The OASIS Obstool provides a simple, efficient and accurate means to
set up OASIS observations. By selecting the (i) spectral
configuration, (ii) spatial sampling, and (iii) observing mode (e.g. an
arc frame) desired, one can use the tool to automatically configure the
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critical mechanisms (i) on the AO bench and (ii) within OASIS itself.
This webpage gives a step-by-step guide to using the OASIS Obstool.
This section gives an overview of how to use the OASIS Obstool and is intended as
a quick reference guide. Detailed instructions on each step are given
in the rest of this user guide.
There are a number of ways to start the OASIS software and obtain the
Obstool GUI. For normal night time observing, however, you should refer
to Situation 1.
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Click on images to enlarge
If you find the status of (i) the
dichroic (on the USP/Obstool tabs) or (ii) the OASIS mechanisms (on the
OASIS/Obstool tabs) to be in an error state:
It is likely that another session of the control software is already
running, perhaps on a different machine. In this case:
1. Identify which machine the software is already running on. On
each possible machine (probably taurus, lpss94 or lpss39) type:
SYS> ps -ef | grep java
and search for the various servers associated with INGRID, USP, OASIS,
Obstool, TCS and SEEMON.
2. Once you have found the servers running (e.g. see here) you can cleanly shut
them down by typing:
SYS> shutdownoasisserver
on the relevant machine.
3. The items that were in an error state on your GUI should recover
their status.
If you find the TCS information
missing (on the TCS tab):
1. One reason could be that the observing system hasn't been started
(properly) on the machine that you are using. The SYS>
startobssys command initiates a couple of communication tasks
that are vital for the TCS information to be accessible. If you need
this information you will need to (re)start the observing system.
2. It is possible that one of the TCS communication tasks has
failed. If there is (or has been) a problem with the
OCSCorbaDramaInterface, then:
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Click on images to enlarge
In the previous section, we discussed the five groups of mechanisms that are
configurable with the Obstool. All the OASIS mechanisms formed one
group and most of the AO bench mechanisms were included in another.
However three
mechanisms remained in their own individual groups (the dichroic, the
filter focus and the iris), with their status and control
treated separately.
The three demand values set earlier uniquely define the position of all the OASIS mechanisms and the majority of the AO bench mechanisms. On the other hand, although one can assign default values to the positioning of the dichroic, the filter focus and the iris, there are a number of reasons why you might wish to overrule these default settings. To do this, you can use the Adjust section of the Obstool GUI.
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Now that you have correctly configured both OASIS and all the AO
mechanisms on the bench, you are ready to take integrations. In the
near future, you will be able to launch these directly from the Obstool
GUI. In the meanwhile it is still necessary to use the command line
interface of the observing system. E.g.:
SYS> run oasis 300 "BD+284211"
SYS> multrun oasis 3 300 "BD+284211"
SYS> bias oasis
SYS> multbias oasis 3
SYS> dark oasis 300
SYS> multdark oasis 3 300
Note that the special bias and dark
commands
are required for bias/dark frames as they prevent the camera shutter
from being opened.
However it is not necessary to replace the run command
with flat, sky, arc,
and pupil
while taking such exposures. The exposure type is
automatically recorded in the image header using an OAFCLASS header,
and is deduced from the observing mode that you requested
in the Set
Demand
section. The actual values are represented as integers (which are
recognised by the data reduction package XOasis), and the
corresponding mappings can be found here.
The Obstool also generates an OACONFIG header, which contains the current configuration of OASIS (e.g. MR661_26). Note that this value corresponds to the Oasis status reported in the first field of the Configure section.
In this section we summarise the OASIS configurations that are currently implemented in the Obstool.
OASIS offers fifteen
spectral configurations, covering a variety of spectral ranges and
resolutions. Their names have a five letter syntax; the first two
letters indicate the resolution (LR, MR and HR for low, medium and high
resolution) while the last three numbers give the central wavelength in
nm. For example, the MR661 configuration is a medium resolution
configuration centred at 661nm.
The filter wheel in OASIS is only capable of holding 12 filters,
whereas each of the 15 spectral configuration has a unique filter. This
means
that at any one time, three filters (and therefore three
configurations) will
not be available. One can determine the 12 configurations that are
currently offered from the drop down menu.
