them within 0.3 AU (about 45m km) of Earth’s orbit, while PHOs have orbital paths that bring them within 0.05 AU (~7.5m km) of Earth’s orbit and are at least 150m in diameter, large enough to cause extensive damage if one were to collide with the Earth.

To cope with the volume of asteroid data that PS1 and an eventual Pan-STARRS 4 (PS4) would need to handle, the Pan-STARRS project devised its own asteroid-finding software, called MOPS: the Moving Object Processing System. MOPS has been under development for about 6 years, and has proven adept at finding NEOs in Pan-STARRS data and in managing its own catalog of newly discovered and known asteroids beside NEOs so that PS1 scientists can do solar system science.

ASTEROIDS

Potentially Hazardous Object ST3 shown moving between two Pan-STARRS images.

By far the largest population of asteroids known lie in the Main Belt between Mars and Jupiter. There are currently about 500,000 known Main Belt Objects (MBOs), a number that increases by a few thousand each month. Occasionally an MBO travels close enough to Jupiter that Jupiter alters the MBO’s orbit so that the MBO transitions to a different orbit. This can be a much more elliptical orbit that sends the MBO well into the inner solar system. If this new orbit brings the MBO close to the Earth’s orbit, it is classified as an NEO. Asteroids range from as large as 950 km in diameter for Ceres (the first asteroid discovered) down to as small as a bus or even a basketball. The smaller asteroids are much more numerous though — while a 1-km asteroid might hit the Earth every million years, a rock the size of a basketball collides with the Earth about once a day.

HOW MOPS FIND ASTEROIDS

Asteroids are first discovered as star-like dots moving between astronomical images taken at the same place on the sky. On short time scales, say less than a day, most asteroids move in a fairly straight line. MOPS uses special spatial-searching software to detect asteroid candidates by playing a large game of dot-to-dot with the millions of star-like sources found in PS1 imagery. PS1′s image processing pipeline (IPP) automatically removes stars, which aren’t moving, so MOPS has the job of trying to find straight-moving combinations of sources in the remaining “transient data” catalogs. We call these nightly associations of asteroid detections tracklets. A large part of the task of finding tracklets is dealing with false sources — star-like image features that come from image artifacts, cosmic rays and random fluctuations in the pixel data. Each night, MOPS scans its transient catalogs for asteroid candidate trackelts, and an IfA scientist confirms real asteroids in each nightly list of candidates.

PS1′s survey designed so that asteroids can be discovered while meeting other science objectives. For example, the PS1 “3π” all-sky survey always obtains images in pairs, so that we can tell if a star-like source is in fact an asteroid because we see it moving between two or more images. About 85% of PS1′s survey time can be used to discover asteroids.

ASTEROID ORBITS

From a single night of observations MOPS cannot determine the complete orbital description of an asteroid. Note that while an asteroid has a straightforward elliptical motion through the solar system, its motion on the sky can be rather complicated due to projection effects. Also, from initial observations we cannot tell how far away an asteroid is from us — we only know its brightness, which can vary according to size and distance. So a faint asteroid might be small or far away; we can’t tell at first.

In order to compute a full six-parameter orbit which describes an asteroid’s motion through the solar system, we need multiple nights of observations of an object, then employ a computational procedure called orbit determination. PS1 uses software provided by NASA’s Jet Propulsion Laboratory — the same software used to guide spacecraft through the rings of Saturn! — and the OrbFit Consortium to fit orbits of solar system bodies to PS1 observations.

FINDING NEOS

Discovering NEOs is even more challenging because they can be found all over the sky, often moving quickly. Unlike main-belt asteroids, which are mostly a similar distance from the sun (2-3 AU) and lie in the plane of the solar system, causing them to appear in a “stripe” on the sky, NEOs can be whizzing by quite close to us and can therefore be projected anywhere on the sky. Repeated PS1 detections of these objects can be quite far apart, and making the dot-to-dot associations more difficult. Because PS1′s survey is largely preprogrammed, PS1 cannot always “chase” fast-moving NEOs to obtain repeated observations. So when we discover a candidate NEO tracklet, we submit the observations to the IAU Minor Planet Center, which maintains lists of NEO candidates that need additional observations. PS1, with its wide field, excels at finding initial observations of new NEOs, but prompt follow-up requires worldwide teamwork and cooperation.

Diagram of the solar system seen from above, showing orbits of NEOs discovered by PS1. Click for large version.

PS1 DISCOVERIES

To date PS1 has discovered 85 new NEOs, two comets, and about 4000 main-belt asteroids. PS1 has also submitted observations for over 200,000 known asteroids — nearly half of all known asteroids! This is an important contribution because PS1′s position measurements are so precise that they substantially improve the accuracy of orbits for known asteroids, allowing us to know their positions even better. Here are some highlights of PS1 discoveries:

2010 ST3. PS1′s first NEO discovery from September 2010.

2011 BT15. An especially hazardous NEO, since we cannot yet rule out an impact in the future between years 2037-2110. JPL maintains a list of still-worrisome asteroids at their risk page.

C/2011 L4. Long-period comet on its way toward the sun from the icy reaches of the outer solar system. This object should be visible to the naked eye in early 2013. PS1SC scientist Richard Wainscoat has more information about C/2011 L4 in another blog post.

OTHER SOLAR SYSTEM SCIENCE

There’s alot more to the solar system than just NEOs and MBOs though. PS1SC scientist Darin Raggozine posted a great summary of outer solar system research, and there’s currently research into newly discovered main-belt comets, “contact binary” asteroids that are fused together, and asteroid impacts. When there’s exciting news to report you can be sure to find it on the PS1SC blog.