Preparations in the Lab Prior to Observing
Setting up Computer in the Control Room
Text Commands for CHARA GUIs
Going on Sky
Procedure for Shutting Down the Array
Co-phasing with the CHARA phase reference
Instructions for using the Six Telescope Simulator (STS)
Using Labao with Starlight
Telescope AO User Manual
New S2 Finder Instructions
Night-time POP Changes
Azimuth coudé alignments
Tip-tilt Splitters Change
Telescope Horizon Limits
Recent fringe offsets
Software setup for specific instruments
Classic Faint Object Procedures
DOCUMENTATION TO BE UPDATED
Note: the information contained in these wiki pages needs to be incorporated into the documentation in the CVS tree.
CHARA Array Operating Procedures
Copyright © 2005-2018 The CHARA Team
Last updated: 2018-01-11
The CHARA optics lab is a building within a building and is intended to provide thermal and vibrational stability. The main goal of the CHARA lab rules is to keep all optics and equipment safe from any hazards. The crucial issue being misalignment of anything. The amount of dust and dander must be kept to a minimum.
A high-powered infrared laser is used for the delay line metrology. This is an eye hazard, so before entering the lab check to make sure the red light above the door is not on. If the laser is activated, it is a must to put on IR-protective goggles. If you are not sure, wear the goggles.
Please remember that:
Procedures in the lab must be followed closely and failure to follow these rules will result in loss of lab privileges.
* Before entering the lab, you must have a reason or tasks at hand.
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Chapter 2: Version 2. August 27, 2012 by Judit, Version 3 January 2015 by Norm, Version ? October 2017 by Norm
These are routine tasks to be performed in and around the lab every evening to prepare the array for regular observations.
Go into vacuum pump shack
Go into building,
The final pressure should be 0.5 - 1.0 Torr in each line. The pump will normally bring all 6 lines down to .2-.3 Torr. The S1 and S2 lines leak the most during the day and will read the highest in the afternoon when you return, usually around 10 and 20 Torr. Note any unusual vacuum readings as they can indicate a leak beyond what is normal. Sometimes a line isn't pumped down the night before and can read higher than 30 Torr. Pump the highest ones down first as stated above.
Fill both chambers on the NIRO camera. Use the gloves and glasses provided on the shelf with the funnels and the thermos. It will normally take 1 liter of LN2 in the outer chamber and 1/2 liter in the inner chamber. Fill it until the LN2 bubbles out of the top. This camera is normally kept cool all the time, exceptions will be noted.
Fill the other dewars ONLY if you were specifically asked to do so. Other IR cameras: JouFLU and Cali (the blue dewar on the JouFLU table).
Record that you filled the cameras in the log book, noting time and cameras filled. If you do not observe due to weather, fire or closure, make sure someone on the mountain will fill it for you.
Go into the lab. The green alignment laser on the light source table is used. To open necessary guis, use laptops or the two tablets inside lab. Tablets are the newest hand held units and are located on the west and south walls plugged into chargers.
2.3.1 In the lab (Beam Combination area)
2.3.2 Check the laser spots on the E table (at North wall of Beam Switching area)
If the telescopes were used on the same beam on the previous night, the next steps may be very close and not need much if any adjustment.
2.3.3 Next check the dichroic target on the beam sampler tables for each telescope. NOTE: As of 2017Jul05, please align the dichroics following the instructions in Setup with LABAO document.
2.3.4 Check the spot on the rail target
2.3.5 The periscope covers are not used anymore so nothing to remember here.
2.3.6 M10 Alignment:
Go to a computer anywhere to check the beam remotely at the telescopes.
2.3.7 Labao wfs camera covers and labao shutters
The labao camera covers should be kept off, but put the covers on gently any time when you need to put the small corner cubes in place at the BRTs to work with the internal sources to protect the cameras.
Covers on when doing the following alignment steps in the lab:
Covers off after you removed the corner cubes from their bases.
The labao cameras (just like the tiptilt camera) are safe during pop changes as long as you do not open any labao shutters. You will notice increased counts on the labao cameras (just like in the tiptilt camera) whenever ND=0 alignment laser is going through the system, but this is not harmful as long as the labao shutters are closed. While observing none of the labao shutters need to be or should be opened. As usual, dim the laser after you are done with the pop change to protect any camera in the lab from ghost reflections and scattered laser light.
The IR mirrors on the beam samplers can be adjusted using Pico 2 controller to targets depending on which IR beam combiner is to be used.
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.
For MIRC or JouFLU, the same target should be placed in the clamps on the MIRC table.
Go to OPLE racks
On computer outside lab, bring up Primary Ople Server
Go inside lab to check carts
Possible fix: to shut off and turn back on OPLE racks, restart OPLE server
Check delay line wires on carts, sure nothing is on tracks
On the Metrology table inside the lab
Chapter 3: (edited 2012Aug29 by Gail and Chris)
Open Cosmic Debris, CD for short, - Primary from the menu and move to screen 4
Set the instrument and settings on Cosmic Debris
Establish connection between tiptilt and the telescopes.
Finish setting up tiptilt GUIs
Turning on the metrology laser
Home each of the active carts
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.
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.
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.
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.
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).
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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.
When the sun has set and before it is dark enough to slew to your first target, you can begin opening the telescope optics. Open the telescope optics one by one using the Control Tab on the Telescope GUIs:
The OPLE carts were homed in the setup procedure. However, it is always a good idea to check to make sure the carts are tracking correctly before slewing to the first target.
Make sure the telescopes being used are in their stow positions. For each telescope, the elevation should be at or near 90 degrees and [SPY1] should show the end ring of the telescope framing the top of the open dome. The azimuth positions for each telescope should be:
On the Power GUI, turn on the [Tel AZ] and [Tel EL] power for each of the active scopes (green means ON).
The new for 2016 stall detection function usually has each scope disabled each evening. They will need to be enabled before checking the dome servers or slewing. Make sure that the telescopes do not move away from their stow positions when enabling the scopes. If they begin moving, then click [STOW] on the Telescope Control Tab or dome gui and make sure that they arrive at the correct stow position. Check for problems with the dome servers by watching each telescope move to the precise stow position, ie. 89.990º and moving to 90.000º. If it stays off the precise stow position, the dome sever may need restarting. Click [REOPEN] on the dome gui if the clock is not the same as the CHARA time.
It is typically dark enough to lock on your first star if TT reports ~ 1000 counts while not point at anything (sky counts) with the SpyCams turned off. This is roughly around 20 minutes after sunset or the time of twilight reported by Cosmic Debris. Here are instructions for slewing to a target and initializing the telescopes on a bright star at the start of the night:
Acquisition Laser Alignment if the star does not lock in Tiptilt on the ACQ window cross hairs
Finishing the slew sequence
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The End Night sequence on Cosmic Debris can be used to end observing and stow the telescopes, carts, and domes. It will only stow the active scopes, carts, and domes, so if there are other scopes open, make them active in the Configure tab of CD or stow them manually with the procedure below, 6.4 Manually Stowing the Telescopes
A list of observed targets and an Observing Report is now automatically generated as part of the End Night Sequence. Click [END NIGHT], then [REPORT] on Cosmic Debris to generate this automatic report email. The report will include the headings: PI name, Program, Observers, Baselines, Weather and Seeing data, and targets on which data was collected. Complete the Observers and Baselines entries, add comments to the bottom of the report and put your name at the end. Check with the observer for completeness of the target list. Some observers will send you comments of their own. Add those to the report. Cut and paste this into an email to CHARA Obs and send it. When the function works, you can also hit the SEND button at the bottom of the report to email this report to the CHARA OBS list.
Note: Classic, CLIMB, FLUOR and PAVO will automatically send the target information to Cosmic Debris after data is acquired. For MIRCx, the [DATA ACQUIRED] button can be clicked on Cosmic Debris after each data sequence is finished or it can be done by the MIRCx operator from his or her station.
If you have other technical information to send out that is not related to the nightly observing runs, use our other lists that pertain to the subject at hand.
In addition to paper observing logs, CHARA offers the option of using electronic logs. At minimum, we request that you fill out the date, UT time, target name, and any comments that would be relevant for subsequent reduction. This information will be useful for building and maintaining the CHARA archive:
CHARA Electronic Logs
It is important to make sure the array gets shutdown properly at the end of the night. This includes stowing the telescopes, closing the mirror covers and domes, powering down equipment, and covering the cameras. Each day many employees are working on various systems from any number of diﬀerent locations around the Array. Any CHARA equipment left on or exposed, can cause damage to other systems or be damaged itself. It is critical that the array is shut down consistently from night to night. Listed below are the procedures for shutting down the array. Please make sure that the Array is secure at the end of the night.
Close vacuum lines and turn off pump
In the computer area of the lab:
Go inside the lab with booties:
Back in the Control Room: