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--- chara:operating_procedures [2019/12/17 07:21]
charaobs
+++ chara:operating_procedures [2020/01/17 18:38]
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 .3.4 Checking the alignment to the rail target
-Put the rail target onto delay lines (toward back of the room from home sensor) Make sure carts are at back of the rails. Check spot on back side of target. If alignment is bad at the back, follow instructions for BRT adjustments. (Printed sheet on metrology table)  Remove rail target and return it to the spare table when done.
+Put the rail target onto delay lines (toward back of the room from home sensor) Make sure carts are at back of the rails. Check spot on back side of target. If alignment is bad at the back, follow instructions for BRT adjustments. (Printed sheet on metrology table) Remove rail target and return it to the spare table when done.
 .3.5 IR alignments are below in 2.4\\
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 .3.6 M10 Alignment
-Go to a computer anywhere to check the beam remotely at the telescopes. Check Vacuum Monitor that the vacuum is below 20 torr. Open telescope gui from pull down menu. Click TV [ON] to open the camera window and click [M10AL] to change view to the M10 alignment view, click [M7 open] to open the M7 mirror cover. Center bright spot in beam on the black reference spot. You may need to adjust the IRIS or the TV brightness to see the bright spot well. [BEAM] cycles the iris from open to closed and gives a good idea of where the center of the spot is. To adjust the position, use Pico 2 to select, for example, E2M10 → [MOVE] (use large steps ~ 100) * Note that the up, down, left, and right buttons do no correspond to the actual directions the spot will move. When the spot is centered, click [M7 close] to close the mirror cover * click TV [OFF] to close the window
+Go to a computer anywhere to check the beam remotely at the telescopes. Check Vacuum Monitor that the vacuum is below 20 torr. Open telescope gui from pull down menu. Click TV [ON] to open the camera window and click [M10AL] to change view to the M10 alignment view, click [M7 open] to open the M7 mirror cover. Center bright spot in beam on the black reference spot. You may need to adjust the IRIS or the TV brightness to see the bright spot well. [BEAM] cycles the iris from open to closed and gives a good idea of where the center of the spot is. To adjust the position, use Pico 2 to select, for example, E2M10 → [MOVE] (use large steps ~ 100). Note that the up, down, left, and right buttons do no correspond to the actual directions the spot will move. When the spot is centered, click [M7 close] to close the mirror cover * click TV [OFF] to close the window
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 For CLIMB 1 and CLIMB 2, the removable 6-beam target should be placed in the clamps on the CLIMB table. This also applies to aligning CLIMB for fringe tracking for VEGA or fringe finding for PAVO.\\
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-For MIRCX, the same target should be placed in the clamps on the MIRCX table. * Place the target to the appropriate table, making sure it seats firmly in the clamps. * Place the small corner cubes (labeled) on their bases at the BRTs. Make sure they seat firmly and correctly. * Open IR shutters, send laser light using VISBEAMS gui to the position you want to check. * Use a tablet to bring up Pico 2 gui. Click on icon or in xterm type: xpico2 * Select the appropriate IR mirror for the beam you are about to adjust. For ex: S1IR. The Beam Sampler gui tells you which telescope is in the beam you are aligning. * When done for all telescope to be used, remove target and place it above the CLASSIC/CLIMB table and remove corner cubes from their stands and place them to the side of the beam path.
+For MIRCX, the same target should be placed in the clamps on the MIRCX table. Place the target to the appropriate table, making sure it seats firmly in the clamps. Place the small corner cubes (labeled) on their bases at the BRTs. Make sure they seat firmly and correctly. Open IR shutters, send laser light using VISBEAMS gui to the position you want to check. Use a tablet to bring up Pico 2 gui. Click on icon or in xterm type: xpico2. Select the appropriate IR mirror for the beam you are about to adjust. For ex: S1IR. The Beam Sampler gui tells you which telescope is in the beam you are aligning. When done for all telescope to be used, remove target and place it above the CLASSIC/CLIMB table and remove corner cubes from their stands and place them to the side of the beam path.
 .5 Starting up OPLE and Metrology
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 Check delay line wires on carts, make sure nothing is on tracks\\
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-On the Metrology table inside the lab * Turn on two blue amplifiers for metrology laser (on button is labeled "line") The units will hum when on. * Turn the key to ON on the laser power box to put metrology laser on standby.
+On the Metrology table inside the lab, turn on two blue amplifiers for metrology laser (on button is labeled "line") The units will hum when on. Turn the key to ON on the laser power box to put metrology laser on standby.
