- Introduction
- Safety
- Troubleshooting
- Areas of the Telescope
- Preliminaries
- Filling the IDS Cryostat
- Zerosetting the Encoder
- Switching the TCS between Computer Mode and Engineering Mode
- Initial Commands
- Setting up the Acquisition Camera
- Loading Catalogues
- Setting up the CCD
- Preparing for Autoguiding
- Opening Up
- Single Star Calibrate of Telescope Pointing
- Focusing the Telescope
- Observing
- Closing Down at the End of the Night
- Closing Down in a Hurry
- Saving Data
- Creating the Night Log
- Filling in the Operations Logbook
- Leaving the Building
- Observers Handover Check
- Acknowledgements
1. Introduction
In this guide, the following syntax will be used:
- The system prompts will appear in the text as typewriter fonts, in the following format:
USER> Commands to TCS (grey window on the Telescope Control System)
SYS> Commands to ICS (pink window on the Instrument Control System)
cl> IRAF commands on INTDRPC1
$> Any other terminal window eg: xgterm
Typewriter text indicates that that exact command should be used. For variable
input, curly braces will be used, e.g {your_input}. So, where the example might say:
SYS> arc {time}
to take an arc of length {time} seconds, at the prompt you would type:
SYS> arc 10
to take an arc of length 10 seconds.
- Words in green correspond to actual buttons to be pressed.
- Words as hyperlinks go to corresponding pictures or further details.
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2. Safety
- Before starting work at the telescope please make sure you read this Important Safety Information! Please also print and read the safety precautions very carefully. You must
agree to all the items, sign it and hand the document to your support astronomer.
- Please use a lone
worker alarm when you are observing alone at the INT. It can be found
on the back wall of the control room (see here). They are specific to each telescope so should never be taken away.
The orange buttons should only be pressed in a real emergency, as it will automatically
call the Incident Officer who will investigate.
- For security reasons you must follow the instructions given to you
by the support astronomer or the WHT telescope operator (e.g.
abandoning site in bad weather or regarding the operation of the telescope
and instrument).
- For safety reasons there is a laser curtain instaled in the
elevator that will stop it if the light path is broken by a person or
object. Chances are that if this happens you will be stuck in the
elevator. Also, due to its age, the elevator is not as reliable. For
these reasons we recommend that you don't use the elevator outside the
Operations Team working hours (9 - 16h) nor on weekends.
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3. Troubleshooting
- A Troubleshooting
Guide is available for non-standard observing modes and to solve the
most common problems.
- Some faults which are not documented in the Troubleshooting Guide may be discussed in the Fault Database,
which may assist you in solving a problem. The fault database can be found here. You may login as a guest and view or search for previous fault
reports. Please use this database to log any faults you encounter.
- In case you encounter problems that you cannot resolve easily by yourself, you can contact your support
astronomer on the first night of your run.
- On subsequent nights, or if your support astronomer is uncontactable, call the WHT Telescope Operator
(white phone 2559 or grey phone 452) who will assist you where possible. Note that the WHT Telescope Operator
will be very busy and is unlikely to be able to visit the INT directly to solve problems.
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4. Areas of the Telescope
The control room is located at the top floor of the building, and has the
following key areas:
- The Engineering Rack,
with all the manual movement controls.
- The Engineering Console, which
contains the dome lights, engineering button lights, Emergency Stop and reset
buttons, and the Computer/Engineering mode switch. There is also the TV showing
the inside of the dome, and the speakers giving sounds from inside the dome.
- The Meteorological
Data Screen
- The Whiteboard,
containing lots of details and information.
- A main desk where, from left to right, the following computers are
located:
- The TCS (Telescope Control System) and slit-viewing acquisition camera
computer inttv (1 screen and a keyboard);
- The ICS (Instrument Control System) computer lpss7 (2 screens and a keyboard);
- The Data Reduction PC INTDRPC1 (1 screen and a keyboard).
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5. Preliminaries
- In the control room, first check the Operations Logbook for any
restrictions that may be still in force.
- In the upper-left corner of the Operations Logbook, write the names
of ALL observers who will be at the telescope at night.
- Turn on the dome lights (MAIN ON/OFF)
from the engineering console and raise
the control room blind.
- Make a visual inspection of the observing floor to check that the
telescope is free to move e.g. no ladders or steps are close to the
telescope or test instruments connected.
- Clear any emergency overrides by pressing the RESET button next to the EMERGENCY STOP button on
the console.
- Turn on OIL PUMP from the engineering rack.
IMPORTANT! The oil pump
MUST be switched OFF at the end of the night, or when the telescope has not been moved for more than an hour (e.g.
bad weather).
When the oil pump is turned off, there will be an alarm after a few seconds, cleared by
hitting the ACCEPT button found on the console.
- If it's not your first night of the run, some initial steps may
be skipped, but have in mind that works carried on the telescope during
the day may have changed your setup. Before starting to observe check
that you have the correct central wavelength, slit width, grating (this should not change), camera
shutter open, no ND filter in, binning, rspeed and window. They can all be seen in the ICS Mimic display.
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6. Filling the IDS cryostat
IMPORTANT! Wear the safety helmet (with visor),
apron and gloves when filling cryostats (example). Have you read the safety information here?
-
The telescope should be parked at zenith.
- On the dewar top, check that the SILVER valve (gas vent)
is closed. Vessels must be left pressurised.
- Use the indicator on top of the dewar (by pressing and holding the
black rubber button) to check the dewar contains enough LN2 (>25%). If
it is lower, the smaller dewar can be used.
Check the pressure valve on the top of the dewar. The pressure should be between 0.5 and 1.5 bar. If this is
not the case, use the other dewar, and fill in a fault report.
- Slowly wheel the dewar over to the cryostat.
- Connect the dewar to earth; use the earthing point on the Cassegrain rotator, located above and to the left of the
cryostat.
- Fully insert the filler tube into the cryostat hole. Take care to hold it by the metallic tube and not the hose.
- On the dewar top, check that the GREEN pressure
build valve is closed. Then OPEN the BLUE decant valve fully. Turn the
valve back one half turn from fully open, to prevent the valve freezing in this position.
- Wait until liquid nitrogen is seen to be coming out of the cryostat and spilling on to the floor.
- CLOSE the BLUE valve.
- Wait for the filler tube to warm up (until it is not rigid anymore)
and remove it from the cryostat.
- Move the dewar back to the position where you found it.
- Note down in the Operations
Logbook what time the cryostat was filled and your initials.
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7. Zerosetting the Encoder
The zeroset of the telescope should be done only in the afternoon of
the first night of your run. On the following nights skip the Complete
Zeroset and go straight to the Abbreviated Zeroset. A Complete Zeroset
is also needed everytime after the
TCS is restarted and also if the telescope pointing is bad.
Complete Zeroset
- Ensure the telescope is in the zenith position, with the HA
and DEC dials located correctly. The dials should be on the rear-side
of the labelled arrows, so that moving the telescope through the
zeroset position in the direction indicated is possible.
If necessary, practise the action of moving the telescope through the zeroset position
using the 'minus' button for HA and 'plus' button for DEC (the lights above the dials will flash).
Make sure you return the dials to the correct position, ready for the zeroset, before continuing.
- In the TCS User window, enter:
USER> zeroset ha target [or: zero ha tar]
USER> zeroset dec target [or: zero dec tar]
Note: These commands need to be typed together and in this order.
Using the HA[-] and DEC[+] buttons with slow motion selected (both QM and SM buttons will be lit up when slow
motion clamps are engaged), move the telescope so that the dial pointers move through the zeroset marks in both
axes. Ensure you zeroset the axes in the same order as the commands were typed, so HA first, then DEC.
The yellow LEDs above the dials will flash as the dials move through the zeroset position. The TCS will also
beep to show that the zeroset is successful.
Note: If the TCS does not beep to acknowledge the zeroset when the dials move through the zeroset positions
(and the LEDs flash), then the entire zeroset procedure must be finished, and repeated again.
