Before lunch time we departed from the hotel at Puerto de la Cruz, and headed to La Esperanza, to get food supplies for the next days at our favorite Hiper Dino supermarket! The menu for the next days is microwave pizza, canned fish, and other nearly-delitious microwave meals.
After shopping, we then proceeded our climb through TF-24 road towards La Izaña observatory.
At 15:00 we were already having lunch in our Casa Solar.
The night was short again! It started very well with a Telluric star on the finder (Alpha Cygni). We acquired its spectra in the same grating position as WR 140 that we also got a spectra for next. However, the MONS telescope operator (person responsible) came to us saying we should close the dome, as the humidity and wind speed were approaching the limits. Later we had green light to open the dome again, but it was only for a short while, as the wind started blowing strong again. Maybe tomorrow it will be a better night..
Saturday, December 27, 2008
Thursday, December 25, 2008
Day #11 (2008/12/25) The tour of the island
Today we went for a ride! We decided to take trip around Tenerife island.We left Puerto de la Cruz around 13:00 and went with the sunny weather towards West in direction of Icod de los Vinos. We filled the gas tank (our expenses control checkpoint) and continued. We followed the north road all the way to Punta Teno, the west-most point in the island. Then we went to Masca - a village in the middle of inhospitable mountains and single lane roads - and continued to the south of the island.
When we reached the crater, we saw the top of the Teide with snow! There was no snow there when we had left the observatory 24 hours earlier! We then came down from the mountain through La Esperanza, Santa Cruz, and back to Puerto de la Cruz. I am curious to see tomorrow how the Teide will look like, when we return to the observatory.This was a nice 5 hour stroll with few stops around the island, that ended with about 40 minutes searching for a parking space near the hotel. When I reserved the hotel, I was told it had parking space for hotel guests, which it has not!
The Bread-Toaster 2000
Just in time for the 10:00 deadline for breakfast, I caught the elevator on the 3rd floor to go down to the 8th floor, which is different from the 8th floor above the 7th for some reason. In this 8th floor just below zero, lays the restaurant area. The restaurant is a vast buffet-optimized room capable of feeding many people.The obvious happened: at 10 minutes before closing time, you could not possibly gather more than one coffee-spoon of "mixed eggs" from the serving place. Bread stock was low, and you could detect several hundreds of starving hotel guests had been in the premises by looking at the disposition of some items, like fruit, milk jars, scattering of corn flakes, precision of cake cuts, number of abandoned toasted bread slices, etc.. The typical scenario for this time of the morning.
But one interesting breakfast asset caught my eye! The Bread-Toaster 2000! I know we are in the XXI century, and nobody names innovative kitchen-of-the-future items as "2000" anymore.. Maybe in 50 years we get to witness the birth of the "2100" naming, but I thing "2000" fits this bread toaster better than any other "3000" labeling..Anyway, the ingenious bread toaster sparkled my engineering interest because of the way it toasts bread: this mass toasting device was a metallic conveyor belt where the hungry and impatient guest places his bread slices. Two bread slices fit side-by-side on the belt, under the constant heating action of the top-placed toasting resistors. The bread slices are slowly rolled deeper inside the oven chamber, becoming evermore unreachable. This slow process allows for enough time to go re-fill your cup with milk and go choose your other ingredients with which to complete your customized toast recipe.
When finally the toasting process finishes, the slices of lightly warmed, minimally-crocking break fall on the deepest corner of the machine, where gravity pushes them down a ramp that redirects them to just below the conveyor belt, available for pick-up by their owner. Finally, the second part in the customization of your toast can initiate, when you combine all the collected ingredients in your most favorable way. However, it can happen, that a frustrated user, starving for food (thus not particularly starving for toasts), may forget about his re-baked bread slice. This generates a mild number of abandoned toasts that subsequent people tend not to reuse to their advantage when already cold. (By "cold" here I mean about 10 degrees C below oven-ready temperature as they don't come out that hot, really: toasted and untoasted bread slices are indistinguishable by color)
Wednesday, December 24, 2008
The Hour Angle!
Today, while calmly seated in the couch of our hotel room 315 (where I'm writing this, actually), I finally understood why my last attempt at pointing the telescope alone did not succeed at first.
