Observatory Still Closed

The Palomar Observatory is still closed to the public and it expected to be closed for the coming weekend. The on-going engineering work taking place on the 200-inch Hale Telescope has prevented the crew from plowing the public parking lot. At this point we do not have an estimated date for our re-opening.

Friday Sunrise

Dual Exhaust Dome

If you have ever been on a tour of the Hale Telescope in winter, you know that the temperature inside the dome is cold. We keep the inside temperature at nighttime temperature all year long. As the seasons change and the weather systems come and go, the temperature inside the dome varies with them.

Heating the dome just doesn't make sense from an energy standpoint when you realize that almost every night the dome is opened and all the hot air would escape.


Astronomically, it is actually worse than that. While having a warm dome would be nice for visitors enjoying a tour and a work crew performing maintenance it would force all of the telescope's parts to adjust daily back and forth from warm in the daytime to that night's much colder temperature. This can take a significant amount of time when the temperature variation is large. During a period of adjustment it would be difficult to use our large telescope and have any useful results.

The temperature equalization of the telescope is one problem. The other is convection. Hot air rises. Heating the inside of the dome and then opening the shutters would essentially force warm air to rise right in front of the telescope. The result would be hopelessly blurry images much like you see when looking down a roadway on a warm summer day.

Last November during an interview for a TV documentary lights were set up to aid in the filming. The lights were both bright and hot. One of the lights was shining toward another one which happened to be close to the inside of the dome. The result is that the hot, rising turbulent air actually became visible as its shadow was cast on the inside of the dome.

Here is a short video clip showing turbulence caused by warm rising air inside our big dome.

Look just above the shadow of the light fixture to see the effect of the warm rising air.

That's exactly what you don't want for astronomy. Of course the interview was held many hours before that night's observing and didn't impact operations much at all because a couple of lights doesn't really change the overall temperature inside the dome.

One in a while it is actually a good thing to heat the inside of the dome.

Right now we are just a few days into an engineering run where the Palomar day crew and support engineers from Caltech will be disassembling the Hale Telescope's mirror supports. Each of the 35 mirror supports to be worked on during the next several weeks contains over 1,000 parts. Many of the parts are tiny and difficult to manage.

For this engineering run, since we will not be performing astronomical observations with the telescope, we will make an exception to the no heat in the dome rule. The heat is on.

Yesterday morning we hooked up two big electric heaters, one of which is seen below.


We also recently modified the dome so that we could run two big propane heaters to heat the interior for the crew. So to safely vent away the exhaust gasses two dual exhaust vents were added. Have a look for them the next time you are visiting the observatory.

The temperature inside the dome has climbed all the way up to 40F, making it not quite pleasant for working yet, but it is improving.

As the engineering run is completed we will open the dome and vent out the warm air and return to nighttime temperatures and astronomical observations.

Photos from the First Day of Mirror Support Engineering

Here are a few photos from yesterday, the first day of engineering on the Hale Telescope's mirror supports.

Tasks for the first day included removal of the Cassegrain cage. Here is the Cassegrain cage after it was removed. No longer hanging from the telescope it is now sitting on the observing floor.


Here is some of the Palomar Observatory crew installing work lights on the telescope itself (left) and removing the rotating ring (center) from the telescope's mirror cell.

The wide shot below gives a better sense of the perspective of the people relative to the telescope.

Finally (for now) here is a photo taken from under the telescope looking directly up at the mirror cell and the 36 mirror supports. You'll see this photo again as I attempt to explain exactly how the mirror supports work and what work is being done as a part of this engineering run.

Mirror Support Engineering in Progress

If you saw the History Photo of the Week, posted earlier today, you know that we are just beginning a major, multi-week, engineering run on the Hale Telescope to clean and refurbish its 35 mirror supports.

You will be able to take peek at some of the action by looking at the Hale Telescope Web Cam. Unfortunately it doesn't provide too close a look at the action, but I will be posting information and updates here on the blog from time to time.

The action so far today has been mostly directed towards preparing for the work to come. The Cassegrain cage should be removed this afternoon which will provide easy access to each of the supports.

Weather Update: The weather on Palomar Mountain is wonderful right now. The engineering work has kept us from plowing the snow from the public parking area so we are still closed at this time.

Palomar History Photo of the Week - January 25, 2010

This week's Palomar History Photo of the Week shows the 35 of the Hale Telescope's 36 mirror supports in the shop where they were made at Caltech. It is a good time to feature the mirror supports as this week we are entering into a major 5-week engineering run where the telescope's mirror supports will be removed, cleaned and replaced.

