Sometimes You WIYN

Back in 2012

In a previous visit to Kitt peak, in 2012, I was observing using the MDM 2.4m telescope. The MDM ‘scopes (they also have a 1.3m) are located a couple of miles down the mountain on a western ridge. There is a great view of the summit from there, you can see the Mayall 4m on the far left (I wrote about recently here), and the Bok 2.3m is right beside (I’ve written about it many times). This picture is of sunrise looking east after a night of observing. The clouds make for pretty mornings, but terrible observing. Sometimes you win, sometimes you lose

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The WIYN 3.5m

I already posted about this pic here, when I visited the WIYN this past week.

Late

This is what 3am looks like in the control room.

This is what 3am looks like in the control room.

Visiting the Mayall 4 meter

The Steward Observatory’s Bok 2.3m telescope sits right beside the largest telescope on Kitt Peak Mountain: the Mayall 4 meter. I’ve posted pics of it many times, like here, and here, and here. I’ve walked up to it a few times and gone inside the visitor centre there, but an up-close look at the telescope is usually only afforded to those that are using the telescope. Happily, we met the operator of the telescope and he offered us a chance to see it. This is what it looks like when astronomers geek out over astronomy-type things:

The Mayall 4m was placed at the highest point of Kitt Peak, and is itself many stories high, making it the highest point on the mountain.

The Mayall 4m was placed at the highest point of Kitt Peak, and is itself many stories high, making it the highest point on the mountain.

Standing next to the telescope operator, I got to ask lots of questions.

Standing next to the telescope operator, I got to ask lots of questions.

Looking down the barrel of the 4m, it was turned on its side to fill up the instrument with liquid nitrogen (just like at the Bok). You'll notice in the mirror Pat is taking my picture...as I take his...

Looking down the barrel of the 4m, it was turned on its side to fill up the instrument dewar with liquid nitrogen (just like at the Bok). You’ll notice in the mirror Pat is taking my picture…as I take his…

From far away, the 4m looks a bit like the Millennium Falcon. Punch it Chewy.

From far away, the 4m looks a bit like the Millennium Falcon. Punch it Chewy.

Pat standing in front of the 4m on its side.

Pat standing in front of the 4m on its side.

Me at the prime focus of the 4m. helluva big scope.

Me at the prime focus of the 4m. helluva big scope.

Visiting the WIYN 3.5 meter

There are roughly 25 observatories atop Kitt Peak mountain, so there’s lots to see and do. I am visiting the mountain in order to use the Steward Observatory’s 2.3 meter Bok telescope (‘the 90inch’). One of the observers on our team was also scheduled to use a different telescope for part of the week; she is working with the WIYN 3.5 meter telescope, which is the 2nd largest optical reflecting telescope on the mountain (1st is the 4m Mayall). As a result, we got to take a quick peak in side:

From the outside, the WIYN 3.5 looks different than most telescopes. Its dome is of a more segmented shape than most spherical domes.

From the outside, the WIYN 3.5 looks different than most telescopes. Its dome is of a more segmented shape than most spherical domes.

The scope set and ready to go for obseving.

The scope set and ready to go for observing.

The operator turned the scope on its side so we could get a look at the primary mirror. At 3.5 m, it's pretty big.

The operator turned the scope on its side so we could get a look at the primary mirror. At 3.5 m, it’s pretty big.

It's a big scope.

It’s got a big mirror.

view

[Roll over to animate] Looking north across the mountain towards the Bok 2.3m telescope, where I’m doing my observations.

Elevation and Atmosphere

tweet

I received this tweet* from Katrina (aka @Astro_yyz), and thank her for the kind wishes. But it got me wondering: what exactly is the difference in atmospheric pressure between sea level and the elevation of Kitt Peak Mountain? To the internet!

The Kitt Peak summit is at an elevation of 2,097 m, just over 2 kilometers above sea level. This is the sign that greets you when you hit the top

Kitt Peak: 6750 feet above sea level

Kitt Peak: 6750 feet above sea level

Sea level atmospheric pressure is (on average) 101.325 kPa (kilo Pascals). The atmospheric pressure reduces as altitude increases, the amount by which can be calculated based on simple physical laws. I used a short derivation of these equations by the Portland State Aerospace Society;^1 their equation 9 gives the value of atmospheric pressure as a function of height:

    \[P=100*\left( \frac{44331.514-height}{11880.516}\right)^{(1/0.1902632)}\]

where ‘height’ is in meters. So subbing in height=2097, the equation gives P=78,543 Pascals, or 78.543 kPa. Therefore, the pressure atop Kitt Peak is:

    \[\Delta P=100\left( \frac{78.543}{101.325} \right) = 77.5\%\]

of the pressure at sea level. Cool! And this lines up nicely with a graph that Wikipedia has:

So does this affect me as Katrina alluded to? It hasn’t so far! and it really isn’t high enough for most people to experience any negative effects (such as dizziness, headache, elevated heart rate). However, walking to the cafeteria every day (up a very slight incline) does seem harder than it should be. Though that may just be because I’m horrendously out of shape.

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* My own twitter account is @jesserogerson, however, for the week of 12-18 May 2014 I was tweeting as @AstroCanada. This is the official account of the Canadian Astronomical Society. Each week a different Canadian astronomer will be tweeting from it.

1. A Quick Derivation Relating Altitude to Air Pressure [PDF], Portland State Aerospace Society, 2004
2. Atmospheric Pressure, Wikipedia, accessed May 2014
3. Effect of High Altitude on Humans, Wikipedia, accessed May 2014