- In the WAPP
Datataking Control GUI, change all the WAPPs from 3-level, 2 Pol.
to 3-level, sum chans.
This produces just total intensity.
- In the same widget "Start observation button"
observations in drift scan mode:
- Go through the system setup, as described here,
except for the pointing part.
- The Telescope Pointing Control Widget appears. Click on the
"AZ/ZA Pointing" button. The "AZ/ZA Pointing Control" widget
- In the box that says "Name", type in a name that helps you figure
out which declination you are covering. For the 327-MHz survey, each
beam can cover about 15 arcminutes (a quarter of a degree). Therefore,
4 beams cover a whole degree of declination. So, the "Name" used in the
327-MHz survey is a 2-digit number obtained by multyplying the Zenith
Angle being used by four.
- If you are using the Carriage House, don't forget to click on the
"Carriage House" button.
- For the purposes of drif scans, the Azimuth angle (AZ) must be
set to either 180 or 360 degrees for maximum sensitivity. At 180
degrees, the Gregorian dome will be due south of the center of the
dish, so the telescope will be pointing at declinations north of the
latitude of the Arecibo telescope (18 degrees and 20 minutes). At 360
degrees, the Gregorian Dome will be due north of the center of the
Dish, so the telescope will be pointing at declinations south of the
latitude of the Arecibo telescope.
- In the "ZA" button (be careful choosing Carriage House or
Gregorian ZA button) type in the zenith angle (ZA). For AZ of 180
degrees, the corresponding declination is 18 degrees and 20 minutes +
ZA. For AZ of 360 degrees, the declination is 18 degrees and 20 minutes
- ZA. The ZA can not be smaller than 1.1 degrees.
- If your drift scan is not at the sidereal rate, you can
also type in the the rates of change for AZ and ZA (degrees per
second, as indicated on the widget).
- Once these coordinates are set, press the "Point" button in the
"AZ/ZA Pointing Control" widget. NOT in the main "Telescope Pointing
telescope will now drive to the
coordinates you specified. In the "Aostatus" display, the "requested"
coordinates are not
those you asked. Therefore, when the telescope gets to those
coordinates, the "Aostatus" display will keep saying "Not tracking".
Ignore that, just pay attention to the present AZ and ZA. When they
attain the values you requested, you are ready to start.
- Make a polynomial coefficient for the day of your observation and
the target pulsar. One way of doing this for, say, PSR J1738+0333 would
For this to work, you have to have the pulsar ephemeris in the
$TEMPO/tzpar directory (you can find the TEMPO directory by typing
"echo $TEMPO", at AO this is /home/pulsar/tempo11/. If the variable is
undefined in your login screen, type setenv TEMPO /home/pulsar/tempo11/)
- Move the resultant "polyco.dat" file to your project directory:
mv polyco .dat
- Press on the "WAPP" button. The following widget appears:
- You should select the options that appear after "folding
- Folding format: select preferably lags. The Fourier transform of
this gives phase bin versus frequency. This is the best way of
preserving the original data, you can work out the correspondence
between the Fourier coefficients and frequencies later. You can trust
the new AO software as well, it is now doing this correctly.
- Save folded data interval - this is the sub-integration time. The
default 2 second is quite small...
- Number of time bins - self-explanatory, number of bins in
- Pess button that says "use", this will activate polyco search
window. There you can browse the directory tree until you find your
polyco file. By default, the file chosen will be one called
"polyco.dat" in /share/obs4/usr/pulsar/p1684, because you typed in
"p1684" as your project name.
source name in your polyco file has to be exactly the same as the name
of the source you are pointing at. So if your target's name is the
globular cluster NGC6760, and you are timing the known pulsar there
(PSR J1911+0101), with that name in the polyco header, the polyco will
not work! To check your
pointing target's name, check the "aostatus" display. This name has to
be the same as the name on top of the polyco file. So be careful about
B/J names and globular cluster or supernova remnant names.
- After this is completed, dismiss the "WAPP configuration window",
and repeat the process for other WAPPS. Alternatively, you can press
the "Copy WAPP1 to all" button on the WAPP
Datataking Control GUI.
- In the same widget, press the "Start observation"
to observe in schedule mode
You might want
to observe a set of sources in quick succession; and
sometimes you might want different integration times, sampling times,
number of lags for each source. To avoid having to do this yourself,
you can prepare a list of sources in advance with observing parameters
for each source. This file should end in .cmd, and live in
Here is how the
entries would look like:
600 usecs3=128 lags3=128
300 cal_toward usecs2=256
- The first column is the source name
- The second column is the integration time
- The remaining columns are commands:
sets the sampling time of
WAPP3 at 128 microsseconds
"lags2=1024" sets the number of lags of wapp2 to 1024
"lagformat" sets the number of bits in each sample. Generally for large
sampling times ( > 256 us) this should be 32 bits, otherwise you
might have bit overflow.
"cal_toward" activates the 25-Hz noise diode on the way to the pulsar -
so no telescope time is wasted with calibration.
Details of other commands in
Now, to make
the observation, do the normal system setup.
- Click on the "Pulsar Catalog Observing" button. The following
widget will appear:
- On the second box, specify which .cmd file you want to use.
- It is
important that the source names are present in the catalog file you
indicate in the first box (for pulsars, the default would be
/share/obs4/usr/aoui/psr.cat), otherwise CIMA won't know where to point
the telescope! For sources unknown to us, you might need to make your
own catalogue. Here are the first few lines of
00:06:04.8 +18:34:59 J 0 topo
J0030+0451 00:30:27.43 +04:51:39.75 J 0 topo
B0045+33 00:48:34.00 +34:12:08 J 0 topo
J0051+0423 00:51:30.1 +04:22:49 J 0 topo
J0137+16 01:37:23.87 16:54:42.23 J 0 topo
J0152+09 015219 094859.1 J 0 topo
First line: source name, second line: Right Ascension, third line:
Declination, fourth line: coordinate system. Fifth
line: associated velocity. Sixth line: reference frame for that velocity.
Zero km/s in the topocentric
reference frame forces the system to use precisely the sky frequency
- On the third box, indicate at which line you want to start your
- Caltype - if you want calibration, select "hcorcal", otherwise
select "nocal". The cal duration could either be "continuous" or
- Press the "Start WAPP Pulsar Catalog Observation" button.
- To stop this observation, got to the AO Observer display widget...
and press the "End at Next Loop"
button, on the bottom. This will end the present observation and stop
the loop, incrementing the line number at the end. If you want to keep
observing, just go back to the "Pulsar Catalog Observing" widget and
press the "Start WAPP Pulsar Catalog Observation" button again.
- The "Abort Observation" button will stop both the loop and the
present observation, leaving it unfinished.
Parameters that can appear in the schedule mode:
- First column: source name ( exactly as in the catalog) For
restarting, the source names must be unique.
- Second column: observation time in secs.
- The third and following columns can be
- adpwr then the
wapp attenuators will be automatically adjusted. It will not adjust
other iflo system attenuators.
- calon, turns the
receiver noise cal on for the duration of the scan. It also appends
_calon to the source name. The GUI allows you to specify which noise
source (e.g. hcorcal) and whether you want the 25 Hz cal or continuous.
- caloff, same as
nothing except it appends _caloff to the source name
- toward, issues the
tracking commands but does not wait. Starts observations immediately.
Appends _to to the source name to indicate this. Useful for certain
- cal_toward, like
toward, issues the tracking commands but does not wait. Turns on the
cal as specified. Starts observations immediately. Appends _calto to
the source name to indicate this. Useful for certain calibrations (Desh
specified this feature)
- usecsn : sets sampling time in WAPP n
- lagsn: set number of lags in pulsar n
- lagformat=32: sets the number of bits per sample to 32
(recommended for tsamp > 256 us)
- There are exceptions to this, mainly when using ALFA
End the session
- Wait until pulsar leaves sky, or your time runs up, or the
integration is over.
- If, by the time your pulsar leaves the Arecibo sky, or your time
is over, and your integration is not over yet, then go to the WAPP
Datataking Control GUI and press the ``stop observation'' button.
Last updated: June 4