Weekend Weather Update

The snow and rough weather has ended on Palomar and the observatory's small weekend crew is still digging out. The observatory will remain closed until it can be properly cleared of snow and ice, which isn't expected until after the weekend.

California Highway Patrol informs us that chains are required and that they are checking to see that people have them. I can say from experience that the roads are very icy. Anyone attempting to visit the mountains should be extra careful. The old adage is don't drive any faster than the the speed you want to crash into something.

The weather brings extra complications for staff at the observatory aside from public safety. This morning I tried to gain entrance to the dome of the 200-inch telescope. While I do indeed have a key to let me in the door marked "No Admittance", the lock was frozen and I could not open the door. Additionally, I am currently snowed out of my office, which is in a different building.

Friday Weather Update

A winter storm warning is still in effect for the San Diego County mountains, including Palomar Mountain. Several inches of snow are on the ground now, with more currently falling. Roads are icy and generally not currently safe for travel. As such, Palomar Observatory is still closed to the public.

Highway 76, beneath Palomar Mountain, from Lake Henshaw to Rincon Ranch Road is currently closed due to mud slides.

The Palomar Mountain Fire Department is recommending that a "Snow Emergency" be declared for Palomar Mountain. This would require all drivers to have tire chains and limit access to parts Palomar, especially to non residents.

All this weather has gotten in the way of some cool astronomy stuff (remember that?) that I am putting off posting for a while. With any luck there should be a lot more of that here on the blog next week.

Weather Update

Palomar Mountain continues to be pounded by the weather and, you guessed it, we are still closed to visitors. Given the weather forecast for the next 48-hours I expect the observatory will be closed through the weekend.

We are strongly encouraging everyone not to travel in the area.


So far we have had fog, trees blown down into road ways, rock/mud slides in the roads, high winds, rain, sleet and snow.

As yesterday drew to a close the snow set in, then it turned to rain. Overnight it snowed and now it is raining again. The rain has given the observatory day crew a chance to clean up a bit in preparation for the next wave, expected later today, that should make conditions worse than they have been all week.

Currently it is raining at the observatory. Winds are around 35 MPH, but I have already seen gusts up to 61 MPH.


Trees weren't the only thing blown down from the high winds earlier this week.

Be safe out there.

Storms Continue. Observatory Still Closed.

Yesterday's storm hit harder than Monday's and delivered rain, sleet, fog and high winds. The maximum wind gust reported at Palomar Observatory was 78.2 MPH at recorded by the weather station at the 200-inch Hale Telescope. There were numerous reports of wind damage and road closures in the area during and just after the storm.

The National Weather Service is forecasting another series of winter storms to hit the area today through Friday (and possibly Saturday). As such it is not recommended that people travel unnecessarily to Palomar Mountain and Palomar Observatory will be closed to visitors again today and possibly for the next several days.

Icy Conditions Close Observatory

Yesterday's storm delivered and left Palomar Observatory coated with a layer of ice. As a result we are closed to the public today as we try to prepare for the next round of winter weather that is expected later today.

Sunset January 16, 2009

Here is last Saturday's sunset as viewed from behind the dome of the 200-inch telescope at Palomar Observatory.

Click to embiggen and you'll see Jupiter and the crescent Moon. Dodging clouds that evening our automated telescopes were working hard on observations for the Palomar Transient Factory while our Caltech observer was using the Hale Telescope to get follow-up spectra on objects discovered as a part of the Catalina Real-Time Transient Survey.

Palomar History Photo of the Week - January 18, 2010

Last August I posted some photos of the old Sky Chair that was used by astronomers observing from the Hale Telescope's Cassegrain focus from the time prior to the 1965 installation of the Cassegrain Cage.

This week's Palomar History Photo of the Week is the Sky Chair with presumably the crew that built it.


The photo came from a collection of pictures and items that once belonged to James "Jimmy" Fassaro. Fassero wrote the text for the book Photographic Giants of Palomar a collection of Russell W. Porter's Palomar illustrations.

I don't know too much about him, but seems that Fassero had talents other than writing. He did co-author paper with H.W. Babcock and Bruce Rule in 1956 "An Improved Automatic Guider" where they describe an improved photoelectric guider that they put into place for the 200-inch telescope's coude spectrograph.

The Palomar Sky

As a teaser, this is a shot of one of our sky brightness monitors (with the dome of 200-inch telescope behind the tree) at Palomar Observatory. We have a pretty cool program involving them that we will launch later this year.

You'll be able to read all about the Palomar Sky right here on Palomar Skies.

Rough Weather Ahead

The National Weather Service is predicting that a series of major storms will impact Southern California, including Palomar Mountain, next week. The details are still a bit uncertain, but in this morning's Forecast Discussion they called the storms "potentially epic" suggesting that more than 20 inches of rain could fall in the mountains, with some areas getting over 30 inches.

