Preparing for using NCDRT
Data from the NRT come in four files with the following structure:
fil050673.213
pou050673.213
log050673.213
sfr050673.213
050673 is the observation id, 213 is the observer id.
The data are stored in the fil file. The pou file contains information on the
observation setup. The log file contains a log of the observations.
The programme NAPS, developed by the NRT-team, must be used to preprocess the data.
NCDRT uses fits files.
NAPS can transform the initial NRT data to fits format.
In order to use NCDRT correctly, the fits files must be in the same
directory as the original data files. In order to achieve this, set
the directory to write the fits files in NAPS:
NAPS> set result fits
NAPS> set dirdata /home/your_name/ncdrt/data/
NAPS> set dirfits /home/your_name/ncdrt/data/
With the NAPS save command NRT data read into NAPS is saved to fits
files with the following file format, averaging over the cylces, one
fits file for each of the eight channels:
f050673_f1.fits
f050673_f2.fits
f050673_f3.fits
.
.
f050673_f8.fits
Text windows and buttons
The NCDRT main interaction widget has several buttons, sliders and
information windows, which are now described.
Description of the left column of the widget and going through the
rows from top to bottom:
Load Data File
load_obs.pro with switch next_obs = 0.
A pick file dialog widget pops up.
The files listed by this widget are the f*_f1.fits files present in the directory.
Select a file to load the data into NCDRT.
The eight channels are loaded and stored.
Seven average channels are being calculated and stored as channels 9-15.
Default is:
channel 9 = (channel 1 + channel 3) / 2
channel 10 = (channel 2 + channel 4) / 2
channel 11 = (channel 5 + channel 7) / 2
channel 12 = (channel 6 + channel 8) / 2
channel 13 = (channel 1 to channel 4) / 4
channel 14 = (channel 5 to channel 8) / 4
channel 15 = (channel 1 to channel 8) / 8
This can of course be changed by the user. In this case, also
change the naming of the channels stored in parameter channel_print
and defined in ncdrt_display.pro.
Average channel calibration needs also to be redefined in the routine write_2_cal_table.pro,
as well as the automatic (de-)selection of averaging channels if the
Averaging Switch (see description of this switch) is pressed for to
change from normal to average mode in the current observation’s
process (ncdrt_display_event.pro).
The sky_load_obs.pro routine also needs to be adapted.
Search for the USER: AVERAGING keyword in these programme files.
Whenever a fits file is loaded, the fits file list of the current
directory is determined and stored in NCDRT. This is used in the
Load Next Data File and Load Previous Data File actions (see below
for description).
Information on the current data is read from the pou file and
displayed in the first text window. This is why it is mandatory to
have these files in the same directory as the fits files.
load_obs.pro will also search for the presence of result files
produced previously. If it finds such a file, it will read and set
the slider settings from it. The order of priority is .res_cal
.res_av_cal, .res .res_av (see Save Result).
The routines involved are read_res.pro and read_res_av.pro.
In case there is no result file, NCDRT will define standard settings for the sliders.
After loading the data and setting the sliders, the result is
determined by calling show_lin_cut.pro and apply_lin_cut.pro
(see section 5.1 on the working of these routines).
The results are shown on the plots (scissors and results) and
written to the large text window in the right column.
The n_channel and ch_address are kept as they are. For the
first file of a new session, they are set to
n_channel = 8
ch_address = 0
This means that the first eight channels are being processed.
Scissor Switch
show_lin_cut.pro with switch scissor.
This function changes the scissor window between the normal mode and
the detailed mode. The normal mode shows the entire drift and the
current cutting settings. The detailed mode devides the drift in
three parts, the offset (left and right) and the central part
(peak). This is useful is the contrast between the peak and the
offset is large.
Load Next Data File
load_obs.pro with switch next_obs = 1.
Loads the next data file in the current directory. In case there
are no more files, the pick file dialog widget appears. The
settings of the sliders are not changed.
Load Previous Data File
load_obs.pro with switch next_obs = -1.
