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Bias Frames
Before taking any bias frames, walk around the JKT and switch off all the
lights in the building (except the control room lights). Make sure that the
dome lights are switched off too (the red button marked "DOME" on the control
panel) and that the doors are closed to the control room. Also close the
shutter on the window looking into the telecope from the control room.
Finally, make sure that the telescope is in computer mode (turn the key).
Taking Bias Frames
In order to take a single bias frame, on the ICS type:
SYS>bias
Alternatively, you may take a set of n biases by typing:
SYS>multbias n
Note that it is usual for the engineering staff to take a bias frame
sometime in the afternoon and that this will appear on the observing log.
Viewing The Data
The software package called IRAF is most commonly used for viewing the data
obtained on the JKT. In order to start up an IRAF session, assuming that one
is not already running, open up an xgterm on lpss10 by clicking the right
mouse button on a clear part of the screen and going to "Programs" followed
by "XGterm...". In the newly opened xgterm, type:
$>cd
$>cl
This starts up the IRAF program and the prompt will change to cl>.
Next, open up an image viewer by typing:
cl>!ximtool &
In the xgterm change directory by typing:
cl>cd /obsdata/jkta
List the directories present by typing:
cl>ls
A directory named with today's date in the format YYYYMMDD should be
present. If this is the case then move to this directory. Otherwise type:
cl>cd /obsdata/jktb
cl>ls
You will find a directory named with today's date in the format YYYYMMDD.
Move to this directory.
Now you should be in the directory named with today's date. Type:
cl>ls
This will list all the files present with names of the form:
DAS1.fit
r136345.fit
r136346.fit
r136347.fit
In order to check what an image is, either look at the observing log or,
alternatively, type:
cl>imhead filename
Note that "filename" refers to the name of the image you want information
on.
In order to display an image, type:
cl>disp filename
Note that "filename" refers to the name of the image you want to display.
You will be prompted to enter the frame number in which to display the
image.
After displaying the image, open the ximtool control panel by clicking
on the button with the rectangle on the ximtool. This panel will allow you
to zoom in/out and change colours/intensities etc. on the image(s) that
you have displayed.
Finally, in order to log out of IRAF, type:
cl>lo
Reducing The Readout Time - Windowing
Windowing the CCD chip is an effective way of reducing the readout time
after exposure. To set a window on the chip, type the following command
on the ICS:
SYS>window 1 xsize ysize xstart ystart
Note that the parameters "xsize", "ysize", "xstart" and "ystart" refer
respectively to the size of the window in the x direction, the size of the
window in the y direction and the x and y coordinates of the bottom left
hand corner of the window (where all numbers are to be specified in pixels).
E.g: SYS>window 1 1000 1000 1074 1074
This command specifies a square window in the centre of the SITe2
chip with a side length of 1000 pixels. Correspondingly this will quarter
the readout time for this chip.
The window parameters are displayed in the CCD status window on the
DAS.
To window the whole chip, type:
SYS>window 1 0 0 0 0
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