Milky Way Over Palomar

Astronomer Iair Arcavi comes to Palomar Observatory to use the Hale Telescope to study supernovae as part of the Palomar Transient Factory survey. The survey is going quite well with over 1,110 supernovae discovered so far.

Iair also manages to find the time to do some nighttime photography with his digital SLR camera. I have posted some of his work here before (See his shot of the Milky Way over the Hale Telescope, his 2 Nights at the Palomar Observatory video and his composite of the Perseid meteor shower).

He managed to shoot some more dramatic images of our Palomar Skies just this last week. Both images nicely show off our domes, the heart of the Milky Way Galaxy and how light pollution is brightening our skies.

This image shows the dome that used to house the 18-inch Schmidt, Palomar's first telescope. The constellation of Scorpius can be seen just to the left of the dome. Note the bright sky glow to the southwest.

The 18-inch Schmidt is now retired but in its lifetime it was used for a tremendous amount of important work. For instance, just yesterday was the anniversary of that telescope being used to make the 1992 discovery of asteroid Braille (1992 KD). Astronomers Eleanor Helin and Kenneth Lawrence found the asteroid as a part of the Palomar Planet-Crossing Asteroid Survey. Just seven years later Braille was photographed as NASA's Deep Space 1 spacecraft flew past it.

Another of Iair's photos shows the Milky Way behind the dome of Palomar's automated 60-inch telescope. The 60-inch telescope is used nightly to perform follow-up observations on the new transient sources discovered through the Palomar Transient Factory survey. It also is a rapid-response telescope that gives astronomers a look at the optical glow of gamma-ray bursts.

An Update on Robo-AO

Last week just about everything here on Palomar Skies was related to PALM-3000, the new upgrade to the Hale Telescope's adaptive-optics system. Readers of this blog may remember that PALM-3000 isn't the only game in town when it comes to adaptive optics on Palomar.

The other program that is pushing the envelope is Robo-AO, a laser-guide star adaptive-optics system for Palomar's automated 60-inch telescope. The Robo-AO team was on the mountain last week and Christoph Baranec, Principal Investigator for the program snapped these false-colors photos of their ultraviolet laser propagating out of the dome.


The laser makes use of Rayleigh scattering, which will ultimately help their system to correct for turbulence in the lower 10 kilometers (~6 miles) of the atmosphere. This will allow the 60-inch telescope to take very sharp images of a wide variety of astronomical objects.

(See that sort of blurry star trail, just to the right of the laser beam? That is the globular star cluster known as Omega Centauri.)

The Robo-AO program is still in the engineering phase. Expect a full science demonstration observing run to take place later this year.

Robo-AO is Moving Forward

The Robo-AO team is back on Palomar for another week of testing new equipment on our 60-inch telescope. I have blogged about Robo-AO before, but for those who don't know, the Robo-AO system will soon be the world’s first laser-guide star adaptive-optics system working on a robotic telescope. When it is in operation it should deliver ultra-sharp imaging for up to hundreds of targets per night.

The system began as a fully-working testbed has been operating at Caltech in the Cahill Center for Astronomy and Astrophysics basement for several months. Starting last fall the team has been given some engineering time every few months to gradually bring the system up and on the Palomar 60-inch telescope.

In September of last year they had their first propagation of their ultraviolet (UV) laser into the sky as a guide star for adaptive optics. Earlier this year they were able to successfully have the beam sent up the telescope's axis and measure the return.


The team is back at Palomar this week for the installation of new equipment and further testing.

In the image above notice the new electronics rack mounted on the telescope at right. In the center is part of their new adaptive-optics instrument and the black box at left is the laser.

Their are still additional components to integrate into the system, but it is expected that start of the science demonstration period will commence in late summer.

Robo-AO in Action

I am hearing that the Robo-AO team has had a good week of testing here on the Palomar 60-inch telescope.

Their ultraviolet (UV) laser is mounted on the south side of the telescope. One of the chief issues for the week was the installation and testing of their periscope which transfers the laser beam from being just offset from where the telescope is pointing to being on axis with the telescope.