OASIS offers four
spatial samplings (and fields of view) through the use of four
different enlargers. The spatial sampling is usually referred to in
terms of the sampling per lenslet, and the available values are
0.09"/lens, 0.14"/lens, 0.26"/lens and 0.42"/lens. Note that the naming
convention for the full OASIS configuration (i.e. both spectral and
spatial configuration) also uses these values, e.g. MR661_26
corresponds to the MR661 spectral configuration combined with
0.26"/lens spatial sampling.
All four spatial samplings can currently be configured from the
Obstool
using the drop down menu. (The 0.42"/pix sampling is not currently used
for science as it has not been commissioned due to severe vignetting.)
Click on image to enlarge
16 OASIS observing modes are currently offered. Here
we give a brief summary:
AO Bench Setup: Note that
the Obstool ensures that (i) the table is fixed if necessary, (ii) the
NCU
is in the appropriate position, (iii) the correct lamp (if any) is on
and set to an appropriate intensity, (iv) unused lamps are switched
off, (v) the correct dichroic is
selected, (vi) the Oasis and Simplex flats are correctly deployed, and
(vii) the filter focus corrector is set to a suitable value, all for the Oasis configuration and
observing
mode requested.
Oasis setup: Oasis is
configured according to (i) the spectral and spatial configuration
requested and (ii) the observing mode. Column 4 summarises whether the
mechanisms are configured for OASIS's spectroscopic, imaging or
micropupil
mode (in the desired spectral/spatial configuration). Note that there
is also a special "Shut" mode,
for which
the Entrance Wheel shutter must be deployed (but the position of the
remaining OASIS mechanisms is irrelevant).
Click on image to enlarge
Back to the top
Earlier we discussed how it was possible to
use the Adjust section of the
Obstool to
change the positions of the dichroic, filter focus, and irises from
their default values. Here we outline possible reasons why this might
be done:
For each OASIS configuration there is a default dichroic assigned to
it. This dichroic must have a large enough bandwidth in order to
enclose the bandwidth of the associated OASIS filter, yet should be as
narrow as possible to ensure that as much light as possible goes to the
WFS (wavefront sensor) of the AO system. Possible reasons to change
from the default position are:
(i) The MR807 configuration can be used with both dichroic #3 and #4. While the current default is to use dichroic #3, in some cases the observations might be better suited to using #4.
(ii) Nine of the configurations that by default use dichroic #1 or #2, could also be employed with dichroic #5. This could be beneficial if one wishes to use an extremely bright AO guide star, as it would reduce the magnitude of the star on the wavefront sensor and help prevent the latter from becoming saturated.
(iii) If you are observing a bright object (and thus are not photon
starved) but require a very good AO correction, it may be beneficial to
use the 50:50 dichroic instead of the default OASIS dichroic. The 50:50
dichroic sends half of the light (at all wavelengths) to OASIS, and the
remainder to the WFS. Depending on the configuration and dichroic that
you are using, you may get an increase in flux on the WFS by adopting
the 50:50 dichroic, and can therefore improve the performance of the AO
correction. Note however that the
flux reaching OASIS will be reduced by a factor of ~2.
(iv) During the daytime setup for an OASIS run, the support
astronomer (SA) must flatten the
DM (deformable mirror). A couple of observing modes [Simplex (AG)
and Simplex
(OASIS)] have been added to allow the SA to both perform the
flattening, and assess the results, using an illuminated pinhole. By
default the Simplex (AG) mode adopts the 50:50 dichroic, while Simplex
(OASIS) uses the default
dichroic for the OASIS configuration requested. However it is possible
that the SA may wish to "simplex" using a different dichroic; similarly
they may want to check the image quality on OASIS using Simplex (OASIS) with the 50:50 dichroic.
The filter focus corrector mechanism is used to apply focus offsets
when one switches between (i) different OASIS filters and (ii) between
OASIS and AG7 (the simplex camera). While default offsets have been
included in the Obstool, the observer may wish to check that these
offsets provide the sharpest focus and, if necessary, adopt a different
value.
Many of the observing modes use one of the four calibration lamps
(Ne, He, continuum or simplex). "Spectral irises" are used to provide
the
large dynamic range in intensity that is required for the many OASIS
configurations. Where relevant, a
default iris setting has been established for every OASIS configuration
and observing mode to ensure that an exposure of a few seconds will
give ~30-40,000 counts. (Aside: Note
that longer exposure times are needed with the Neon arc lamp for the
bluer configurations; in future a new Argon lamp will be used instead.)
