Remote Observing with the Arecibo Telescope

The following protocol has been devised for remote observations with the Arecibo telescope. Users should also consult the accompanying on-line manual to the graphical user interface which is available at the following URL: http://www.naic.edu/~cima.html. For pulsar observers, there are detailed instructions for the use of the CIMA/WAPP combination in pulsar mode.

Getting an account at Arecibo

The most important thing to be able to observe remotely with the Arecibo Telescope, is, of course, to have an account at the Arecibo Observatory (AO), otherwise, you can't do any of what is described below.

• If you don't have an account at AO, and wish to have one, call Arun Venkataraman at extension 340, or email ‘arun’ (at naic dot edu). Explain clearly why you need an account, and when your observations are scheduled.

To gain access to your account at AO, type

> ssh -X ⟨username⟩@remote.naic.edu

The ‘-X’ switch sets up all the environment variables relevant for the transmission of graphics across the link. If this does not work try ‘ssh -Y ...’ instead of ‘ssh -X ...’.

Using VNC at Arecibo Observatory

By far the best way of running complex graphical interfaces on any remote computer is to use vnc. This applies to almost any work you might want to do at AO, but it applies particularly to observations with CIMA and any setup or practice you might want to do with the offline version of CIMA. Apart from the fact that vnc will make things go much faster (it uses bandwidth very efficiently), it is also robust to temporary disruptions of your (or AO's) internet link.

Setting up the VNC session

If you have logged into AO remotely, you will now be on the ‘remote’ computer. Don't be surprised if it doesn't show the name ‘remote’ on the command line. From this compute your should run:

> ssh dataview

On dataview, type

> 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 or 1500x1100, etc). It is best to make it slightly smaller than the resolution of the monitor that you are working on, however the size should not be much less than 1000 in either dimension to ensure that all parts of CIMA can be accessed.

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

The command above will return something like:

New 'dataview.naic.edu:48 (⟨username⟩)' desktop is dataview.naic.edu:48

Note the '48' on this line, this is the vnc desktop number

For Linux

Back at your own local computer, type

> vncviewer -via ⟨username⟩@remote.naic.edu dataview:N

(where N is the vnc desktop number you're using, i.e. 48 for the example above).

This assumes you're using a regular version of linux. For some Linux versions, the -via option is not available so you will need to make an SSH tunnel as described below for a Mac..

For Macs

Before trying to connect, you will need to install a vncviewer (e.g. Chicken of the VNC or something similar). Having installed this, open a terminal or x11 window and run:

> ssh -f -L 59MM:dataview:59NN ⟨username⟩@remote.naic.edu sleep 14400

where, NN is the vnc desktop number from above (including a leading 0 if necessary), and MM (again including a leading 0 if necessary) is the local desktop number. If you get an error that the local port is not available, then that local desktop number is already in use - try changing MM to a different number. For example, if vncserver has returned desktop number 39 on dataview, you could forward that to desktop 1 on your lcal machine using:

> ssh -f -L 5901:dataview:5939 ⟨username⟩@remote.naic.edu sleep 14400

(note that desktop 0 is the main display - you will not be able to forward to this!)

On entering this command, you will be asked for your Arecibo account password and will then return to your command prompt on your home machine. Next open your vncviewer (click the icon) and create a new connection to display M on the host 'localhost'. On Chicken of the VNC this is under

     Connection > New Connection..

Versions of Linux that do not include the -via option

You should use the same ssh line as above for a Mac to forward the desktop from dataview to your local machine, then run:

> vncviewer localhost:M

For Windows

Before starting, you should download and install Tight VNC (a vnc viewer) and Putty (an ssh client).

Running Putty, set

     Session
        Host name              = remote.naic.edu
        Protocol               = ssh
     Connection > data
        Auto-login username    = ⟨username⟩
     Connection > SSH > Tunnels
        Source port            = 59MM
        Destination            = dataview:59NN

In TightVNC you should now open a connection to

     localhost:M

You'll be asked for two passwords; the first is your regular AO password; the second is the vnc password you created when you first ran vncserver.

Running CIMA on the VNC desktop

Now you should have a big window on which you can open xterms, and start CIMA. To start CIMA you should log onto observer2 as dtusr, using:

dataview> ssh dtusr@observer2

and using the dtusr password that you will have got off the telescope operator.

Once logged onto observer2 in an xterm, you can start cima by simply typing:

observer2> cima

CIMA will then prompt you for what version you want to run in the xterm window. 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 (unless sound is not supported or is disabled in 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’ box on Chicken of the VNC. 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 in a terminal window and close the VNC desktop down using:

> vncserver -kill :N

(where N is the vnc desktop 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.

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 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 and other monitoring programs.