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Engineering
7 Star calibrate
If the pointing is bad, even after doing a single star calibrate, a 7
star calibrate is needed. There is an automatic version of it, but it may
lead to a wrong pointing solution if the current one is not close to the
correct one. It is thus strongly recommended to do a manual 7 star
calibrate, which is described in the following.
Manual 7 star calibrate
SYS> agwin acq pos 1032 512
USER> ENTER APERTURE 0 1065 -42 (re-defines AP0, i.e. the
default pointing position, for centre of auto-guider chip)
On the auto-guider window mark the autoguider window centre (SETUP/TOGGLE
CENTER CROSS), and choose an integration time of 500ms.
If available you may put a narrow band filter, to prevent saturation.
SYS> autotv on
USER> CAL FAINT
The handset window comes up automatic; centre the star on the blue center
cross. Once the star is well centred, press the 'Do' button located on TCS keyboard, the TCS
then slews to the next star and the handset window comes back again.
After all stars have been centred answer to questions with 'Y'.
USER> ENTER APERTURE 0 -251 326 (back to normal AP0, centre
of chip 4)
SYS> autotv off
Automatic 7 star calibrate (not recommended, see above)
SYS> autocal - Starts the automatic calibrate routine
Wait until it completes and follow the instructions on screen. The whole
process takes15-20 minutes to complete,
Closing down fast
- First close the primary mirror cover.
- Then switch the TCS to engineering mode: USER>eng
- Close the dome. Bring the lower shutter down first: press 'lower
micro' while in 'main over travel', otherwise 'lower main'.
- Now bring the upper shutter down using the same technique.
Observing at low elevation
If you want to observe at a zenith distance between 57 and 70 degrees
(33-20 degrees elevation) then you need to rise the lower shutter. There
won't be any warning from the telescope control, so you will have to check
the ZD from time to time.
- Push the yellow button under "SELECT MANUAL CONTROL", labeled "DOME
SHUTRS" to get the control of the shutters.
- On the engineering rack, under "LOWER SHUTTER", push the "RAISE MICRO"
button until the "MAIN OVER TRAVEL" light underneath goes off.
- Push the "RAISE MAIN" button on the side of the previous; while rising
you hear two bangs caused by the segments of the shutter catching the next,
keep the button pressed until you hear the motor stop. It takes approximately
30 seconds.
- * Undo * the "DOME SHUTRS" button, otherwise the dome wont track
the object anymore.
You can now observe below 33 degrees elevation.
Remember to lower the shutter again when you go to a new source above
33 degrees elevation. To do this:
- Select manual control as before with the "DOME SHUTRS" button.
- With "LOWER MAIN" bring the shutter down as far as it goes.
- With "LOWER MICRO" fully lower the shutter, keep the button pressed
some 10 seconds to be sure.
- Undo the "DOME SHUTRS" button.
Note that if you don't lower the bottom shutter completely the upper
shutter won't seal the dome at the top, so with rain and wind water
will penetrate into the dome.
Observing at different Rotator Angle
If you wish to observe at a rotator angle different from the nominal 180
degrees, follow these instructions carefully:
- Park the telescope at Zenith - USER>park zen
- USER> rot sky X, where X = 0,90,180,270. Wait until
rotator has stopped moving (1 minute).
- In the green "Prime Rotator Info" window (intics - workspace /program
window) type PLUNGER_IN
If after a couple of seconds you get a message SUCCESS CODE = N, it is
safe to continue observing.
If SUCCESS CODE = T (time out) then execute step 4.
- In the green "Prime Rotator Tip Session" window type PLUNGER_OUT
followed by CLAMP_OFF
Assuming you have a SUCCESS CODE = N for both of these actions, type PLUNGER_IN
and after a SUCCESS CODE = N type CLAMP_ON
It should then be safe to continue observing.
- Close down the green window by typing ~. (twiddle dot)
Differential tracking (solar system targets)
If you wish to observe a moving target, you first need to compute its
motion rates in the equatorial coordinate system.The TCS requires the differential
tracking rates to be expressed as
da = d(alpha)/dt in SECONDS/sec
dd = d(delta)/dt in ARCSECONDS/sec
often (e.g. JPL), ephemerides are given as
d(alpha)/dt x cos(delta) in ARCSECONDS/hour
(1)
d(delta)/dt
in ARCSECONDS/hour
(2)
So, to transform these for TCS input, compute
da = (1) / (3600 x 15 x cos(delta))
dd = (2) / 3600
The differential tracking rates are then input to the TCS using the following
sequence of commands:
*USER> gocat {object name}
*USER> diff_rates da dd
*USER> next
To return to sidereal tracking (e.g. for standards) issue the TCS command
*USER> diff_rates 0 0
Finding Guide Stars
Automatic predicting guide stars with rotator at 180 degrees and nominal
pointing:
SYS>cmd INFODISP PREDICT ON
SYS>gocat 'name'
See guide star positions in the TALKER window. You can then take these
and start guiding with:
SYS>guide on pixel x y (with x y taken from the prediction)
Whenever you use a rotator position different from 180 degrees or
an aperture different from nominal you need to run gsc_apm!
The HST guide star catalogue to V of approximately 15.5 magnitude is
stored on /catalogs/hstguide.sun. This 300 Mbyte file contains the complete
GSC catalogue and can be efficiently searched for guide stars for the WFC.
To run the software the following environment variables and alias have
to be set up in an observing system xterm window on intics or on the TO window
(these are automatically setup by startobssys but if you want to run it from
some other window then type
>setenv GSC_DATA /catalogs/hstguide.sun - pointer to the HST
catalogue
>alias gsc_apm '/home/mike/soft/wfc/gsc_apm' - the latest version
with 6+Nom beamswitch options
The program is usually invoked using command line options such as:
SYS>gsc_apm RaDec="10 30 0 -1 0 0" Rotpos=180 Equinox=J2000 Beam=N
SYS>gsc_apm Rotpos=90 Equinox=B1950 RaDec="21 30 11.3 12 10" Beam=C
Command lines arguments are:
RaDec="hh mm ss dd mm ss"
RotPos=angle (180 default)
Equinox=J2000 (or B1950)
Beamswitch=N (or A,B,C,D,E,F)
(A=centre of CCD#1, B=centre of CCD#2, C=centre of
CCD#3, D=centre of CCD#4 E=centre of Autoguider F=rotator
centre, located on CCD#4)
Changing Apertures
USER>show aper - Lists the defined apertures. The list should
read:
| ap 0 |
-251 |
326 |
nominal aperture, object centred on CCD#4 |
| ap 1 |
704 |
5 |
centre object on CCD#1 |
| ap 2 |
357 |
-1043 |
centre object on CCD#2 |
| ap 3 |
-701 |
-10 |
centre object on CCD#3 |
| ap 4 |
0 |
0 |
nominal aperture, object centred on CCD#4 |
| ap 5 |
1316 |
-368 |
centre object on AG-CCD (X=1032, Y=512) |
| ap 6 |
251 |
-326 |
centre object on RC (rotator centre) |
You can change the default pointing aperture (ap 0) by entering e.g.
USER>enter ap 0 0 0
In this case, the telescope will point at the rotator centre instead of
centre of CCD#4.
NB: Do NOT change the default apertures before calibrate.
New apertures can be defined by entering e.g.:
USER> ENTER AP 7 0 -350 or from the observers console with
SYS> cmd TCS USER "ENTER AP 7 0 -350"
Apertures > 0 are invoked by entering e.g.:
USER> AP 1 or from the observers console with
SYS> cmd TCS USER "AP 1"
and are only active until the next SYS>gocat 'source' command.
Closed loop offsets
You can offset by some arcseconds you may do this without opening the
guide loop using either aperture offsets on the TCS handset or you can use
the "tweak" command: SYS>cmd TCS USER "TWEAK 10 10 0" 10 arcsec correspond
to 27 pixels on the A/G (0.37"/pix) so you need a guide window which can
cope with the offset.
Faults - In General
Most of the faults can be cleared by typing:
SYS> startobssys
Try to avoid 'shutdownobssys' followed by 'startobssys' as in most cases
such a drastic measure isn't needed. SYS> shutdownobssys should only
be used to shutdown the observing system at the end of the night.
If a sub-system (DAS, TCS or Autoguider) is corrupted 'shutdownobssys'
wont help. First the sub-system has to be brought back, then
SYS> startobssys
will re-establish contact between the observing system and the sub-systems.
No guide stars, bad pointing
First repeat ZEROSET at zenith in engineering mode followed by:
USER> CAL LAST
Check pointing with a pointing grid star and the autoguider:
USER> GOCAT pointing-star
USER> AP 5
mark the autoguider window center (SETUP/TOGGLE CENTER CROSS)
SYS> agwin acq pos 1032 512
SYS> autotv on
If the star comes up within 15 arcsec from the center, the pointing is
fine.
If no bright star is seen may be the last pointing solution is wrong
or got corrupted somehow. Before calling for help try this:
Repeat ZEROSET at zenith in engineering mode followed by:
USER> CAL DEFAULT
and check again the pointing with a pointing grid star and the autoguider.
The TCS disconnects
Most likely the TCS TELD task has died. To restart go to the xterminal
were the TCS user interface and info display are running. Open a LAT terminal
and log on to lpas2 (see label on screen for uid and passwd). From the main
menu then select 'options' and 'teld' from the options menu, afterwards
SYS> startobssys
will re-establish contact between the observing system and the TCS.
The WFC disconnects
If WFC disconnects, as shown by the orange warning-label on the mimic,
the DAS has probably crashed.
Check the orange telnet window that's logged on to the DAS. If not available
you have to start a new telnet connection from the background. Run first
'obssys' with the actual option first in order to get the DAS> prompt.
Type return to see if there is a termination message for udas_server (the
WFC task is an instance of the udas_server program). If udas_server has
stopped running, do this:
1. Type startobssys at the DAS> prompt.
2. Watch the talker. Wait until you have seen WFC come on-line.
3. Type startobssys at the SYS> prompt.
4. Wait for the mimic to reconnect to WFC.
Dome problems
If the dome does not rotate when the telescope is preset to a target,
the dome might be erroneously left in 'local' mode. Turn the key in
the dome control panel located inside the dome to set it back to 'remote'.
Shutter problems
It happens when you start an exposure that you get the message 'The shutter
failed to open at the start of the exposure' (red/blinking/beeping).
Simply quit the alarm and repeat the last command in this case.
Elapsed time is counted in a blue box on the GUI while the shutter is
open. After the read out the box turns to green. There is a fault when the
box goes orange with time elapsed=0. The exposure is logged with 0 seconds
exposure time or not quoted at all in the observations log and in the headers.
The fault has to do with the MCA controller. To recover type:
SYS> cmd MCA RESET
With the next exposure the exposure time should be recorded correctly
again.
If this doesn't help bring the telescope to access park and power cycle
the MCA controller, this is the controller on the bottom of the WFC assembly
(rotator at 180 deg.), followed by:
SYS> cmd MCA RESET
Filter wheel problems
On WFC startup, it is NOT uncommon for the MCA controller (the electronics
rack mounted on the WFC which drives the shutter and filter wheel), to have
problems identifying the filters which are loaded. In this case, it may be
necessary to send the command:
SYS> cmd MCA RESET
When changing filter-position you might get the message 'The filter-wheel
detent pin is malfunctioning' (red/blinking/beeping) or 'filter wheel movement
timed out'.
Simply quit the alarm and repeat the filter command if this happens.
If this doesn't help bring the telescope to access park and power cycle
the MCA controller, followed by:
SYS> cmd MCA RESET
Data acquisition problems
By Data acquisition we mean the management of an exposure, reading of
data from the CCDs and saving to disk. This may fail in one of several stages,
for example:
- Run, Finish, Abort or Re-time commands are not successful
- Run process stops after CCD clearing
- Run spontaneously aborts during readout or transfer to disk
- Transfer to disk does not complete to 100%
- Data on disk is corrupted (e.g. torn frames)
These may or may not be accompanied by a pop-up error box/alarm. If the
error pop-up mentions the (ultra)DAS or "reset the camera", and you cannot
continue observing, then the following procedure is recommended (pink
window):
SYS>dasreset WFC
(i.e. startobssys is unnecessary, unlike in e.g. WFC fault)
When this completes, try a new Run and see if the above fault recurs. If
it does, then a lower-level reset of the CCD controller may necessary and
you need to move the telescope to access park.
Power cycle the unit labeled SDSU CCD controller, located to the left of
the cryostat, followed by:
SYS>dasreset WFC
Starting up the TCS
- Open telnet to lpas2
Username: INT_LOGIN
Password: ******** (as shown on monitor)
- At next menu type START.
This will bring back the Telescope status display and the USER>
prompt
Remember to do a zeroset whenever the TCS is started!
Starting up the ICS and DAS
The ICS
- On the ICS Sparc. Log on as:
Username: intobs
Password: ****** (as shown on monitor)
- Two windows pop up, a pink window from where you run the observing
system on this machine and an orange window which is connected to the DAS.
In the orange DAS window enter:
obssys
- Choose the menu option number for running the correct version (see
white board).
- In the same orange DAS window, enter:
startobssys
- Now enter in the pink ICS window
obssys
using the same menu option as for the DAS and
startobssys
to start the observing system.
- Check you have the prompt:
SYS>
in the pink window and make sure the following windows on either the ICS
monitor or it's second display screen are present:
- TALKER
- LOG of observations
- TCS INFODISPLAY (Check UTC and LST are updating)
- AUTOGUIDER
- MIMIC for the WFC
After the mimic has started and communications have been setup, the
software will carry out some self tests on the WFC. Check the mimic for:
- The WFC SHUTTER opening and closing.
- The FILTER WHEEL moving to determine what filters have been installed
and in what positions.
Important note
On WFC startup, it is NOT uncommon for the MCA controller (the electronics
rack mounted on the WFC which drives the shutter and filter wheel), to have
problems identifying the filters which are loaded. In this case, it may be
necessary to repeat, perhaps several times, the command:
SYS> cmd MCA RESET
to resolve this problem.
Starting up the reduction sparc
- Log on to the INT Data Reduction Sparc.
Username: intguest
Password: ******** (as shown on monitor)
- After logging on, three windows should startup:
- A pink Xterm
- IRAF showing the "cl>" prompt
- XIMTOOL
n.b. If the IRAF or XIMTOOL windows do NOT start, bring them
up manually using the procedure below:
- Move the mouse over the background and press the right mouse
button.
- Keeping it pressed, select "Programs" and then "XGterm". A blue
XGterm window will appear.
- Repeat the above procedure and select XIMTOOL from the "Programs"
menu.
- To start IRAF, enter "ncl" in the XGterm window.
- In the IRAF window, move into the "date" directory where the images
are stored. The current date is entered in the format 'yyyymmdd' e.g.
cl> cd /obsdata/inte/20020319/
