JKSRT5 Trainer Applet
Some quick and basic explanations:
The SRT trainer applet is a simulation of the JKSRT5 application. With the
exception of a few options, it works in the same way.
The following steps guide you to some basic operations:
- the applet opens a large window which contains the main
graphic user interface, and a smaller window which will
serve as the output of the recorded measurements.
- the main window is dominated by a display of the sky,
as seen at the current time, looking in south direction
(azmimuth = 180°). The blue dots mark a number of astronomical
sources, for instance G30 is the position in the Galactic
Plane at Galactic Longitude of 30°. The shaded areas indicate
foreground objects, such as the ISU library and trees on the
- with the buttons +1 hr and -1 hr you can step
forward and backward in time, Now brings you back
to the current time.
- step forward or backward in time, until you see the Galactic
Plane between the Galactic Centre (SgrA = Sagittarius A) and
G90 and all the positions inbetween.
- click on any of those G-sources, say G40. Then the telescope
will move from its "stow" position to the requested source
- it takes a few seconds to reach the source - in reality it
takes a bit longer. When it is reached, the spectrum display
in the upper center will show the simulated spectrum. The
black curve is the current spectrum, the red curve is the
average over all spectra taken at that source.
- since the default spectral span of 500 kHz will show only
a portion of the simulated galactic signal, you might find
it more convenient to select with the choice at right centre
a larger span, such as 2000 kHz span, and/or to shift the
centre frequency a bit. Whatever your choice, click the green
OK button to make the selection.
- larger frequency spans take more time - the default span of
500 kHz takes one second per spectrum, 2000 kHz takes four
- you will see the results in the spectrum display. If you click
at any position within this plot, the frequency will be displayed
in blue letters below the frequency menu on the right.
- the colour display near the upper rightish centre is a
false colour waterfall display, showing the spectra in the
form of a coloured bar, and placing one spectrum below the
previous ones. The rainbow colours give an indication of
the intensity at each frequency. When you have a spectral
feature - like from one of the positions between SgrA and G90 -
this feature will show up as in a 'brighter' colour, and
as one stays at the same position, this will form a vertical
band of that colour. In the simulated data generated in the
trainer applet, nothing else will happen; however, in reality,
this display is very important for identification of any
interference: any momentary interference or fluctuation of the
system sensitivity shows up as a horizontal
band with changed colours, any narrow band interference might
show up as a 'bright' signal at some frequency for some time ...
- other sources whose signal is simulated are: the Sun, Moon, CasA,
M31, CygA ... but all except the Sun are very weak, as in reality!
- since an applet is not allowed to access the user's file system,
the output of measurements are routed into the smaller window:
to record measurements, click on Record button to start
the recording. OUTPUT brings that window to the foreground.
Recording ist stopped by another click on Record.
- to take the data, simply copy it by dragging
the mouse over all lines, and then paste them into a normal
text editor, such as WordPad. Thereafter it can be stored and
imported by e.g. Excel. The recorded data is in exactly
the same format as from the real telescope's software.
- the Help button opens a window with more explanations.
- there are options by the other buttons as well as more
details which I did not cover in this brief "tutorial"
- WARNING: it might be that some details in the explanations
are still missing or need to be updated ;-)
- these sources are simulated: SgrA, G5, G10, G15, ... , G90,
the Sun, M31 (for the very patient ones), the flux calibrator
(the area about the stow position: the ISU building), and Cas A.
Cyg A (with an entirely imaginative line), the Crab and Orion
nebulae are done merely for fun only ...
In some browsers the main window of the applet does not
open immediately. If you don't see it happen, click on the small
white rectangle above.
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last update: Feb. 2012 J.Köppen