GBT Remote Observing Manual
Make sure to email the GBT telescope operator (email@example.com
day before you are schedule to observe to let him that you will be doing
the observing (and remotely) and at what telephone number you can be reached.
This starts 30 min. before the scheduled start time.
See Remote Observing on the GBT
for detailed instructions.
-You need two programs to do remote observing:
1) A Terminal Emulator such as Terminal, X11 or Putty
2) A VNC viewer. "Checking of the VNC" for macs (download from here
). For PCs use TightVNC or RealVNC.
1.) SSH to GB.
On your computer open a terminal or xterm and ssh to stargate.gb.nrao.edu first and then to tiania.
computer % ssh firstname.lastname@example.org [enter password]
stargate % ssh titania [enter password]
2.) Start the VNC Server
Now start the vncserver on titania with the right geometry for your screen.
titania% vncserver -geometry 1200x800
- Make a note of the number it returns, i.e. ":3". This is your display number that you'll need later on.
- The "-geometry 1200x800" tells the VNC Server how large of a window you want. You might have to play around with this to figure out the best window size for your computer.
- To stop the VNC server type:
titania% vncserver -kill :3
3.) Start SSH tunneling
- Make sure you use the display number for your session (that was given to you when you started the VNC server)
computer%ssh -N -C -L 590#:titania.gbt.nrao.edu:590# email@example.com
4.) Start the VNC viewer on your computer
- Start "Chicken of the VNC" (or the PC version).
- Open a new connection.
- Put the right vncserver session number in the "display" box and then "localhost:590#" (where # is your vncserver session number) in the server/host type.
- It should ask for your password (this is your VNC password), and then a window should pop up. I would not run it in "Full Screen" mode, so click on "cancel" if it asks.
If you are using a Mac then you might have to modify the way the mouse
buttons working "Chicken of the VNC". To do this go to "Connection" and
"Connection Profiles". Click on the "Emulation" tab. The way I have it set
up is "Center Mouse Button=Modifier Click", Modifier Key=Option,
"Right Mouse Button=Modifier Click", Modifier Key=Command. So you need to
hold down the option key and click to do a center click and hold down the
command key and click for right click.
If the window does not open
There might be too many displays running with the vncserver. If the display number
that you got is larger (9 say) then that's probably the problem. You'll need to kill
all the other displays that are running (and sending signals nowhere). Do the following.
Run the kill command
vncserver -kill :#
, substitute the # for the display number) on all
display numbers less or equal to yours
all the way down to 1. So if your display number is 9 then kill 9,8,7,6,5,4,3,2,1. Then
try going through the above steps again to start the vnc window.
5.) Start "Talk and Draw" so you can chat with the operator.
b) Start the "Talk and Draw" program
titania% cleo talk_n_draw
-In 10-30 seconds a new window should open up that with the "Talk and Draw" program.
-The top part of the panel shows what people have written
-To communicate type in the bottom panel and hit return. You should see the text appear in the top panel in your corresponding color.
-I like to have the chat window show up on all dekstops. To enable this, click on the button in the upper-left hand corner of the chat window and select Desktops->to all desktops. Now it should appear in all desktops.
6.) Start Astrid, after confirming with operator that it is ok to start observing.
titania% astrid &
7.) Start gbtstatus.
- When it starts up it will ask you which mode you want to run it in. Select the last option "Working online with control of the telescope".
- There are several ways of doing this. I normally use option 1.
Option 1.) Using the Cleo "Status" and "Scan Coordinator" windows.
(b) Under the "Launch" menu select "Status". That will bring up a fancier version of the
(c) You can also start the "Scan Coordinator" by selecting "Scan Coordinator" from the "Launch"
menu. This gives you more information about each scan, such as the file it's writing to
and the time the scan was started and finished.
You can make any cleo window smaller by pressing CTRL+ALT+"-" or larger by pressing CTRL+ALT+"+".
Option 2.) For doing this on the VNC, simply type
in a terminal window on the VNC.
Option 3.) There is a gbtstatus tab in Astrid that gives the same information.
Option 4.) For doing this on your own computer:
computer% ssh firstname.lastname@example.org
b) Start the gbtstatus program that tells you what the telescope is currently doing.
8.) Start GBTIDL.
