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WORKING WITH AUTOFIB/WYFFOS
Autofib is a robotic fibre positioner at prime, feeding light to
WYFFOS in GHRIL. The optical configuration of the telescope is FOLDED (BROKEN)
CASS, in order to direct the light of the WYFFOS calibration unit via
the nasmyth flat up to prime.
Vital information like recovery procedures can be found on the AF2 main index
Startup
TCS:
- USER> STATION PRIME
- USER> INSTRUMENT AUTOFIB
- USER> AGSELECT AF2_TV
- Zeroset AZ and ALT
to zeroset on the targets switch to computer control:
- USER> AZ 298
- USER> ALT 89
- USER> ENG
- USER> ZERO AZ TAR
- USER> ZERO ALT TAR
Drive AZ and ALT slowly in + direction over the zeroset target
points, then switch to computer control again
to zeroset absolute:
- USER> ZERO AZ ABS
- USER> ZERO ALT ABS
Zeroset absolute will go wrong in case an absolute encoder bulb
is broken! When slewing to the first object check azimuth and altitude
incremental and absolute encoders are in close agreement and updating.
- USER> ZERO ROT ABS
- USER> WAVELENGTH ...
- USER> TEMP ...
- USER> PRESS ...
- USER> HUMI ...
- USER> CAL LAST
- USER> FOCUS 82.45
Focus (depends where you are looking!):
The best focus both on the WYFFOS detector and on the TV fibre-view
is 82.25 mm. However, due to aberrations intrinsic to the WHT (mostly spherical),
the best focus in the outer parts (>=20 arc minutes off axis) of the
field may be as high as 82.65 mm. Hence a compromise value of e.g. 82.45
mm can be used. Fiducial stars right at the edge of the 29 arcmin field
will be elongated by as much as 3-4 arcsec!
On the mobile probe the best focus is at a position of about 83.20
mm. This may be important to know when acquiring faint sources with help
of the uDAS TV.
new uDAS Autoguider:
The camera looks at the output end of the guide fibre bundles (also
called "fiducial fibres").
The new Small Fibres unit has 10 fiducial bundles:
- Each consists of about 10,000 (yes!) individual fibres.
- These make up a coherent bundle about 100 microns wide.
- Each give a view of about 8 arcseconds on the sky.
- The 10 bundles are arranged in a rough circle with numbers
in this order:
(clockwise from bottom) 144, 128, 112, 16, 32, 48, 64, 80, 96 with
160 in the middle.
- The arrows indicate the direction a star moves on uDAS Autoguider
when in XY handset mode.
+------+
| |
| | |
| v |
| |
+------+------+------+
| | | |
| | ^ | |
| <- | | | -> |
| | | |
+------+------+------+
Centres of the Fiducial Fibres:
It has been found that the fibre positions and/or shapes on the
TV change with time, perhaps they depend slightly on EL. Before acquiring
a new field check and if necessary move the marks of all fibres, illuminating
the fibres using
ICL> wcal 4 on.
The marks are then saved to the file /home/whtobs/af2.reg, see
the Region-menu of the display tool DS9.
uDAS Autoguider commands and startup:
The camera can be used as a conventional science camera as far
as uDAS is concerned:
DAS> run AG4 2 "acq of NGC1162"
DAS> finish AG4
The first command will save the image on /obsdata... (e.g. for
measuring seeing using IRAF, the pixel scale was measures 2/1/2003 to
be 0.125"/pixel), the second command will finish an active exposure.
uDAS Autoguider has some extra features, that allow it also to
be used as a TV.
- On LEO or CETUS, log in as 'whtobs'
- Type 'obssys' or 'obssys dev' in the pink window and select
option 'manual camera selection'
- Type 'startobssys' in the pink window
- To start the camera running as a TV then type 'startsdsuag
AG4' in pink window, followed by option '1'
- Windows can be set up using the usual uDAS syntax. The suggested
AG4 window is as follows:
SYS> window AG4 1 "[330:730,250:700]"
- Display the region file /home/whtobs/af2.reg, marking the fiducial
fibres
The script will start the SDSU Autoguider GUI, a DS9 display tool
and the talker window providing information on the system. The GUI allows
you to change the exposure time, define the guide box size, choose between
guide modes or TV mode and provides you with important information as the
S/N ratio.
To start guiding:
- Set integration time and guide box size
- Decide where to guide and enter the pixel values
- Select 'guide on pixel'
- Click on 'guide'
Note that switch-box for autoguider has to be set to the corresponding
UDAS AG (LEO or CETUS)!
Images are piped directly to the display tool.
new uDAS TV:
The camera looks at the output end of the mobile probe fibre bundle.
