Last modified:
Thursday, 01-Jul-2004 09:14:44 EDT
Instructions for Observing with the Spigot
Postscript and PDF versions available
Current instructions for running the spigto are available here
A. Talk to Operator
- Ask operator to put you in the gateway
- Once he/she is done with that, ask operator to slew to, and track, source
B. Start up the GBT configuration tool
- Type "source /home/gbt/gbt.bash" or
"source /home/gbt/gbt.sh" (for bash or csh)
- Type "config_tool". This starts up the GBT configuration tool.
- Type "g = gbtsetup()".
- Type "g.set_manager_on('Spectrometer')".
C. Configure front end, IF Paths, etc.
- type "CONFIGGUI"
- In the blue CONFIGGUI screen, set the following:
- Obstype = "Pulsar"
- Backend = "BCPM/ACS"
- SwitchMode = "tp_nc" {for no cal switching}
- Select the receiver (on the top right. e.g. rcvr1_2 is the L-band, 1-2 GHz receiver)
- Under "ACS mode" (far right) select desired the bandwidth (for the data, not the spigot)
- Enter the desired center band frequncy, under "Rest Frequency"
- Press the "set it up" button
D. Balance the IF Rack & Spectrometer
Back in the window where you are running the GBT configuration tool do the following:
- If you are going to run the 12.5 MHz or 50 MHz bandwidth modes:
Type "balance((9,21))." This balances the IF rack and spectrometer.
- If you are going to run the 200 MHz or 800 MHz bandwidth modes:
Type "balance((1,4))." This balances the IF rack and spectrometer.
- Check that the last lines of the screen have J9/J21 or J1/J4 values between 0.7 - 1.0
- If not, repeat the appropriate balance command. If this still doesn't work, tell the operator
you cannot get the IF & spectrometer to balance.
- If so, the spectrometer and IF path are balanced. Keep going with these instructions.
- Type "g.set_manager_off('Spectrometer')". This turns off the spectrometer manager.
E. Turn on automatic balancing
(Optional for 16-bit and 8-bit modes, needed for 4-bit modes)
- The automatic balancing monitors the power levels going into the spigot (at the analog filter rack)
and modifies the attenuators before the spectrometer (in the convertor rack)
to keep the power levels the same
- The 4-bit modes will have their power levels saturate if you do not run this.
- To start, go to an xterm window and type "bash"
- Then type "source ~pulsar/scripts/spigot.sh"
- Then, type "holdInputLevel -f" for the 200 and 800 MHZ bandwidth modes,
or "holdInputLevel -s" for the 12.5 and 50 MHz bandwidth modes.
- To stop the program, just hit control-D
F. Point & Focus - For Higher Frequencies Only
NOTE: If you are running remotely, you will likely want the operator to do this for you.
- In a new xterm window, type "source /home/gbt/gbt.bash" (if you are running bash)
or "source /home/gbt/gbt.csh" (if you are running tcsh)
- Type "gfm &"
- When the gfm window appears, go to the "File" menu and click on "Work Offline"
- Check the box next to "I want to make updates to the telescope" and hit "OK"
- In the same xterm window as before, type "GO_LITE"
- Once a new (grey) window opens (be patient, it takes a bit), do the following:
- Change "Switching Mode" to "Total Power" (left side of screen)
- Change "Observing Type" to "Continuum" (left side of screen)
- Change "Observing Procedure" to "Peak" (left side of screen)
- After "Source Name" enter the name of the continuum source you wish to point on
Good choices for pointing can be found here
- Change the "Primary Mode" to the correct epoch for your coordinates (right side of screen)
- Change the "AZ Length", "El Length", "AZ rate", and "El rate" as follows:
Band | AZ & EL Rate | AZ & EL Lengtha | Comments
|
---|
PF | | | Don't bother with this
|
L-band | 260 '/min | 130' | Pointing is likely unnessary
|
S-band | 180 '/min | 90' |  
|
C-band | 80 '/min | 40' |  
|
X-band | 40 '/min | 20' |  
|
Ku-band | 30 '/min | 15' |  
|
K-band | 18 '/min | 9' |  
|
Q-band | 8 '/min | 4' |  
|
- Change "Real Time Display" to "Python"
- Hit "Start"
- The telescope will now slew to the continuum source you chose and do a
cross-scan on it, taking a total of 4 scans. The "gfm" screen will fit
the data and determine the pointing offsets. These will both be displayed
on the "gfm" screen and sent to the telescope.
- Once the observations are done, you need to focus the telescope
- On the "GO_LITE" window, make the following changes:
- Change "Observing Procedure" to "Focus subreflector"
- Set the "Start Focus", "Stop Focus" and "Focus Rate" as follows:
Band | Focus Rate | Start/Stop Focus | Comments
|
---|
PF | | | Don't bother with this
|
L-band | 480 mm/min | -/+240 mm | Focus is likely unnessary
|
S-band | 480 mm/min | -/+240 mm |  
|
C-band | 480 mm/min | -/+240 mm |  
|
X-band | 480 mm/min | -/+240 mm |  
|
Ku-band | 480 mm/min | -/+160 mm |  
|
K-band | 320 mm/min | -/+80 mm |  
|
Q-band | 160 mm/min | -/+40 mm |  
|
- Hit "Start"
- The telescope will now take a scan varying the position of the subreflector.
The "gfm" screen will fit the data and determine the best focus. These will both be displayed
on the "gfm" screen and sent to the telescope.
- On the "GO_LITE" window, make the following changes:
- Change "Switching Mode" to "Total Power, No Cal"
- Change "Observing Procedure" to "Track"
G. Move to your first source
If you are using the BCPM please follow the directions on the BCPM page for moving from source to source
If you are not going to be switching source often, or if you are running remotely,
the easiest way to switch sources is by giving the telescope operator a source list
and having him/her move to the telescope to your sources for you.
If you wish to move the telescope yourself, do the following:
- If you haven't already started a "GO_LITE" session (Step E) then you must do so:
(If you already have "GO_LITE" running, skip this step.)
- In a new xterm window, type "source /home/gbt/gbt.bash"
(if you are running bash) or "source /home/gbt/gbt.csh"
(if you are running tcsh)
- Next, type "GO_LITE". This will open a grey "GO_LITE" window.
- In the GO_LITE window, do the following:
- Change "Switching Mode" to "Total Power, No Cal" (left side of screen)
- Change the "Observing Procedure" to "Track"
- Enter your Source Name, RA, and Dec
You can make a source catalog for this. Look here
for more info
- Be sure the track rates (RA/Dec or Az/El) are set to 0
- Hit "Start" and the telescope will slew to your source
**** If you are also running the BCPM, you can start running the
BCPM monitor scans at this point ****
BCPM instructions are available here.
H. Spigot Setup
First, log-in to both "earth" and "spigot2" (on different windows) as yourself.
Commands with green background only apply in certain circumstances
Description |
Commands |
Comments |
On Earth |
On Spigot2 |
Sets your environment variables
| source /home/gbt/gbt.bash source /home/gbt/gbt.csh
|
| Choose the correct script to source for running bash or tcsh
|
| source ~pulsar/scripts/spigot.sh source ~pulsar/scripts/spigot.csh
|
For 50 MHz & 50MHz DN (12.5 MHz) single polarization modes only
Sets the spectrometer to have the correct samplers
| LSS_1
|
| For 50 MHz & 50MHz DN (12.5 MHz) single polarization modes only
|
For 50 MHz & 50MHz DN (12.5 MHz) summed polarization modes only
Sets the spectrometer to have the correct samplers
| LSS_2
|
| For 50 MHz & 50MHz DN (12.5 MHz) summed polarization modes only
|
Loads the Xilinx personalities
| loadXilinx |
|
Only needs to be done after resetting the spectrometer |
Sets up the spigot for mode of choice
| SpigotSetup nmode
| |
See table for mode options. |
Create data directory
| |
mkdir New_Directory
cd to your new directory |
|
I. Do Calibration on Spigot
Description |
Commands |
Comments |
On Earth |
On Spigot2 |
Loads default scales and offsets |
|
OPTIONAL: [export SIGMAXBIT=N] |
set sigma of the noise for calibration:
X=16, 8, or 4; If this is not run,
the default values are: SIGMA16BIT=1000, SIGMA8BIT=28, SIGMA4BIT=2 |
|
load_vs A B |
|
startSpigot -now |
|
Begins taking calibration data |
stopSpigot |
|
Completes taking calibration data |
|
load_vs A B |
|
Takes a calibration data set, saving it as calib.fits.