 .6 Final steps in the lab
@@ Line 159: / Line 159: @@
 .3 Servers required for observing
-Servers can be opened from the pop up menu at bottom of screen 1, using the black platter icon or using the Observation Setup icon which opens them all at once. * The GPS server and the METROL server should always stay on and remain on screen 1 Close and re-open all Telescope servers after UT 0h in screen 2 (because of tiptilt connection issues). Open Primary OPLE Server and gui, Open Classic, Climb1, or Climb2 if needed, Open Tiptilt Server, Open Metrology Monitor (METROL) gui, (upper right of screen 3), this gui usually remains open. * Open Metrology Laser (METLAS) gui, (upper right of screen 3), this gui usually remains open.
+Servers can be opened from the pop up menu at bottom of screen 1, using the black platter icon or using the Observation Setup icon which opens them all at once. The GPS server and the METROL server should always stay on and remain on screen 1 Close and re-open all Telescope servers after UT 0h, (because of tiptilt connection issues) in screen 2. Open Primary OPLE Server and gui, Open Classic, Climb1, or Climb2 if needed, Open Tiptilt Server if needed, Open Metrology Monitor (METROL) gui, (upper right of screen 1), this gui usually remains open. Open Metrology Laser (METLAS) gui, (upper right of screen 1), this gui usually remains open.
-.4 Open Telescope guis, o(bsgtks) from icons on desktop
+.4 Open Telescope guis, or obsgtks from icons on desktop
-.5 Open GUIs required for observing from the menu under GTK: Open Primary OPLE gui (move to right side of OPLE server) * Open Classic, Climb1, or Climb2 gui if needed (put on right side of server) * Open LDC1 and LDC2 if VEGA or PAVO programs are observing * Open Tiptilt GUI * This will bring up Tiptilt GUI and Tiptilt viewing screens for all telescopes * Move viewing screens near telescope TV screens
+.5 Open GUIs required for observing from the menu under GTK or the desktop icons: Open Primary OPLE gui, Open Classic, Climb1, or Climb2 gui if needed, Open LDC1 and LDC2 if VEGA or PAVO programs are observing. Open Tiptilt GUI, This will bring up Tiptilt GUI and Tiptilt viewing screens for all telescopes * Move viewing screens near telescope TV screens
 .6 Using the Cosmic Debris job sequencer
-\\
+Open Cosmic Debris, CD for short, from the desktop icon. On the CONFIGURE tab, check to make sure the PoPs and telescope beam assignments agree with the white board or the setup email. If the POPs are wrong on CD, then open the "PoPs" gui, click on the [Overview] button on the PoPs gui. If nonsense comes up in the overview, then click [FLUSH] and then [REOPEN] on the PoPs gui, then click [UPDATE] on the PoPs Overview. If the PoPs Overview is now correct, then click the [GET] button on the CD Control Tab, this should update the PoPs. If the beams are not assigned correctly, move the beams accordingly to the proper telescope using the BeamSampler GUI and click [GET] on CD to update. Select the active telescopes on the tab labeled "Configure", choose a suitable reference cart, using the same one from the night before to make fringe finding easier.  After everything is set correctly, then click [SEND] on Cosmic Debris to send the active scope information to Ople.\\
-Open Cosmic Debris, CD for short, - Primary from the menu and move to screen 4 * On the CONFIGURE tab, check to make sure the PoPs and telescope beam assignments agree with the white board * If the POPs are wrong on CD, then open the "PoPs" GUI from the menu * Click on the [Overview] button on the PoPs GUI * If nonsense comes up in the overview, then click [FLUSH] and then [REOPEN] on the PoPs GUI * Then click [UPDATE] on the PoPs Overview * If the PoPs Overview is now correct, then click the [GET] button on the CD Control Tab, this should update the PoPs * If the beams are not assigned correctly, move the beams accordingly to the proper telescope using the BeamSampler GUI and click [GET] on CD to update * Select the active telescopes on the tab labeled "Configure" * Choose a suitable reference cart, using the same one from the night before to make fringe finding easier. * After everything is set correctly, then click [SEND] on Cosmic Debris to send the active scope information to Ople\\
+Set the instrument and settings on Cosmic Debris. On the "Control" tab on Cosmic Debris, select the beam combiner or combiners to be used. If using CLIMB or CLASSIC, also select the filter and beam\\
-Set the instrument and settings on Cosmic Debris * On the "Control" tab on Cosmic Debris, select the beam combiner or combiners to be used. * If using CLIMB or CLASSIC, also select the filter and beam\\
+Establish connection between tiptilt and the telescopes. On the Control Tab on Cosmic Debris, click on [TIPTILT COMM]. Click [START JOB QUEUE] on CD to continue the Tiptilt Communication sequence.  After several seconds, the telescope servers will indicate that the Socket (SOC) connection is established and turn on the tiptilt rate display. Cosmic Debris will usually display a lower rate, such as 42Hz, to indicate tiptilt is running. The servers will display 158Hz to show a proper functioning of the tiptilt system. If the connection is not established the first time, try again until CD shows rates for each telescope used. If a telescope server will not display a TT signal rate, you may need to shut it down and restart it. Once the telescope WFS's are used for tiptilt, these steps for the lab tiptilt will not be used.\\