The FOV is approximately 20" by 30". The mobile probe is used for
acquiring, especially standard stars on individual fibres and science
fields if the telescope pointing isn't very good. With good pointing you
may try to acquire science fields directly with the uDAS Autoguider.
On the mobile probe the best focus is at a position of about 83.20
mm.
The arrows indicate the direction a star moves on uDAS TV (mobile probe)
when in XY handset mode.
+------+
| |
| <--- |
| |
| |
+------+------+------+
| | | |
| ^ | ---> | | |
| | | | v |
| | | |
+------+------+------+
uDAS TV commands and startup:
This is the same as for the uDAS Autoguider. The TV is called AG2.
- On LEO or CETUS, log in as 'whtobs'
- Type 'obssys' or 'obssys dev' in the pink window and select
option 'manual camera selection'
- Type 'startobssys' in the pink window
- To start the camera running as a TV then type 'startsdsuag
AG2' in pink window, followed by option '1'
- Windows can be set up using the usual uDAS syntax. The suggested
AG2 window to view the mobile probe fibre only is as follows:
SYS> window AG2 1 "[95:650,250:750]"
- Display the region file /home/whtobs/af2_ag3auto040727.reg,
marking the mobile probe, rotator centre (big circle) and the gripper
centre (small circle)
Atmospheric Dispersion Corrector:
Check the PF atmospheric dispersion compensator is in 'ADC Only
mode' (top right of prime mimic on ICL). If in doubt type:
ICL> PF_MODE ADC_ONLY
ICL> ADC_AUTO ENABLE
Other screens and consoles:
- The AF2 TV screen is used to view the back illuminated fibres
when a new field is set up. You see the white spots defocussing as the
robot picks the fibre up. Please record every new setup with the VHS video.
- Configuration screen (on the side of AF2 TV) with the coloured
map of the fibres positions.
Preparation (first night after instrument change)
Rotator centre:
The MOUNT PA range is -163.37...193.63 degrees, thus 357 degrees
total. Hitting the limit you can't simply unwrap, you have to wait a
certain time until you got past the 3 unreachable degrees. This may take
a while, depending were the object is on the sky; therefore watch carefully
what the limits are, each time you move to a new source!
- Move to a 12th mag.
star
- TV in continuous readout, viewing mobile probe
- ICL>AFVIEWS 100 900 (choose values such mobile probe views
rotator centre)
- USER>ROT SKY 0
- When in position measure x and y of the star image
- Rotate 180 degree, then measure x and y again
- Calculate the new rotator centre (x= 300 y= 235 with AFVIEWS
100 900 and AG2 window set as mentioned above on 28/7/2004)
- Mark the rotator centre for further reference.
Calibrate:
- ICL> AFVIEWS 100 900 (same as before)
- USER> ROT MOUNT 'angle' (to avoid problems with rotator
limit)
- USER> CAL FAINT
- TV in continuous readout, viewing mobile probe
- Centre up all stars on the rotator centre
Define aperture offset:
Using a multi-object instrument it is recommended to define the
aperture 0 offset, such the field rotates around the instrument centre.
The instrument centre is defined as centre of the mobile probe, thus AFVIEWS
at 0,0.
- ICL> AFVIEWS 100 900 (same as before)
- Go to a 12th mag. star
- Centre the star on the rotator centre with the XY HANDSET
- ICL> AFVIEWS 0 0
- Using HANDSET in APOFF mode, move star back to the centre of
the mobile probe (new rotator centre with aperture offset)
- USER> STORE AP 0
- The last aperture offset found was X= -6.0 Y= -4 (21/11/2004).
Last Parameters
Gripper centre
|
163,272
|
21/11/04
|
Afview [0,0]
|
196,201
|
21/11/04
|
Telescope aperture
|
-6,-4
|
21/11/04
|
Telescope focus
|
82.6
|
21/11/04
|
AG2 window: [110:500,40:500]
|
notes.
- The nominal offset for the rotator is -0.24
(22-11-04)
- When the external temperature goes below 5 degrees, the robot has
to be awake and sleep. This can be done when an exposure has finished to
avoid possible light to the detector.
|
Observing
Acquisition (first with uDAS TV, then with uDAS Autoguider):
This assumes the sequence 'rot centre' -- 'calibrate' -- 'aperture
offset' has been executed successfully. You must have a field setup (AFSETUP)
ready, the telescope must track the field and the rotator must track
the demanded sky PA of the field.
- To acquire move the robot to a fiducial object close to the
instrument centre e.g.
