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2. INGRID real time display
INGRID real time display (RTD) consists in two elements: a RTD
control panel and an Ximtool in which data is displayed.
- RTD control panel. INGRID fits data files contain two
extensions (e.g. r414230.fit[*,*,1] and
r414230.fit[*,*,2]) which correspond to the array readout after the
reset process and before the integration (the pre-read, extension 1)
and the readout of the array after integration has finished: the post-read
or post-integration data set with extension 2. (Click
here
for a more detailed explanation.)
The RTD control panel (image below) includes several options which
allows the user to display either the post-read or the pre-read extentions
or the post-pre image of a certain observation data. Also it is possible to display
the subtraction of one image from another (e.g. a sky subtracted image).
This operation affect only the displayed data (i.e. only raw
data is stored on disk).
On the RTD control tool window, from up to botton:
- Observation data Shows the file name of the image actually
displayed on the Ximtool.
- Reference data Shows the file name of the image loaded as
reference data (see below).
- Status Status of the RTD. It is ``scanning'' if the
Data detection is selected to be on (clicking on the
corresponding diamond), and ``data detection off'' if Data
detection is off.
- Data directory Shows the directory in which the data is beeing stored on.
- Data detection If this box is selected to be
on (clicking on it), the new images are automatically loaded into
the RTD.
- Display state This section offers
several options to display the data, which are activated by clicking on the
diamonds on the left:
- OBS-REF Displays the post-pre of the observation data minus the
post-pre of the reference data
- OBS/REF pre Displays the pre-read of the observation/reference
data
- OBS/REF post Displays the post-read of the observation/reference data
- OBS/REF post-pre Displays the post-pre of the observation/reference data
- Refresh Click on this button to refresh the display on the Ximtool.
- OBS->REF Load the current observation data as reference data.
- Quit Click on this button to quit the RTD.
- Load OBS/REF data This buttons can be used to load any fits file of the
Data directory as Observation data/Reference data: type the file name
of the image in the corresponding box and click the associated button.
In the example above, the post-pre of the file s1.fit is displayed on the Ximtool
and no data has been loaded as reference frame.
- Ximtool It is a typical Ximtool image display window but in addition
it turns red the pixels which value in the post-pre of the data set
is higher than the full well (22000 ADU).
For values higher than 22000 ADU in the post-pre, deviation from linearity
starts to be high (higher than ~8%) and pixels are shown in red. Since the full well
can change slightly, keep away from
this limit by decreasing your exposure time, if necessary.
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3. INGRID mechanisms
INGRID mechanisms comprises a pupil stop wheel, two filter wheels
(one for narrow
filters and another one for broad band filters), the focus drive and a pupil imager.
- Status of INGRID mechanisms
The position of the filter wheels, the pupil stop wheel, the instrument
internal focus and the pupil imager can be checked by means of the
mechanisms' windows or using the command line:
- The INGRID mechanism mimic
summarizes the selected position in the filter
and pupil stop wheels, the pupil imager and the
instrument internal focus value in microns.
A graphical user interface
(GUI) can be obtained from the
File menu, selecting Control. The
selected positions in each wheel are coloured in green.
- In the pink instrument control system window, the command mchstat:
hh:mm:ss>mchstat, shows the status of the INGRID controller and all the mechanisms.
- Moving INGRID mechanisms
Mechanisms can be moved using either the GUI or the command line interface
(pink window), however it is recommended to move them using the command line.
- From the GUI
- Filters and pupil stops. To move any of the three wheels, click
on the filter/pupil stop you want in the beam. Whilst moving, the whole wheel is
coloured blue and the position selected yellow. When it is well positioned, the
selected position is coloured green and red if it is in an undefined position.
If the latter occurs, datum the corresponding wheel (click in the
datum button or type e.g.: hh:mm:ss>datum fwheel1 (or fwheel2, or pstop)).
- Focus drive. To select an array focus value, type the required focus value
in microns and into the box and hit return). Not available actually.
- From the command line in the ``pink window''
- Filters. Independent filter movements can be
performed with the commands fwheel1 < filter name > or
fwheel2 < filter name > for broad band and narrow band filters
respectively. It is however recommended to use the command filter:
hh:mm:ss>filter < option > , where
< option > can be blank,z,j,h,k_s,k,fe,brg,kcont,
hcont, h2v1-0, h2v2-1.
With the filter command, filter movements are tied to other filter
movements and/or pupil stop
movements to eliminate as much unwanted radiation as possible before entering
the camera and thus it is recommended to use this command to change the filters.
These filters-pupil stops combinations are:
| < option > |
Pupil stop wheel |
Filter wheel 1 |
Filter wheel 2 |
| blank |
blank1 |
blank2 |
blank4 |
| z |
cl |
z |
clear |
| j |
cs |
j |
clear |
| h |
cs |
h |
clear |
| k_s |
cl |
k_s |
clear |
| k |
cl |
k |
clear |
| fe2 |
cs |
h |
fe2 |
| brg |
cl |
clear |
brg |
| kcont |
cl |
clear |
kcont |
| hcont |
cs |
h |
hcont |
| h2v1-0 |
cs |
k_s |
h2v1-0 |
| h2v2-1 |
cs |
k_s |
h2v2-1 |
- pupil stops are changed independenly of filter movements with the
command:
hh:mm:ss>pstop < option > ,
where < option > for observations at the Cassegrain focus are:
(CHECK OPTIONS AND NAMES!!!)
- cs Pupil stop with short central obscuration. Used
for observations at cassegrain with wavelength< 2µm
- cl Pupil stop with large central obscuration: observations at
cassegrain with wavelength> 2µm.
- clear No pupil stop in the beam.
- blank1 Aluminium blank for darks frames acquisition.
Other options are: ns, nl, osca-cl,
osca-obs,ker,kel,focus.
- ingrid focus drive.Type hh:mm:ss>ifocus < position in microns >.
INGRID internal focus is stuck actually (01/07/2001); it is not possible to move it.
- pupil imager. Only used in engineering mode. In normal astronomical use the
pupil imager position must be out of the light beam. Type
hh:mm:ss>pimager out if necessary.
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4. Focussing INGRID-telescope
When observing with INGRID, focussing is a two step procedure
which involves focussing the telescope and then focusing INGRID
itself (i.e. changing the distance between the array and the INGRID foreoptics).
It is important to focus the telescope before focussing INGRID. If INGRID is focussed before
then we are correcting telescope focus errors with the instrument focus giving place to
image quality degradation. Thus, focus INGRID only after you have focussed the telescope.
Focussing the telescope
The best telescope focus value for observing
with INGRID is ~99.0mm. Use this value as starting point.
- Select a star of magnitude ~10-11 to focus on and tell the telescope
operator (TO) to move the telescope to it.
- Select a filter, e.g.: hh:mm:ss> filter h
No focus offset has been observed
between different broad band filters.
- Take a sequence of images for different values of the telescope focus
using the command whtfocusrun followed by:
- the number of images (i.e. number of telescope focus movements),
- the exposure time,
- the number of coaverages of the given exposure time
performed in each image of the sequence,
- the telescope focus value for the first image in the sequence (in mm) and
- the focus increment between each image (in mm)
*Example:
hh:mm:ss>whtfocusrun 9 8 2 98.5 0.1
In this case, nine scratch files (s1.fit, s2.fit,...,s9.fit)
would be saved on disk, each one corresponding to a telescope focus value (starting
at 98.5mm with steps of 0.1mm) and obtained after coaveraging two 8s exposures.
It is recommended to exposure for at least a total of 10-15s in each
image in order to average seeings effects.
- On lupus, in the iraf session and within the INGRID quick look
reduction package, find the best telescope focus value, so type:
in>istarfocus s1,s2,s3,s4,s5,s6,s7,s8,s9 focus=TELFOCUS
and follow the instructions (i.e. mark with an m one or more stars
in the image, type q and wait until an xgterm appear showing
the fwhm and ellipticity plotted versus the telescope focus value, and finally
type q again to find the best value).
- IMPORTANT: Set the telescope value to the best value determined above; e.g.:
since the telescope focus is set to the last value of the sequence after running
whtfocusrun.