- Start a new terminal in the VNC (probably on a new desktop) and start gbtidl.
a) Start gbtidl
b) Once you've started observing type "online" so we have access to the current data
(titania) GBTIDL> online
c) Type "summary" to see a summary of the scans that have been observed.
d) Type "getfs,scan_number" to view a scan (replace "scan_number" by the actual scan number in the first column of the summary output).
SETUP THE DAY'S MAPPING SCRIPTS
- We are using very large RALongMap mapping scripts that should run for many hours.
- Before a session a new mapping script for that session needs to be created and saved to the database. This is quite simple and normally means just making a copy of the script from the last session and making some small edits.
- Check the logbook and see where the last session left off and the new mapping script on the next scan.
- Make sure that there are enough scans to last for the entire session. Setup takes about 20-30 minutes and each scan takes a little less than 18 minutes.
- We want to balance every 5 scans/rows and use the closest balance position (one every degree).
Now that we're all set up we can start observing.
1.) Enter in the information our project and observing session
b) Enter session number (should have incremented automatically)
c) Select your name under "observer" (it's ordered alphabetically by the first name).
d) Select the current operator. I normally have to ask them what their name is in
the "Talk and Draw" window. BEWARE, there is a bug, you can't select the first
name unless you select another one first.
2.) Start feeding it scripts!
-This is the general order of an observing run:
VIEWING SPECTRA WITH GBTIDL AND ASTRID
There is a new feature of Astrid that allows you to view the raw spectra. In the
"Data Display" tab there is a new tab called "Spectra Line Beta". It should show you
the latest raw spectra. You can select Reference/Cal, Signal/Cal, Reference/No Cal, Signal/No Cal
and the polarizations (XX or YY). I've been viewing Reference/Cal and both polarizations.
This gives you a good sense of the baselines.
You'll want to view the data every once and a while. When in GBTIDL make sure that
you are "online" if you haven't done so already. Type "summary" to view the scans
that are completed.
To View a scan type:
GBTIDL> getfs, ##
where ## is the scan number. By default it plots the whole scan at once, with
polarization 0 or YY. You can select a specific integration (one of 37 per scan)
by adding "intnum=##". You can also select a different polarization by adding
"plnum=#" where # is 0 or 1. For example, if you want to see scan 13, integration 15
and polarization 1 (XX) you would type:
You can box average channels by typing:
GBTIDL> boxcar, ##, /decimate
where ## is the number of channels you want to box average. I normally use 7, because
that brings the resolution to ~1 km/s.
To take out the baseline you want to select the regions first that it uses to make
the fit. Type "setregion" and left click on the plot (once for the beginning and another
for the end of each region). Right click to get out. Then set the order of the polynomial
by typing "nfit,#" (3 is a good starting point). Type "bshape" to show the fitted baseline
and "baseline" to remove the baseline and replot.
For more help on any command type "usage,'command',/verbose"
There is a GBTIDL user's guide:
and full documentation:
At the end of a session, one of the bricks is likely to get cut off. To do this properly
hit the "Pause" button in Astrid. That will finish the current scan. When it's done
hit the "Abort" button and the "Pause" button again.
Let me operator know in the "Talk and Draw" window that you're shutting down. Quit
Astrid by pulling down the "File" menu and hit "Exit". Click the "Quit" button on the
botton of the "Talk and Draw" to quit that application. Hit "q" to quick gbtstatus.
Type "exit" to quit GBTIDL. Exit all terminals.
Now you need to kill the VNC server on prospero. In the terminal on your computer type
"vncserver -kill :3" where you put your number instead of "3". Then close your terminal.
KEEPING A LOG IN THE NOTEBOOK
Please keep a log in the electronic logbook on this wiki page.
If any time was lost due to technical difficulties then the telescope operator should
log this in the operator's observing log.
You can also email the helpdesk about any lost time.
(304) 456-2341 Telescope Operator
(304) 456-2346 Telescope Operator (speaker phone)
(304) 456-2275 Toney Minter
(304) 456-2302 Jay Lockman
(434) 249-6845 David cell
(434) 296-7618 David home
GB Observing Information:
GBT Staff List (with contact information):
GBT Observing Schedule Website:
How to Reduce Frequency Switched Spectra: