Remote Observing

Scientist Tools

The following protocol has been devised for remote observations with the Arecibo telescope. These are instructions on how to connect to the telescope control system remotely, not instructions on how to observe with the telescope. Users should also consult the on-line manual to the user interface. Pulsar observers should also see the instructions for the use of CIMA with the WAPPs in pulsar mode or the PUPPI.

Arecibo computing accounts

To observe remotely with the Arecibo telescope, you will need an account on the Arecibo computing system.

If you have used Arecibo in the past you should already have an account, but if you have not used it for a while then it may have been suspended. You should check that you can log into you Arecibo account at least a month before your observations using:

> ssh ⟨username⟩

If you do not know how to make an ssh connectio to Arecibo, please see the OS-specific instructions below.

If you do not have an Arecibo account, or cannot access your account then you should contact Arun Venkataraman by emailing arun at naic dot edu or on 787-878-2612 extension 340 at least a month before your observations. If your account does not work and you have not contacted Arun to enable it, you will not be able to carry out your observations.

Using VNC at Arecibo Observatory

VNC (Virtual Network Computing) is a platform-independent system for viewing and controlling a remote graphical desktop. This makes it ideal for using the CIMA user interface at Arecibo, both in online (controlling the telescope) or offline (preparing setup) mode. VNC makes efficient use of bandwidth and is robust to disruptions of your internet connection to the Observatory. VNC viewer clients are freely available for most major OSs, including Windows, MacOS, Linux, Android, iOS and ChromeOS.

Setting up the VNC session

Before you can connect to Arecibo using VNC, you will need to start a VNC session on a computer at Arecibo. When you log on to the Arecibo system, you will normally use or You should not be surprised if this is not the computer name shown in the command prompt, these are aliases used from outside. These ‘gateway’ machines are not particularly powerful, they exist to provide a link between the outside world and Arecibo, not to run programs. Many programs, including aostatus and vncserver will not run on these machines. You should therefore log onto another machine before running your VNC session; for remote observing the machine normally used is ‘dataview’, one of the observer's machines in the control room. You should log onto this using:

> ssh dataview

On dataview, you should start your VNC session by typing:

> vncserver -geometry 1280x1024

The geometry parameters can be anything you like (they don't have to be ‘normal’ values like 1024x768 etc. They can be 1200x900, 1500x1100, etc). I like to set it up so that it fills my screen when running in full-screen mode, however the size should not be much less than 1000 in either dimension to ensure that all parts of CIMA can be accessed.

The computer should return something like:

New ' (⟨username⟩)' desktop is

Note the ‘48’ on this line, this is the display number on which your VNC session is running. The port number (which you will need with some VNC viewers) is 5900 + this screen number, so 5948 in this example.

If something else happens

If the computer replies “vncserver: program not found”, you need to make sure that the directories /bin and /usr/X11R6/bin are in your path. You can check this by typing:

> echo $PATH

This will print out a list of all the directories in your path – this is where the computer looks to find programs. If /bin and/or /usr/X11R6/bin are missing, you should contact Arun (see above for contact details).

If this is the first time you have run vncserver at Arecibo, the computer will ask you to set a VNC password. As you may want to share this with others who will join your session (observatory staff giving assistance, students being trained, collaborators looking at data, etc.) you should not use the same password as you use elsewhere.

The computer will also create the (hidden) .vnc subdirectory of your home directory at Arecibo. You can change to this directory using:

> cd .vnc

from your home directory (where you start when you log in). There are a couple of important files in this directory. The first is ‘passwd’ – delete this if you want to change your VNC password, you will be prompted for a new password when you next run VNC server. The other is ‘xstartup’ – this contains default settings for you VNC session.

Connecting to your VNC session

Dataview is not visible from outside the Arecibo network. In order to connect to your VNC session on dataview, it is therefore necessary to make a ‘tunnel’ to pass the data through remote. Some VNC viewers have this functionality built in, others require you to setup the tunnel manually (using SSH) and then connect to the forwarded VNC session on ‘localhost’ (your machine). The following section describe how to do this on various different OSs.

Running CIMA on the VNC desktop

Having connected to your VNC session at Arecibo, you now have a remote desktop on which you can open terminal windows and start CIMA. You will normally start with at least one terminal open. To open others you can type ‘xterm’at the command prompt of the terminal you have open; you can reight-click the background and open a terminal window from the menu that appears (it may be called something slightly different, look for something like ‘xterm’, ‘terminal’ or ‘console’); or (on some X windows managers) launch it from a bar at the bottom or side of the screen.

In a terminal window, you should logon to observer2, the machine that actually provides control of the telescope. You will need to have obtained the password from the operator for this, the password is changed regularly so do not rely on one you had previously still working. Logon from dataview using:

> ssh dtusr@observer2

If you try an login using your own account, you will not be able to run the online version of CIMA and therefore will not be able to control the telescope! Once logged onto observer2 as dtusr (data taking user), you can start cima from your terminal on observer2 using:

> cima

CIMA will then prompt you in the terminal window for the version you want to run. You will have to wait for the previous observer to quit, and may get a message to this effect. If the previous observer has not quit CIMA and your observing time has started, you should phone the telescope operator, who can kill a previous CIMA session that has been left running at the end of an observing session. When CIMA starts, you will first be prompted for your name, project ID and telephone number; once these have been supplied the telescope operator will grant permission for you to start.