If seeing is very good, repeat the telescope focus procedure with
smaller steps (e.g. 0.05mm).
Focusing INGRID
INGRID internal nominal focus is -50 microns.
It is very stable
and usually not focus optimization is observed over a wide
range of instrument focus positions. So that it can be left at its
nominal position. However, in case you want to focus INGRID, the
procedure is very similar to focussing the telescope:
- Take a sequence of images for different values of
the instrument focus, using the command ifocusrun, with the
same arguments than for the whtfocusrun, but refereing the
two last to the start instrument focus value and the instrument
focus increment (both in microns) respectively.
*Example:
hh:mm:ss>ifocusrun 9 8 2 -90 10
Again, nine scratch files would be created
(s1.fit, s2.fit,...s9.fit) in this case.
Keep in mind that the units by which INGRID moves are very small (microns)
and that it is not worth it to use instrument focus offsets smaller than 10
microns.
- Use istarfocus again, but to determine
the best instrument focus; e.g.:
in>istarfocus s1,s2,s3,s4,s5,s6,s7,s8,s9
and proceed as before.
- Set the instrument focus to the best value; e.g.:
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5. INGRID data acquisition commands
Below are some of the most important commands related to data adquisition (arguments are noted by
< >:):
- numreads < Nr>Sets the number of MNDR
(multiple non-destructive reads) to Nr. Nr is the
number of times that the array is read not-destructively prior and
afterwards to an integration period.
The array data from the Nr pre and post-integration reads are averaged respectively.
Nr is an integer between 1 and 16 (default is 1; i.e. correlated double sampling).
- dark < int time> < N coav> <"title">Takes
a run and set the OBSTYPE header parameter to DARK (arguments are described below).
- flat < int time> < N coav> <"title">
Takes a run and set the OBSTYPE header parameter to FLAT.
- glance< int time> < N coav> <"title">Takes a
glance and save it in glance.fit.
- run < int time> < N coav> <"title">Takes a run and save
it in: rxxxxxx.fit.
- multrun < m> < int time> < N coav> <"title">
Same as run but repeat the run sequence m times and generates m output files.
- scratch < k> < int time> < N coav> <"title">
Takes a run and save it in: sk.fit.
- dithern < int time> < N coav> < x offset> < y offset><"title">
Takes n runs with the required integration time and number
of coaverages
and moves the telescope between them using the quantities entered on < x offset>, <
y offset>. Each run is saved in a fits file (rxxxxxx.fit).n defines the
dither pattern and can takes the values 2, 3, 4, 5, 8 and 9. In all cases the telescope starts
and ends at the centre of the pattern.
The arguments above stand for
< int time>Integration time in seconds
< N coav>Number of coaverages. Number of accumulated
exposures that are averaged and written as a single output file.
< "title">Integration time in seconds
< x offset>Telescope offset in arcsec
< y offset>
A complete command list and description of the commands can be found in the
command dictionary of the IMPB Software manual.
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6. Shutting down the system
- Put blanks into the light path
hh:mm:ss>filter blank
- hh:mm:ss>shutdownobssys
Answer yes to all the questions.
- Close manually the observing log window.
- Quit the RTD
- Close the INGRID mechanism mimic.
Close the TCS information window.
Log out of the INGRID's control computer (click on the right mouse
button in the screen and select exit).
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7. Writing data tapes
- Get a DAT tape from the box located in the terminal area of the WHT,
and fill in your initials, date, etc in the folder.
- Put the DAT tape in the DAT drive in lupus or auriga.
- Open up an xgterm.
- >cd /obsdata/wht?/yyyymmdd
- >fitsinit follow the displayed instructions and answer the questions.
- >fitsout and answer the questions again.
A DDS tape (90m) should be able
to store xxx Gb (~xxx runs) whereas a DDS3 tape, xxx Gb (~xxx runs)
If you prefer, you can also use the tar command to write the data tape.
NOTE: Due to the fact that INGRID images are multi extension images, use the mscrfits
command in the mscred IRAF package for reading the data if you have used fitsout to write
the data tape.
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Last Updated: 20 June 2001