Remote Observing

This guide is intended to focus specifically on remote observing. Please note that the new remote observing procedures for 2017 eliminate operating of telescopes by remote observers. This page will still explain remote operations, but understand you may not be able to do these procedures. A comprehensive overview of CHARA operations can be found here:
CHARA Operating Procedures

Remote Observing Protocol

The current CHARA protocol is that if Remote Observation time is allocated, the Remote Observer should be familiar with Array operations, preferably after having observed in person at the Array before. It is best if remote observers are acquainted with the software manuals and procedures and have reviewed the latest versions of these documents. Also desired for first time observers is a visit to Mount Wilson for an accompanying observing run at the CHARA Array to learn observing techniques first-hand. It is hard to understand the flow of observing if you have not seen it in person.

As a rule, the observing specialist will handle all the preparations through slewing, acquiring the target and initializing the scopes. All slewing of scopes will be done at the CHARA Control Room. Experienced observers who are present at CHARA may be allowed to slew the telescopes when multiple programs are run. Remote observers will no longer slew the telescopes. All remote observers will be limited to collecting data.

Modes of Operation

Since several beam combiners can run simultaneously at CHARA, it is important that the remote observers follow the observing procedures correctly and maintain good communication with the Array Operator (or Observing Specialist). The Array Operator will determine the priority and order in which to address problems that arise. Sometimes the Array Operator may be quite busy. If a serious situation occurs with the OPLE carts or the Telescopes, this will require immediate attention and notification on Skype. If there is no response from Skype place a phone call to the CHARA Array Control Room.

Pre-Observing Communications

Please send your configuration request to at least two days prior to the beginning of your scheduled observing time with the following information:
  • Date of program start. Please specify UT dates if observing from France or Sydney.
  • Program PI and designation
  • Beam Combiner(s)
  • Telescopes used in first configuration and back up scopes or configurations. Please don't just list telescopes and beams, give the first configuration you will be using.
  • Beam order (if you have a preference)
  • PoP combination to start and PoP changes during the night
  • First target (or designated check star for first target) so operator can init scopes in the proper part of the sky
  • Filter (if using CLASSIC or CLIMB)
  • Any special requirements you might have (LDCs, CLIMB for fringe finding/tracking, etc)
  • Skype or phone contact if remote (in case we do not already have it). Skype is the preferred means of communicating so please create an account if you do not have one.

Understand that this email is used to align the lab, set the configuration and get you on sky as efficiently as possible.
It goes to all staff who do alignments and who operate. You do not need to send it to individual staff members.
Failure to provide all of this info can cause a delay in getting on sky so please be thorough when submitting request. Also, be clear about dates when submitting requests for subsequent observing nights. Your nights or days may not match ours and giving UT dates will help avoid confusion.

On the first night of your run, please contact the appropriate Array Operator via skype or email at least half an hour before sunset if you are observing remotely. The observer work schedule is posted in the Online Observing Schedule. The operator can provide an update on the status of the array, current weather conditions, and whether there is a need to go on stand-by status or that the night is being cancelled.

Pre-Run Assessments

Due to the nature of remote observing, it is beneficial to assess a few things before the evening’s run. First would be the weather. Everything from the Weather Service page, The Clear Sky Clock and the Jet Stream can be checked to have an idea of what kind of night is ahead. Although the Observing Specialist on Mount Wilson will be responsible for these assessments, it's a good idea to check anyway. During the day, maintenance or upgrades may have taken place with the Array so look for updates via email and the Array status from the observing specialist and/or CHARA staff on Mount Wilson. Use the links below

Essential Observing Links

150-Foot Solar Tower Current TowerCam Image ( a live view of the mountain. Check the time stamp when viewing this page as the image can sometimes fail to refresh.

Caltech Millikan Library Camera ( A view of Mt. Wilson from the south, good for watching low clouds and marine layer.

National Weather Service ( Mount Wilson weather and 5 day forecast

CHARA Array weather ( Centralized weather station for CHARA.
Confirm the date and time on this page as well.

CHARA telescopes spy cams and weather graph ( Status of each CHARA telescope. Confirm the date and time on this page as well.

Aerospace Corporation weather station ( Another local station at Mt. Wilson Observatory.

Jet stream forecast ( Monitors high level winds which degrade seeing

IR satellite loop ( Keeps an eye on storms and clouds coming in

California Regional Weather Server ( A variety of weather links

Clear Sky Clock ( 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

Remote Observing Setup

The observing specialist on Mount Wilson will run all the servers locally. Before setting up, contact the mountain observing specialist to make sure the instrument is stable and ready. At this time nothing by the Remote Observer should ever be turned on unless an "All Clear" has been given by the observing specialist. The first order is to set up the remote observing station monitors and or control panel. This is done with a background click to bring up the menu options and drop down choices for the various clients and GUI’S that will be used for the night's observing session.

The clients that we will use are:
  • OPLE PRIMARY or OPLE SECONDARY GTK (Dependent on Observing Schedule – Ask the Observing Specialist)
  • CLASSIC/CLIMB GTK (Dependent on beam combiner use)
  • Visible programs will also use the LDC's

NOTE: If a Client does not appear this means that the server is not yet running. Ask the Observing Specialist or standby for more information.

Each GUI has a STATUS button. The Status gives the observer information about the current status of that particular system. Since the servers are all run from the Mountain, it is essential that the STATUS GUI be run on the following systems that have a STATUS GUI option to use. A STATUS GUI should be used for the following:
  • OPLE
  • GPS
  • CLASSIC (or Beam combiner choice)

Cosmic Debris - The Sequencer

Cosmic Debris is the main sequencer or control panel for the Array. This is a tabbed interface and what we use to execute the commands to observe and collect data. Cosmic Debris also gives the necessary information needed for observational targets. Inputting the stars designated number, then hitting the corresponding catalog name next to the the star (for example HD, HR, SAO, IRC), and clicking WHEN, will give the AZ & EL plus sky availability and the hour angle in the CD display window. The remote observer may use Cosmic Debris to follow along with the observations. It also will list information about the observing session. For example, when going to a star it will give the status of the acquisition procedure and also any error messages. Remote observers will not use Cosmic Debris to slew.

Cosmic Debris Setup

• To set up Cosmic Debris , click on the background (or the Applications menu bar on GNOME environments) and, depending on which observing slot you fall into, click

Cosmic Debris ->Primary, or
Cosmic Debris ->Secondary

  • Once Cosmic Debris comes up, go to the "CONFIGURATION" tab up top. Then choose the 'ACTIVE SCOPES’ and the ‘REFERENCE’ cart. If the lab alignments are finished, then the Beams and PoPs should be set correctly since they are read automatically from the servers. If the Beams and PoPs are listed incorrectly, please notify the Observing Specialist.
  • Check with the observing specialist about the reference cart selection.
  • After confirming that the configuration is correct, click the [Send].
  • On the CONTROL Tab of Cosmic Debris, choose the beam combiner by checking the proper box for the instrument you will use for the evening’s observing session. If using Classic or CLIMB, also choose the filter.


• Check the TIPTILT STATUS GUI. If it reads that the selected beams are correct for the combiner you’re using, then all is well.
• If not, notify the Observing Specialist so that they can run the TIPTILT COMM sequence again. [TIPTILT COMM] is a button on Cosmic Debris. When selected, Cosmic Debris will put 7 items in the job queue and then run them. If the communication is established there will be messages in the status window of the Cosmic Debris indicating signal rates for tiptilt for the chosen telescopes.

Synchronizing the Clocks

Will be done by the observing specialist at start up using [SYNC CLOCKS] function on Cosmic Debris.

System Check

The observing specialist on the mountain will have opened up the telescope enclosures, dome slits, and optics covers, as well as have things powered up. Anytime the telescopes are open and used it is important to keep a watchful eye. Weather conditions may change and, on occasion, telescopes may move in unexpected ways. The Remote Observer should ALWAYS remain at the control station while the telescopes are slewing. Also, keep an eye on the azimuth and elevation of the telescopes while they are in motion. The telescopes can be watched visually by using Spycam 1 (‘SPY1’) to make sure things are moving correctly on the first slew. The declination should never go below 15 degrees. If a situation arises and one must leave the control room for other issues, make sure the scopes will not track into the ground during this time. Once the confirmation has been given from the observing specialist, you can begin to acquire the first star.

First, make sure that all telescope optics covers are open. Visually check the ones you can by using ‘SPY1’ and ‘SPY2’.
Next, make sure the telescopes being used are in their parked positions. Check by referring to the telescope STATUS GUI AZ and EL positions. For each telescope, the elevation should read 90.0, and ‘SPY1’ should show the end ring of the telescope framing the top of the open dome. The azimuth values should read the following:
Scope Azimuth
S1 and S2 82.0
E1 and E2 55.9
W1 and W2 99.3

Finally, check the POWER GUI to make sure that the AZ and EL power is on, denoted by the color green. It is suggested that one double check the Cosmic Debris Setup steps (see [ Cosmic Debris], page 7). If any of these steps do not make sense do not turn anything on and contact the observing specialist for assistance.

6.7 Slewing with Cosmic Debris Note: Remote observers will no longer be slewing telescopes

Check with the Observing Specialist to find out if it is safe to slew to your first target. Often the Observing Specialist will slew and initialize the telescopes on the first target and will let the remote observer take over after all systems have been checked. For completeness, here is a list of instructions for slewing and aligning on the first target:

  • Find a bright star near your first target to initialize the telescopes. The [FIND STAR] button on the Telescope Control Tab can be useful in finding a suitable, bright star.
  • Enter the HD number of the star into Cosmic Debris using the Object or Calibrator Tabs. Click the [HD] button to register the entry. (Alternatively, you could enter a CHARA NUM, IRC, HR, HD, or SAO number and click the corresponding button.)
  • Check to make sure that EL/AZ reported by Cosmic Debris are correct (never point below 15-20 degrees elevation). It is recommended to initialize the telescopes at the start of the night on a target between 40-70 degrees elevation.
  • Slew to the target by clicking [OBJECT], [CHECK STAR], [CALIBRATOR 1], or [CALIBRATOR 2] on Cosmic Debris (depending on which field you entered the target information). Note that these buttons will slew the telescopes AND send the carts to their positions.
  • Verify that the telescopes are moving by checking the azimuth and elevation status in the telescope servers (the first set of numbers show the commanded EL/AZ of the target while the second set of numbers show the current location of the telescope). Also view "SPY1" to check that the telescopes and domes are moving. The telescopes will move to the elevation of the target first and then move in azimuth.
  • After the Cosmic Debris job queue ticks for a minute or so, the CD information window will give the ideal position for the reference cart. After this appears, hit [Stop Job Queue] to stop the job queue for the first target to make sure that the domes line up with the telescopes and to do the initial alignments. (If you already initialized the telescopes, you can let the job queue continue to automatically acquire the star.)
  • Enter the ideal reference cart position into the REF text window on the Cosmic Debris Control Tab. Click the [REF] button to send the reference cart position to OPLE. Make sure all carts are tracking. You might have to click [TRACK] for the reference cart on the OPLE Control Tab. The [OL] buttons should be depressed gray for ALL active scopes (including the reference cart). The [MAN] buttons should be depressed gray for the moving carts to allow the beam combiners to send manual offsets to the carts. (The [MAN] button for the reference cart should be green.)
  • When the telescope slew finishes, check the spy cameras to make sure that the domes are aligned with the telescope.
  • Click [FIND] on the Telescope guis to view the finder field if the star does not appear in the ACQ window. If it is off center in the finder, click [MOVE] under the TV Tracking menu on the Main Tab of the Telescope GUI and click the star to get it to the cross hairs.
  • Switch to the ACQ window by clicking ACQ on the Main Tab of the Telescope GUI. Click MOVE and the star again to bring it to the center of the crosshairs. Lock tiptilt if the tiptilt plots show you have counts. If it does not lock, follow the alignment steps below.

Acquisition Laser Alignment
  • Check availability of VISBEAMS with Observing specialist.
  • Put the Neutral Density Filter on ND 3.0 using the Laser_Filters GUI.
  • Using the SHUTTERS GUI, open the laser shutter and the corresponding B1-B6 shutters.
  • Put the corner cubes in with the [CC IN] button on the telescope gui CONT tab.
  • You will see the star and reflection and the laser and reflection in the ACQ field of view.
  • Use the "ORIGIN" paddle on the ADJUST Tab of the Telescope GUI to align the TV cross-hairs to coincide with the left laser spot.
  • Close the laser shutter and the B1-B6 shutters. Hit [CCOUT] to move the corner cubes out.
  • Hit [MOVE] under the TV tracking menu on the Main Tab of the Telescope GUI and click the left star to bring the star to the cross-hairs.
  • Initialize the pointing of the telescopes on your first target by going to the Control Tab of the Telescope GUI and click [INIT]. This may have to be repeated if the pointing drifts during the night.
  • You may need to redo the ACQ laser alignment during the night, especially if slewing far in azimuth.

