Monday, August 30, 2010

Palomar History Photo of the Week - August 30, 2010

This photo of the dome for the 200-inch telescope was taken 73 years ago - August 31, 1937.

Okay, I am one day early. Sorry about that. Still, it is a wonderful photo of the dome under construction. Don't you agree?

Saturday, August 28, 2010

Asteroid Discovery Video

Check out this cool video by Scott Manley of asteroids as they are discovered from 1980 to the present time. Many thousands of the ones shown here were discovered at Palomar Observatory (and lots of other places too).

Check out the full resolution version here at YouTube. You can get the full text there, but note that most of asteroids are discovered in the opposite direction of the sun. That is until the very end when a new set of discoveries shows up, those asteroids discovered by the Wide-field Infrared Survey Explorer.

Friday, August 27, 2010

Astrophoto Friday - Saturn's Moon Titan

It is Astrophoto Friday! This week's image shows a unique event that was captured by the 200-inch Hale Telescope armed with adaptive optics.

What might look like Pac Man swallowing a dot is actually Saturn's moon Titan occulting (passing in front of) a binary star system (named NV0435215+200905). The two stars are separated in the sky by just 1.5 arc seconds (One arc second is 1/3600 of a degree).

Because fantastic resolving power of the Hale using adaptive optics you can see that the light of the star nearest to Titan is being refracted by Titan's dense atmosphere. Such events are rare, but valuable. The starlight as it is seen passing through Titan's atmosphere is essentially a probe providing clues as to the density, temperature and wind patterns of this distant world. The team of astronomers (Antonin Bouchez, Michael E. Brown, Mitchell Troy, Rick S. Burruss, Richard G. Dekany and Robert A. West) that observed this event December 20, 2001 was fortunate that both of the stars were seen to pass behind Titan. This provided two passes through Titan's atmosphere - effectively doubling what could be learned from the event.

Be sure to check out the movie of the event. As you watch it will look like Titan is still and the stars are moving behind it. As they pass behind Titan be sure to look for the refracted light of each star on either side of Titan's atmosphere. It is an impressive sight!

The result? Jet stream winds were discovered in Titan's atmosphere.

For those so inclined you can read a pdf of one of the scientific publication that came out of these observations.

Thursday, August 26, 2010

Mammatus Clouds Over Palomar

There has been some strong thunderstorm activity nearby the observatory today. While we haven't had any rain, there has been lightning in the area and an impressive display of mammatus clouds.

Here is a close-up of the mammatus clouds:

Thunderstorms can bring dangerous weather here in the back country. It is important for visitors to the area to pay attention to any weather alerts and to do their best to use common sense to try to be safe, especially when there is lightning in the area.

Update: Clouds cleared by sunset and a full night (9.5 hours) of observing was enjoyed by astronomers using the Hale Telescope.

Cleaning the 200-inch Telescope

If you have checked the Hale Telescope Web Camera in the last few days you may have seen the 200-inch pointed to the extreme north, as it is here in this view from yesterday morning:

This is being done so that the support structure of the telescope can be washed.

It is a tough job, but somebody's gotta do it.

Having the telescope pointed to the extreme northeast, as it is for these shots, certainly gives some unique photo opportunities. Wouldn't you agree?

The work is continuing for a while yet and is not a disruption to nighttime work. Last night, for instance, the telescope saw a full 10 hours of use.

Monday, August 23, 2010

Palomar History Photo of the Week - August 23, 2010

Palomar Observatory is located not in, but right next to the Cleveland National Forest. Ocer the years there has been a long standing relationship between the two organizations.

This week's history photo of the week highlights that relationship with a vintage (likely from the 1940s) photograph of an unknown forest ranger with his vehicle parked in front of the dome of the 200-inch telescope.

If anyone can identify the ranger or knows anything even about his vehicle please leave a comment or send an email.

Sunday, August 22, 2010

Get Your Dark-sky Light Fixtures in San Diego County

It is a fact of life that outdoor lights are need. Visibility, safety and security are necessary.

Unfortunately there is too much light at night as much of it does not help with visibility, safety or security. This wasted light is also wasted energy. Bad lighting often causes glare which can reduce visibility -- the opposite of what a light is supposed to do. Well shielded fixtures eliminate glare and put light where its needed to see well.

The San Diego Chapter of the International Dark-sky Association has combined forces with Lights of America, San Diego Gas & Electric, Dixieline, and Palomar Observatory to offer an affordable and very effective Outdoor Light Fixture to San Diego Residents. How affordable is it? It checks in at less than $10.00 each after rebates! That is a deal.

This fixture is available NOW at any San Diego County Dixieline Stores. Hurry to get yours and take advantage of this great limited time offer.

