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Remote Observing

Note: As of June 2018, we are using a new remote observing procedure. Details can be found here: and a full description of the remote observing system can be found here:

Last updated 2-13-2023 by Norm

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, initializing the scopes, and perfoming beacon alignments and sky flats. 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 operating beam combiners and 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 something wrong occurs with the OPLE carts, cameras or telescopes, this will require immediate attention and notification on Discord. If there is no response from the operator, place a phone call to the CHARA Array Control Room.

Pre-Observing Communications

Please submit your configuration request to this new form at least two days prior to the beginning of your scheduled observing time with the following information. It replaces the previous email to

  • Date of program start and number of nights. Please specify local dates for all observations
  • Program PI and designation
  • Beam Combiner(s)
  • Telescopes used in first configuration and back up scopes or configurations. Please do not 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 and align beacons in the proper part of the sky
  • Filter or prism desired if using MIRCX/MYSTIC. H, K or J for CLASSIC/CLIMB
  • Any special requirements you might have (LDCs in or out, CLIMB for fringe finding/tracking, scope dichroic, lab tiptilt, etc)
  • Discord or phone contact if remote (in case we do not already have it). Discord is the preferred means of communicating so please create an account if you do not have one or ask for an invitation to the CHARA Discord group. We use night-time operations as the channel for remote observers.

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 local dates will help avoid confusion. Please advise the staff if the configuration is not decided upon before the evening so they don't align to an incorrect setup.

CHARA now uses Discord for communication between remote PI's and operators. Be sure to ask for an invitaion or create an account before your night. On the first night of your run, please contact the Array Operator via Discord in the night-time operations channel at least half an hour before sunset if you are observing remotely. Those needing to align MIRCX/MYSTIC or use STS can message in earlier to see when the lab is available for STS use. 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.

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. Your observing success may depend on how the weather is cooperating so have back ups for clouds, wind/poor seeing, etc. 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

HPWREN cameras on the 150 foot Solar Tower 360 degree view around the mountain

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

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

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

CHARA telescopes spy cams and weather graph ( Not updated.

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 Array is stable and ready. 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. Also, the remote observer will need to establish a connection to the array with a vnc. You should have the info provided by Jeremy Jones.

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)
  • PAVO and SPICA 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 server GUI has a STATUS tab. The Status gives the observer information about the current status of that particular system and displays the same info as the server. Since the servers are all run from the Mountain, the status display can be run on the following systems that have a STATUS GUI option to use.

  • OPLE

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, (PAVO is always 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.

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. Set up can be continued as beacon alignments and sky flats are performed.

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, notify the observer.

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 track 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/s then need to be placed to allow room for them to track between 0-44m. If the moving cart is out of this range, change the reference cart position to accommodate the moving cart/s or check if the pops are set correctly if no delay is available on any delay line.
• 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 5 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 for the CLASSIC, CLIMB, PAVO, and JOUFLU programs. MIRCX/MYSIC now use the FT buttons fro fringe tracking.

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 scopes are locked on the stars and carts are tracking, the Remote Observer can start fiber mapping, camera aligning, searching for fringes and taking data. If problems occur, notify the observer.

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. Please give the PoP's for only the telescopes that need changing. Use this format: E1-1, E2-2, W1-3, etc. Give only the final PoP.

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. If a scope runs out of delay, please inform the operator if you want the star to be locked on subsequent slews or if the scope can be put away for the night.

Monitoring MIRCX/MYSTIC observing

When running MIRCX/MYSTIC, the operator may want to have the windows open to follow the fiber mapping, scanning for fringes and data recording. The windows can be opened with the command mircx_launch_all_guis on a desktop terminal. It will open 5 windows for each combiner, but they do not need to all be open. Close what you don't want to monitor. The fiberexplorer, gdt, rtd, and super_gtk windows are most helpful.

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.

chara/remote_observing.txt · Last modified: 2023/02/13 16:59 by charaobs