We had been told to consult a given IAC site for calculation of the Hour Angle (HA). But, if I happen to know the real Hour Angle, why should I need to use that site? - I though.
The trouble was that my Hour Angle values did not match up with the ones that were the "correct" ones. I noted that there were 2 hours difference in them. This did not make sense, as the Hour Angle I had in mind was being correctly calculated based on longitude of the site. This made me lose confidence in pointing with my calculated HA.
The Hour Angle is a local time-invariant angle coordinate useful for pointing at something in the sky. This angle is dependent on the position of the observer around the Earth (Longitude) and on time. The value of the Hour Angle when pointing at the vertical at observer's location (or anywhere on the local meridian) is zero 00:00 (or 12:00, when you are using an equatorial mount with the scope on the East of it, pointing West).
I decided to download the javascript calculator, and edit it to make it less annoying for personal use on my laptop, inside the dome. It was only now that I noticed the small letters at the bottom of the page that say "Estos cálculos ya tienen incluido el ERROR en Ángulo Horario (1h 55,5m)".
So there is a capital-lettered ERROR on the AH coordinate circle of the telescope of nearly 2 hours! So finally now I understood why the HA coordinate don't match right. I was doing it right all along, and the problem was not me.
We had been told to consult a given IAC site for calculation of the Hour Angle (HA). But, if I happen to know the real Hour Angle, why should I need to use that site? - I though.
The trouble was that my Hour Angle values did not match up with the ones that were the "correct" ones. I noted that there were 2 hours difference in them. This did not make sense, as the Hour Angle I had in mind was being correctly calculated based on longitude of the site. This made me lose confidence in pointing with my calculated HA.
The Hour Angle is a local time-invariant angle coordinate useful for pointing at something in the sky. This angle is dependent on the position of the observer around the Earth (Longitude) and on time. The value of the Hour Angle when pointing at the vertical at observer's location (or anywhere on the local meridian) is zero 00:00 (or 12:00, when you are using an equatorial mount with the scope on the East of it, pointing West).
I decided to download the javascript calculator, and edit it to make it less annoying for personal use on my laptop, inside the dome. It was only now that I noticed the small letters at the bottom of the page that say "Estos cálculos ya tienen incluido el ERROR en Ángulo Horario (1h 55,5m)".
So there is a capital-lettered ERROR on the AH coordinate circle of the telescope of nearly 2 hours! So finally now I understood why the HA coordinate don't match right. I was doing it right all along, and the problem was not me.
Room 315 (2008/12/24)
We arrived at Sol Puerto Playa hotel around 15:00, after making the journey through the curvy TF-21 road.
There were a few fast local drivers on that road, as well as slow tourist drivers. The typical local driver drives heavy-loking four-wheel drive vehicles, frightening commercial vans, or tuned exhaust pipe "normal" cars. All these vehicles appear daily-durty. On the other hand, tourist drivers, like me, drive easily identifiable, beautifully clean, un-muscled rental cars. Going down this road between a jeep and a commercial van was a bit tense experience.. But we made it to the Autopista del Norte at La Orotava.
As we approached civilization, we also approached the "zone of rare road indications". So we made 26 unnecessary kilometers of this highway because we passed the place to turn to Puerto de la Cruz (In fact we should have not turned right, but left!). After this we only took two attempts to reach our hotel, navigating inside the city with only a rought memorized map.
Of course something had to go apparently wrong: when we got to the hotel's reception, there was no reservation on my last name! They used my 3rd name, instead.. Nothing severe.
So we finally made it to this room, number 315.
Our room is nice! Two silent beds, wonderful view to the mountains behind the city, luxuriously "large" bathtub, aerodynamic water taps, but... our room only has one power outlet on the wall! There is a TV already plugged there, and we cumulatively have two laptops, and a Play Station Portable to charge.
So, we made it to the Hotel where we will stay two nights!
There were a few fast local drivers on that road, as well as slow tourist drivers. The typical local driver drives heavy-loking four-wheel drive vehicles, frightening commercial vans, or tuned exhaust pipe "normal" cars. All these vehicles appear daily-durty. On the other hand, tourist drivers, like me, drive easily identifiable, beautifully clean, un-muscled rental cars. Going down this road between a jeep and a commercial van was a bit tense experience.. But we made it to the Autopista del Norte at La Orotava.