If you look at the photo below you can see the location of the laser, which is located in the black box just under the telescope on the right side. From this position the laser will propagate to the upper left where their periscope assembly is located. You can see that as the black end of the telescope with something hanging off of it.


The second photo shows the whole set up from a different perspective. Note that the cover to the laser has been removed. Click on the image to get a better look at its innards.

Photo by Christoph Baranec

The third photo shows the periscope assembly from a different vantage point. Christoph Baranec (Robo-AO's principal investigator) can be seen adjusting a mirror. In this image the UV laser is on. UV light is invisible, but still potentially damaging so you'll notice that Christoph is wearing a face shield to protect his eyes (I was wearing one too when I took this photo). Also notice that the mirror on the center axis of the telescope is fluorescing due to the UV light shining on it.

Saving the best for last, this final photo shows the top of the telescope. It was taken with a camera that records UV and visible light, so it reveals both the telescope and the normally invisible UV laser beam.

Photo by Christoph Baranec

The team has also been evaluating any flexure in the telescope and laser pointing to better ensure better results in the future.

Stay tuned for more on the Robo-AO program. Their next observing run will be in March.

Robo-AO Returns to Palomar

This week the Robo-AO team is back on Palomar for some tests of their laser-guide star adaptive optics system for our 60-inch telescope.

I will post some updates and shots of the laser in action over the next week or so, but here is a shot looking at the back end of the telescope showing some of the equipment that is in use for the project:

40 Years Ago Today

40 years ago today Palomar Observatory's 60-inch telescope was dedicated. The telescope is currently seeing heavy use as a part of the Palomar Transient Factory survey and next year it will be fitted with adaptive optics as a part of the Robo-AO project. But 40 years ago it was brand new. For your enjoyment below is a copy of the dedication program as the telescope was commissioned.

Robo-AO Comes to Palomar

Robo-AO, a new laser-guide star adaptive optics system for Palomar's 60-inch telescope, had a successful test of their laser last weekend.

False-color composite image of the Robo-AO laser & 60-inch telescope

Adaptive optics is a technique that allows ground-based telescopes to remove the blurring affects caused by Earth's atmosphere. The adaptive optics system uses a star as a calibration source and then deforms a small mirror to correct for distortions caused by the atmosphere. The corrections are made faster than the atmosphere can change -- often thousands of times per second.

By projecting a laser into the sky astronomers can expand this technique to cover a larger fraction of the sky.

Here is the 60-inch telescope last Sunday night just after the dome was opened.

The 12-Watt laser is in the black box mounted on the south side of the telescope (between the arms of the mount).

Here is the view with the lights turned off and the laser turned on:

Notice that you can't see the laser (but you can see where it is making a part of the telescope's insulation fluoresce!). Being invisible is one of the chief advantages for the laser.

The light that the laser emits is invisible ultraviolet light. Because you can't see the laser light this system requires no human spotters to be staged outside looking for air planes. All laser-guide star systems (like the one that has been used on the 200-inch Hale Telescope) that make use of visible light are required by the FAA to have spotters. Even hand-held laser pointers can be a danger to aircraft.

The Robo-AO system does not require spotters, which is perfect because the telescope normally operates in robotic mode without any people being present.

As the UV laser shines up toward its astronomical target astronomers make use of something known as Rayleigh scattering. The UV light scatters off of molecules in the air, giving a return signal that tells the deformable mirror in the adaptive optics system how to correct for atmospheric turbulence.

The Robo-AO system will be the first robotic laser-guide star adaptive optics system, delivering high-angular-resolution observing in the visible for up to hundreds of targets per night. This will enable the exploration of science parameter spaces inaccessible to large diameter telescope adaptive optics systems. A fully-working testbed has been operating at Caltech in the Cahill Center for Astronomy and Astrophysics basement for several months, and the system is expected to start its science demonstration period in early 2011 at Palomar Observatory's 60-inch telescope.

From there the Robo-AO system will be available as a relatively affordable and portable option for to 1-3 meter class telescopes around the world.