| |
get_spigot_data -t 2 -w -l 10 -m nmode [-d] -f freq -c calib.fits |
There are numerous other options for the get_spigot_data command. If you are having calibration problems,
or are just curious, please see the full list of options.
Modes are given in this table.
|
startSpigot -now |
|
This starts data taking for the calibration |
stopSpigot |
|
This stops data taking for the calibration |
SpigotSetup nmode --noload |
|
Needed only for even modes.
See table for mode options.
|
load_calib -r calib.fits
| Loads the newly created calibration file
|
|
J. Check Data is o.k.
Description |
Commands |
Comments |
On Earth |
On Spigot2 |
Takes 0.4s of data
|
| get_spigot_data -t 2 -w -l 10 -m nmode [-d] -f freq -r calib.fits |
See list of get_spigot_data commands for other options
and table for modes |
startSpigot -now |
|
starts the actual data taking |
stopSpigot |
|
Run after spigot2 computer says scan is done. |
Checks data is okay
| |
spigot_rawlaghist.py filename
| Shows the distribution of the zero lag power (Use only on small files)
|
|
spigot_bandpass.py filename
| Shows the bandpass of the data (Use only on small files)
|
K. Take real data with Spigot
Description |
Commands |
Comments |
On Earth |
On Spigot2 |
Takes data
| |
get_spigot_data -t 2 -w -l time -m nmode [-d] -f freq -r calib.fits |
See list of get_spigot_data commands for other options
and table for modes |
startSpigot -now |
|
starts the actual data taking |
stopSpigot |
|
Run after spigot2 computer says scan is done. |
L. Other Info
- To balance the power for the spigot, the easiest method is to simply type
"bal_if()" in the "config_tool" xterm window (opened in
section B). If you are running in 16-bit mode this is likely all that is needed
to keep the power levels reasonable. However, if you are running in 8-bit or lower mode(s),
then you should also re-calibrate the spigot (step I).
M. Additional Spigot Commands
- resetSpigot: (earth) Resets the spigot cards
- serialEDT: (earth) Returns the Spigot card serial link to the data-acq computer
- serialEng: (earth) Returns the Spigot card serial link to the Engineering port
Notes:
- "-l" gives length of scan in units of 0.04192 sec;
10 ~> 0.419s, 100 ~> 4.19s ~> 1000 ~> 41.9s, 1422 ~> 60s, 7111 ~> 300s
- "-m" gives mode number.
- "-f" gives center frequency of band in MHz.
- "-d" used for double nyquist mode.
N. Looking at the Data
If you are not reducing data on the spigot2 computer, first source
~pulsar/scripts/spigot.csh or ~pulsar/scripts/spigot.sh for tcsh/bash.
More info can be found in the file reduce_data.shtml
- spigot_info.py:Displays vital info about spigot files
Common usage: spigot_info.py infile
- spigot_bandpass.py::Plots bandpass for samples 0..max_sample from the files provided
Common usage: spigot_bandpass.py infile
- spigot_rawlaghist.py:Plots histogram for an unscaled lag for specified files
Common usage:spigot_rawlaghist.py infile
- pyhead.py: Used to print/modify headers
Common usage: pyhead.py -u OBJECT PSR name -u RA RA -u DEC DEC file.fits
- prepdata: PRESTO data-preparation/de-dispersal
Common usage: prepdata -dm dm -shorts -o output_name -nobary file.fits
- prepfold: PRESTO folding software
Common usage: prepfold -psr pulsar_name output_from_prepdata.sdat
P. Contact Information
Click here
(Available only from within NRAO)