-Establish connection between tiptilt and the telescopes. * On the Control Tab on Cosmic Debris, click on [TIPTILT COMM] * Click [START JOB QUEUE] on CD to continue the Tiptilt Communication sequence * After several seconds, the telescope servers will indicate that the Socket (SOC) connection is established and turn on the tiptilt rate display. Cosmic Debris will usually display a low rate, such as 42Hz, to indicate tiptilt is running. The servers will display 158Hz to show a proper functioning of the tiptilt system. * If the connection is not established the first time, try again until CD shows rates for each telescope used. If a telescope server will not display a TT signal rate, you may need to shut it down and restart it.\\
+Finish setting up tiptilt GUIs.  Click re-open on the Tiptilt GUI. This will update the TT labels on the TT viewing screens from B1,B2,etc to the telescope names. Click on the [SERVO CONTROL] tab on the tiptilt GUI to bring up a second window and move to screen 5 with the telescope guis. The Servo Control GUI allows you to turn ON the servo for the TT loop and make biases for individual beams (DBIAS and ZBIAS)
-Finish setting up tiptilt GUIs * Click re-open on the Tiptilt GUI. This will update the TT labels on the TT viewing screens from B1,B2,etc to the telescope names * Click on the [SERVO CONTROL] tab on the tiptilt GUI to bring up a second window and move to screen 5 with the telescope guis. * The Servo Control GUI allows you to turn ON the servo for the TT loop and make biases for individual beams (DBIAS and ZBIAS) === 3.7 Turn on metrology laser and home the carts ===\\
-Turning on the metrology laser * Make sure that no one is in the lab. * Turn the Laser on using the metrology laser GUI. The [Laser Power] button will go from red to green. * On the Metrology Monitor GUI, click [INITIALIZE] to initialize the metrology. A window will pop up to indicate a successful initialization. Hit [OK] on the window to close it. * Select REFALL and the UNK signal for each cart being used. Hit "OK" to bring up plots. * Click [CLEAR] on the metrology monitor to turn the unknown signals from red to white * The signals should look like nice sine waves. If they are too narrow or erratic, a metrology alignment or self interference may be the reason. * To close the metrology signal windows, click on [RUN MULTIPLE] again\\
+.7 Turn on metrology laser and home the carts
-Home each of the active carts * The carts must be homed before observing or else fringes will not be found. Do not forget this step or endless frustration will follow. * At the start of the night the carts will usually be at the back of the rails with the back switch (BS) column marked with an "X" on the OPLE server * On the "Control" Tab on the OPLE GUI, click [HOME] on each of the active carts. This will move the carts to the front of the rails where the home switch is located. * If the carts do not appear to be moving after clicking "Home," go into the computer area of the lab to make sure the power for the carts and the cable pullers are turned on. If they are, then you can put IR laser googles on and go into lab to listen if the carts are making loud grinding or squealing noises when they are trying to move. If they are, then the VME may need to be restarted or the cart inspected (serious problems with the carts need to be fixed by daytime staff). * After the carts finish homing, the ople server will say "HOMESETDONE" * To check that the carts have homed properly, click [TRACK] on the Control Tab of the OPLE GUI * The cart will track to home switch at the target position of "0.000000" on the OPLE Server * Make sure the "X" lights up and stays steady under the HM column on the Primary OPLE Server for each cart you will be using. * Also make sure that the errors between the laser and target position are small, (0.007µm or less is typical), when tracking at the home switch * If the errors jump when the cart is tracking on the home switch, then turn the cart [OFF], move the cart [BACK] about a meter from the home switch, turn the cart [OFF], and try clicking [TRACK] again. Please wait for each command to register on the OPLE server before clicking the next button in this sequence. If the errors do not stay near zero, the metrology laser may be out of alignment and the signal is low or the VME may need to be restarted. Pull up a metrology signal window as shown above and confirm the signal is strong. It will look like a sine wave with an amplitude the same as the window height. If it is low, adjust it carefully with the MET2 gui in PICO 2. Get the sine wave to equal the window height. If it is ok and the problem persists, go to the lab, turn off the Burleigh amplifiers, turn off the VME, wait 15 seconds, turn it back on and wait for the red light to go off. Turn on the Burleigh amplifiers when the light has gone off. Try