As we approached civilization, we also approached the "zone of rare road indications". So we made 26 unnecessary kilometers of this highway because we passed the place to turn to Puerto de la Cruz (In fact we should have not turned right, but left!). After this we only took two attempts to reach our hotel, navigating inside the city with only a rought memorized map.
Of course something had to go apparently wrong: when we got to the hotel's reception, there was no reservation on my last name! They used my 3rd name, instead.. Nothing severe.
So we finally made it to this room, number 315.
Our room is nice! Two silent beds, wonderful view to the mountains behind the city, luxuriously "large" bathtub, aerodynamic water taps, but... our room only has one power outlet on the wall! There is a TV already plugged there, and we cumulatively have two laptops, and a Play Station Portable to charge.
So, we made it to the Hotel where we will stay two nights!
Morning #10 (2008/12/24)
Its cloudy now, at 12:30 in La Izaña. Windy, and with hight humidity. Not a good day for observations, I think. This is not bad to leave in a time like this. It would be more frustrating if we would feel tonight would be an excelent night. It's time to leave the observatory complex, as it closes at 15:00 for holidays. We will just go by MONS to close all stuff, check on the latest FTP transfer of the data from previous nights. Then we go down the mountain through the curvy FT-21 by La Orotava, to check in at a hotel in Puerto De La Cruz. Sol Puerto Playa is its name. Maybe there will be internet connection there; or maybe not.. So, I'll write to you later..
Merry Christmas!
Merry Christmas!
Dark flats bias neons
Flatfields, flats, dark frames, darks, biases, neons..
These words you have read quite a few times on my posts, and will likely continue to read.. These are necessary images we have to do. They are of specific things, and in a way they are always the same.. So why not make one and use it forever?
The answer to this question makes it clear that some of these images really must be "repeated".
CCDs are noise accumulation devices, that also have this side-effect of accumulating interesting signal. But since both things are accumulated together, there is no clear way to separate them. However, you can do several things that help: You can ask the CCD several times what it is seeing and then average that (this is why several images are usually taken). But since the noise is still there, you may want to ask the CCD what it sees with his eyes closed! This is an apparently stupid question to ask a CCD, but if we think a bit we will understand that in this case we know for certain what the CCD is seeing: nothing!
So if the CCD is seeing nothing, and it says it saw something, you know how much of what it says is a lie. Since CCDs are usually not very imaginative, you can assume the lie is always of the same amount. This allows you to subtract (callibrate) all your measurements by this amount of lies and uncertainty.
Well of course there are different kinds of lies.. there are those that happen because you asked the question, and those that keep getting more complex as time goes by. Therefore you need different kinds of measurements. Biases are those used to determine the uncertainty due to only reading the CCD. And Dark Frames ("darks" for short) are measurements for what nonsense has been accumulating during the time of an exposure.
Now imagine you want to measure the length of something but the ruler that is given to you has no zero marked on it. How can you possibly measure this? Well, you can't!.. With a single measurement, at least. You must take two measurements, and subtract both, to get a "distance".
In spectroscopy, the same happens. You take an image, convert it to a "unidimensional graph", and now somewhere on that jagged graph is supposed to be an emission line of H-alpha, that we have learned to be "precisely" on 656.281 nanometers. This is just like that joke about mathematicians: what I have said so far is correct, but arguably useful, because we don't know where in the graph that frequency must be. This is were the "neon calibration images" come in! This second measurement of something absolutely stupid like an unintelligent neon light bulb, that you don't find on stores often, is the key to knowing where some emission lines are.
So if you don't touch anything on the telescope after you have taken the measurement of the target star, and immediately after that you take an exposure of a neon light, you can assume that the position of the neon emission lines are the same as if the star also emitted them. So is to say that if a line of the neon spectrum appears at pixel x=342, and if you see something on your star's spectra 5 pixels to the left of that, than you can calculate the difference in wavelegth.
