Computing support

The Observatory has two computer-equipped classrooms with Linux desktops and a number of PCs to control our telescopes and astronomical cameras.  We have local printers for student use and user data is held on a central server and backed up daily. Files can be recovered by the system administrator up to six months after deletion.

The Linux-based computing resources at UCLO are accessible over the internet via remote login. If you have any issues regarding hardware or software please contact Thomas Schlichter, the UCLO Computing and Instrumentation Officer.

The use of our computing resources is governed by UCL rules and regulations. Please note that misuse may lead to a withdrawal of access.

Printing

The UCLO printers can be accessed from Windows and Linux via the usual print dialogues. Command line printing is available under Linux.

Library Printer

The Library houses a Xerox AltaLink A3/A4 colour printer and copier, with UNIX print queue name uclo_liblaser for stapled A4 B/W prints. Please see the UCLO system administrator if you need colour printing.

3rd-Year Classroom Printers (South Wing)

The default printer is an A4 black and white laser printer with UNIX print queue name ulo_swlaser.

Printing from the Command Line

The print system recognises a large number of file types and will print them correctly without additional user specification. For example, to print a file named test.jpg from the command line to the laser printer in the library, type:

  lp -d uclo_liblaser test.jpg

This will do all the necessary conversions and send the file to the selected printer. If the destination printer is omitted, the file will print on the default printer.

Remote Access to the UCLO Linux Cluster

By default, remote access to all UCLO accounts is disabled, for security reasons. However, any user with a UCLO account can request authorization for remote access by sending an email giving their name and UCLO username to the UCLO system administrator. You will normally then be added to the list of remote users within a day or two (and will be sent an email confirmation when this has been done).

[Please note that UCLO accounts are normally only available for students undertaking coursework at the Observatory; and that only the GNU/Linux system – not Windows accounts – can be accessed remotely.]

Remote Logins

From Linux/Unix:

To login from a Linux machine, type in the following at the command line:

  ssh -l “your_uclo_username” -C -X unity.ulo.ucl.ac.uk

(where, of course, you should substitute the appropriate value for “your_uclo_username”). You’ll then be prompted for your UCLO password.

To run applications you need to ‘hop’ to URANIA by typing

  ssh -X urania

You’ll be prompted for your UCLO password again and can then start your applications on URANIA.

From Apple Mac OS X:

To run X-Window applications remotely on a Mac you need to install XQuartz. To enable remote running of OpenGL applications like ‘nightfall’ issue the command below in a Mac terminal (put the two lines below on a single line, followed by ENTER): 

  defaults write org.macosforge.xquartz.X11 enable_iglx -bool true

For XQuartz 2.8.0 and later settings have changed and you should enter this command (again, all on a single line followed by ENTER):

  defaults write org.xquartz.X11 enable_iglx -bool true

You can find more detailed and up-to-date information here.

For logins from machines running OS X, use:

 ssh -l “your_uclo_username” -C -Y unity.ulo.ucl.ac.uk

(where, of course, you should substitute the appropriate value for “your_uclo_username”). You’ll then be prompted for your UCLO password.

To run applications you need to ‘hop’ to URANIA by typing

  ssh -X urania

You’ll be prompted for your UCLO password again and can then start your applications on URANIA.

From Microsoft Windows:

To login from an MS Windows machine you need to have a Secure Shell (SSH) Client (like PuTTY) installed.

For graphical output you’ll also need an X-Window server running on your machine like XMing; download and install the latest Public Domain Release (currently version 6.9.0.31, direct download link here).

Start XMing first, it runs in the background and does not open an application window. To check if it’s running look for the X-icon in your icon tray. Then start PuTTY and select SSH login. You need to set the address to

  unity.ulo.ucl.ac.uk

and  enable “X11 Forwarding” and “Compression” before connecting to allow the display of graphical output (select Connection → SSH → X11 and tick the checkboxes) 

To run applications you need to ‘hop’ to URANIA by typing

  ssh -X urania

You’ll be prompted for your UCLO password again and can then start your applications on URANIA.

Running programs remotely

Doing your data processing or other compute-intensive tasks on URANIA avoids heavy loads on the UCLO login host UNITY and keeps it responsive for all users. URANIA is configured the same way as the UCLO desktops, but will not be switched off arbitrarily.

Remote File Copy

File copy uses SFTP, the Secure File Transfer Protocol and you don’t need to ‘hop’ to URANIA..

FileZilla is a graphical user interface for file transfer and can be downloaded and installed on Windows and Mac OS X. On Linux you can use the package manager to install it.

On MS Windows machines you could also install an SFTP client like WinSCP.

A command line alternative on computers running unix-like operating systems (such as Linux or OS X) is the sftp command:

  sftp unity.ulo.ucl.ac.uk

or

  sftp “your_uclo_username”@unity.ulo.ucl.ac.uk

All telescope data is archived on the central Linux server under the path

  /ulo/data

In case of access problems contact the UCLO system administrator.