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Observatories that I have visited:
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2: Kvistaberg's Schmidt telescopeAlready after we did our first visit here one year ago I started to search for someone who could let us into the observatory and have a look at the telescope. After a while I came in contact with the astronomer Eric at Uppsala University, he offered us to make a visit later, and now in November we are here. The observatory we shall visit is the observatory that Uppsala University built during the 1950s. The telescope in this observatory is impressive, a Schmidt telescope, an astrograph with a mirror diameter of 135 cm. There are not many of this type and size and this is the second largest in the world, enjoy the photos. 
We met Eric at the observatory at 5 p.m. In November it's very dark at that time in Sweden and it's cold too. Here we have come into the building. 
Follow the staircase up and we can now get the first look into the telescope room. The hydraulic operated lid is open and let us in. 
Eric walks around and turn on all lights he can find, still it's dark here. I don't like flash photos and crank up the ISO setting on the camera to a hefty ISO3200. What a first impression we got, it's like a big canon pointing up in the sky ! 
Have you seen the old movie Alien, the first one ? This view remind me of that movie when they found the body of an alien sitting behind some sort of ray gun. 
A device hanging at the telescope, a closer look and I see that it's the remote control. Guide telescope:
This looks to be the guide telescope, in old time there was not a camera and computer controlled guiding system. They did it manually by looking in a separate guide telescope attached to the main telescope. The black device is an eyepiece with a red illuminated crosshair. With the screws on the sides it can be placed on a reference star, hours and hours they stood here and looking at the star and fine corrected the speed of the telescope's motors. This room can not be heated so it's very cold too. Heat make turbulence in the air and that disturb the sharpness of the stars. 
A wheel to control something, it looks to be a motor connected to it, maybe the focus control. It must be correct to a 1/200 of a mm or better. 
Another help telescope with a revolver and three eyepieces. It's smaller than the guide telescope, both these extra telescopes are of refractor construction. |
I don't know the size of these help telescopes but I can guess that the smaller is a 5" and the big a 7". For an amateur astronomer even these small telescopes are very big. They started to build this observatory on Nils Tamm's land 1953, it was also a donation from him to Uppsala University. It was finished 1963, sorry to say Nils Tamm died before that but he could see when the big mirror was installed about 1956. 
On top of the dome can be seen the lid that slides aside when doing observations. Fork mount:
The mount that hold the telescope is of fork type. There is no need for a counter balance of this type of mounts and no meridian flip either. The shaft that goes down in the floor is the R.A., Right Ascension axis. It's a equatorial mount and this R.A. axis is parallel to Earth's axis to a high precision. With this construction there is only need to compensate Earth's rotation in one of the axis. It does one revolution in 23 hours and 56 minutes, that's a 'star' day. I say telescope, but it's actually more than that, it's an astrograph. You don't use it for visual viewing, you take photos with it. It has a corrected field to fill a wide 200x200 mm glass plate with focused stars all the way out to the edge. It's the Schmidt corrector that correct the field, an extra weak lens at the front. The primary mirror also have another shape compare to a normal telescope. R.A. worm gear:
The R.A. shaft use a high precision worm gear and the motor that drive this gear is placed in the basement. Maybe it needs a heated room to conserve its precision. See how the shaft goes down through (right) the floor down to the basement. 
The bearings of a mount for a telescope must be of very high precision otherwise the stars can be fuzzy on the photographic plates. It rest on two steel rollers, one of them can be seen to the right at the floor. Declination shaft motor drive:
The other shaft of the telescope is the DEC axis, declination, it's only used when moving the telescope to new objects. When doing guiding of RA axis they maybe do some very small correction of the declination too. 
The motor that operate the Declination shaft, the brown canister in front of it can be an angle sensor. It tell the operator where the telescope is pointing. 
On the other side of the telescope we found another guide telescope, which to use depends to where the telescope is positioned on the sky. 
There are many brackets and openings around the telescope to attach devices on. 
The telescope is of Schmidt Cassegrain type, with that construction the main mirror has a hole in the center to let the light beam out to the instruments. In that mode it get a long focal length. Eric told us that hey never had used the telescope in that mode. They want the telescope to operate in wide angle mode. Then they take the light beam out in the middle of the telescope with a diagonal mirror. Some modern amateur telescope has this Schmidt-Newton design. The viewing field is a couple of degrees. More common is that a curved photographic plate sits inside the telescope with no diagonal mirror, maybe it was so when it was delivered as new, a Schmidt camera. But not usable with modern electronic cameras with a flat sensor. More about details of Schmidt Cassegrain and Schmidt-Newton telescopes:
Even if the mirror has a diameter of 135 cm the opening of the telescope is smaller, the Schmitt corrector, a weak lens at the opening, it has maybe a diameter of 100 cm. Lenses is very difficult to have bigger than this, because Earth's gravity deform the shape of the lens. 
The green hatch, it is here the photographic glass plate is installed. Every time they load a new glass plate they must go up here, many meters up. Did they use a ladder or did they tilt the telescope down ? An exposure could last for 20 minutes to several hours if it's a spectrum they take. Poor students who have to guide this telescope during a long exposure. 
Eric points on this device and explain: It's a place to install a camera here for drift scan of the sky and the stars. The telescope is not moved but the camera read out the signal in the same pace as the stars move (Earth rotate). It was in the beginning of 2000s and prof Claes-Ingvar Lagerkvist did some research about asteroids. Last year this telescope was used for science work was 2007 and it's now a museum. One interesting thing, this telescope is similar to the telescope in the Kepler satellite, the space observatory that hunt for Exoplanets. The mission is finished now but the data is still there. I used its data to hunt for variable stars and found a micro variable star that is reported in my name. The data is free to use and you can read here how I did it: Kepler data. The museum:
It's not only the telescope in this room, other things that the astronomers has left is still here. This is something from later time they have constructed to assist the observations. They have arranged a kind of museum in this building with old equipment. |
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Binocular:
In one corner of the telescope room we found this, a binocular of long focal length. 
I try to read the sign on the binocular, something like: Srnat Leftz Wetzlar, for sure a German quality instrument at that time. Glass plate star analyzer:
This is an instrument they used when they measured the photographic plates to find the positions of the stars. We talked about a lot of other things than the telescope too. I mention that we knew prof Gösta Gahm who passed away not so long time ago. Eric said that he knew him very well and they have done a lot of work together. Old time memory store:
Magnetic tape, used to store data on. Maybe one tape can store a couple of hundred Mega Bytes, compare to a modern USB memory that can store hundred times more. 
A photo of the Andromeda galaxy, maybe taken with this telescope. The Andromeda galaxy is three degrees wide on a long exposed photos like this. This is about the field you get with a DSLR camera of APS-C type with a 250 mm lens. How it come the size of the galaxy on the photo is about the same ? It's because this big telescope also have big photographic glass plates, about 200x200mm compare to the camera sensor 23x18 mm. The big difference is that the telescope collect an enormous amount of photons compare to the small camera. The model of the telescope say 100/135/300. I think 300 is the focal length in cm when in Schmidt camera mode, f/3, that's a wide field camera in the astronomy world. |
On the desk some star charts and to the left under the cover a Facit type writer, Swedish made. It's so fascinating to see all these old things left here. 
Inside a glass box is this device, is it a filter holder ? 
Another exiting instrument, no idea what it was used for but a guess is that is an instrument to attach to the telescope or a test equipment. I will ask Eric later. Control room:
The control room, when the outdoors temperature falls down to minus 20 degrees it can be nice to have a heated room to stand in. Maybe more built in concern to the sensitive instruments, not the astronomer. 
On the displays can we see the star coordinates (R.A., Dec) that the telescope is pointing to. 
A more modern equipment to control the telescope's position. With this new technology I'm sure they had some auto guiding system of the telescope too. 
A glass plate cassette, the glass plates has the size 20 x 20 cm, about. The shutter is the black metal plate we see here, instead of pushing a button when photographing they pull out this metal plate. But how did they do it when this cassette sit 5 meters up on the telescope ? There is another problem here, a telescopes of this kind has a curved focus plane and then the glass plates must be curved too to get the stars in focus all over the field. Normally they used film which is more elastic on this kind of telescope, or they could have additional optics that flattens the focus plan. More questions to ask. 
The incoming power for the observatory. In a humid environment like this copper cables oxidizes which cause problem. It could be a safety problem too. |
Doom's fundament:
The dome is big and heavy, still it must rotate to let its opening follow the telescope when it moves. The dome rest on rollers like this, there are many of them around the rim and a chain connect them to an electric motor. Eric did a test that it worked because after us he will guide a group of visitors up here. Eric told us later that hundred people came and the sky got clear so they could observe the planet Jupiter. Now when I look at the photos I see something, there are no rails to transfer the electric power to the dome. But I saw these power outlets, down left. Could it be that the dome can only rotate a limited distance, then they must move the power cable to a new power outlet ? 
Big telescopes and heavy devices, it's a need of a lift, this one can handle up to two ton of load. 
Eric and I stands in front of the telescope. This was really an exiting evening, to get to see all these old instruments and how they were used. 
We now take the staircase down, but we are not finished yet. We have to look at the clock machine in the basement that move the telescope slowly with high precision. Notice the power cable hanging up there in the dome. One reason that I think they have to shift the power cables when pointing to different positions on the sky. Clock room:
This is the clock machine, it control the telescopes rotation with a very high precision. The motor to the left looks to be a high speed motor which is used when moving between different objects. The green box to the right is the slow moving high precision mechanics and electric motors. 
The shaft that goes up through the floor to the telescope mount. |
Shaft with flex couplings between the different gear boxes. 
The high precision gears encapsulated behind a glass window. Down in the box is a oil bath for the gears Eric pointed out. 
The power system that control the motors. 
I had brought some soda and cakes, but I didn't find any office room in this building to eat them. We ate them here with the old astronomers watching over us. Thanks a lot Eric for let us in here to do a report about this fascinating observatory. More about Kvistaberg's observatory:
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