In addition to all the usual features of CIMA, the remote-observing version has a talk window that allows you to communicate with the operator. You can use this to send messages (text only!) to the operator - simply press return and it will be sent. The operator can also use this to send you messages, you should hear a chime noise when these arrive (if sound is supported and enabled on your VNC viewer). You can use this to find out the weather conditions at AO (particularly important for high-frequency observers) and you should use it to tell the operator that you will be finishing soon shortly before you exit.

It is possible for anyone else to join your VNC session,if you give them your VNC password and the desktop on which you are running. They will then be able to see all that you're doing (or do it for you) and offer advice, by following the same steps as above for their computer. If multiple people are joining a VNC session, it is important that they set their viewers to allow other viewers. On Linux, this is done with the -shared switch, while it is done by ticking the ‘Allow other clients to connect’ on Chicken (for MacOS). If this is not done, then any other viewers connected to that session will be thrown out and will have to reconnect, but the session itself will not be affected.

It is also possible to re-connect to your desktop after a temporary disruption of your link to AO. You simply need to connect again as above. Note that if you are forwarding the port (Mac, Windows and some varieties of Linux) you may need to forward it to a new local desktop number (MM in the examples above) if the connection is not automatically re-established.

At the end of the session, you exit CIMA as normal from within the VNC window and logoff from observer2. You should also close any other programs you have running on the VNC desktop before closing the VNC window itself. After you have closed everything down, you should log back into dataview via SSH and close the VNC desktop down using:

> vncserver -kill :N

(where N is the VNC display number). This will free up system resources, and will also prevent anyone who has your VNC password from using this to access your account.

You can create multiple VNC desktops by simply running vncserver multiple times. By then connecting to these separately you can have one window running CIMA that is actually carrying out the observations and a second window running data-monitoring or data-analysis to check the quality of your data.

Things to do a few days before the observation

If you are the PI on a scheduled proposal, you will be sent automatic e-mails reminding you of your incoming observation at several given intervals before the observation is supposed to occur. However, it is a good idea to contact your assigned "Friend of the Telescope" in case there is any new information regarding your time slot. You can also check the receiver status on-line to make sure everything is fine.

When does your observation start?

The times indicated in the Telescope Schedule are in Atlantic Standard Time (AST). This is:

  • UTC - 4 Hours
  • EST + 1 hour (EST is observed in wintertime in Eastern US)
  • Equal to EDT (which is observed in summertime in Eastern US).

If you have trouble reading the schedule, you can also search for your project using the ‘Current and Upcoming Schedule’ button at the top-left of the schedule page. Note, however, that this does not necessarily show times within an hour of midnight, i.e. an observation starting at 23:30 and running until 02:30 the following day will be shown as starting at 00:00 the following day only while an observation starting at 21:30 and running until 00:30 the following day will be shown as finishing at 24:00 on that day. An observation starting at 21:30 and finishing at 02:30 the followind day would be shown as two observations, one starting at 21:30 and running to 24:00 and a second on the following day starting at 00:00 and running to 02:30.

Running CIMA offline

Before observing, you can setup your observations in the offline version of CIMA from your AO account. In a vnc desktop at AO (being viewed by a vncviewer in your local computer), open an xterm and type:

> cima

to open the default version of CIMA, or:

> cima --X

(note the double dash) to choose which version of CIMA to run.

You can do this on any AO computer except observer2. It does not matter if it is a linux or solaris machine. You can use the offline version of CIMA to setup your observations and save them as a configuration file, which you can then load back in at the start of your observing session rather than setting up CIMA by hand every time.

Things to do 15 minutes to an hour before your observations

You don't need to waste telescope time doing this! You can and should take your time to do these steps BEFORE your scheduled observation time starts. When that happens, you will be much better prepared.

Have at least one vnc desktop running at AO and a vncviewer running in your computer viewing it, and open at least one xterm inside it.

Call the operator at (+1) 787 878 2612, Ext. 211, and make sure you learn what is the password for user dtusr on observer2. You should also ask him about the status of the receiver(s) you are about to use. If you don't let the operator know that you are there and ready to observe, they may allow the previous observer to continue until you do phone in. The password for dtusr changes frequently, so do not rely on knowing what it was last time you observed!

In the xterm in your vnc session, type:

> ssh dtusr@observer2

and then enter the password obtained from the operator.

Advanced - starting other monitoring windows

This will be enough for most purposes. However, if you want extra monitoring capability and a have a fast link, there are other monitoring programs that can be run. The information that is of most use to remote observers has now been rolled into the CIMA interface and the use of these prgrams for remote observing is deprecated. However, if you really want all the displays that are available in the control room, read on...

From a terminal window type:

> /home/aoui/bin/aostatus

(or just aostatus, if /home/aoui/bin/ is already in your $PATH environment variable). Like the ‘show graphically’ option in CIMA's pointing window. this shows you the present position of the telescope, but with some more variables being displayed and without the source position. See details.

You can also run:

> rxview &

This will let you know the status of the IF/LO system: sky frequencies allowed in by the receiver filters, Intermediate frequency path (from telescope to control room) as translated to a sky frequency, filter and backend frequencies as translated to sky frequencies.

IF you want to have access to the engineering screens instead, which provide detailed information on the IF/LO setup, telescope pointing parameters and tie-down status, as seen in the control room, but with a nice friendly format, then call:

> monallsm &

If you have a slow connection, you can setup the refresh time for these screens. Alternatively, you can request larger screens, exactly the ones you see in the control room. More information on other monitoring programs is available from Phil's pages.