to initialize ING specific packages (includes routines for checking focus, rotation and tilt of the detectors).
SYS@taurus>
rfilta 3 (introduce the GG495 blocking filter)
- Select slit mode to observe (remove the comparison mirror in case it
is in)
SYS@taurus> agslit
- Select comparison mode to take lamps (introduce a mirror in the beam
to drive the light from the lamps into the spectrograph)
SYS@taurus> agcomp
3.3 Controlling
ISIS mechanisms from the GUI
In addition to the
control of ISIS mechanisms from the WHTICS console command,
there
is a GUI that also allows to control them. Manuals of
the new ISIS Control System and the A&G Control
System that explain how to use the GUIs can be found
here
and
here.
The use of the GUI is very simple. A number of icons buttons are used
throughout the GUI in order to perform specific tasks.
The GUI has several windows, the relevant for the ISIS user is
here.
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Note that all UltraDAS commands are
introduced in a unix window (
"WHTICS"), thus can be
executed in a background mode (with an & at the end of the command
line). This enables you to take images simultaneously with both red and blue
arms. Also UltraDAS commands can be combined with
ISIS commands to create scripts. A complete list and description
of the
commands can be found in the
command dictionary of the UltraDas Software manual. A summary of
the most commonly used commands is given here for a quick reference:
-
Data acquisition commands
Some of the most important commands related to data acquisition are
listed below (arguments are denoted by <>):
- run <camera> <int time> <"title">
Takes a run and saves it in: rxxxxxxx.fit.
E.g. run blue 600 "N157 B", takes a 600s exposure
with the blue arm and stores it in the output file (e.g. r1826342.fit).
The title of the fits file is set to "N157 B". If you do not specify a
title, the name in a header will be the same as in your catalogue.
- multrun <camera> <m> <int time>
<"title">
Same as run but repeats the run sequence m times and
generates m output files.
- flat <camera> <int time> <"title">
Takes a run and set the OBSTYPE header parameter to FLAT.
- multflat <camera> <m> <int time>
<"title">
Same as flat but repeats the run sequence m times and
generates m output files.
- arc <camera> <int time> <"title">
Takes a run and set the OBSTYPE header parameter to ARC.
- multarc <camera> <m> <int time>
<"title">
Same as arc but repeats the run sequence m times and
generates m output files.
- bias <camera> <"title">
Takes a run and set the OBSTYPE header parameter to BIAS.
- multbias <camera> <m> <"title">
Same as run but repeats the bias sequence m times and
generates m output files.
- glance <camera> <int time>
Takes an exposure and saves it in s1.fit.
This file is overwritten when a new glance is taken.
- scratch <camera> <k> < int time>
<"title">
Takes a run and saves it in: sk.fit. k is an integer
within the range 1-99. The scratch file sk.fit
is overwritten when a new scratch<k> is taken.
- abort <camera>
Abort an exposure. The data is not saved to disk.
- finish <camera>
Terminates an exposure and save the data to disk.
- newtime <camera> <int time>
Change the length of an exposure (e.g. newtime red 900 for
the red arm)
The arguments above stand for
<
camera> Indicates
which CCD you want to use, the red
or blue one. Enter red or blue.
< int
time> Integration time in seconds.
< "title"> Title
of the exposure recorded in the image header (optional argument).
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5. Afternoon settings and calibrations
5.1 Setting
the
CCDs from the observing system (WHTICS)
Before starting the calibration images
in the afternoon you should set the readout speed and the
windowing of the CCD camera.
- Set the detector readout speed to
slow or fast (as desired) by typing for example:
SYS@taurus> rspeed <camera> slow
Have a look at the blue
and red
for details on the operational characteristics for each readout
speed. Normal observations are usually using the slow readout speed. Be careful as
the default is fast and you have to set to slow before
starting
to take your calibrations in the afternoon.
- Windowing the CCDs. Note that the
ISIS detectors cover more than 4 arcminutes in the spatial direction.
It
is therefore necessary to window each CCD to an appropriate length
by defining an effective slit length.
SYS@taurus> window red 1 "[585:1550,1:4200]" (3.5 arcminutes for red arm+REDPLUS)
SYS@taurus> window blue 1 "[585:1550,1:4200]" (3.2 arcminutes for blue arm+EEV12).
- Binning the CCDs.
SYS@taurus> bin red 1 2 will bin x1 in the spatial direction and x2 in the dispersion direction.
Once the CCD windows have been defined, the system will automatically create and save two files, one for each CCD, which contain the window, bin and readout speed parameters. The default file names are udas_REDPLUS.cfg and udas_EEV12.cfg. Different names can be used with:
SYS@taurus> saveccd <camera> <filename>
To load the CCD parameters use:
SYS@taurus> setccd <camera> <filename>
To load the default CCD configuration files just omit the field <filename>.
The setccd command is especially useful after issuing a dasreset. This command resets the software and hardware of a CCD camera (e.g. when one camera stops working):
SYS@taurus> dasreset <camera>
After a dasreset the bin, window and readout speed data of the reset camera will be lost.
Please bear in mind that other useful data such as both collimator focuses are not saved.
5.2 Taking arcs
SYS@taurus> agcomp
SYS@taurus> complamps cuar+cune
and take a test exposure:
SYS@taurus> arc red 5 test
This exposure
will
allow you to compute the exposure time to obtain a reasonable intense
arc and to define the CCD window such that no dekker vignetting is
seen. The same procedure with the blue arm. Take into account that
usually long exposure times of > 40 s are needed in the blue.
5.3 Taking lamp flats
Before taking
flats turn off all the dome lights and close the courtains in the
control room.