What does the observatory like about this? When properly installed it is a full-cut off fixture, meaning that there is no up light. While it is not a low-pressure sodium (our favorite!), they aren't well suited for lights around the house. This fixture is of a low color temperature (2700K), which gives a warm glow that limits the amount of blue light making it better for astronomy than a high temperature light.

Saturday, August 21, 2010

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:

Two Nights at the Palomar Observatory Video

Here is a follow-up to yesterday's astrophoto. A YouTube video of Iair Arcavi's night shots taken during his observing run at Palomar a week and a half ago.

It is simply stunning. Here is a direct link to the video on YouTube.

Friday, August 20, 2010

Astrophoto Friday - Perseids over Palomar

This week's astrophoto comes from Iair Arcavi of the Weizmann Institute of Science in Israel. Iair happened to be observing with the 200-inch Hale Telescope the night of the peak of the Perseid meteor shower. He managed to pull enough time away from his observations of Type Ia supernovae (discovered by the Palomar Transient Factory survey) to take some camera on tripod images of the shower.

I think that you'll agree that he did a super job in capturing the shower. You can easily see that the meteor trails all point back to the radiant (where the meteors seem to stream from) to the left of the open dome.

I had several request from both professional and amateur photographers who wanted to visit the site to capture the shower. Unfortunately I was unable to make it work for them as it isn't easy to gain access to the observatory grounds after hours. Of course it is much easier if you are scheduled to be using the big telescope.

Thursday, August 19, 2010

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.

Tuesday, August 17, 2010

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.

Monday, August 16, 2010

Palomar History Photos of the Week - August 16, 2010

Some of the few remaining relics from the era of grinding and polishing the 200-inch mirror are these glass pyramids:

They were made of Pyrex glass by Corning Glass Works, just like the 200-inch mirror was. In the Optical Shop at Caltech they were fashioned into tools that were used for both grinding and polishing the 200-inch.

The two pictures below, Taken January 3 1938, show opticians creating the full-sized polishing tool. In the first picture the optician at right is placing one of these glass pyramids into a big metal disc to form a pitch lap.

The second view shows the broader view with three men working on the polishing tool. Several of the glass pyramids can be seen on the nearside of the tool.

Saturday, August 14, 2010

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.

Friday, August 13, 2010

Astrophoto Friday - the Milky Way

It has been a busy week, but I did manage to take a moment to snap this photo of the summer Milky Way on Wednesday evening:

It was a beautiful evening, but you can certainly notice the light pollution coming from the many lights of San Diego County.

Due to an active marine layer San Diego has had a colder than normal summer this year. This has generally been good news for the observatory as the low coastal clouds often effectively block the light produced by the cities below, giving the observatory darker skies.

Monday, August 9, 2010

Palomar History Photo of the Week - August 9, 2010

The 200-inch telescope was fabricated at the Westinghouse Electric and Manufacturing Company's plant in South Philadelphia. I believe that the largest single piece was the yoke for the south bearing of the telescope.

Here it is back at the Westinghouse plant:

As you can see it is pretty huge. As you can imagine the task of bringing it into the dome was not easy. Ronald Florence described it nicely in his book about Palomar, The Perfect Machine:

The Caltech engineers had calculated the size of the hatch in the dome the way a mover can calculate whether a sofa or piano will fit through a doorway. The opening was mathematically large enough for the largest components--the sections of the horseshoe and the lower section of the yoke mounting, which held the two tubes that connected to the horseshoe. A draftsman with a slide rule could demonstrate that with the right twists and turns the hatch would accommodate everything that had been shipped.


For one piece, the bottom section of the yoke, the engineers at Caltech had designed a special lifting harness to bring the assembly off the truck and up through the hatch. The harness didn't arrive in time for the unloading, so [superintendent Byron] Hill and his crew did it with lifting hooks and slings they put together on the spot. The unit had been trucked lying on its back and had to be tipped onto its side to fit through the hatch. Tipping a structure while it is hanging from rigging is a tricky operation, because the center of gravity of the item shifts as it turns. The fit was tight. The next day, when the yoke had been squeezed through the hatch and the exhausted crew had gone to bed, Hill said he finally understood what women went through at childbirth.

Here is the view of the yoke as it was brought in through the hatch and into the dome:

I think that it is no exaggeration at all to say that it was a tight fit.

Saturday, August 7, 2010

Web Cam is Back on Line

The Hale Telescope web cam had been off line for a couple of weeks. It is up and running again.

The views are pretty good in the daytime, but don't expect to see anything at night as it is far too dark. My favorite views are those that come in twilight, like this shot recorded this morning with the 200-inch looking far to the north.

Friday, August 6, 2010

We are the World

Palomar Observatory has always had an international following and now you can read the main page from the observatory's website in Belorussian thanks to Patricia Clausnitzer, who did the translation!

