Remote Observing with CHARA

For remote observing, we are running a virtual machine on the CHARA server in Atlanta. The machine runs all the graphical user interfaces (GUIs) for the control software that is used in remote observing. These GUIs connect to their respective servers on Mt. Wilson using a process called SSH port forwarding (often referred to as SSH tunneling). This virtual machine also runs a VNC server so it can be accessed from anywhere. This system is currently functional and has been used for operations with all current beam combiners.

Arranging Use of the Remote Observing Machine (Pre-pandemic)

At least one week before your remote observing run, fill out this form. Shortly thereafter, you will receive an email with the address and password to use when connecting. The address may change on occasion and the password will change frequently. Only observers who have been trained on the mountain will be given access to the remote observing machine. Best results are achieved when using a good internet connection on a computer using multiple monitors. We do not recommend observing from home.

Arranging Use of the Remote Observing Machine (Mid-pandemic)

During the COVID-19 pandemic, all CHARA observing will be done remotely. Two weeks before your run, you will be sent an email requesting that you fill out the remote observing signup form. Three to five business days before your observing time, you will be sent login credentials. First-time observers should seek assistance with their observing from experienced observers. Best results are achieved when using a good internet connection on a computer using multiple monitors. We do not recommend observing from home, but we do recommend that you stay safe.

Connecting to the Remote Observing Machine

  • Download and install a VNC viewer. We recommend tigervnc ( because of the viewers we’ve tested, it runs the fastest. Others do work, though.
  • If using tigervnc's viewer, run the vncviewer command. This should open a window that looks like this:

tigervnc viewer connection window

  • Input the address you are given into the "VNC server" prompt. This should bring up a password prompt. This will connect you to the Atlanta remote observing machine.
  • If you get the error "unable to connect to host: Connection timed out (10060)", you are likely behind a firewall and should try again from another network or get in touch with your IT people to open up the 5900 range of ports (5900-5999).

remote machine desktop

Notes on tigervnc

  • tigervnc only allows one active viewer at a time to connect, so if you want multiple connections to the Atlanta machine, you can use the “view only” password (given upon request), but as the name suggests, that only allows you to view what the active user is doing.
  • The tigervnc VNC viewer can be spread out over multiple monitors and made fullscreen. Use the F8 key to open the context menu to see more options and to exit out of fullscreen.

Check the SSH Tunnel

  • The SSH tunnel should start automatically at 4pm Pacific time and disconnect at 8am.
  • If the SSH tunnel is not connected, GUIs will either not open or will be riddled with errors due to the fact that there is no communication between GUIs and their servers on the mountain.
  • To confirm that the SSH tunnel is running, run the Check SSH Tunnel script from the desktop icon or the Applications/CHARA menu.

tigervnc viewer connection window

  • This script will tell you whether the SSH tunnel is running or not and give you the option of starting or stopping it.

Setting Up

The following GUIs are available for use and accessible through the Desktop icons or the Applications/CHARA/ menu:

  • Cosmic Debris (primary and secondary)
  • OPLE (primary and secondary)
  • Telescope Launcher - select the telescopes you are using to run smaller GUIs than what you see at the Array that allow less control, but take up less screen space
  • Classic
  • CLIMB (1 and 2)
  • JouFLU
  • MIRCx (server, rtd, sequencer, and gdt)
  • PAVO
  • VEGA (power, tracker, detectors, ics, and central control)
  • Pico 7 Controller
  • Shutters
  • Tiptilt
  • Visbeams
  • Weather
  • Lurkgtk - a compact view of the AO system that allows monitoring, but no control

Because the remote observing machine is not on the same network as the computers on the mountain, you will not be able to ping any mountain computer with the exception of michelson. Proxy commands have been set up for the mircx, pavo, and pc-ctrlvega machines, so you can ssh into those directly (e.g., ssh This email address is being protected from spambots. You need JavaScript enabled to view it.), but for all other computers, you must ssh into michelson first.

VEGA Users

The remote desktop program is needed to connect to three different windows machines on the mountain. Because they are all using the default port for remote desktop, we cannot add the appropriate port forwarding to the standard SSH tunnel. You will need to run a custom ssh tunnel just for using remote desktop: ssh -f -N -L localhost:4001: -L localhost:4002: -L localhost:4003: This email address is being protected from spambots. You need JavaScript enabled to view it. sleep 50000

Then, to use remote desktop for these three machines, run rdesktop -g 1000x1000 localhost:400X where X is 1, 2, or 3 for each of the three machines.

Exiting the VNC viewer

When exiting the VNC viewer, please close all windows and close the VNC viewer by closing it directly or by using the "Exit viewer" command in the F8 context window. DO NOT log out of the vroc account. If the previous user logged out of the vroc account, you will see only a black screen when you connect.

Links for Current Conditions on Mount Wilson


Below are some potential issues that occur with the remote observing system and their solutions.

  • Windows on the VNC desktop cannot be moved or resized. However, they can be opened/closed.
    • Solution: Enter the command xfwm4 --replace &. This will refresh the desktop environment and should solve the problem.
  • Keyboard input is "weird" - as if the ALT key is being held down. For example, the "m" key enables move mode for the active window. This suggests the VNC viewer's "ALT mode" has been inadvertantly toggled.
    • Solution: Press F8 to open the VNC viewer's context menu and toggle the "ALT mode". This may need to be done twice.
  • The screen is totally black when connecting to the VNC server. This happens when a user attempts to log out of the vroc account.
    • Solution: Restart the VNC server.
  • MIRC-X guis running very slowly, but everything on the desktop (moving windows, typing in terminal, etc.) responds normally.
    • Solution: Check that you have opened the guis on the VNC machine and not the mircx machine. One way to test this is to close the guis and reopen them using the desktop icons or open a new terminal and run mircx_launch_all_guis.


Please direct any questions to CHARA Data Scientist Jeremy Jones (This email address is being protected from spambots. You need JavaScript enabled to view it.)