Locking Tiptilt
  • With the star aligned with the acquisition ticks, check to make sure there are counts on the TipTilt server or white plots in the TT windows.
  • On the Tiptilt Servo Control GUI, turn tiptilt [ON] for that telescope.
  • On the Main Tab of the Telescope GUI, click [TIPTILT] under the Pointing Servo menu. If this button is not pressed, the telescope will not be guided by the TT servo and TT will lose the star as the pointing model takes the star out of the range of the TT mirror. It can be seen by the green dots drifting to one side on the tiptilt windows.

Finishing the slew sequence
  • If the Job Queue was stopped and the star was acquired manually, then click [Clear Job Queue].
  • Click [Star Acquired] on the Control Tab on Cosmic Debris to update the target information listed at the top of the Cosmic Debris window.
  • You can now point to your first science target/calibrator or fringe finder and begin the alignment sequence for the beam combiner and then start searching for fringes.

Automatic Acquisition Sequence Not recommended
  • After the telescopes have been initiliazed and the laser alignment has been checked, then you can let Cosmic Debris run the automatic acquisition sequence to acquire stars (by clicking the [SLEW TO] button next to the OBJECT, CHECK STAR, CALIBRATOR 1, or CALIBRATOR 2 fields).
  • The automatic sequence will slew the telescopes, start ATROLIB, and send the moving carts to the proper positions. The sequencer will check to see if the star is in the acquisition/finder fields and grab the star. It will also lock tiptilt and update the "star acquired" information.
  • If an error comes up, the job queue will stop. After the issue has been fixed, the job queue can be restarted to continue the sequence, if it was not cleared.
  • After the stars are locked in Tiptilt, the flux values look good, and the carts are tracking, then everything should be set.

6.8 OPLE Cart Operation
While operating the OPLE carts, the remote observer should keep an eye on the delay lines as much as possible. Do not change the direction of the carts too quickly. When moving them, click STOP, wait, and then restart them. Also watch for warnings on the OPLE server STATUS display. If the FH= Front Hard or BH = Back Hard lights up it means the hard limit switch has been contacted by the cart, and the observer needs to notify the Observing Specialist and turn the carts OFF. If you suspect that the carts aren’t moving, or are stuck, or are not moving at the correct speed, IMMEDIATELY stop and notify the mountain staff.

Checking the Cart Positions
• The reference cart is stationary. Astrolib will give a TARGET position of where the Ref cart should be. When this position is set the other cart should come into range leaving plenty of delay space to slew through. If not, recheck or reset the REF position.
• For example, Astrolib gives a TARGET position of 30 Meters. The reference cart should be set to that position give or take. The moving cart then needs to be placed to allow room for it to slew between 0-44m. If the moving cart is out of this range, change the reference cart position to accommodate the moving cart.
• On Cosmic Debris, type in the reference position in the empty field next to the ‘REF’ input. The empty space next to this is for controlling the speed of reference cart, which we shall leave alone for now.
• The position that was just set will register in about 10 seconds on the OPLE server STATUS display under ‘Target’.
• Once the REF position has registered, the carts can go into place by clicking TRACK on the OPLE GUI.
• Once each cart has reached its position and the ERRORS are low, everything is set.
• Also once the carts are tracking, click the ‘MAN’ and ‘OL’ buttons for the moving carts and the OL button for the ref cart.

6.9 Routine Observing

It is at this time that you can settle down to the standard, and sometimes mundane, part of observing. Not to be taken for granted, data means WINNING!!! As soon as the carts are tracking and the Tip Tilt beams are locked, the Remote Observer can start taking data. Remember the Array is made up of many systems and at anytime one could falter. As Array Observers, it is most pertinent that we keep watch 100% of the time. If problems occur notify the Mountain Staff. When trouble arises proceed slowly and carefully. Don’t forget to check the CHARA Array Control Software Manual or in the worst case scenario call the CHARA Control Room.

6.10 PoP changes during the night

It is proper protocol for the PI's or remote observers to announce any PoP changes 10 minutes before needed so the operator can bring up the required windows and look up the values for the change. Please give the PoP's for only the telescopes that need changing. Use this format: E1 3 -> 1, E2 3 -> 5, W1 5 -> 3, etc. Give the current PoP and the desired PoP.

6.11 Configuration changes during the night

It is also proper protocol for the PI's or remote observers to announce any configuration changes 30 minutes before needed so the operator can open telescope domes and have the scopes ready for the change. Failure to announce changes causes observing time to be lost. Please also include additional configurations in your set up request.

6.12 Nightly Observing Report

The Observing Report is automatically generated by Cosmic Debris at the end of the observing. Check the report for completeness and accuracy and inform your observing specialist if there are notes which you would like to have added to the report.

Last updated 2017-7-21