GETTING STARTED
- At least once during the run (but it is safer to get several),
you should have obtained bias files :
- One for the spectrographic frames, which is a full frame,
unbinned one. It should be a median of at least 20 (50 is better)
biases. But as long as LORAL3 exhibits the offset
problem, you may have preferred to come back home with N individual
biases. If this is the case, check them with the
Check Overscan
tool, then use the
Build bias
function on each of them, then median them outside XOasis
(as this function is
not yet provided in the current release) to obtain the final median bias
file. But if you perform on Mauna Kea a median over, say, 40 or 50
individual biases, you would have to be very unlucky to get a polluted
median.
- One for the imagery frames, which is a full frame,
4x4 binned one. It should be a median of at least 20 biases.
- For each scenario, you should have obtained, with the
telescope in zenithal position, with no beamsteerer rotation in
between, and in time-adjacent periods :
- A micropupil exposure.
- A very high signal-to-noise ratio GUMBALL white light
spectroscopic flat field frame, which must be a median
of at least 10 exposures (or a set of at least 10 exposures,
not medianed (see the bias paragraph above, relative to LORAL3
issues).
- A GUMBALL spectral lamp calibration exposure, associated with
the preceding one.
- A high signal-to-noise ratio dawn or dusk skylight spectroscopic
flat field frame. Sky must be quite bright to get a good SN
within a reasonable time; remember the spatial sampling...
- A GUMBALL spectral lamp calibration exposure, associated with
the preceding one.
- For each scenario, you should have obtained at least
one spectrographic exposure of a spectrophotometric
standard star. It is much better to obtain several
exposures at various zenithal distances.
- For each spectroscopic exposure, you should have
obtained an associated spectroscopic GUMBALL spectral lamp
calibration exposure without moving
the telescope, and without rotating the
beamsteerer between the two.
Use some standard UNIX tool to download,
from the CFHT data save tape, the
set of files needed to reduce this scenario's data :
- All the science imagery exposures (object, stars for seeing
evaluation).
- All the science spectroscopy exposures (object, standard star(s))
pertaining to this scenario, each one
with its associated wavelength calibration exposure.
- The micropupil exposure from this scenario.
- The GUMBALL flat field exposure from this scenario, with its
associated wavelength calibration exposure.
- The dawn or dusk sky flat field exposure from this scenario,
with its associated wavelength calibration exposure.
- The two bias frames, for spectroscopy and imagery exposures.
Note that separate directories must be used for various scenarii.
It may even be a good idea, if you reduce data for several objects
observed
with several configurations, to separate completely the service files
and the objects files. This is an example of a directory structure
which may prove to be quite handy (forget the 3C numbers, chosen at
random!) :
- Radiogal98 : Father directory, with the following
sub-directories :
- CCD : All the basic CCD files (raw bias frames
and final biases)
- mr2f8 : All the files (from raw frames to
datacubes and correction spectra) to be used to reduce
objects observed with configuration MR2 f/8. The
standard stars, sky and Gumball flats, flux correction
curves, etc... are there.
- mr4f20 : All the files (from raw frames to
datacubes and correction spectra) to be used to reduce
objects observed with configuration MR4 f/20 (AOB). The
standard stars, sky and Gumball flats, flux correction
curves, etc... are there.
- 3C248mr2f8 : The object files (from raw frames
to final merged datacubes) of 3C248 observed in this
configuration.
- 3C253mr2f8 : The object files (from raw frames
to final merged datacubes) of 3C253 observed in this
configuration.
- 3C285mr4f20 : The object files (from raw frames
to final merged datacubes) of 3C285 observed in this
configuration.
It is easy, in XOasis, to navigate in the directory structure, and so
to pick up the configuration files, when they are needed, in a
parallel branch. More, after you point once to, say, the flux correction
curve, XOasis remembers the full path, and you no longer have to
bother about that, as long as you stay in the same work directory.
IMPORTANT WARNING : in the present release (4.3) it is
mandatory to have the preprocessed calibration frame associated with
the continuum
exposure used to create the extraction mask (ouch...) visible from
every directory where data are to be reduced which belong to the
same configuration. This is because this frame is used as a reference
for the wavelength calibration. This is not nice, and will be
corrected in futur releases. Just link the original file to
every work directory concerned. For example, in the above example of
directory structure, assuming the preprocessed calibration frame of
the MR2 f/8 continuum is p438445c.fits :
- cd ...../3c248mr2f8
- ln ../mr2f8/p438445c.fits .
- cd ../3C253mr2f8
- ln ../mr2f8/p438445c.fits .
- And so on...
And remember not to compress inadvertently this frame before all the
wavelength calibrations are done !
Go to the work directory of your choice, and
start the reduction program by typing :
XOasis
See the installation instructions (readme file) to know how to make
XOasis executable on your system.
Click on Settings then on Preferences
in the main horizontal menu.
A window pops up, which offers you to modify ten classes of
parameters :
- File format
- File overwrite
- Debug
- History
- Misc
- Log
- Assistant
- User
- Help
- Windows
All these possibilities are fully described in the
Settings section
of this manual.
This tool is provided to take advantage of original CFHT file
information to ease the reduction process.
Click on Tools in the main menu bar, then on Observation Log
Book. In the new window, all the FITS files present in the current
directory are listed, with their main characteristics (identifier,
type, integration time, alpha, delta, airmass, and so on...).
Please note that file names can be Activated (left click
anywhere on their line in the display, the line is now displayed on
a light blue background), then Dragged and Dropped in any
of XOasis file name input fields ( with the left mouse button kept
depressed). By clicking the middle button on an activated file, you
get a small pop-up menu which displays first the complete name
of the file, and offers you to :
- View : the image is displayed using RTD.
- Info : as you expect...
- Descriptors : the image descriptors, written into the
file, can be read or modified (be careful...).
- Top : the display is shifted to the beginning of the
list.
- Bottom
: the display is shifted to the end of the
list.
The main menu offers three possibilities :
- File
- Load Logbook :
- Build Logbook : This has to be done at the very
beginning of the reduction process, once the original
files have been copied to the work directory, before
preprocessing them. All the FITS files present in the
current directory are listed, with their main
characteristics (identifier, type, integration time,
alpha, delta, airmass, and so on...). This reminds the
user of the content of every file he brought back from
the OASIS run.
- Print Logbook : Does what you expect, if you
correctly filled in the [Settings/Preference/Misc]
print command] field...
- Close Logbook : The Observation Logbook management
window is closed; if you reopen it later, you will
retrieve the Logbook as it was at closure time.
- Patch all FITS files : This must be used if you are
to reduce data obtained before December
1998; since then, an inproper keyword writing on
original CFHT files have been corrected, and
this function is no longer useful. Before, it
is mandatory !
- Selection
In this window, the selection of a file is made by
checking the button in the [S] column,
at the beginning of the line, or by
using mass-selection functions :.
- Select all
- Deselect all
- Invert selection
- Actions
- Download from tape :
Not yet implemented...
- On selected files :
Once some files have been selected, the following functions
will do what you expect...
- Move
- Copy
- Delete
- Compress : using the program you specified
with the
Settings function. In my opinion,
this is definitely NOT a well-tested feature of
XOasis :-(
- Uncompress : same remark as above.
Display options are set up with :
- Scenarii
You may choose here to list all the frames pertaining to any of
the sceanrios, or to restrict the display to some specific
scenario(s).
- Exposure types
In the same way, you may choose here to list al the classes of
exposures, ore only a subset.
- Comment for the current exposure
Enter here any text you want to be associated with a particular
frame. This frame must be first activated by clicking on its
line in the display window (the line is then written on a
light blue background); the comment will be displayed each
time the file will be activated.
Click on [Log] in the horizontal menu. A window pops up, which
offers you to edit a logbook :
- You may enter any comment you need to be recorded, and use the
usual editing commands on any block of text.
- In addition, if you have checked that option in the Log section
of the [Settings] function (see above), an ASCII report of every
command you apply to your data is continuously appended to the
reduction logbook file.
- Lastly, at the end of each reduction step, you may record an ASCII
summary of the results in the logbook.
The commands from the File pull-down menu, as well as the six
icons at the top allow you (from left to right) to :
- Open a new Reduction Logbook : used to start a new logfile,
to be saved under some another name, or to flush the entire contents
of the present logbook, by keeping the same name when saving.
- Load (open) an already existing Reduction Logbook.
- Update the Reduction Logbook : the contents of the file
is replaced by the current contents of the editing window.
- Save the Reduction Logbook as... (under a new name).
- Print the Reduction Logbook; does what you expexted, if you
correctly filled in the [Setup/Misc/Local print
command] field...
- Quit the Reduction Logbook editing; before leaving,
the user is offered to save or not the current contents of
the editing window.
- Principles :
- This tool is provided to maintain an (hopefully) clear list of the
already processed files, their nature, their relationships. Click on
[Tools] in the main menu. then on [Reduction Folder].
- Note first that, as in the Observation logbook,
you may obtain information about, display, and so on... or drag and
drop an activated file; read the
Observation logbook paragraph
for details. It is possible to perform multiple-selection
à la Windows : click on a file, then shift-click on
another; all the in-between files are selected, too.
- At the very beginning of the reduction, only the original CFHT files
are shown, with minimal information : identifier, type, file name.
- Every time you process a file, the display is automatically
refreshed; use [File]/[Scan Directory] to force an
update of the display.
- The files are displayed arranged into folders. For instance, all
the datacubes and reconstructed images or spectra which derive from the
same raw frame remain in the same folder, whose head is the mother
table created at spectrum extraction. Folders maybe opened or closed
at will : click on the [+] or [-] sign to the left of the folder icon
to open or close the folder. Once open, the folders show the files
identified by their name, and by a specific icon telling which kind of
data they hold.
- Menus :
- File :
- Scan directory : refreshes the display, including the
newly created files.
- Close folder : closes the window.
- Selection
In this window, the selection of a file is made by
checking the button in the [S] column,
at the beginning of the line, or by
using mass-selection functions :.
- Select all
- Unselect all
- Invert selection
- Actions
- On selected files :
Once some files have been selected, the following functions
will do what you expect...
- Move
- Copy
- Delete
- Compress
- Join to catalog
This is a very useful function. If you select a number of files
by checking their [S.] button, at the very left of the
reduction folder's lines, and then use this [Join to catalog]
function, a new window pops up. You may then either select an
existing catalog file (ending in .cat), or give a name
for a new one in the [Selection] field, then click on [Accept].
The files you selected are then appended to this catalog. The
nice point is that the name of the catalog can now be given in
place of the name of the [Input frame] in the [Preprocess],
etc... windows, and all the files in the catalog are processed
in a row.
- Display options are set up with :
- Classes
You may choose here to list all the frames pertaining to any of
the scenarios, or to restrict the display to some specific
scenario(s).
- File types
In the same way, you may choose here to list all the types of
exposures, or only a subset.
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Last update: 11/01/1999. Send comments to
martin@cfht.hawaii.edu