tracking the cart again. * After checking to make sure the carts track properly, turn the carts [OFF] === 3.8 Synchronizing the clocks === * Synchronizing the clocks is very important for positional calculations of the telescopes and ople carts. * All clocks are synchronized with the [SYNC CLOCKS] button on Cosmic Debris. Push the button, and after 17 seconds, a series of messages will display on CD to indicate that the various systems and servers are sync'ed. Check the OPLE server to confirm that the OPLE Tm clock is the same as CHARA time and that the error in the parentheses is (0) or (1). A reading of (0) and (-1) may cause problems. Use [SYNC CLOCKS] again to get the OPLE errors to (0) or (1). A reading of a different time with (!!) behind it means the clocks have not been synced. === 3.9 The following windows should be opened on computer screen 3 (these are usually kept open all the time): === * Telescope monitor * Beam Samplers and PoPs * Visbeams, Shutters and Laser Filter Wheel * VEGA Periscope * Iris * Metrology Laser and Metrology Monitor * Pico 2 === 3.10 See the instruments page for information about starting different instruments at the beginning of the night: ===\\
+Make sure that no one is in the lab. Turn the Laser on using the metrology laser GUI. The [Laser Power] button will go from red to green. On the Metrology Monitor GUI, click [INITIALIZE] to initialize the metrology. A window will pop up to indicate a successful initialization. Hit [OK] on the window to close it. Select REFALL and the UNK signal for each cart being used. Hit "OK" to bring up plots. Click [CLEAR] on the metrology monitor to turn the unknown signals from red to white. The signals should look like nice sine waves. If they are too small in amplitude or erratic, a metrology alignment or self interference may be the reason. To close the metrology signal windows, click on [RUN MULTIPLE] again\\
+Home each of the active carts. The carts must be homed before observing or else fringes will not be found. Do not forget this step or endless frustration will follow. At the start of the night the carts will usually be at the back of the rails with the back switch (BS) column marked with an "X" on the OPLE server. On the "Control" Tab on the OPLE GUI, click [HOME] on each of the active carts. This will move the carts to the front of the rails where the home switch is located. If the carts do not appear to be moving after clicking "Home," go into the computer area of the lab to make sure the power for the carts and the cable pullers are turned on. If they are, then you can put IR laser googles on and go into lab to listen if the carts are making loud grinding or squealing noises when they are trying to move. If they are, then the VME may need to be restarted or the cart inspected (serious problems with the carts need to be fixed by daytime staff). After the carts finish homing, the ople server will say "HOMESETDONE" * To check that the carts have homed properly, click [TRACK] on the Control Tab of the OPLE GUI * The cart will track to home switch at the target position of "0.000000" on the OPLE Server * Make sure the "X" lights up and stays steady under the HM column on the Primary OPLE Server for each cart you will be using. Also make sure that the errors between the laser and target position are small, (0.007µm or less is typical), when tracking at the home switch. If the errors jump when the cart is tracking on the home switch, then turn the cart [OFF], move the cart [BACK] about a meter from the home switch, turn the cart [OFF], and try clicking [TRACK] again. Please wait for each command to register on the OPLE server before clicking the next button in this sequence. If the errors do not stay near zero, the metrology laser may be out of alignment and the signal is low or the VME may need to be restarted. Pull up a metrology signal window as shown above and confirm the signal is strong. It will look like a sine wave with an amplitude the same as the window height. If it is low, adjust it carefully with the MET2 gui in PICO 2. Get the sine wave to equal the window height. If it is ok and the problem persists, go to the lab, turn off the Burleigh amplifiers, turn off the VME, wait 15 seconds, turn it back on and wait for the red light to go off. Turn on the Burleigh amplifiers when the light has gone off. Try tracking the cart again. After checking to make sure the carts track properly, turn the carts [OFF]
+.8 Synchronizing the clocks
+Synchronizing the clocks is very important for positional calculations of the telescopes and ople carts. All clocks are synchronized with the [SYNC CLOCKS] button on Cosmic Debris. Push the button, and after 17 seconds, a series of messages will display on CD to indicate that the various systems and servers are sync'ed. Check the OPLE server to confirm that the OPLE Tm clock is the same as CHARA time and that the error in the parentheses is (0) or (1). A reading of (0) and (-1) may cause problems as the clock is synced one second off from usual. Use [SYNC CLOCKS] again to get the OPLE errors to (0) or (1). A reading of a different time with (!!) behind it means the clocks have not been synced.