You may need to adjust the default iris settings for the following
reasons:
(i) The actual lamps are brighter or fainter than when the default
values were measured (in particular when the lamp is about to fail).
(ii) The lamp has just been replaced. Note that if the lamps appear a
lot fainter than they previously were, it could indicate a problem with
their alignment; you should ask Olivier Martin or Tom Gregory to check
this.
(iii) The dichroic you are using is not the default one (see here).
(iv) There is some hysteresis in the iris mechanisms, which may have an
effect particularly for small irises.
(v) In the short term, the iris
settings have only been measured for the 0.26" spatial sampling. It may
be possible to simply adjust the exposure times to compensate for the
increase/reduction in flux when using coarser/finer samplings, but in
some cases it may be necessary to adjust the iris.
Please report any major changes in the required iris settings to Chris Benn or Sam Rix.
Note that the default iris settings may be found to be unsuitable
simply because the iris mechanism needs initialising. Go to the USP tab of the Oasis
software, find the appropriate
iris ("Spectral" for the Ne or He lamp, "Continuum" for the continuum
lamp, and "Simplex" for the simplex lamp), and select "Initialise" from
the drop down menu. The mechanism will take a few minutes to
initialise, then you can move it again to the default setting.
In this section we illustrate the use of the OASIS Obstool by using an
example sequence of events that demonstrate the key features. (Click on the images to enlarge.)
1. The image below shows the Obstool after it has been successfully
configured for an MR516_14 continuum exposure. All the fields in the Configure section are in green,
meaning that their status satisfies the 3 demand values in the Set Demand section.
2. We now decide to take a arc exposure, using the Neon lamp, with
the MR661_26 configuration. First we change the 3 demand values. We can
now compare the status of the five fields in the Configure
section to their previous states. First note that the status of
OASIS, the dichroic and the filter focus remains unchanged. However, as
our demand observing mode has changed from continuum to arc, the iris
status displayed has changed from that of the continuum iris to that of
the spectral iris. Finally the "Naomi other" status has changed from
"CONFIGURED OK" to "NOT CONFIGURED". More strikingly, the colour coding
of all the fields has changed from green to pink,
indicating that none of the groups of mechanisms are
correctly configured for the new demand values.
3. Next we ensure that all five tickboxes are ticked, and click on Configure Selected Items. The appropriate mechanisms are moved to the correct position and their status is shown in blue while they are moving.
Once the mechanisms have stopped moving, and they are correctly positioned for the three demand values, their status is shown in green.
Note that if you wish to see the corresponding status of the
individual OASIS mechanisms you can click on the OASIS tab. Normally this is not
necessary, but it can be useful if one of the mechanisms has gone into
an error state.
Similarly the status of the individual bench mechanisms can be
checked by clicking
on the USP tab.
4. Having taken a test exposure, we might decide that the arc lamp
is
a little too bright. We can reduce its intensity by stopping
down the spectral iris. We go to the Obstool's Adjust
field, select Edit value, type
in -310, and hit enter. The spectral iris mechanism moves to the new
demand position, and the final status is displayed in pink to
remind us that this is not the default position for the MR661_26 Neon
arc configuration. We can now take our arc exposure.
5. We now decide to take another Neon arc, but with the MR516_26
configuration. Selecting the new demand values, we find that the "Naomi
other" mechanisms are correctly
configured, but the positions of the OASIS, dichroic, filter focus and
iris
mechanisms are incorrect.
6. We decide to configure all the mechanisms except the filter
focus, as the latter is not so important when taking arc frames. To
deselect the filter focus we click once on its tickbox. Note that we do
not need to bother unticking the "Naomi other" box even though it is
correctly configured.
7. We click on Configure Selected Items and the relevant mechanisms are repositioned. The filter focus remains in its current position and is colour coded pink to remind us that it is not in the default position for an MR516_26 Neon arc frame. Note that the spectral iris has been reconfigured i.e. if you put a tickmark by the iris field, and click on Configure Selected Items, the mechanism will be moved to its default position regardless of the value previously selected in the Adjust section.
At the end of the night (or the end of daytime work),
you
should configure both OASIS and the AO bench into the "Shutdown"
mode:
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Last Updated: 18 August 2006
Samantha Rix, srix@ing.iac.es |