Astrophoto Friday - Supernova 1972E

Astrophoto Friday returns with a pair of photos of the galaxy known as NGC 5253.

The photo on the left was taken with Palomar's 48-inch Schmidt telescope (now known as the Samuel Oschin Telescope) the night of June 4, 1959 by Milton Humason. The right-hand picture was taken by Charles Kowal with the same telescope the night of May 16, 1972.

Notice that the photo on the right has an extra star, visible to the lower right of the brightest part of the galaxy. The photo on the right has captured an explosion known as a supernova. This particular supernova (SN 1972e) was classified as a Type Ia supernova, which is thought to occur with the explosion of a dead star known as a white dwarf.

Supernova 1972e was found as a part of an organized survey for supernovae at Palomar that photographed thirteen of them in 1972. The old technique of photographing the sky and comparing the new images with older ones taken years before has now been supplanted by surveys that scan large volumes of sky and compare the new pictures with ones taken often days earlier. The Palomar Transient Factory survey has, at last count, bagged 622 supernovae since they began scanning the skies (also with Palomar's 48-inch telescope) last year.

That's quite an improvement, wouldn't you say?

Thursday, August 5, 2010


We have had quite a large number of rattlesnake sightings at the observatory the last two weeks or so. I have personally encountered two of them in the last two days.

The picture below shows the one I sighted about 11:00 a.m. today, just outside the observatory's front gate:

Visitors to the observatory may have noticed the signs that warn people not to venture out into the fields of ferns. That's because you would not be able to spot a rattlesnake until it was too late.

Remember, should you see a rattlesnake, leave it alone and put some distance between you and the snake.

Should someone get bitten call 911 immediately. Cell phones rarely work on Palomar, so you may need to head for the gift shop or flag down someone who works here.

Be careful out there.

Wednesday, August 4, 2010

Another Fine Model Hale Telescope

A little over two years ago I got an email question with regard to a blog post I made with photos looking into the west arm of the Hale Telescope. I didn't realize at the time that the person asking the question, Rick Etheridge, was building a 1/63 scale model of the Hale.

Recently Rick sent me some photos of his model and he has allowed me to post them here for everyone to enjoy.

If you look closely you'll see that Rick has paid close attention to detail and added nice extras like the Hartmann screen (at right) and the dark, open mirror cover. Another fine example of his work is the view looking down into prime focus:

Notice that there is a chair for the observer and what looks to be a plate holder. The dark thing directly above (from this perspective) prime focus is the housing for the coudé mirror.

Finally, here is a look at the west arm of the telescope. Notice that he included the stairs inside the arm. Nice work, Rick!

This isn't the first model of the Hale to be featured here, you may recall the one I posted back in June that was also in Sky & Telescope magazine.

Palomar Poem

This poem, dedicated to the observatory, was recently sent my way:

A Poem For Mount Palomar Observatory



Starry, Starry Night

Infinity of Light

Distant Futures

Nexus Here!

Photons, Photons, Photons!

My Brain

A Microstar

In Awe

Of Celestial Parents

~Ian Oliver Martin

Tuesday, August 3, 2010

Hoaxes, Tours, Galileoscopes & More!

There is a lot to catch up on, but for now I'll post a few quick links to some things.

First up, it is August, so that means it is time for the Mars Hoax to rear its ugly head once again. NASA has just put out a story on it. This is the kind of thing that gets people excited about astronomy (a good thing), but then dashes their hopes (a bad thing). This year Mars will not be visible in the sky at all and will be about as far from Earth as it can get--making the story about as untrue as it can possibly be.

Don't forget that Julian Starfest takes place later this week. It should be a fun event and there is a free public star party taking place there Saturday, August 7th.

A couple of weeks ago, I had the pleasure of hosting a 7th grade science teacher from Boston as she makes the trek to 12 observatories of the southwestern U.S. She is blogging about it, so go on over to check it out.

The photo at the top of this post was from earlier today, as a group of students from UCSD's COSMOS program got a tour of the 200-inch Hale Telescope. Don't forget that you can go on your own tour of the Hale on Saturdays & Sundays through October. Click here for the details.

Speaking of tours, for the last year or so we have been giving out one Galileoscope on each tour. Over 300 were given out. Many of the galileoscopes were given out in the memory of one of our docents, Fred Givant. Last weekend we gave out our last one. I'd like to take this moment to remember Fred and to thank the people who helped continue the program in his memory.

Fred, we still miss your enthusiasm and your dedication to public outreach.

Palomar Skies has Returned

I just wanted to let everyone know that I was away on a vacation, but have returned. August should be a pretty busy month at the observatory and once I dig out most of my email you'll start seeing regular posts here again.