+.9
+The following windows should be opened on computer screen 1 (these are usually kept open all the time):  Telescope monitor, Beam Samplers and PoPs, Visbeams, Shutters and Laser Filter Wheel, VEGA Periscope, Iris, Metrology Laser and Metrology Monitor, Pico 2
+.10
+See the instruments page for information about starting different instruments at the beginning of the night:\\
 [[:chara:instruments|Instruments: CLASSIC, CLIMB, MIRC, PAVO, VEGA, FLUOR]]\\
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-**Chapter 4: ** === = Observing Conditions ====\\
+**Chapter 4: **Observing Conditions
+\\
+.1 Observing Conditions Intro
+In opening the CHARA Array, conditions should be, for the most part, ideal. It is best if the sky is 60% to 70% clear and conditions stable before commencing. Delicate optics and electronics make up the majority of the Array and it’s better to err on the side of caution. In preparation for observing, the Mount Wilson weather server and web-based weather pages should be consulted. The telescopes can now be closed in about 5 minutes from the control room. With this in mind, don’t open up the telescopes to observe if conditions can change for the worse rapidly enough that you don’t get 10 minutes or more to close down safely. Weather stations now exist at each bunker and there is a control system software application to display the current conditions.  One can also use the white Radio Shack thermometer/hygrometer outside of the control room. With the Array becoming more fancily automated and weather monitoring technology becoming more robust (weather servers, satellite images, web cams, etc.), almost all weather monitoring can be done seemingly without ever leaving the cozy control room. Unfortunately this is not a good policy and nothing beats going outside for a gander and giving the sky a good old fashioned assessment. Obviously weather variations do exist from telescope to telescope, as much as 20% in RH at times. Most of the time this just means something is blowing through and opening is not a good idea. These circumstances need to be dealt with cautiously depending on the given weather conditions. Allowing extra time to close is advised in case of any problems. If any questions or doubts arise contact one of the CHARA staﬀ.
+.2 Humidity
+Only open the telescopes if the humidity is steady or dropping, at 75% or below. If the roofs outside the control room are ever dripping, then the telescopes should not be opened or should be closed immediately. If when starting out, the RH is above 80%, do not open unless it drops to below 75% and stays there for at least 30 minutes. If you do open after that, be wary and watch the RH, and if it starts rising, be prepared to close. Closing up takes about 5 minutes, so be ready for that. The array operator is in charge of protecting the telescopes and makes the final decision on whether the conditions are safe to open. If the RH is low at the beginning of the night, and rises after you are already open, the array operator should inform the PI around 70-75%, and start closing between 80-85%. Other humidity warning signs are: 1) water dripping oﬀ the OPLE building (or wet spots on the asphalt straight down from the eaves); 2) cold, clammy feel to metal objects such as railings; and 3) dew forming on the parked cars. It is important to note that the humidity can rise from 50% to 80% in as little as 10 minutes, so please keep a close eye on the rate of change of the humidity plots. It can also rain or hail from small, passing clouds when the humidity is quite low, even 40% RH or lower. Operators have been surprised before by small puffy clouds in unsettled air with low humidity.  If in doubt, stay closed.  The HPWREN webcams are a good resource to view the bottoms of clouds.  If there is any virga, the clouds are holding moisture and try to rain out.  Stay closed if you see anything streaming below the clouds.
+.3 Dust
+Gauging the airborne dust and pollen can be problematic because you need a bright light and a relatively dark night. In general, you want to look in the bottom 0.5 meter of the light column. There will be a diﬀuse column lit up by the beam – don’t worry about it, just follow the dust glints. If you can count the dust glints, the conditions are safe to observe. If it looks like a blizzard, close up. If any of the dust glints shine with an orange or a peach hue, or the dust glints look abnormally large, the dust is probably ash – close up immediately. Ash seriously degrades bare aluminum coatings. Dust and wind go together. But, just because it is calm, the dust conditions might still be bad. If it was windy a few days earlier, it could have kicked up a lot of dust, which can take several days to settle. Finally, during late spring to early summer, conifer tree pollen can be problematic. If particulates are borderline please email the CHARA day staﬀ so they can clean the optics as soon as possible.
