chara:operating_procedures
Differences
This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision | ||
|
chara:operating_procedures [2023/08/18 20:56] gail_stargazer |
chara:operating_procedures [2023/09/01 02:50] (current) gail_stargazer |
||
|---|---|---|---|
| Line 1: | Line 1: | ||
| - | ===== Observing Procedures ===== | + | ====== Observing Procedures |
| - | [[: | + | [[: |
| \\ | \\ | ||
| Line 270: | Line 270: | ||
| 4.2 Humidity | 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. Be aware that if the RH is at 100% for many hours, things will be very wet, even if the RH drops dramatically below 75%. 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. | + | 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. Be aware that if the RH is at 100% for many hours, things will be very wet, even if the RH drops dramatically below 75%. 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. | ||
| 4.3 Dust | 4.3 Dust | ||
| Line 277: | Line 279: | ||
| 4.4 Wind | 4.4 Wind | ||
| + | |||
| + | **Use caution if wind gusts > 15-20 kph** | ||
| + | |||
| + | **Close up if wind gusts > 30 kph** | ||
| 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. | 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. | ||
| Line 282: | Line 288: | ||
| 4.5 Snow and cold weather | 4.5 Snow and cold weather | ||
| - | Because of the nature of the snow that falls on Mount Wilson, it is usually not a problem.* (Winte 2023 would like to speak with you.) 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. | + | 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. |
| - | Cold temperatures around freezing also can be problematic. Several components are not rated to operate at freezing temps. Do not open unless it is above freezing and keep an eye on the temps if they are still dropping. Otherwise, you are free to observe (assuming the humidity, dust, and wind conditions allow it). Here are limits for observing close to 0ºC. | + | Cold temperatures around freezing also can be problematic. Several components are not rated to operate at freezing temps. Do not open unless it is above freezing and keep an eye on the temps if they are still dropping. Otherwise, you are free to observe (assuming the humidity, dust, and wind conditions allow it). Here are limits for observing close to freezing: |
| - | Temp_warning: T_tel < 2C or T_outside < -3C | + | **Temperature warning: T_tel < 2C or T_outside < -3C** |
| - | Hard_limit: T_tel < 0C or T_outside < -5C | + | **Hard limit for closing: T_tel < 0C or T_outside < -5C** |
| 4.6 Essential Observing Links | 4.6 Essential Observing Links | ||
chara/operating_procedures.1692406609.txt.gz · Last modified: 2023/08/18 20:56 by gail_stargazer
Page Tools
Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Share Alike 4.0 International
