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AF2+WYFFOS 

essential Observing Guide

Introduction


Three main computers are used by the visiting astronomer when observing with AF2+WYFFOS:

The telescope control system (TCS) computers are instead ran by the Telescope Operator (TO).

The commands generally used by visiting astronomers are listed below.

WYFFOS commands (ICL)


hh:mm:ss> wcenwave xxxx y
sets central wavelength to xxxx angstrom for order y (the latter parameter to be entered only for the echelle mode).

hh:mm:ss> wslitf xxxx
set instrument ("slit") focus to xxxx nm.

hh:mm:ss> wslitt xxxx
sets "slit" translation to xxxx nm.

hh:mm:ss> wfilta in/out
Puts filter A in/out of the beam. The slit focus will be automatically compensated to take into account the filter optical thickness. However, you MUST wait until all actions are completed (filter movement AND focus change, giving TWO messages "Action complete"), before issuing any other command.

hh:mm:ss> wfiltb in/out
The same as above, but for filter B.

WYFFOS calibration unit commands (ICL)


hh:mm:ss> wcal x on
switches on calibration lamp at position x. See the list of currently available lamps.

hh:mm:ss> wcal off
switches calibration lamp off.


AF2 commands  (taurus)


General

All AF2 commands are run from the WHTICS Observing System  window in taurus. They  consist of the string 'af2followed by a space, another string specifying the action, and in some cases also a list of parameters needed by the action. By typing

SYS> af2

the list of all AF2 commands is printed on the screen.

Copying fibre configuration files to the Observing System and check them

Before setting up a field, the corresponding configuration file (.cfg) should be copied into the Taurus machine. In Taurus, within account whtobs, enter subdirectory /home/whtobs/AF2, and copy there your .cfg file from any other ING machine
(subdirectories with your name within the AF2 directory can also be created).

SYS> af2 check name_of_file.cfg.x
allows  you to check the validity of your configuration file withouth performing physically the fibres setup.

SYS> af2 checkt name_of_file.cfg.x hh:mm:ss.s
the same as above, but allows different choices of the sidereal time hh:mm:ss.s

Setting up a field

SYS> af2 wake
switches the AF2 robot on

SYS> af2 setup name_of_file.cfg.x

sets the configuration contained in file named name_of_file.cfg.x. You will be asked for the SIDEREAL TIME  for the configuration: this provides the HOUR ANGLE used to transform sky coordinates into plate coordinates, overriding the value of the parameter "H.A." in the .cfg.x file. Once issued the command and entered the Sidereal Time, the process can be sent to background execution (Ctrl Z and SYS> bg).

Note that with the new AF2 software a complete setup usually takes less than 20 minutes.

SYS> af2 recover
If a fibre is lost during a setup, try to recover it by issuing this command. If the fibre is recovered, you can restart the setup. If not, try again afrecover, and if it fails again ask for help from the TO, SA or Duty Engineer.

SYS> af2 sleep
switches the robot off. This is recommended after a setup is finished, and is mandatory if working in the far red, as near-IR inspection lights in the robot would cause scattered light to appear in frames.

Note that the fibres configuration can be done at any telescope position, as fibres do not move on the plate when telescope is moved. So, it is safe to set in the afternoon the first configuration field used at night. However, as the xy plate coordinate system might have a general drift with large telescope movements, if the same field has to be reconfigured during the night, we suggest to run the AF2 command

SYS> af2 loadmodule

(this takes 2 min) before reconfiguring the field. 

Other useful commands

SYS> af2 allcircle
puts all fibres in a circle

SYS> af2 allpark
parks all fibres

SYS> af2 park
parks robot out of field of view

UltraDAS commands (taurus)


The complete list of commands can be found in the UltraDAS dictionary. Some of the most important ones are listed below.

SYS> window wyffos 1 "[1:4300,1:4200]"
windows the CCD mosaic so that both frames are mosaiced into a single frame.

SYS> rspeed wyffos slow/fast
sets readout speed of the camera to slow/fast mode.

SYS> bin wyffos x y
bins camera pixels to x and y values

SYS> bias wyffos
takes one bias

SYS> multbias wyffos n
takes n biases

SYS> run wyffos xxx "title" &
runs (in background) a science exposure of xxx sec, and puts a title in the FITS header.

SYS> multrun wyffos nn xxx "title" &
starts nn science exposures each of xxx seconds.

SYS> abort wyffos
aborts current exposure. No image is saved on disk.

SYS> finish wyffos
stops immediately the current exposure, and the frame is saved on disk.

SYS> newtime wyffos xxx
changes the exposure time of the current exposure to xxx seconds.

The same syntax as for the "run" command is used for the flat (flat fields), arc (arc lamps), sky (sky offsets), with the only difference that the corresponding FITS header is filled with the exposure type.

Observing


Observing a science field

When a field is setup for the correct Sidereal Time, just give the coordinates of its centre, equinox, and the sky Position Angle to the TO, and he will acquire the field and start guiding. Exposures are defined using the UltraDas commands in the previous section.

Acquiring a standard star

This requires knowing the offset between the gripper centre (where fibre is) and the mobile probe sky viewing camera. To do it, youmust have a field setup ready.

  • Step 1 (done only once in a run or a night, usually by TO+SA)
  • This assumes the sequence rot centre, calibrate, aperture offset has been executed successfully by the TO at beginning of run.

    Move the telescope to a relatively bright star;

    SYS> af2 wake

    SYS> af2 viewsky 0 0
    and centre the star on the probe centre.

    SYS> af2 offsettel SKYPA STARNAME FIDUCIALFIBRENR
    where FIDUCIALFIBRENR is the number of a fiducial fibre inside the field (better close to the centre), SKYPA is the current sky position angle, and STARNAME in any string of characters.
    Answer the questions (first 'no' then 'yes'). This offsets the telescope to ideally put the fiducial fibre on the top of the star, and also moves the mobile probe to see the star.

    SYS> af2 park
    remove the mobile probe, and centre accurately the star on the fiducial bundle using acquisition camera.

    SYS> af2 viewobject FIDUCIALFIBERNR
    (same fiducial fiber nr as above). See where the star ends up on the mobile probe sky viewing image, and mark its position with a cross. This cross reflects the gripper centre. When acquiring another field or standard, use this cross.

  • Step 2 (done every time you want to observe a standard stars)
  •  Move the telescope to the standard star;

    SYS> af2 offsettel SKYPA STARNAME SCIENCEFIBRENR
    where SCIENCEFIBRENR is the science fibre where you want to obtain the standard spectrum, SKYPA is the current sky position angle, and STARNAME in any string of characters. Answer the questions (first 'no' then 'yes'). Ask the TO to centre the star in the cross marked on the mobile probe camera.

    SYS> af2 park (or af2 sleep) Park the robot and take an exposure.

    Writing data tapes



    Get a DAT tape from your support astronomer or TO, and put it in the DAT drive in the whtdr machine
    Open a terminal window:
    > cd /obsdata/wht?/yyyymmdd
    > tar -cvf /dev/rmt/0lbn .


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    Last Updated: June 2005
    Romano Corradi, rcorradi@ing.iac.es