+.4 Wind
+Wind has the eﬀect of degrading the seeing as well as kicking up dust. The wind eﬀects are ampliﬁed in the tunnel between the OPLE building and the oﬃce building, so look for other places to gauge the wind conditions. The intersection of the road and the trail to the eastern telescopes is a good place to gauge conditions. To be on the safe side, we only observe under calm to light breeze conditions (gusts less than about 10 knots, or 15 kph). Windy conditions we try to avoid. If you can hear the gusts from your desk, whistling from the light pipe supports, or the chain banging, it is too windy to observe. Occasionally you will hear the wind rustling the tops of the tall trees, but it is calm at ground level. This is a symptom of chaotic wind conditions, and almost always happens during windy episodes (Santa Anas, onshore ﬂows, etc.), during which you shouldn’t observe – the seeing will be bad anyway. Be cautious about opening if wind gusts are above 15-20 kph; winds this high are usually correlated with bad seeing and poor data quality. Telescopes and domes should be closed if the wind gusts get up to 30 kph. This will protect the optics from branches and debris that can be blown in from the surrounding trees.
+.5 Snow
+Because of the nature of the snow that falls on Mount Wilson, it is usually not a problem. If snow/wind conditions are such that drifting occurs, don’t open up. If there is still any snow stuck to the telescope dome itself, don’t open up. If there is snow still on the trees and branches procede with caution and make a visual assessment. Otherwise, you are free to observe (assuming the humidity, dust, and wind conditions allow it).
+.6 Essential Observing Links
+-Foot Solar Tower Current TowerCam Image ([[http://www.astro.ucla.edu/%7Eobs/towercam.htm|http://www.astro.ucla.edu/~obs/towercam.htm]]) a live view of the mountain. Check the clock when viewing the page as it can sometimes fail to refresh.
+Caltech Millikan Library Camera ([[http://library.caltech.edu/milcam/|http://library.caltech.edu/milcam/]]) A view of Mt. Wilson from the south, good for watching low clouds and fog that cling to the mountain.
+National Weather Service ([[http://forecast.weather.gov/MapClick.php?site=lox&textField1=34.2231&textField2=-118.0587&smap=1#.VKsuq2TF8rO|http://forecast.weather.gov]]) Mount Wilson weather and 5 day forecast
+CHARA telescopes spy cams and weather graph ([[http://astro.gsu.edu/~weather/chara_scopes.html|http://www.astro.gsu.edu]]) Status of each CHARA telescope
+Mount Wilson HP Wren Cameras ([[http://hpwren.ucsd.edu/cameras/wilson.html|http://hpwren.ucsd.edu/cameras/wilson.html]])
+Aerospace Corporation weather station ([[http://www.weatherlink.com/user/mocam/index.php?view=summary&headers=1|http://www.weatherlink.com/user/mocam]]) Another local station, always current.