ICL> AFVIEWO 96
and centre the star with the XY HANDSET on the GRIPPER centre (how
to define - see next section) (last gripper centre found was x= 259 y=
250 with AG2 window set as mentioned above on 28/7/2004.
- Now move the mobile probe to another fiducial star at the edge
of the field; this time move the rotator to centre the star as good as
possible, then park the robot
ICL> AFPARKR and switch the power off
ICL> AFSLEEP as now we proceed with the final tweak using the
Autoguider.
- The last step is to tweak telescope and rotator to centre all
guide fibres in use. Remember to set the telescope focus to the right
value and to check/remark all fibre centres before as the fibre positions
on the Autoguider might change with EL! If you can't see the fiducial
stars perform a spiral search, in this case it is recommended to re-define
the GRIPPER centre on the mobile probe (see next section).
Once found the best compromise start guiding.
Before you start to expose sleep the robot!
Standard Star:
Follow this to acquire a standard star on an AF2 science fibre,
correcting for a possible offset between GRIPPER centre and MOBILE PROBE
centre and also for a possible small displacement of the mobile-probe
fibre at the AG CCD end. This assumes the sequence 'rot centre' -- 'calibrate'
-- 'aperture offset' has been executed successfully. You must have a field
setup (AFSETUP) ready and the rotator must track the demanded sky PA of
the field.
- USER> gocat 'standard star'
- now put the star under a fiducial fibre:
- ICL> afoffset SKYPA STARNAME FIDUCIALFIBRENR
- answer the questions (first 'no' then 'yes')
- centre the star on the TV where you think is the GRIPPER centre
- ICL> afparkr (otherwise you won't see the star on the Autoguider)
- centre the star on the fiducial fibre (Autoguider)
- ICL> afviewo FIDUCIALFIBRENR (same fiducial fibre nr as
above)
- see where the star ends up on the mobile probe CCD image
- mark this position for further reference
- this point is the GRIPPER centre, last found at x= 259, y=
250 (28/7/2004)
- now do the final step to put the star under a science fibre:
- ICL> afoffset SKYPA STARNAME SCIENCEFIBRENR
- Answer the questions (first 'no' then 'yes')
- centre the star (TV) on what you now know is the GRIPPER centre
- ICL> afparkr (or afsleep)
Once the GRIPPER centre is defined the procedure is reduced to:
- ICL> afoffset SKYPA STARNAME SCIENCEFIBRENR
- Answer the questions (first 'yes' then 'yes')
- centre the star (TV) on what you now know is the GRIPPER centre
- ICL> afparkr (or afsleep)
The D-tour via a fiducial fibre is to determine the gripper centre
as the fiducial fibres have the same optical centre as the science fibres;
this way you cannot miss the standard star.
Arcs:
When you take an arc, remember to offset the telescope away from
the object or close the primary mirror cover as otherwise you get the
two signals superimposed.
Data Handling
- Put the DAT tape in the DAT drive in lupus (in the
terminal area).
- Open up an xgterm.
- cd /obsdata/whta/yyyymmdd
- Use the tar command to write the data tape, e.g.:
tar -cvf /dev/rmt/0n *.fit
Miscellaneous
Access park:
Move first to AZ 300, EL 15; Switch to ENG; Press AP2 on platform;
Open gate; Press AP3 on platform
ICL:
ICL>AFVIEWS(KY) x y
ICL>HELP AF2
ICL>AFWAKE
ICL>AFSLEEP
ICL>AFVIEWO(BJECT)
ICL>AFPARKR(OBOT)
Some more info from old Autofib notes:
How to reset the micro in GHRIL:
On the AF2 mimic, there is a status of the network connection. If this is
showing 'micro off the network', reboot the AF2 VME crate in GHRIL by turning
the plug for the crate off and then on after 10 seconds. Also check that the
network connection is properly plugged into the front of the crate.
If the ICL is giving problems after this consider killing and restarting the
AF2 task.
Added 02/08/2001:
1. To eliminate WYFFOS warning messages from ICL command window
2. afsetup fails continuously
3. af2 drops off the UTILNET
4. afsetup fails to ftp files
solutions:
1. ICL>kill wyffos
start another Decterm on the ICL VAX
in the new window type "lpvg" and log on as observer
following login, type 'ICL' and
>load wht_wyffos_dir:wyffos_define
>wyffos_load
>wyffos_begin
2. >kill af2_setup
>kill af2
>af2_load
>af2_begin
3. and 4. - reboot the af2 crate
-------- © 2004 Isaac Newton Group of Telescopes --------
Last Updated: 22 November 2004 Juan Carlos Guerra jcg@ing.iac.es