The Robo-AO project is a collaboration between Caltech Optical Observatories and the Inter-University Centre for Astronomy and Astrophysics and is partially funded by the National Science Foundation.

60-inch Aluminizing - Wrap Up

Here is a photo from earlier this week as the aluminizing chamber was opened up to reveal the newly re-coated 60-inch mirror.


If you look carefully just to the upper left of the mirror you can see that there was something taped to the ring that surrounds the glass. That is one of the four "witness slides" that were placed inside the tank. Since everything on the inside of the chamber gets a coating of aluminum the slides can be used to study the aluminum that was deposited.

Here is a closeup of one of the witness slides where it was aluminized:


And one, with the tape removed:


With the sample and the tape removed it is possible to measure the thickness of the aluminum coating, which is useful to know to try and improve the process for future coatings.

The tape that held the witness slides in place was clear. Like the slides, the mirror and everything inside, the tape was also coated with a thin layer of aluminum.


If everything on the inside of the chamber was coated with aluminum, why isn't everything nice and shiny? It is only the materials that are very smooth, like glass, that give a good reflective coating.

Finally, to close out my coverage of re-coating the 60-inch mirror, here it is as it was being returned to the telescope:

60-inch Aluminizing - Before and After

Aluminizing the 60-inch mirror has been completed. I have a lot of shots that I could post, but first I wanted to show off the before and after:

I think that most people would agree that the Palomar crew does pretty good work.

A Dirty Mirror

Work is progressing on this week's re-aluminumizing of the primary mirror for the Palomar Observatory's 60-inch telescope. Yesterday the mirror was removed from the telescope and today it was transported to the dome of the 200-inch telescope where it will be washed stripped and re-coated. Work on that is taking place as I type.

I have lots of pictures to go through and more to take, but here is a shot of the dirty mirror as it looked just before lunch today.


If you click to enlarge the image you can see various water spots (likely from dripping condensation that dripped off of the dome on to the glass sometime in the last 2 years) on the surface of the glass.

I Melt With You

It is time once again to re-coat the primary mirror of Palomar's 60-inch telescope. This was last done in August 2008. For some pics and commentary on when when this was last done see 60-inch Aluminizing Part I, Part II, Part III, and Part IV from this blog.

The mirror does not get pulled from the 60-inch telescope until Monday, but the process of getting ready for the job began quite a while ago. I thought I would show one piece of that process that I have not documented before. One of the key elements in re-coating a telescope mirror is the preparation of the filaments that go into the aluminizing chamber.

The big task is to melt some of these:

onto thirty two of these:

Specifically 0.165 grams of aluminum (about 3 of the pieces shown above) gets melted on each of the 32 tungsten wire coils. Those coils get placed into the aluminumizing chamber where a total of 5.28 grams of aluminum gets vaporized to provide a thin, even coating of the top surface of the mirror.

To get the wire coils prepared the aluminum pieces are draped on the coils which are then attached to this device which holds just 6 coils:


A glass bell jar with a protective wire cage is lowered over the device and the bell jar is pumped down to a vacuum.


Once a vacuum has been achieved electric current is individually applied to each of the coils in turn.


This is actually done twice. Once to melt the three staple-like pieces of aluminum to the coil. The second application actually causes the melted aluminum to wick out across the wire filament which will later help to provide a more even coating to the glass surface.

The prepared coils are later loaded into the aluminumizing chamber. Next week, once the 60-inch mirror is washed, stripped, and fully clean and dry it will join them as the new coating is applied.

Palomar History Photo of the Week - June 7, 2010

The Hale Telescope has been the focus of many of our history photos of the week. It is time to have a look at some of the other telescopes and locations at Palomar Observatory.

The Oscar G. Mayer Memorial Building, which houses Palomar's 60-inch telescope, was built in 1968-69. Here is an aerial photograph showing the construction site before any work had begun on assembling the dome.

The photo comes from Robert Gandolfi. Back in the day he worked for Western Gear Corporation, one of the contractors on the project.

