4. Software
4.1. Logging in
and firing up the Arcon/Mosaic software
Before you can begin to take data you must log in on both
the data acquisition (rush/rust) and data reduction (tan/emerald)
computers. We are currently controlling the Mosaic-1 with rush (KP4m) or
rust (W0.9m) with the data handling and analysis being done with tan
(KP4m) or emerald (W0.9m). Both emerald
and tan have 3 monitors labeled tan/emerald:0.0
(center monitor), tan/emerald:0.1
(left monitor), and tan/emerald:0.2
(right monitor). At the 4m there is an additional data reduction computer, nutmeg,
which has a dual processor. Note that the home directory for tan is
/md1/4meter and on nutmeg is /md4/4meter.
To begin your observing
session you should follow these steps at either the 4m or 0.9m.
- Log on to tan (emerald)
as user 4meter (36inch). The computer tan is a fast computer with
two CPUs (1.667 GHz AMD processors) and 1 Gbyte of memory operating under
Linux. The computer emerald is also a fast Linux box with a 3.4 GHz
(Pentium 4) CPU and 2 Gbytes of memory.
- On the central console
(tan:0.0 or emerald:0.0) right click on the background to bring up the
menu of options. The top option is "Start Interfaces for MOSAIC
CCD". Select this option. This will open the VNC
client in tan:0.1 (or emerald:0.1) in which the windows from rush
(or rust) will be displayed. It will also start the DCA (Data
Capture Agent) and associated GUI of the data handling system in the
center monitor (tan:0.0) as well as the Ximtool display in tan:0.2 (or
emerald:0.2), displayed on the right monitor. The right monitor is only an
8-bit display (to accommodate the current version of X-imtool; a new
version with 24-bit color is under development) and should only be used
for the display window or there will be problems with the allocation of
colors to the display window. We are still working out some undesirable
features in this display. If you would rather use DS9 as an option for the
image display, kill the Ximtool window, right click on the background of
tan:0.2 to bring up the menu, and select DS9. DS9 should work fine as your
display device. If you want to switch back to Ximtool, you will have to
log out of tan and then log back in and restart as described above.
This will not affect the operation of rush, but should not be done
when you are reading out an exposure or you will lose that exposure.
- In the VNC viewer window on tan
or emerald, click in the background of the display and select
(Re)START ARCONS. This should bring up all of the MOSAIC GUI's controlled
by rush (rust).
This process takes about 2 minutes and you
must also answer one question. A small window labeled "ARCON Console"
will appear near the left center of the screen in which various messages will
scroll by. After a few seconds a larger window labeled "ARCON
Acquisition" will open immediately below this; this is the window you will
use for entering all data acquisition commands. A brief greeting message will
appear in this window and, eventually, you should be asked
Do you want to synchronize parameters?
(yes)
When you reply "yes" (or just hit
[cr]), the detector parameters loaded into Arcon will match those stored in
detpars and the positions of the motors recorded in instrpars will correspond
to reality. We currently recommend saying yes at the start of an observing run,
but "no" during subsequent restarts. This saves slightly on the
start-up time. In either case the IRAF package menus will be printed and the
cl> prompt will appear. Some further windows will also pop up at this point.
The system is now ready for you to begin observing.
Occasionally things will get hung up during
the process of downloading and initializing the Arcon software. If this happens
you may see the message (but probably not)
****************************************
**
*FAILURE DURING ARCON STARTUP !!!*
**
*Use re-start button to try again*
**
****************************************
In the majority of cases, simply performing
the restart procedure will fix this problem, although it may be necessary to
try this more than once. If after repeated attempts the system will not start,
refer to the Frequently Encountered Problems section for further advice.
Right click on the background of TAN:0.0 (or
Emerald:0.0) and select (Re)start DCA. When you started ARCONS on rush
(rust), the start-up procedure will have killed the previously started DCA.
You can restart the DCA right after you start the ARCONS on rush (rust),
you do not need to wait until the ARCON start-up has completed.
The system is now ready for you to start
observing.
4.2. Autologging
If you would like to use electronic
auto-logging of your observations, you will need to follow the instructions here
(http://www.noao.edu/kpno/manuals/aol), including running loginit in a
data-reduction window on tan (or emerald)
4.3. Restarting
the Arcon software
Every so often,
something or other happens which causes the Arcon software to hang, or
otherwise get confused. In the vast majority of cases this can be fixed by
simply restarting the software running on rush/rust. This takes only a
couple of minutes.
On rush/rust (inside the VNC window on tan:0.1 or emerald:0.1): Move the mouse
pointer to an empty section of the desktop and hold down the right hand button
to bring up the desktop menu. Select the item "End ARCON Session"
and release the mouse button. After a few seconds the ARCON console,
Acquisition, status and countdown windows will disappear. Once the windows have
successfully closed, and the CPU meter has dropped to zero you can then restart
the Arcon Session. Again bring up the desktop menu via the right hand mouse
button and select "(Re)Start ARCON session". The software will
go through the startup procedure described in [4.1]. You should normally answer
"yes" to "do you want to synchronize parameters". This
ensures that the detector parameters and filter positions, etc. match those in
use prior to the re-start. Any other windows on the desk top will be untouched
so any processes running in them will be unaffected, and you can continue to
work in these windows.
When you (Re)Start
Arcons the DCA on tan or emerald will close. You will need to
restart it again. To do this, hold down the right hand button to bring up the
desktop menu and select "(Re)Start DCA" and release the mouse
button.
4.4. Restart and
Power Cycling of the Arcons and Nexus/Tram box
Occasionally, the
Arcon controllers get into a weird state. There are roughly 5 levels of
severity with which the user can respond.
1) Restart the Arcons: Use the
pull-down menu on the data taking computer (rush/rust) to select End
ARCON session. After the windows have successfully closed and the CPU has
returned to zero, select Start ARCON session from the background pull-down
menu. This will take a little while. It may take several (3-5) Restarts to
succeed. Always try at least 3 Restarts before proceeding to the next level of
severity listed below.
2) Logout and Restart the Arcons: End the ARCON session on
the data acquisition (rush/rust) computer and completely log out of the
data reduction (tan/emerald) computer. Log back in and select
"Start Interfaces for MOSAIC CCD". This will start the ARCON session,
DCA, and Ximtool-alt. If there are still problems starting the ARCONs go to
level 3.
3) Try some diagnostics: open a Unix window on the Data
Acquisition computer, and then run the following diagnostic commands that check
for communication with the Arcons:
/xp/source/sun/bin/nexus0123
/xp/source/sun/bin/aset0123
These should complete normally for all 4
Arcons. If they fail to complete, try a few more times. If the errors are
persistent, power cycle the TRAM box (see figures 4.4.1). At the KP4m power
cycling the TRAM box is done remotely. At the W0.9m this is done
manually (see below).
REMOTE POWER CYCLING OF THE
TRAM BOX (4M ONLY)
a) Open an xterm window on Rush.
b) Telnet 4m-nexus-power (140.252.52.74).
c) Log in as 4meter - enter the password.
d) This window will print some information. Type off 1
and confirm with Yes.
e) Count slowly to 50. Type on 1 and confirm with Yes.
MANUALLY POWER CYCLING OF
THE TRAM BOX (0.9M ONLY)
a) Locate the TRAM box in the computer room (see figure 4.4.1
below).
b) Turn the power on the TRAM box off, wait 30 seconds and
turn the power back on.
Try the "/xp" commands again. If the
"/xp" commands succeed, then try the following commands from a Unix
window on the Data Acquisition computer. This is a subset of the normal Arcon
startup.
cd
arcon_user
This will take a few minutes and tries to
bring up the Arcons completely, but not the other windows (GUI, IRAF). If it
fails the first time, try a few more times. If it succeeds or fails, type
"arsh stop" to exit the window. If successful, attempt another Arcon
restart. If it fails, try 3 more times. If you still cannot get arcon_user to
complete, go to level 4.