Imagine now that you are using spectacles. Better yet, imagine you haven't cleaned them for two months! Or imagine that your eye is less sensitive to blue than to green (like most people). How can you possibly measure the amount of light of a given color that is independant of glasses used, or eye sensitivity? Simple: you look at what you are measuring, and then look at a white wall thing that fills your view; next you divide what you saw the first time by the whitish stuff. So if there was a stain in the glasses that darkened what you saw, it also darkened the white color. Again white is something you know what it is, so a darkened white can be measured as white if you divide it by itslef. If you divinde A by B and get the right thing that you wanted to measure (even if A = B) then you know that what ever you measure must also be devided by that B. You must, of course, try to guarantee the B stays very much away from zero, as that would allow you to measure infinity..... A/0?
That B is called flatfield image, or flat for friends.
Some of these things stay rather constant with time: biases and darks, if temperature is constant, or flatfields if you have not changed the grating position on the spectrograph, or even neon lines if the spectrograph has not moved much so that gravity pulls on internal spectrograph parts differently. As soon as any of those parameters change, new respective calibration images need to be made.
Every night we are supposed to change grating position once, so we need two flatfields per night. We are also pointing at different targets so we need two neon frames per target. Luckily our CCD camera is cooled to a controlled temperature, so we don't need those many dark and bias frames..
Some of these calibration images can be made during the day (flatfields, darks, biases), which occupies some daylight time, and frees other in the nighttime. The normal day-to-day routine in an observatory is doing this, and managing all other stuff like conciliating sleep times with meal times or other services that are only available on specific hours.. In the end, weather spoils the routine more than the data.
These words you have read quite a few times on my posts, and will likely continue to read.. These are necessary images we have to do. They are of specific things, and in a way they are always the same.. So why not make one and use it forever?
The answer to this question makes it clear that some of these images really must be "repeated".
CCDs are noise accumulation devices, that also have this side-effect of accumulating interesting signal. But since both things are accumulated together, there is no clear way to separate them. However, you can do several things that help: You can ask the CCD several times what it is seeing and then average that (this is why several images are usually taken). But since the noise is still there, you may want to ask the CCD what it sees with his eyes closed! This is an apparently stupid question to ask a CCD, but if we think a bit we will understand that in this case we know for certain what the CCD is seeing: nothing!
So if the CCD is seeing nothing, and it says it saw something, you know how much of what it says is a lie. Since CCDs are usually not very imaginative, you can assume the lie is always of the same amount. This allows you to subtract (callibrate) all your measurements by this amount of lies and uncertainty.
Well of course there are different kinds of lies.. there are those that happen because you asked the question, and those that keep getting more complex as time goes by. Therefore you need different kinds of measurements. Biases are those used to determine the uncertainty due to only reading the CCD. And Dark Frames ("darks" for short) are measurements for what nonsense has been accumulating during the time of an exposure.
Now imagine you want to measure the length of something but the ruler that is given to you has no zero marked on it. How can you possibly measure this? Well, you can't!.. With a single measurement, at least. You must take two measurements, and subtract both, to get a "distance".
In spectroscopy, the same happens. You take an image, convert it to a "unidimensional graph", and now somewhere on that jagged graph is supposed to be an emission line of H-alpha, that we have learned to be "precisely" on 656.281 nanometers. This is just like that joke about mathematicians: what I have said so far is correct, but arguably useful, because we don't know where in the graph that frequency must be. This is were the "neon calibration images" come in! This second measurement of something absolutely stupid like an unintelligent neon light bulb, that you don't find on stores often, is the key to knowing where some emission lines are.
So if you don't touch anything on the telescope after you have taken the measurement of the target star, and immediately after that you take an exposure of a neon light, you can assume that the position of the neon emission lines are the same as if the star also emitted them. So is to say that if a line of the neon spectrum appears at pixel x=342, and if you see something on your star's spectra 5 pixels to the left of that, than you can calculate the difference in wavelegth.