SYS@taurus> agcomp
SYS@taurus> complamps w
and take a test exposure:
SYS@taurus> flat red 1 test
This exposure
will
allow you to compute the exposure time to obtain a reasonable intense
flat. Flats should not be brighter than 42000 ADUs. When using low
resolution gratings in the red arm, the use of a
neutral density filter is needed. ND filters can be put in place with e.g.
SYS@taurus> compnd 0.8
To remove the ND filters type
SYS@taurus> compnd 0
Once the proper neutral density filter and exposure
time is set, do a multflat:
SYS@taurus> multflat red 11 5 "good flat"&
5.4 Taking bias
Before taking bias turn off all the dome
lights and close the courtains in the control room.
SYS@taurus> agcomp
SYS@taurus> complamps off
SYS@taurus> multbias red 11 & multbias blue
11 &
5.5 Taking sky flats
Sky flats with ISIS are useful in order to calibrate particular place
along the slit (e.g. in case of having two targets on the
slit, observing galaxies etc.). To take sky flats with ISIS leave the
telescope at Zenith in engineering mode (i.e. no tracking). No offsets between
individual flats are needed.
For a higher resolution gratings (R1200R, R1200B, H2400B), you
should start 10-15 minutes before a sunset. For lower resolution gratings
it is enough to start around a sunset.
SYS@taurus> agslit
take a test exposure to decide the exposure time:
SYS@taurus> sky red 1 test
Once the counts level is good, take sky flats with the following command
SYS@taurus>sky red <exp_time> & sky blue
<exp_time>
Back to the top
6.1 Focusing the telescope
To focus the telescope point to a bright star (V=9-10, it can be one of your
standards) at low airmass and open the slit to 8 arcsecs
SYS@taurus>slitarc 8.0
This will ensure that the
profile of the spectrum will be defined by the seeing only and not by the slit.
Use fast readout speed and take an image with one of the arms (usually red,
because the seeing is better in red than in blue)
SYS@taurus>agslit
SYS@taurus>rspeed red fast
SYS@taurus>glance red 7 &
Exposure times of 7 s or more should be used to adequately sample the
seeing. Look at the image to check if the level of counts is correct and execute
SYS@taurus>focusrun <camera> <num_exp>
<exp_time><start_position> <focus_increment>
Typical values are
SYS@taurus>focusrun red 9 7 97.7 0.05
This will take 9 images of 7 s changing the focus of the
telescope from 97.7 mm with an increment of 0.05 mm between the images.
All images are saved and you can determine the best focus by analyzing the
spatial profile in each image. Once the value of the focus is determined
(e.g. 97.85) set the value of the focus by
SYS@taurus> focus 97.85
Do not forget to change back the readout speed
SYS@taurus>rspeed red slow
6.2 Taking spectra of an object
First select the slit mode and slit width
SYS@taurus> slitarc 1.0
SYS@taurus> agslit
Ask the OSA to point to the object (you
can give in advance
an
object list with the coordinates of the objects you
plan to observe during your run). Also tell the Position Angle you
want for the slit. The OSA will take an image of the slit with the TV
camera and will use it to center your object in slit. If your objects
are faint (V>20) it is a good practice to center a brighter object
in
the field close to the target and do offsets. In this case prepare blind
offset stars in advance to save time. For an accurate blind
offsets, both target and offset star should have at least two decimal places
in seconds of RA and one decimal place in arcseconds of DEC. Once your object is in the slit do
SYS@taurus> run red <exp_time> "<comment>" &
run blue <exp_time> "<comments>"&
6.3 Night calibrations
If you need arcs of lamp
flats during the night proceed as in section
5.2.
6.4 Observing bright targets
If you need to observe bright targets you can use the main neutral density
filters in the light path, common for both red and blue arm. Take into
account that these neutral density filters are not uniform, mostly outside the
useful area of the chip. The table below indicates the area of the chip in pixels
where the filters were observed to be "gray".
In addition to the non-uniformity all these filters have small-scale structures,
difficult to be removed by flat-field correction. If there is a need to use these
filters, flat-fields should be taken to mask regions with small-scale structures out.
To insert the main neutral density filter, use the command:
SYS@taurus> mainfiltnd 2
to insert 0.3 neutral density filter (see the table below).
The available options are the following:
| mainfiltnd |
ND |
useful window |
| 1 |
0 |
- |
| 2 |
0.3 |
[500:1600,1400:2800] |
| 3 |
0.9 |
[500:1600,1900:3000] |
| 4 |
1.3 |
[600:1600,1400:3000] |
| 5 |
1.8 |
[500:1600,1400:2800] |
| 6 |
3.0 |
[1050:1550,1900:3000] |
6.5 Quick-look spectrum extraction
Run the ISIS quick-look script at IRAF with e.g.:
ecl> ing
ing> isis
isis> isis_ql r1234567 252
where the image name is given without the '.fit' extension, and the last
number on the line is the approximate x position of the spectrum on the CCD
(not dependent on binning). The script carries out an optimal extraction
(takes ~ 1 sec) and displays the spectrum in the iraf graphics window using
splot, so all the usual keystrokes are available. No wavelength calibration
is provided.
Back to the top
You can either copy your data on your laptop or external disc on ingext network
- rsync -av whtobs@taurus.ing.iac.es:/obsdata/whta/yyyymmdd/ .
OR
copy the data to FTP areas
- follow these
instructions
OR
write your data on a DVD (~4 Gb)
- get a DVD from your SA or OSA and
put the DVD in the DVD burner (located in the computer room)
- follow the instructions here