4) Reboot the data-taking computer (rush/rust):
a) End
the ARCON session by selecting "End ARCON session" on the Data
Acquisition computer (rush/rust).
b) Open an xterm window from the background menu on rush/rust.
c) Type "reboot-rush" (at KP4m) or
"reboot-rust" (at W0.9m).
d) Wait a couple minutes for the reboot to complete. While
waiting, cycle the power on the TRAM box (see the TRAM box power cycling
procedures above).
e) Restart the VNC client to rush/rust via the
background menu on tan/emerald and start the Arcons via the background
menu "(Re)Start Arcon Session".
f) You may have to execute the level 3 commands to make any
progress.
g) At this point, it probably won't hurt to restart the DCA
on the data reduction computer using the pull-down menu.
5) This is the most serious mode and it should be done with
the cognizance of NOAO personnel. This will be a total restart of the system.
Follow the process in item (4) above for the data-taking computer, but only
through step (c). Then quit the DCA on tan or emerald
AT THE 4-M it is possible to cycle power to the
instrument and Nexus/Tram box remotely:
a) From a UNIX prompt type telnet 4m-nexus-power. Use
4meter as the username. The password is posted in the control room. To turn off
the power to the Nexus/TRAM box type off 1 at the prompt and confirm
with Yes.
b) From another UNIX prompt type telnet 4m-pf-power.
Use 4meter as the username. The password is posted in the control room. To turn
off the ARCON power controller type off 1 at the prompt and confirm with
Yes.
c) Slowly count to 50.
d) Turn on the ARCON power controller by typing on 1
at the prompt in the 4m-pf-power window.
e) Turn on the Nexus box by typing on 1 at the prompt
in the 4m-nexus-power window.
f) If the system still fails to run, try steps (1-3) several
times. If that fails, call for help.
AT THE 0.9-M you will need to bring the telescope to
zenith and cycle the power on the instrument manually:
a) Power off the Nexus/TRAM box in the computer room (see
figure 4.4.1).
b) Go to the instrument and power off the Arcons. There are 4
red power switches located on a power plug strip (see figure 4.4.2). Wait 10
seconds. Power on the 4 Arcons.
c) Complete step (4d) by powering the TRAM box on.
d) Log back into both computers to restart the Arcon and DCA
software.
e) If the system still fails to run, try steps (1-3) several
times. If that fails, call for help.
Figure 4.4.1: The Arcon "TRAM" box with Power Switch
noted. At the KP4m you should not need to use this switch - see section 10.2.
Figure 4.4.2: The Arcon power strip with 4 power switches noted.
4.5. Shutting down the software and Logging out
During your run,
you may wish to stay logged in continuously to maintain your window
environment, especially if you've taken some time to move and resize dozens of
windows. On the other hand some folks feel that a "clean" environment
makes for healthier observing, thus you may wish to log out at the end of every
night to reset any gremlins back to their initial conditions. In all cases,
after your last night, you should log out completely from both rush/rust and
tan/emerald.
To log out of tan or emerald
it is not necessary to shutdown Arcons - you can simply close the VNC window.
However one can first end the Arcon session on rush/rust if desired.
On rush/rust: Move the pointer to an
empty section of the desktop (in the rush-VNC window) and hold down the right
hand button to bring up the desktop menu. Select the item "End ARCON
Session" and release the mouse button. After a few seconds the Arcon
console, acquisition, status and countdown windows will disappear. Any other
windows on the desk top will be untouched so any processes running in them will
be unaffected, and you can continue to work in these windows. Then close the
VNC window by clicking the 'X' in the upper right-hand corner of the window.
On tan/emerald: select "Logout
'4meter'..." from the 'K' start menu at the bottom left corner of the
screen.
At the very
beginning of your observing run, you should clean off all of the previous
observer's images and files, and reinitialize all of the IRAF parameters to
their default values. This must be done separately on both rush/rust and
tan/emerald.
You, or the instrument assistant, can
accomplish this as follows:
On tan (or emerald)
Log on using the observer login and password
posted on the machine.
In the IRAF "Data Reduction" window,
and any other IRAF sessions that may be running, type logout. The window
should vanish.
Select "Unix Xgterm" from the root
menu. (Move the mouse to any blank area of the screen, and hold down the right
mouse button. Slide the mouse down to "Unix Xgterm".)
In the new window, type obsinit and
answer the questions appropriately.
On rush (or
rust):
If an Arcon session is active on rush
or rust,
Shutdown the Arcon session. (Move the mouse to
any blank section of the desktop and hold down the right hand button. Select
the item "End ARCON Session" and release the mouse button.
Log out of any IRAF cl sessions that may be
running.
Select "Unix Xgterm" from the root
menu. (Move the mouse to any blank area of the screen, and hold down the right
mouse button. Slide the mouse down to "Unix Xgterm".)
In the new window, type obsinit and
answer the questions
On rush (or
rust):
If an Arcon session is not active on rush/rust,
Open a "xgterm" window in the VNC
window for rush/rust.
At the rush UNIX prompt, type obsinit and
answer the questions
The reason for the
above procedure is that you cannot have IRAF running during an obsinit
because parameters will not be reset correctly. Make sure that you have logged
out of each IRAF window before running obsinit.
Note that the user has the option of
selecting whether CNTL-z or CNTL-d will be the default for an end-of-file
command; the former is the standard at NOAO, but the latter is the standard at
many other places. If you simply wish to set all of the IRAF parameters back to
their default values, you may run this in the middle of your observing run
without losing any files.
4.7. Re-starting the MSE and related software
The software (MSE)
which controls the instrument (filter track, TV cameras, etc.) and the
communications software which links everything together (MPG-router) are
normally started by support personnel when the instrument is installed on the
telescope. However, a restart may be necessary from time to time. If the MCCD
configuration screen shows ????? instead of numbers for the TV camera focus and
temperature readouts, then there may be a problem with this software.
rush% rsh taupe
(at the 0.9-m, or cinnamon at the 4-m)
taupe% ps -ax |
grep msmid
is it there ? no
taupe%
start-msmid
4.8. Observe - The Only Command You Really Need to
Know
All data taking
can be done by using a single command: observe. This command takes one or more
CCD exposures, as in the following example:
cl> observe
Exposure type (|zero|dark|object|comp|pflat|dflat|sflat|focus) (zero):
obj
Number of exposures to take (1:) (1):
Exposure time (0.:) (0.): 300
Title of picture: M33 V
Filter in wheel one (B): V
Telescope focus (0.): -10200
Filter1 = VTelfocus = -10200.00000
Image obj022
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1
cl>
Observation finished...
You will be prompted for all the information required which
includes:
Exposure type: can be "zero"
(sometimes referred to as bias), "dark", "object",
"dflat", "sflat" or "focus". Note that when
selecting from a list of options like this you may enter any unique
abbreviation. Focus exposures, which are somewhat special, are described fully
below in taking a focus frame.
Number of exposures to take: a sequence of this
number of pictures, all having the same parameters, will be taken.
Exposure time: the integration time in seconds
(which need not be an integer). This parameter will not be requested in the
case of exposures of type "zero" for which it is 0.0 by definition.
Title of picture: this will be included as the
title in the image header.
In each parameter
query you are supplied with a default value, which you can accept by simply
hitting [CR]; these default values are just the previous entries. If you make a
mistake, or change your mind, you can abort the command during the parameter
entry stage by typing ctrl-c; the superstitious may enter the command flpr at
this point in order to ward-off the evil eye. For exposures of types other than
"zero" and "dark", you may also be prompted for the
following parameters of the instrument/telescope:
filter in wheel one: the required filter. Note
that filters are specified by name, rather than by their position in the filter
wheel; the way this translation is set up is described in wheel psets.
Telescope Focus: the telescope focus setting
You can control
whether you will be prompted for these instrument-related parameters during
observations (see section on motor control). Once you have entered all the
necessary information, there will be a short pause while the motors in the
instrument are moved to the required positions and then your CCD exposure will
begin. A short message will be printed which includes the name of the picture
which will result. This name is derived from the exposure type by appending a
running number which is automatically incremented after each exposure (how this
number can be adjusted and alternate naming schemes are described in obspars).
The image will be created in the current directory (at the time the observe
command was issued).
The observe command terminates as soon as
the exposure starts and you can enter other commands in the IRAF acquisition
window. While you could type any IRAF command you like, we suggest you keep
this window free for entering the special exposure control commands.
The status window will keep you informed of
the progress of your exposure. As soon as the exposure starts the first line
will change from 'CONTINUOUSLY_ERASING' to 'INTEGRATING' and the status window
will also show parameters of the exposure such as the picture title. A counter
in the status window, and more legibly the countdown window, will begin
counting down the time remaining in the exposure. Another counter will count up
the dark time - the time since the CCD stopped being erased. This will be
slightly greater than the elapsed exposure time due to overheads in the
controller, and will of course be very much longer if you paused the exposure.
When the exposure finishes, the CCD will be
read out. The first line in the status window will change to "READING"
and the "buffers read" counter will indicate the number of buffers of
data successfully transferred to the Sun. The data is initially written in the
controller's internal format to a spool file, but it is automatically converted
into a FITS format image on tan/emerald within a few seconds of the
exposure finishing. The end of each exposure is accompanied by distinct sound
from tan's speakers.
If you requested that observe take only a
single exposure, the message "observation finished ....." will appear
in the IRAF interface window as soon as the readout is complete; things are
then ready for you to start another exposure. If, instead, you requested a
sequence of several pictures, the next exposure will start automatically. You
may immediately examine or process the resulting image even though the sequence
is not complete. Note that the "pictures remaining" counter in the
status window shows how many exposures remain in the sequence. Once the final
picture has been readout, the message "sequence finished ......" will
appear in the IRAF interface window. Should you miss the end of sequence or end
of exposure message, note that the CCD is idle and things are ready for you to
initiate new exposures, whenever the top line of the status display reads
'CONTINUOUSLY_ERASING'.
4.9. Exposure
Control Commands
The following
commands can be used to modify an ongoing exposure:
pause - Pause the exposure e.g. while
waiting out passing clouds.
resume - Resume a paused exposure.
tchange - Change exposure time. You will
be prompted for the amount by which to change the exposure, which may be
positive or negative. If used during a sequence the duration of the present
exposure and all subsequent exposures is changed.
stop - Stop the exposure early, read out
the CCD and save the data to disk. If used during a sequence, the sequence is
also terminated.
abort - Abort the exposure. The CCD is
not read out and any data collected during the exposure is irrevocably lost. If
used during a sequence, the sequence is also terminated. Do not abort a
PAUSEd exposure! - resume first, or suffer serious consequences! (i.e.,
results in a hung system, which will need a restart).
pictitle - If when entering the title you
typed M31 when you meant M33 you can use this command to give your image a new
title.
4.10. Other
Commands For Taking Data
4.10.1. Taking exposures of
specified type
In addition to
observe, there are specific commands to take one or more pictures of each type:
dark - Take one or more exposures of type
dark
dflat - Take one or more exposures of
type dome flat
object - Take one or more exposures of
type object
sflat - Take one or more exposures of
type sky flat
zero - Take one or more exposures of type
bias
Except, of course,
for the exposure type, these commands take the same parameters (and prompt for
them in the same order) as does observe. Apart from saving you entering that
one extra parameter, use of these commands allows one to set default parameter
values, and also select which parameters are prompted for according to picture
type.
While we were
having trouble taking bias sequences at the KP4m during 2002-2003, they are
working again. Please feel free to take sequences of exposures without fear of
hanging the system. At the W0.9m there is still a problem. Please use the
script biases9.cl to take a sequence of biases.
4.10.2. Getting more of the
same
Another useful command is:
more -Take one or more exposures exactly
like the previous one
The more command
is slightly unusual in the way it prompts for parameters (it is patterned after
commands like directory and help). If you type
cl> more
you will not be prompted for the number of exposures (as one
might expect) but rather a single exposure will be taken (which more often than
not is what you actually wanted to do). Conversely
cl> more 10
will take ten more exposures.
4.10.3. Taking a test
exposure
The test command
is just like observe except that instead of creating a new image it always
writes to an image called test.fits (overwriting any earlier version).
This can be useful e.g. for checking you have the field centered correctly. If
you change your mind and decide you want to keep the data just rename the image
test.fits.
4.10.4. Taking your flats
the easy way
It's the end of
the night. You have taken data through a bunch of different filters. Now you
need to get flats for them all. And all you really want to do is go to sleep
.....
Well doobs is for you. With this task
it is possible to take flat fields, or exposures of the same object, in a list
of filters. [The major limitation for taking flats is that the lamp brightness
level will be the same for all exposures.] For example,
cl> doobs
Exposure type (|object|dflat|sflat|): df
Number of exposures to take in each filter (1:) (1): 5
list of filters in wheel1: B,V,R,I
List of exposure times: 15,10,5
The following pictures will be taken:
PicturesFilter1Exposure
31 - 35B15
36 - 40V10
41 - 45R5
41 - 45I5
Title for pictures: Dome flats night1
Filter1 = BTelfocus = -9300.0000
Images dflat031 - dflat035
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1
Sequence finished... .............
Filter1 = ITelfocus = -9300.0000
Images dflat041 - dflat045
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1
Sequence finished...
All exposures finished ...
will take sequences of 5 dome flats each in B (15s
exposures), V (10s), and R and I (5s each). Note that the list of exposure
times may be shorter than the list of filters; in this case the last exposure
time is used for all the remaining filters as in the example. The list of
exposure times can also be longer in which case multiple exposures of different
times will be taken in the last filter. Thus, for instance, a list of filters
of "B" and a list of exposures of 30,300 would take a 30s and a 300s
exposure in the B filter.
Note that doobs is simply a cl script
based on the observe command. One consequence of this is the user's terminal
will be tied up while the script is running. If you realize you have made a
mistake after starting the script and want to stop execution of doobs,
first type Ctrl-C which will abort the script, then type abort (stop) which
will terminate the sequence of exposures currently being executed.
4.10.5. Grids and Dithering
If you want to
make a cosmetically clean image, it is necessary to take multiple exposures at
slightly different telescope pointings to fill in the gaps between CCDs (and
eliminate bad columns). Two scripts have been provided to help in this task
- mosdither - takes
images at a series of positions read from a file:
cl> lpar mosdither
exposure= 420. Exposure time
title= " Tr7 I dithered" Title for pictures
(offsets= "ditherdb$todd.dat") file containing offsets
(npics= 1) Number of exposures at each position
(units= "pixels") units of offset
(gohome= yes) return to starting position at end of grid
(guider_contr= "offon") Guider control mode
(resume= no) start at position_number rather than beginning
(position_num= 2) starting line number in file
(old_mode= no) run in old (but tested) mode
(fd= "") internal use only
(mode= "ql")
cl> mosdither
Exposure time (0.:) (420.):
Title for pictures (test): Tr7 I dithered
Filter in wheel one (I):
Telescope focus (3000.:6000.) (4400.): 4440
Filter1 = I
Telfocus =
4440.00000
Image obj026
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1
Observation finished...
Hit any key when ready (guider working etc.) >
Image obj027
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1 ......
Observation finished...
All exposures finished ...
After each telescope movement the program
pauses to allow time to reposition the guider; hit any key when ready to
continue. At the end of the sequence the telescope will (by default) be
returned to the starting position so that the process can be repeated in
another filter.
The telescope positions are expressed as
offsets in RA and Dec relative to the position of the telescope when the
command is started; they may be given in units of pixels or of arcseconds. The
file ditherdb$todd.dat contains a recommended dither pattern for filling in the
interchip gaps.
# Todd
Boroson's canned dither scheme for the NOAO mosaic
# Offset
relative to current telescope position
# RA
(pixels) Dec (pixels)
0 0
200 -200
-200 200
100 100
-100
-100
The user may instead use their own file by
setting the parameter offsets to the name of the file. Phil Massey contributes
the following table of aerial coverage when using the above dither offsets.
Entries in the table represent what fraction of the imaging area receives 20%,
40%, 60%, 80%, and 100% of the integration time.
|
Fraction of Exposure Time
|
Total Image area (8697 x 8642)
|
Central Image Area (8297 x 8242)
|
|
20%
|
4.6%
|
0.0%
|
|
40%
|
4.4%
|
0.0%
|
|
60%
|
4.4%
|
4.9%
|
|
80%
|
11.8%
|
13.0%
|
|
100%
|
74.5%
|
81.8%
|
Many mosdither options have now been used.
Feel free to contact us for more advice on setting up your own custom pattern.
- mosgrid - is similar
except that it takes images on a regularly spaced grid. The grid is
specified by the starting offset, spacing, and number of positions in RA
and Dec; again these may be given in arcseconds or in pixels.
cl> lpar mosgrid
exposure= 60. Exposure time
title= "Tr7 I grid" Title for pictures
(npics= 1) Number of exposures at each position
(xstart= 0.) initial offset in RA from current position
(xstep= 20.) step size in RA
(xsteps= 20) Number of steps in RA
(ystart= 0.) initial offset in Dec from current position
(ystep= 20.) step size in Dec
(ysteps= 2) Number of steps in Dec
(units = "pixels")units of offset
(gohome= yes) return to starting position at end of grid
(guider_contr= "none") Guider control mode
(resume= no) resume at next position in grid (after quitting
(position_num= 4) starting position in grid
(mode= "ql")
cl> mosgrid
Exposure time (0.:) (60.):
Title for pictures (Tr7 I grid):
Filter in wheel one (I):
Telescope focus (3000.:6000.) (4440.):
Filter1= I Telfocus = 4440.00000
Image obj031
Mosaic1 [1:8315, 1:8220] bin=[1:1], gain 1
Observation finished...
Hit any key when ready (guider working etc.) > .......
Observation finished...
All exposures finished ...
Both mosdither and mosgrid
include several important user options as hidden parameters. First, there is
guider_control, which can be set to "none" if you are not using the
guider at all, "wait" which waits for the observer to do whatever
they wish to do before starting the next exposure, and "onoff" which
should be used most often when you are using the guider. In the
"onoff" mode, the guider is turned off, the telescope is moved by the
proper dither/grid motion, and you are prompted to hit any key when the guider
has been readjusted for the motion of the telescope/guide star; when you hit a
key, the guider control is automatically restarted.
In addition, position_num provides
control to pick up in the middle of a dither/grid sequence should a crash occur
before the sequence was completed.
4.11. Controlling
the Data Capture Agent (DCA) on Tan or Emerald
A
screen capture of the current set of graphical user interface (GUI) control
windows that control data acquisition and post-processing on tan/emerald
is shown below. Most operations should be self-explanatory, but for that rare
button that defies interpretation, the on-line help button should clarify the
situation.
Figure
4.11.1: The main GUI panel for the DCA. Verify that the directory shown is
where you want your pictures to go (controlled via the Arcon IRAF window using
"cd"). You can watch the packets count up as the picture is read
out.
Briefly, the Main DCA GUI provides control
for you to:
- turn
on or off the auto-display of images ("Display Enable" box) as
they are being read out. Turn this off for very short exposures (e.g.,
biases).
- enable
the post-acquisition processing ("Postproc Enable")
- allow
auto-termination of the current display process if another image is read
out before the previous display completes ("Auto-Kill Enable")
You can also monitor the status of the
readout (bottom line gives percent of readout), and verify that the filter and
image type are correct.
Figure 4.11.2: The Display Options Editor GUI panel for the DCA. This
GUI offers control of several complex functions.
The "Display Options Editor" panel
allows you to:
- enable
"on-the-fly" processing (overscan subtraction, flat-fielding) of
the raw image (flat-fielding applies to 'object' types only) to provide a
cleaner image for quick-look examination; otherwise, sensitivity variations
across the chips make it very hard to see faint objects. This option
requires about 20 CPU seconds beyond a simple display of the image. It
does not affect the saved data, but only the appearance of the displayed
imaged.
- override
the flat-field to be used in the "on-the-fly" processing. You
must pull-down the proper filter name prior to the start of readout -
in some cases, the proper flat-field may not be available for the filter
you are using, but a recommended alternative can be used (noted with the
"->"
sign).
- postpone
the display until full readout is complete ("Display After Readout
Completes") - this option provides a speed advantage when displaying
over a network to another computer.