Loads the previous data file in the current directory. If there are
no previous files, the pick file dialog widget appears. The
settings of the sliders are not changed.
Averaging Switch
ncdrt_display_event.pro switches n_channel and ch_address.
The n_channel and ch_address switches are changed to their
other values. The possible values for these switches are
(n_channel,ch_address) = (8,0) or (7,8)
The first set means that the first eight channels are being
processed, the second set is for the last seven (averaging
channels).
Upon changing from normal to averaging the channel select string
information of the normal setting is kept. Also an average
channel is automatically deselected if one of the normal channels
that are included in this average channel are deselected.
Apply Calibration (Short Cut)
apply_calibration.pro
Using this button the calibration of the current calibration table
is applied to the data without having to go to the Calibration Tool
Widget. It is the same as Apply Calibration button of the
Calibration Tool.
The function will only be active if a calibration table is present.
This and all other calibration functions have to be performed with the Calibration Tool.
Save Result
save_res.pro
Save the current result to a standard file. There are four types of
result files, depending on the status of the process:
f050673.res, first 8 channels with no calibration applied
f050673.res_av, averaging channels with no calibration applied
f050673.res_cal, first 8 channels with calibration applied
f050673.res_av, averaging channels with calibration applied
Do never change the structure of these files. NCDRT will not be
able to read them afterwards.
Sliders
ncdrt_display_event.pro and show_lin_cut.pro
There are four sliders:
Offset Low
Offset High
Peak Low
Peak High
The offset sliders determine the part of the data to be used for
the determination of the offset. There is a build-in protection
that prevents these sliders from having inappropriate values: the
peak sliders must be at least 4 time units apart for the curve_fit
procedure in the apply_lin_cut.pro routine to work, and the low
offset slider cannot be larger than the high offset slider. low
sliders cannot be set to more than half the range, Also, the offset
sliders cannot be set to 0 or to the maximum of points. This is
checked in show_lin_cut.pro. See section 5.1 for further detail
on the working of show_lin_cut.pro and apply_lin_cut.pro.
The result of the cutting can be seen in the Scissors plot window.
They change dynamically as the slider values are changed. See also
the explanation of the Scissor Switch section.
Information Text Window
This window shows the result of the current fit to the data. It are
the values which will be written to a file if you press the Save
Result button. See section 5.1 for more details on the meaning of
the numbers.
Channel Select String
The last text window in the right hand column contains the editable
channel select string. A ‘1’ means that the selected channel is
processed and written to the result file, if this action is
required. A ‘0’ means that the channels is ignored. In the case of
processing the fours averaging channels, only the first four
switches of the channels select string are taken into account. The
use of the Averaging Switch resets the channel select string to all
default values (all ‘1’).
Quit
ncdrt_display_event.pro
Quit NCDRT and close all the windows.
The planet.longitude file
NCDRT will search for a file named planet.longitude in the directory
/home/your_name/idlproc/NCDRT/planet. This file contains a list of
the scan numbers (preceded by the letter ‘f’, and without the user
id), and the Central Meridian Longitude, Sub Earth Latitude and
Distance to the Earth (AU) of the planet that the user has observed.
The user must create this file. It is read in the ncdrt_display.pro
routine (near the end). The user can change the filename, place, and
formatting at wish. The format of the file must correspond to the
format of the reading.
If an observation of the planet is reduced and a result file is
saved, and if that file is listed in the planet.longitude file, then
an information line is written just below the comment line in the
result file. If the file is not found, or if the observation is not
in the list, then nothing is written (see the routine save_res.pro ).
This feature can be helpful if a study of the radio emission of a
planet as a function of Central Meridian Longitude and time is made.
An example file is included in this distribution, corresponding to
the Mars file in the /home/your_name/idlproc/NCDRT/demo directory.
Comment Text Window
This window is an editable window. It allows the user to write a maximum of 40 characters long comment line. The line is included in the result file when the Save Result buttom is pressed, preceded by the word ‘ Comment : ‘. By using the grep and awk function in a UNIX operating system on all the existing result files a log file of all the comments can easily be made.