Imagine now that you are using spectacles. Better yet, imagine you haven't cleaned them for two months! Or imagine that your eye is less sensitive to blue than to green (like most people). How can you possibly measure the amount of light of a given color that is independant of glasses used, or eye sensitivity? Simple: you look at what you are measuring, and then look at a white wall thing that fills your view; next you divide what you saw the first time by the whitish stuff. So if there was a stain in the glasses that darkened what you saw, it also darkened the white color. Again white is something you know what it is, so a darkened white can be measured as white if you divide it by itslef. If you divinde A by B and get the right thing that you wanted to measure (even if A = B) then you know that what ever you measure must also be devided by that B. You must, of course, try to guarantee the B stays very much away from zero, as that would allow you to measure infinity..... A/0?
That B is called flatfield image, or flat for friends.
Some of these things stay rather constant with time: biases and darks, if temperature is constant, or flatfields if you have not changed the grating position on the spectrograph, or even neon lines if the spectrograph has not moved much so that gravity pulls on internal spectrograph parts differently. As soon as any of those parameters change, new respective calibration images need to be made.
Every night we are supposed to change grating position once, so we need two flatfields per night. We are also pointing at different targets so we need two neon frames per target. Luckily our CCD camera is cooled to a controlled temperature, so we don't need those many dark and bias frames..
Some of these calibration images can be made during the day (flatfields, darks, biases), which occupies some daylight time, and frees other in the nighttime. The normal day-to-day routine in an observatory is doing this, and managing all other stuff like conciliating sleep times with meal times or other services that are only available on specific hours.. In the end, weather spoils the routine more than the data.
Night #9 (2008/12/23) Last before Christmas
Dome opened at 18:30
Here was our plan:
1 WR 140
2 HD 14134
3 telluric star in M45 (near zenith, so at low air mass)
4 WR 6
5 one Oe star
6 same Telluric star in M45 (closer to the horizon, so at high air mass)
Guess what we did!
Correct, only WR140! Clouds rolled in again on the last exposure of WR 140.
Bad weather is arriving always at the middle of something. Its curious that every time we can do something in a night, it is always WR 140, but if bad weather appears, it is only after we have measured it.
Well, the dome is closed already, and we are now cleaning everything on the observatory. Tomorrow we must not be here. The whole observatory complex will close for Christmas, and we must go down to Puerto de la Cruz to a new hotel. We must check in at the hotel before 18:00. this means that it is likely that I will no longer have easy internet connection. So there might be a short break on posting for two days. On the 26th, we shall return to MONS again, and posts will find their way into this blog again.
Note that I can write posts offline, so a few may appear on the 26th ;)
Merry Christmas!
Here was our plan:
1 WR 140
2 HD 14134
3 telluric star in M45 (near zenith, so at low air mass)
4 WR 6
5 one Oe star
6 same Telluric star in M45 (closer to the horizon, so at high air mass)
Guess what we did!
Correct, only WR140! Clouds rolled in again on the last exposure of WR 140.
Bad weather is arriving always at the middle of something. Its curious that every time we can do something in a night, it is always WR 140, but if bad weather appears, it is only after we have measured it.
Well, the dome is closed already, and we are now cleaning everything on the observatory. Tomorrow we must not be here. The whole observatory complex will close for Christmas, and we must go down to Puerto de la Cruz to a new hotel. We must check in at the hotel before 18:00. this means that it is likely that I will no longer have easy internet connection. So there might be a short break on posting for two days. On the 26th, we shall return to MONS again, and posts will find their way into this blog again.
Note that I can write posts offline, so a few may appear on the 26th ;)
Merry Christmas!
Tuesday, December 23, 2008
Domes of all colors!
Ah!!... Astronomical observatories... Places of domes of all colors!.. No?
Oh yes! Is not White composed by all colors?? Well, but there really are other dome colors too.. Green domes: Why not?
This recycling container for glass, for instance, is -- like our Sun -- green. And it has the shape to mingle with its astronomic-purposed companions. But this non-atypical fiberglass container further has two round entrances, to allow bottle-sized glass objects (or chunks of them) to be thrown in. However, is this not a strange asset to find in an observatory?
Astronomical observatories are filled with glass objects! I would estimate 5% of total glass to be on bottled drinks at the bar; maybe 10% on windows; but quite possibly more than 70% of the volume of glass to be in telescope mirrors!
Now, why would someone design bottle-sized glass intakes when most of the surrounding recyclable glass clearly will not fit through them?? Are they saying that when a telescope mirror breaks, it does so into small enough pieces?