To put things in perspective, here is a modern aerial photo showing the completed building and dome:

Palomar Transient Factory Hits High Gear

Last Thursday there was an Astronomer's Telegram issued about a new supernova discovered earlier that day by the Palomar Transient Factory team.

How does that happen? Wide-field images of the sky are made with Palomar's 48-inch Samuel Oschin Telescope. A new portion of the sky is photographed approximately every 90 seconds. Data is beamed away via High Performance Wireless and Research and Education Network to the Internet and then on to Lawrence Berkeley National Laboratory and the National Energy Research Scientific Computing Center. Once there computers using an "autonomous inspection code" identify new sources and transmit the findings back to Palomar where the robotic 60-inch telescope gets called upon for follow-up observations. Once confirmation of the object is obtained from the 60-inch telescope (and in this case also from PAIRITEL) the next wave of observers is alerted.

In last week's discovery all of this happened as expected. Ultimately a spectrum was obtained with the 10-meter Keck I telescope which was used to identify the transient. The new object was found to be "a peculiar Type Ia supernova". The really amazing thing is that from discovery to spectrum less than half an hour had elapsed! That is an amazingly short period to time to photograph, identify and garner observations from multiple telescopes.

Since it began last year the Palomar Transient Factory has so far discovered and spectroscopically classified 432 supernovae. There should be plenty more discoveries to come.


The 48-inch Samuel Oschin Telescope, where the Palomar Transient Factory begins.

Astrophoto Friday: the First Brown Dwarf

A brown dwarf is an object that is more massive than a planet like Jupiter, but not massive enough to undergo sustained nuclear fusion like a star. For many years they existed only in theory, as they had not been found in nature.

All of that changed in 1994 when a team of astronomers using Palomar's 60-inch telescope (armed with an early form of adaptive optics) captured the first image of one:


The big blob in the image is a dwarf star known as Gliese 229. The smaller blob to the right is Gliese 229B, the first brown dwarf discovered. The discovery was confirmed just over a year later by the Hubble Space Telescope.

60-inch Telescope. Milky Way Galaxy.

Too Far to Be Seen

Sometimes it is pretty exciting when you look for something and don't see it. Last April there was a gamma-ray burst (GRB 090423) detected by NASA's SWIFT satellite. One of the first ground-based telescopes to look for the visible light afterglow was the automated 60-inch telescope at Palomar. The 60-inch was imaging the source within three minutes of the satellite's detection of the GRB. The result? The 60-inch didn't see it.


You might not expect that I would devote any time or space on this blog for talking about something that we didn't see. But that non-detection (unlike LCROSS) was pretty exciting.

As Brad Cenko said in his report:

The lack of an optical afterglow, together with the fact that the X-ray column density is consistent with the Galactic value (Krimm et al., GCN 9198), make GRB 090423 an interesting candidate high-redshift event. We encourage observations at longer wavelengths to search for a NIR counterpart.

Translation: This object should be bright, but it wasn't seen in visible light. That means it could be an extremely distant event. So distant, that the expansion of the universe shifted its light completely out of the optical and into the infrared. That was indeed the case.

Telescopes observing the object in the near infrared and radio wavelengths did indeed see the optical afterglow of the event and it is the most distant object ever observed.

How far is it? Just over 13 billion light-years from Earth. GRB 090423 occurred 630 million years after the Big Bang, when the universe was only four percent of its present age of 13.7 billion years. Explosions like this give us a glimpse into the early universe and confirm the idea that massive stars, like the one that blew up creating the gamma-ray burst, existed even back then.

Palomar Transient Factory Video

Here's a video with me talking about Palomar Transient Factory:



Here's a direct like to it on YouTube. That's Hans-Werner Braun, from HPWREN, giving an introduction to the piece.

Oscar Mayer & Palomar Observatory

Earlier this week I learned of the passing of Oscar G. Mayer, of meat-processing fame. I was a bit confused as I confess that I had already thought that Oscar G. Mayer had passed years ago. Why? Because at Palomar Observatory our 60-inch telescope resides in the Oscar G. Mayer Memorial Building. Here is the plaque that is inside the building:

As it turns out our building is named for Oscar G. Mayer, Sr. who passed in 1965. It was the younger Oscar G. Mayer who died this week.