The snow level currently expected to be somewhere between 5,000 and 6,000 feet which means that Palomar Mountain could get 100% rain or a mix of rain and snow.

If the storms deliver, travel on and near Palomar might be dangerous next week. Rock and mud slides on the roads would be likely.

Please check on weather and road conditions before making any plans to visit the observatory or the general area.

Click here for the latest forecast from the National Weather Service.

The Scoop on Palomar

In 1954 the trading card company Topps issued a series of cards called Scoops. The series featured 156 cards with artwork on the front and on the back was a newspaper headline from an event in history. The events covered a very wide range of topics such as Magellan's round the world trip, the Chicago Fire, the destruction of Pompeii, Lewis and Clark, and various events from World War II. There were numerous science events in the mix such as the bouncing of a radar beam off of the Moon and the dedication of the world's largest telescope.


Like a lot of things from this era that were aimed at kids, the fact checking wasn't the best.


Click on the image to embiggen and you'll see that they made the common mistake of referring to "Mt. Palomar" when the name is actually Palomar Mountain, but then again almost nobody gets that right even today. Their big mistake was saying that the telescope was named after Dr. Emery Hale. That is at least sort of close to George Ellery Hale.

This card was the last in the series and took me a while to tack one down that was both in good condition and at a decent price.

Palomar History Photo of the Week - January 11, 2010

Here is a drawing of the 200-inch dome by Russell W. Porter.
(Please note that the horizontal line in the sky left of the dome is a scanning artifact that I hope to remove soon.)

The drawing is new to me. The small transparency copy of the drawing was just found in a cache of other old images in storage here at the observatory. This cache represents another vast source of perhaps largely unknown images (Unlike this one almost all of them are actual photos).

The Porter drawing came in an envelope labeled:

"Palomar Observatory, sketched in crayon by R. W. Porter"

If is from early 1936. Porter signed it "R.W.P. '36", but the envelope says that is was copied Feb 13 1936.

To me the biggest surprises of the image is that the dome, which would soon be under construction still resembles the dome for the 100-inch telescope on Mt. Wilson and the fact that Porter drew a taxiway and runway out in front of the dome (click to read his labels). There was indeed an airstrip on the Palomar back during construction but I do not know where it was located.

Palomar Observatory at the National Air and Space Museum

I recently had the chance to visit the National Air and Space Museum in Washington, DC. While I was there I had to check out the display on Palomar Observatory, which is a part of their Explore the Universe exhibit.

A great artifact in the collection is the Hale Telescope's old Prime Focus Spectrograph.

A cool thing about the display is that you can actually see one of the spectra captured by the instrument.

These spectra are so tiny that they can only really be inspected with a microscope. In the image above the spectrum of radio galaxy 3C 327 isn't the feature that looks like bar codes, it is what you see between the "bar codes" which are reference lines.

I shot a short movie of the exhibit with my iPhone. You can see it below:




Palomar shows up in a number of other places as well. Perhaps the most notable artifact is the prism for the 4-Shooter camera. The 4-Shooter, tested with the 200-inch telescope, was the prototype instrument for the Hubble Space Telescope's Wide-field Planetary Camera known as WF/PC (pronounced "wiff pic"). For anyone interested in learning what it was like to observe with the 4-Shooter at Palomar in the 1980s, I highly recommend the book First Light by Richard Preston.

New Exoplanets

Yesterday at the winter meeting of the American Astronomical Association the team from the Kepler mission announced the discovery of five new exoplanets. Palomar's 200-inch Hale Telescope was one of several ground-based telescopes that helped to confirm the discoveries. These discoveries came from just the first few weeks of observations and many, many more exoplanets are expected as the mission continues.

In addition to the five new exoplanets the team also announced the discovery of what might be a new class of astronomical object. Stay tuned as the science from this mission is just beginning.

Palomar History Photo of the Week - January 4, 2010

This week we head back seventy three years to January 3, 1937 when the 200-inch telescope's prime focus elevator arrived on Palomar. The photo shows the prime focus elevator on the truck that bought it here, parked just outside the dome of the 200-inch telescope.

You can see the prime focus elevator as it is installed today in this modern photo below:


The elevator is bright thing middle right in the image.

Recall, that people used to observe with the 200-inch telescope by actually riding inside it. Even though those nights are long gone (the observer sits in a nice warm room) the prime focus elevator still is the preferred mode of transportation to get someone to the upper part of the telescope or dome.

You can hear the prime focus elevator in action in a podcast that I did last year.