What other strange things might one find on astronomical observatories?
Oh yes! Is not White composed by all colors?? Well, but there really are other dome colors too.. Green domes: Why not?
This recycling container for glass, for instance, is -- like our Sun -- green. And it has the shape to mingle with its astronomic-purposed companions. But this non-atypical fiberglass container further has two round entrances, to allow bottle-sized glass objects (or chunks of them) to be thrown in. However, is this not a strange asset to find in an observatory?
Astronomical observatories are filled with glass objects! I would estimate 5% of total glass to be on bottled drinks at the bar; maybe 10% on windows; but quite possibly more than 70% of the volume of glass to be in telescope mirrors!
Now, why would someone design bottle-sized glass intakes when most of the surrounding recyclable glass clearly will not fit through them?? Are they saying that when a telescope mirror breaks, it does so into small enough pieces?
What other strange things might one find on astronomical observatories?
Day #8 (2008/12/22)
Today we woke up late, and slept much. But, as a result, lunch was postponed somewhat.. We headed to the observatory to make flatfield exposures.
High clouds started to roll in with the looks of wanting to stay fo a long time..
Later in the afternoon, we decided to go eat somewhere, because of the weather. Unfortunately, there is no open restaurants after lunch time within 1400m below us. But as we were finding this out, we met 8 stranded guys on 4 scooters that had run out of gas on one of them. We decided to help them. We tried putting the scooter inside the car to take it to a gas station, but it didn't fit inside. So we gave a lift to three of them, and the guy on the "gasolineless" scooter grabbed our car on the window to take it up-hill. We went to the observatory in search for a hose to get gasoline from the car to the scooter, but hoses were all very thick and long! So we got back to the road and helped them to reach the down-hill part. We ended up taking them to the nearest gasoline station, 30km away through the mountain road. All four scooters dancing happily in front us us, as we descended the mountain road TF-24 in direction to La Esperanza, with the hope of gasoline in mind, reminded me of a Spanish television series a long time ago called "Verano Azul".. I even remembered its music: too-roo to-ro-ro too-roo..
We took this opportunity to buy stuff to eat for our dinner.
We finally got back to the observatory at 21:00 or slightly later..
The sky was cloudy the whole time. We could only see a few blurry stars near the zenith. Not a good time for measurements. This night we did not open the dome..
High clouds started to roll in with the looks of wanting to stay fo a long time..
Later in the afternoon, we decided to go eat somewhere, because of the weather. Unfortunately, there is no open restaurants after lunch time within 1400m below us. But as we were finding this out, we met 8 stranded guys on 4 scooters that had run out of gas on one of them. We decided to help them. We tried putting the scooter inside the car to take it to a gas station, but it didn't fit inside. So we gave a lift to three of them, and the guy on the "gasolineless" scooter grabbed our car on the window to take it up-hill. We went to the observatory in search for a hose to get gasoline from the car to the scooter, but hoses were all very thick and long! So we got back to the road and helped them to reach the down-hill part. We ended up taking them to the nearest gasoline station, 30km away through the mountain road. All four scooters dancing happily in front us us, as we descended the mountain road TF-24 in direction to La Esperanza, with the hope of gasoline in mind, reminded me of a Spanish television series a long time ago called "Verano Azul".. I even remembered its music: too-roo to-ro-ro too-roo..
We took this opportunity to buy stuff to eat for our dinner.
We finally got back to the observatory at 21:00 or slightly later..
The sky was cloudy the whole time. We could only see a few blurry stars near the zenith. Not a good time for measurements. This night we did not open the dome..
How to ruin simple, useful and mandatory interfaces
Our house has these water taps that have knobs... Well, this description does not exactly reveal how unique they are! Like hinted on the post about TASCS, the knobs are expertly crafted to possess extreme grip when dry, and not so when wetness is present! In the shower the cold water knob needs an initial offset rotation of half turn for water to start running, and then must keep about 3/2 of the rotation of the hot water counterpart so that temperature is kept constant (the water can get really hot, as noted on the post about our "home").
In the kitchen, the hot water knob is hard to turn (imagine your hands full of dish washing liquid). In Usability Design, there is an evaluation heuristic for this: H2-3 "Ensure user control and freedom". This "rule" was clearly violated!
On the shower, you have two knobs that don't have a feature that let you know how much has been opened or closed. The state of the system can only be extrapolated a posteriori based on the burning sensation upon skin contact with the water. If you are not the one taking the shower, you can also get a screaming sound as an indication of incorrect water mixture. The heuristic failing here is H2-1 "Ensure good visibility of system status".
Then on the bathroom sink, the cold water rotates the opposite way! A clear violation of usability heuristic H2-4 "use consistency and standards". So what?! - you ask - Ok, it takes you two iterations to open it, but when you want to close it, you naturally open it even more! Luckily the water goes directly to the fosset and does not ricochet anywhere; however, you now need two turns to close the water tap!
I could point out a few other heuristic violations, such as H2-5 "Design to prevent user errors", or H2-6 "Design to facilitate recognition rather than recall memory".. There are other water taps that only have a single handle to control both water throughputs, this is arguable if it is decent, but it would improve heuristic H2-7 "Provide for flexibility and efficiency of use"..
As someone said, "poor usability is everywhere"!.. Our water taps may not be the best in the world.. But without them, we would either drown or have no water!
Monday, December 22, 2008
Night #7 (2008/12/21) Visitor's night
During the week we had received an email from Jorge Prieto, from the IAC at La Laguna saying he would like to stop by on Sunday night to take a few astro-pictures of the sky using our electricity..
Indeed he came, and we had our first "external" visit!
While he went to set up his equipment we started our observation of WR140, our early night target.
Later when his camera was taking pictures of the Pleiades, he came inside the warmf of our observatory and we talked a bit. He was kind enough to invite us to visit the IAC-80, the 80cm telescope. We were in the middle our exposures of WR140 by this time, so only one of us could go visit. The lucky fellow who went was me! :) Thomas stayed at the observatory to guide our exposures, and make sure the target would stay on the spectrograph's slit.
I don't want to talk much about the impressive IAC-80 now, because it was dark (telescope in use, we weren't allowed to light anything inside the dome) and because this deserves a separate post later when me and Thomas visit it again in daylight. But it was a pleasant visit! Guiding is not done manually there! It is now being used for photometry.. I promise more details later :)
Anyway, I had to go back to MONS before Thomas would end our observation of WR140, so that we could point the telescope to our next target. One can do it, but two people do it better and faster.
So we proceeded to WR 1, and for the second consecutive time, we could find it. Success again! After practicing and knowng our targets, finding them becomes almost easy..
Around midnight our visiting astrophotographer from the IAC had to leave.. These people work in astronomy and need to be in an office during the day the next day? Well, I guess it happens.
We had taken no spectra of Oe stars recently so, after WR 1, those were our zenith-close targets (HD 45314 and HD 60848). These are two of the only eight known Oe type stars... These are special giant stars that have strong emission lines.. But I will talk about them later as well.
Unfortunately, we were so tired that we both fell a sleep while guiding on the last exposure of HD 45314.. On that exposure, the star drifted out of the slit, and very little light made it through to the CCD camera!
The curious thing about sleeping, is that when you wake up, you wake up! Indeed we woke up and were still able to point to the second Oe star. Of course, at 6:00 am, as soon as our priority target list was finished, we wanted to go to bed!
Still, this was again a succesful night, because we images the only 2 Oe stars visible at this time from our location. We had not pointed at them because of bad weather, that have cut our night down to half.
Indeed he came, and we had our first "external" visit!
While he went to set up his equipment we started our observation of WR140, our early night target.
Later when his camera was taking pictures of the Pleiades, he came inside the warmf of our observatory and we talked a bit. He was kind enough to invite us to visit the IAC-80, the 80cm telescope. We were in the middle our exposures of WR140 by this time, so only one of us could go visit. The lucky fellow who went was me! :) Thomas stayed at the observatory to guide our exposures, and make sure the target would stay on the spectrograph's slit.
I don't want to talk much about the impressive IAC-80 now, because it was dark (telescope in use, we weren't allowed to light anything inside the dome) and because this deserves a separate post later when me and Thomas visit it again in daylight. But it was a pleasant visit! Guiding is not done manually there! It is now being used for photometry.. I promise more details later :)
Anyway, I had to go back to MONS before Thomas would end our observation of WR140, so that we could point the telescope to our next target. One can do it, but two people do it better and faster.
So we proceeded to WR 1, and for the second consecutive time, we could find it. Success again! After practicing and knowng our targets, finding them becomes almost easy..
Around midnight our visiting astrophotographer from the IAC had to leave.. These people work in astronomy and need to be in an office during the day the next day? Well, I guess it happens.
We had taken no spectra of Oe stars recently so, after WR 1, those were our zenith-close targets (HD 45314 and HD 60848). These are two of the only eight known Oe type stars... These are special giant stars that have strong emission lines.. But I will talk about them later as well.
Unfortunately, we were so tired that we both fell a sleep while guiding on the last exposure of HD 45314.. On that exposure, the star drifted out of the slit, and very little light made it through to the CCD camera!
The curious thing about sleeping, is that when you wake up, you wake up! Indeed we woke up and were still able to point to the second Oe star. Of course, at 6:00 am, as soon as our priority target list was finished, we wanted to go to bed!
Still, this was again a succesful night, because we images the only 2 Oe stars visible at this time from our location. We had not pointed at them because of bad weather, that have cut our night down to half.
Sunday, December 21, 2008
Night #6 (2008/12/20)
Another night started off quite good!
We pointed again to our daily early-night target, WR140. Then we revisited HD14134.. But the most important step of the night was our first spectra of WR 1 (HD4004). This is a tough target to find, because it is a faint star, with little visual clues around. This was our second real attempt at pointing at it, and we finally made it!
Our plans for the second half of the night were to image Oe type stars. I am yet to talk about these stars, as I promised in early December.. But for now, just imagine there are only 8 of such stars known on our galaxy!..
Unfortunately, humidity rose, and we had to close the dome. But, it dropped to 50% and we decided to open the dome and try again, but it came again, managed to get one 20-minute exposure of HD45314.
The weather is really not favoring our targets of this type. They only reach a good observing position with our equipment at the end of the night (after 02:00 am). And for the last 2 nights, weather did not allow any observation.
After that sole exposure of the Oe star, we were forced to cose the dome again, due to - you guessed it - humidity. 5 minutes later, we were inside a cloud again. It was time to leave the camera making Darks (calibration exposures) and head "home"...
We pointed again to our daily early-night target, WR140. Then we revisited HD14134.. But the most important step of the night was our first spectra of WR 1 (HD4004). This is a tough target to find, because it is a faint star, with little visual clues around. This was our second real attempt at pointing at it, and we finally made it!
Our plans for the second half of the night were to image Oe type stars. I am yet to talk about these stars, as I promised in early December.. But for now, just imagine there are only 8 of such stars known on our galaxy!..
Unfortunately, humidity rose, and we had to close the dome. But, it dropped to 50% and we decided to open the dome and try again, but it came again, managed to get one 20-minute exposure of HD45314.
The weather is really not favoring our targets of this type. They only reach a good observing position with our equipment at the end of the night (after 02:00 am). And for the last 2 nights, weather did not allow any observation.
After that sole exposure of the Oe star, we were forced to cose the dome again, due to - you guessed it - humidity. 5 minutes later, we were inside a cloud again. It was time to leave the camera making Darks (calibration exposures) and head "home"...
Casa Solar
Our home for these days is amicably called "Casa Solar". Solar house, in English. Why so? I suspect of two reasons. The first is related with the observatories that surround it. Two of these are dedicated to Solar observation, and among them is the largest solar telescope on Earth, the Vacuum Tower Telescope (VTT). So this neighouring solar hospitality may have given the name to the house.. There is also another reason for naming our house that way: All heat, and hot water is energized by solar action! The roof of the house is covered with water heating solar panels. There is a small (1,5x larger area than our house) solar water heating system nearby as well.
I am amazed at how, after two days of cloudy weather, there still is hot water. But you can still note the temperature of the heaters go down on the cloudy days.
I am amazed at how, after two days of cloudy weather, there still is hot water. But you can still note the temperature of the heaters go down on the cloudy days.
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