Here is a short obituary from Google News:

Oscar Mayer

MADISON, Wis. (AP) — Oscar G. Mayer, retired chairman of the Wisconsin-based meat processing company that bears his name, died Monday. He was 95.

Mayer died of old age at Hospice Care in Fitchburg, said his wife, Geraldine.

He was the third Oscar Mayer in the family that founded Oscar Mayer Foods, which was once the largest private employer in Madison. His grandfather, Oscar F. Mayer, died in 1955 and his father, Oscar G. Mayer Sr., died in 1965.

Mayer retired as chairman of the board in 1977 at age 62 soon after the company recorded its first $1 billion year. The company was later sold to General Foods and is now a business unit of Kraft.

Our condolences go out to the Mayer family. The 60-inch telescope continues to generate impressive results. All these years later we still very much appreciate the Mayer Family's gift to astronomy. Here is the Oscar G. Mayer Memorial Building:


And the Hot Wheels version of the famed Oscar Mayer Weinermobile that resides on my desk:

Palomar Transient Factory

Unique Sky Survey Brings New Objects into Focus

Partnership involves Caltech's Palomar Observatory and other world leaders in astronomy

San Diego, Calif.–An innovative sky survey has begun returning images that will be used to detect unprecedented numbers of powerful cosmic explosions–called supernovae–in distant galaxies, and variable brightness stars in our own Milky Way. The survey also may soon reveal new classes of astronomical objects.

All of these discoveries will stem from the Palomar Transient Factory (PTF) survey, which combines, in a new way, the power of a wide-field telescope, a high-resolution camera, and high-performance networking and computing, with rapid follow-up by telescopes around the globe, to open windows of discovery for astronomers. The survey has already found 40 supernovae and is gearing up to switch to a robotic mode of operation that will allow objects to be discovered nightly without the need for human intervention.

The Palomar Transient Factory is a collaboration of scientists and engineers from institutions around the world, including the California Institute of Technology (Caltech); the University of California, Berkeley, and the Lawrence Berkeley National Laboratory (LBNL); Columbia University; Las Cumbres Observatory; the Weizmann Institute of Science in Israel; and Oxford University.

During the PTF process, the automated wide-angle 48-inch Samuel Oschin Telescope at Caltech's Palomar Observatory scans the skies using a 100-megapixel camera. The flood of images, more than 100 gigabytes every night, is then beamed off of the mountain via the High Performance Wireless Research and Education Network­–a high-speed microwave data connection to the Internet–and then to the LBNL's National Energy Scientific Computing Center. There, computers analyze the data and compare it to images previously obtained at Palomar. More computers using a type of artificial intelligence software sift through the results to identify the most interesting "transient" sources–those that vary in brightness or position.

Within minutes of a candidate transient's discovery, the system sends its coordinates and instructions for follow-up observations using the Palomar 60-inch telescope and other instruments.

Soon all of the steps in the process will be completely automated, including decisions about which transients merit a second look. When follow-up observations indicate that candidate transient detections show promise, a prioritized list of candidates is brought to the attention of astronomers from the PTF member institutions. Finally, an astronomer becomes personally involved, by performing detailed observations using telescopes such as Palomar's 200-inch Hale Telescope, a Keck Telescope in Hawaii, or other partner telescopes around the world.

The PTF is designed to search for a wide variety of transient sources with characteristic timescales ranging from minutes to months, giving astronomers one of their deepest and most comprehensive explorations of the universe in the time domain.

"By looking at the sky in a new way, we are ushering in a new era of astronomical discovery," says PTF principal investigator Shrinivas Kulkarni, MacArthur Professor of Astronomy and Planetary Science at Caltech and director of the Caltech Optical Observatories. "Nimble automated telescopes and impressive computing power make this possible."

"No one has looked on these timescales with this sensitivity before. It's entirely possible that we will find new astronomical objects never before seen by humans," says Nicholas Law of Caltech, the project scientist for PTF.