- change
the resolution of the display (Stdimage) to speed up the display process,
or to improve the visual look of the display (smaller imt numbers
make the display faster, but average more pixels together when displaying
the image, thereby losing resolution).
- change
the "Node", or name of the computer being used for the display -
normally, this is the same computer that the DCA runs on (usually tan
or emerald) and no entry is needed here.
- preset
the primary display parameters (zscale, zrange, z1, z2)
- select
which frame the new frame will be displayed into
- choose
whether the display screen will switch to the frame showing the new data
automatically (if you are examining an earlier image, the change to the
new picture is disconcerting)
- adjust
the delay before display begins - usually 7% of the picture is enough; the
display program must collect some data to determine the data range before
showing you the image; otherwise, the image might appear all white or all
black, causing great, but unnecessary, concern about the data.
Figure
4.11.3: The Path Options Editor GUI panel for the DCA. This GUI controls the
names of commands and locations of files. Normally, you never need to see this
panel. If you change the command names for the display task or the
postprocessing script, you are flying solo.
In order to calibrate new images as they are
being read from the Mosaic on-the-fly, typical biases and flatfield images are
kept in a directory. The "Calibration Dir" allows you to change the location
where these images are stored. We are developing tools so that the average user
can build the specially processed and compressed flat field images used by the
display processor. When these are completed, it may be useful to construct your
own directory of flats. For now, adjust this parameter at your own risk.
4.12. Observing in Binned Mode
Some science programs need the full field of
view of MOSAIC, but greatly need to reduce the amount of over-head in taking an
image (down to 1:06 from 2:34 for 2x2 binning). If you do not need the
full spatial resolution, one way to reduce the over-head is to read-out the
CCDs in binned mode. There are other reasons some programs might want to bin
their data during readout. In this section we describe how you can switch the
binning and provide some additional information on how the operational behavior
of the observing system works when using binning.
To set the binning, in the ARCON console (on
rush or rust), run setdet and be sure to exit setdet with Ctrl-D.
I R A F
Image Reduction and Analysis Facility
PACKAGE = astronomer
TASK = detpars
(gain = 2) Gain setting
(xsum = 2) pixels summed in X direction
(ysum = 2) pixels summed in Y direction
(ysize = 8192) Height of centered ROI (full width)
(pixsize= 15.) Pixel size in microns
(nxpixel= 2048) Detector size in X
(nypixel= 4096) Detector size in Y
(detname= Mosaic1) Detector identification
(mode = ql)
After exiting the setdet parameter file with
Ctrl-D you should get the following feedback. If it does not appear, most
likely you have not successfully changed binning modes.
DEBUG -- Starting continuous erase
DEBUG -- Starting continuous erase
DEBUG -- Starting continuous erase
DEBUG -- Starting continuous erase
In the example above we have set the binning
mode to 2 by 2 by adjusting the xsum and ysum parameters. To
switch back to unbinned mode, run setdet again and reset these parameters. Do
not adjust the GAIN mode. After running setdet, subsequent exposures should
appear in the desired mode. Check your first exposure to make sure it is the
format you desire. We have occasionally seen the setdet task fail to reset the
mode. Normally just running the task again will succeed in adjusting the mode,
but occasionally you will have to restart the ARCONS and try setdet again.
Please note that several features of the
MOSAIC system do not currently work as well when observing in binned mode.
These include the following:
- The display processing
controlled by the DCA (applying the on-the-fly flat and over-scan, bias,
correction) does not work as well. We suggest you turn off this feature.
- The mscexamine, which can
normally be used to display object shapes and intensities of portions of
the image even while the image is being readout, will not work properly.
Images of objects which are round will appear pixelated when the
"e" (contour-plot) and other options are used.
- The cores of
bright/saturated stars are not handled properly and will be negative.
These will appear as white "holes" in the centers of these stars
when the image is displayed. Photometry of the other objects (lower
counts) is not affected.
Remember that you will need to take bias
frames and flats in binned mode to go with your binned science frames.
One can also block average the images
(MSCBLKAVG) after readout if data volume is the real issue.