+Jet stream forecast ([[http://squall.sfsu.edu/scripts/jetstream_modelsml_fcst.html|http://squall.sfsu.edu/scripts/jetstream_modelsml_fcst.html]]) Monitors high level winds which degrade seeing
+IR satellite loop ([[http://www.wrh.noaa.gov/lox/scripts/animate.php?root=sat_4km&list=IR4.GIF.3.jpg,IR4.GIF.4.jpg,IR4.GIF.5.jpg,IR4.GIF.6.jpg,IR4.GIF.7.jpg,IR4.GIF.8.jpg|http://www.wrh.noaa.gov]]) Keeps an eye on storms and clouds coming in
+California Regional Weather Server ([[http://squall.sfsu.edu/|http://squall.sfsu.edu/]]) A variety of weather links
+Clear Sky Clock ([[http://cleardarksky.com/c/MtWilsonOBCAkey.html|http://cleardarksky.com/c/MtWilsonOBCAkey.html]]) a forecasting tool, but be aware that the humidity forecast is often incorrect on this site as it incorporates the marine layer forecast for the valley below, which does not affect us 80-90% of the time
 \\
-Picture_4.png === 4.1 Observing Conditions Intro ===\ \ In opening the CHARA Array, conditions should be, for the most part, ideal. If the weather is questionable, it is best if the sky is 60% to 70% clear and conditions stable before commencing. Delicate optics and electronics make up the majority of the Array and it’s better to err on the side of caution. In preparation for observing, the Mount Wilson weather server and web-based weather pages should be consulted. The telescopes can now be closed in about 10 minutes from the control room. With this in mind, don’t open up the telescopes to observe if conditions can change for the worse rapidly enough that you don’t get 10 minutes or more to close down safely. Weather stations now exist at each bunker and there is a control system software application to display the current conditions. Soon this application will also issue warnings. One can also use the white Radio Shack thermometer/hygrometer outside of the control room. With the Array becoming more fancily automated and weather monitoring technology becoming more robust (weather servers, satellite images, web cams, etc.), almost all weather monitoring can be done seemingly without ever leaving the cozy control room. Unfortunately this is not a good policy and nothing beats going outside for a gander and giving the sky a good old fashioned assessment. Obviously weather variations do exist from telescope to telescope, as much as 16% in RH at times. Most of the time this just means something is blowing through and opening is not a good idea. These circumstances need to be dealt with cautiously depending on the given weather conditions. Allowing extra time to close is advised in case of any problems. If any questions or doubts arise contact one of the CHARA staﬀ. === 4.2 Humidity ===\ \ Only open the telescopes if the humidity is steady or dropping, at 75% or below. If the roofs outside the control room are ever dripping, then the telescopes should not be opened or should be closed immediately. If when starting out, the RH is above 80%, do not open unless it drops to below 75% and stays there for at least 30 minutes. If you do open after that, be wary and watch the RH, and if it starts rising, be prepared to close. Closing up takes about 10 minutes, so be ready for that. The array operator is in charge of protecting the telescopes and makes the final decision on whether the conditions are safe to open. If the RH is low at the beginning of the night, and rises after you are already open, the array operator should inform the PI around 70-75%, and start closing between 80-85%. Other humidity warning signs are: 1) water dripping oﬀ the OPLE building (or wet spots on the asphalt straight down from the eaves); 2) cold, clammy feel to metal objects such as railings; and 3) dew forming on the parked cars. It is important to note that the humidity can rise from 50% to 80% in as little as 10 minutes, so please keep a close eye on the rate of change of the humidity plots. It can also rain from passing clouds when the humidity is quite low, even 50% RH or lower. If in doubt, stay closed. === 4.3 Dust ===\ \ Gauging the airborne dust is problematic because you need a bright light and a relatively dark night. In general, you want to look in the bottom 0.5 meter of the light column. There will be a diﬀuse column lit up by the beam – don’t worry about it, just follow the dust glints. If you can count the dust glints, the conditions are safe to observe. If it looks like a blizzard, close up. If any of the dust glints shine with an orange or a peach hue, or the dust glints look abnormally large, the dust is probably ash – close up immediately. Ash seriously degrades bare aluminum coatings. Dust and wind go together. But, just because it is calm, the dust conditions might still be bad. If it was windy a few days earlier, it could have kicked up a lot of dust, which can take several days to settle. Finally, during late spring to early summer, conifer tree pollen can be problematic. If particulates are borderline please email the CHARA day staﬀ so they can clean the optics as soon as possible. === 4.4 Wind ===\ \ Wind has the eﬀect of degrading the seeing as well as kicking up dust. The wind eﬀects are ampliﬁed in the tunnel between the OPLE building and the oﬃce building, so look for other places to gauge the wind conditions. The intersection of the road and the trail to the eastern telescopes is a good place to gauge conditions. To be on the safe side, we only