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The data taking system (DTS) runs from the user account on shanepc.
To start the DTS, type dx.
A sample DTS screen is shown in Figure 1. The red and blue sides are
run independently, with a separate set of display parameters for
each. The screen refers to only one of the two CCDs, either blue ("CCD
1") or red ("CCD 2"). The CCD in use is identified in the middle of
the sixth line of the screen display (see Figure 2). To switch
between CCDs, simply press the number 1 or 2 from the numbers at the
top of the keyboard. If you wish two data takers can run simultaneously,
one controlling the red side and the other the blue (see Figure 3).
To either initiate an action or to change an observing parameter,
simply type the letter corresponding to that function. For example,
type "r" (not case sensitive) to start and exposure. If the option
selected involves a choice, you will be prompted at the bottom of the
screen. It's an exceedingly easy to use system. What follows are
brief comments just to get you oriented.
Option A on the DTS screen allows you to choose between up to 10
selections. A selection consists of those items specified by lines B,
and D through I. A common reason to specify more than one selection
might be if you wish to intersperse direct and spectra observations
during the night, which require very different areas of the chip to be
read out. It's easier to switch between, say selection 1 for spectra
and 2 for directs, than to continually change the window
specifications under line D.
The integration time (option B), may be 1 to 32,000 seconds.
Fractional seconds are not allowed. Exposure lengths can be different
for the two sides, and they must be started independently, so it could
turn out (for example), that several red-side exposures are taken and
read out while the less sensitive blue side is taking a single
exposure.
The observation number (C) is arbitrary (that is, start your own
number sequence wherever you wish), and is incremented only when an
observation is recorded. Observations from both sides are numbered in
a single sequence in order of readout, but each image number is
prefixed by a color code; e.g., b105.ccd and r106.ccd. The only
caution is that an image already on disk will be overwritten by a new
image with the same observation number.
During setup you may wish to use the fast readout mode (option F).
This will read out the chip significantly faster, but at the expense
of increased read noise. During setup the read noise is usually
irrelevant, but don't forget to switch back to slow mode before
recording any real data.
To make your data taking window follow your choice of CCD, type n,
then t for track; the window will than track your CCD selection.
Object name (I), may be a string of up to 63 characters in length.
This field is examined by the DTS only at the beginning of readout, so
except in the case of very short exposures, it will probably be more
efficient to get the exposure under way before recording the name of
the object.
If you have already started an observation, and realize you wish to
change either the integration time or the selection, you must use
options V or W to revise your choice. The system looks at A and B
only when an observation is first initiated.
When doing polarimetry, the waveplate rotation is the only
motor not controlled from the
Kast Controller software. Option
L allows you to move to one of four waveplate rotations.
Option Z ("Special"), will prompt you for a choice of five submenus.
The ones commonly used are Z-3 for header information (see Figure 4)
and Z-5 for telescope offsets (see Figure 5). Note that menu Z-2 is
defunct, as we no longer use 9-track or Exabyte tapes.
Under Z-3, update the observer's name as you would like it to appear
in the tape header. Nothing else in the menu should need updating.
Another way to add information to the header is via the option X for
comments. It allows you to add up to five comment lines to the
header. If you precede a line with an asterix, it will be retained and
added to every image; otherwise it will be added to the next image
read out, then discarded.
Menu Z-5 allows you to move the telescope (please let the telescope
operator know that you will be moving the telescope). Moves can be
specified as offsets in arcseconds or as moves between two positions
on the chip. Option T allows you to enter an offset in arcseconds in
either Dec or RA (positive moves are N or E,
respectively). Alternatively, you can use options A and B to designate
two positions (row,column) on the chip (e.g., the position of the star
and the position of the center of the slit) and use option C to move
the telescope from position A to B, or vice versa. This second method
is particularly convenient when the TUB is rotated to some position
angle and using direct imaging to identify your target.
The image last read out is displayed using the XVideo display windows. It has a wide
variety of display options,such as different color maps, zooming,
etc.. The display software is widely used at Lick Observatory, so
futher information on it can be gained from the
Vista Display User's Guide.
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Figure 1: Data Taking System
Figure 2: DTS Menu, Blue Side
Figure 3: Data Taking System, both Blue and Red
Figure 4: DTS Z-3 Menu
Figure 4: DTS Z-5 Menu
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