Because it looks for anything changing in the sky, the PTF survey covers a vast variety of different astronomical targets. The wide range of the survey extends across the entire universe. Astronomers expect to discover everything from stars exploding millions of light-years away to near-Earth asteroids that could someday impact our planet.

Much of the survey's time is spent searching for so-called Type Ia supernovae. These supernovae, formed from the explosion of a class of dead star known as a white dwarf, are very useful to astronomers because they can help determine the distance to galaxies located across the universe. Those distances allow astronomers to probe the origin, structure, and even the ultimate fate of the universe.

By operating more rapidly than previous surveys, PTF will also detect objects of a completely different nature, such as pulsating stars, different types of stellar explosions, and possibly planets around other stars.

PTF's innovative survey techniques also have raised astronomers' expectations of finding new, unexpected, astronomical objects.

The PTF already has found many new cosmic explosions, including 32 Type Ia supernovae, eight Type II supernovae, and four cataclysmic variable stars. Intriguingly, PTF also has found several objects with characteristics that do not exactly match any other objects that have been seen before. PTF astronomers are eagerly watching these objects to see how they change, and to determine what they might be.

The quantity and quality of incoming data have astonished astronomers working in the field. On one recent night, PTF patrolled a section of the sky about five times the size of the Big Dipper–and found 11 new objects. "Today I found five new supernovae before breakfast," says Caltech's Robert Quimby, a postdoctoral scholar and leader of the PTF software team. "In the previous survey I worked on, I found 30 in two years."

Images and more information on the PTF survey are available on the PTF website at http://www.astro.caltech.edu/ptf

One of the most intriguing PTF discoveries, the object known as "PTF09dh" (above, right)appeared in a blank patch of sky and brightened as PTF watched from Palomar Observatory. The PTF collaboration is packed with supernova experts, but this discovery already has the team stumped--and excited. "For a cosmic explorer like me, the stream of curve balls served up by the universe makes for good job security. I take this as a sign there is plenty more waiting to be discovered.", said Robert Quimby, PTF's Software Lead.

Credit: PTF Collaboration

Comet 65P (Comet Gunn) as seen by PTF. The moving, and well known, comet was detected as a changing object by PTF on several nights, and was one of the first system verification images.

Credit: PTF Collaboration

Lifting the Veil on Dark Gamma-Ray Bursts

Credit: Aurore Simonnet/Sonoma State University, NASA Education & Public Outreach

Gamma-ray bursts are some of the most energetic explosions in the universe. They come in two varieties: long and short. The short bursts are thought to be the result of the collision and merger of objects like neutron stars and black holes. The long burst (those that last longer than 2 seconds!) are the result of the collapse and explosion of a massive star.

While the burst of actual gamma-rays is short they are often accompanied by a flash of visible light that can last minutes to hours. Astronomers use a variety of telescopes to track down this "afterglow". Gamma-ray bursts (GRBs) are first identified by NASA's SWIFT or other orbiting satellite (gamma-rays do not penetrate our atmosphere). Rapid follow-up observations are often made from ground-based telescopes like the Palomar 60-inch telescope. Through March 2008, the 60-inch telescope conducted follow-up observations of 29 GRBs discovered by Swift. 14 of those bursts were classified as "dark" - meaning there was little or no visible light observed.

GRBs are usually bright enough to be observed from billions of light years, essentially from about as far away as can be observed. Why were these GRBs dark? Astronomers like Brad Cenko and others (formerly with Caltech and now with UC Berkeley) have been checking into the mystery by looking following up on the dark GRBs identified at Palomar with the twin 10-meter Keck telescopes in Hawai'i.

Massive stars live fast and die young. It makes sense that such stars would lie in or near the nebulae from which they were born (like the artwork above). The findings on dark GRBs, announced at the AAS meeting this week, suggest that these GRBs are dark because the massive stars that formed them were hidden in vast, dusty nebulae. These nebulae are dense enough that they absorb much of the light from the explosions that the GRBs.

Read the full story here.