observe under calm to light breeze conditions (gusts less than about 10 knots, or 15 kph). Windy conditions we try to avoid. If you can hear the gusts from your desk, it is too windy to observe. If you hear whistling from the light pipe supports, it is too windy to observe. If you hear the signs on the chain banging, it is too windy to observe. Occasionally you will hear the wind rustling the tops of the tall trees, but it is calm at ground level. This is a symptom of chaotic wind conditions, and almost always happens during windy episodes (Santa Anas, onshore ﬂows, etc.), during which you shouldn’t observe – the seeing will be bad anyway. Be cautious about opening if wind gusts are above 15-20 kph; winds this high are usually correlated with bad seeing and poor data quality. Telescopes and domes should be closed if the wind gusts get up to 30 kph. This will protect the optics from branches and debris that can be blown in from the surrounding trees. === 4.5 Snow ===\\
-Because of the nature of the snow that falls on Mount Wilson, it is usually not a problem. If snow/wind conditions are such that drifting occurs, don’t open up. If there is still any snow stuck to the telescope dome itself, don’t open up. If there is snow still on the trees and branches procede with caution and make a visual assessment. Otherwise, you are free to observe (assuming the humidity, dust, and wind conditions allow it). === 4.6 Essential Observing Links === * 150-Foot Solar Tower Current TowerCam Image ([[http://www.astro.ucla.edu/%7Eobs/towercam.htm|http://www.astro.ucla.edu/~obs/towercam.htm]]) a live view of the mountain. Check the clock when viewing the page as it can sometimes fail to refresh. * Caltech Millikan Library Camera ([[http://library.caltech.edu/milcam/|http://library.caltech.edu/milcam/]]) A view of Mt. Wilson from the south, good for watching low clouds and fog that cling to the mountain. * National Weather Service ([[http://forecast.weather.gov/MapClick.php?site=lox&textField1=34.2231&textField2=-118.0587&smap=1#.VKsuq2TF8rO|http://forecast.weather.gov]]) Mount Wilson weather and 5 day forecast * CHARA telescopes spy cams and weather graph ([[http://astro.gsu.edu/~weather/chara_scopes.html|http://www.astro.gsu.edu]]) Status of each CHARA telescope * Mount Wilson HP Wren Cameras ([[http://hpwren.ucsd.edu/cameras/wilson.html|http://hpwren.ucsd.edu/cameras/wilson.html]]) * Aerospace Corporation weather station ([[http://www.weatherlink.com/user/mocam/index.php?view=summary&headers=1|http://www.weatherlink.com/user/mocam]]) Another local station, always current. * Jet stream forecast ([[http://squall.sfsu.edu/scripts/jetstream_modelsml_fcst.html|http://squall.sfsu.edu/scripts/jetstream_modelsml_fcst.html]]) Monitors high level winds which degrade seeing * IR satellite loop ([[http://www.wrh.noaa.gov/lox/scripts/animate.php?root=sat_4km&list=IR4.GIF.3.jpg,IR4.GIF.4.jpg,IR4.GIF.5.jpg,IR4.GIF.6.jpg,IR4.GIF.7.jpg,IR4.GIF.8.jpg|http://www.wrh.noaa.gov]]) Keeps an eye on storms and clouds coming in * California Regional Weather Server ([[http://squall.sfsu.edu/|http://squall.sfsu.edu/]]) A variety of weather links * Clear Sky Clock ([[http://cleardarksky.com/c/MtWilsonOBCAkey.html|http://cleardarksky.com/c/MtWilsonOBCAkey.html]]) a forecasting tool, but be aware that the humidity forecast is often incorrect on this site as it incorporates the marine layer forecast for the valley below, which does not affect us 80-90% of the time\\
 [[:chara:operating_procedures|Back to Main Menu]]\ \ {{:chara:files:picture_6.png|Picture_6.png}}\\
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-**Chapter 5:** ==== Going on Sky ==== === 5.1 Opening the Telescope Domes and enclosures ===\\
+**Chapter 5:** Going on Sky
+.1 Opening the Telescope Domes and enclosures\\
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 You can begin opening the telescope domes and enclosures about an hour or two before sunset. This will help air out the domes and improve seeing at the start of the night. Hot days benefit from an earlier opening to allow the scopes to cool. Before opening the domes make sure to check the current weather conditions and the forecast to make sure conditions are safe to open and are likely to be stable as you wait for it to get dark. Also confirm that Judit has finished the alignments in the lab as opening the domes will not allow the completion of the M10 alignments. If you do not see her, call the computer room phone number listed on the clipboard on the wall. * Monitor the progress of opening the domes by turning the televisions [ON] using the telescope GUIs. Click [SPY1] to view the dome slit. * Use the Dome GUI for each telescope to rotate the domes to the east. This will position the dome slit away from the sun so that you can open the slit before sunset. * Go to the Dome Tab on the Dome GUI. In the text box on the right, enter 90 and press [GOTO]. This will move the dome slit to the east. * When the domes are facing east (and all lab alignments are finished), click [SLIT OPEN] on the Control Tab of the telescope GUI to open the dome slit. * On the enclosure GUI, click the [OBSERVE] button to open the lower cylinders to the observe position. * Wait for the slit and enclosures to open and then wait for the sun to go down. === 5.2 Opening telescope optics ===\\

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