- To finish off the zerosetting procedure, the pointing model should be loaded. On the first night of your run,
or if the TCS has been restarted, type:
USER> calibrate default
(cal def) |
Loads the default TCS pointing model. |
Abbreviated Zeroset
On subsequent nights of the observing run, and if the TCS has not been restarted, type:
USER> calibrate last
(cal last) |
Loads the previous TCS pointing model. |
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8. Switching the TCS between Computer and Engineering Mode
To put the telescope into Computer Mode, turn the COMP key on the console to the right.
The green section of the ENG/COMP push button switch should
illuminate showing that Computer Mode has been selected. The system
only switches to computer mode if the OIL PUMP is on, no emergency
override is active (press the RESET button close to the ENG/COMP
button) and if HA and DEC slow motion controls (SM) are active.
To switch back to Engineering Mode, on the TCS type:
| USER> eng |
The ENG/COMP push button should return to yellow, showing that the TCS is in Engineering Mode. |
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9. Initial commands
TCS computer:
| USER> show focal |
Show the focal station setup. If not already set to Cassegrain/IDS, run
the command SYS>startobssys on the ICS. |
| USER> focus 14.85 |
Set focus to a 'good' value. |
ICS computer: |
SYS> slitarc x.x |
Set the slit width to x.x arcsec. The slit width is variable from 0.2 to 9.7 arcsecs.
|
SYS> cenwave xxxx |
Set the central wavelength to xxxx Angstroms. |
IMPORTANT: if any of the slitarc or cenwave
commands tries to move the corresponding mechanism by a large amount
(e.g. slit wide open or a central wavelength change of several hundred
Angstroms), a time-out error can be produced. If this happens, please
move the mechanisms in smaller steps.
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10. Setting up the Acquisition Camera
In the orange DAS6 window on the TCS, define a 3x3 binning of the acquisition
camera, which allows fast readout and display cycles. Type the command:
DAS6@miranda> bin 3 3
On the ICS, centre the acquisition camera AG0 on the slit using the command:
SYS> tvxy 498000 500000
In
ds9, you should check that the image has been inverted in the y-direction (From the top menu choose
Zoom
then check that the
Invert X option is checked).
A green cross
+
for the instrument rotator centre, and a blue cross
+
at the slit centre should also be displayed. In case they do not appear then, from the top menu
Region you can (
Load Regions...)
and load the most recent region "IDS_centres_bin3" file for 3x3
binning. To load the regions you need an image being displayed. You can
acquire one by pressing
Field.
If the green and blue crosses disappear after starting acquisition, click on
ds9 top menu
File,
Preserve During Load, and check the box
Regions.
Note: The AG0 camera covers an area of approximately
1.2 x 1.2 arcmin around the centre of the slit.
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11. Loading Catalogues
Check which objects are loaded into the TCS current list of targets by typing:
USER> out term
If there are objects loaded which you don't need, then the command
USER> erase
can be used to delete all targets from the current list. Note that the catalogues will still be
stored on the computer, but will no longer be loaded into the TCS.
It is possible to load your own catalogue onto the TCS with all your
targets in it. They can
be created with any text editor, and should be saved as
{your_catalogue}.cat. The filename
must not contain any upper-case
letters. Each line of the file should contain one object
and its coordinates in the
following format:
[object] [ra] [dec] [epoch] [!comments]
So, for an example object SN 1987A:
sn1987a 05 35 27.9 -69 16 10.00 J2000 ! comment
The line must be delimited by spaces (
not tabs!), and there should be
no spaces in the object name (only underscores). They can then
be loaded into the /int/cat/ directory on the ICS computer. This can be
done using the scp command on the data reduction computer next to the
ICS:
$> cd directory_containing_catalogue
$> scp {your_catalogue}.cat intobs@lpss7:/int/cat/.
The username and password are shown on the label on the computer's monitor.
The catalogue can then be included using the command:
USER> include {your_catalogue}
Note: The .cat extension is not required.
It is also possible to add and remove individual objects using the following commands:
USER> source sn1987a 05 35 27.9 -69 16 10.00 J2000 Creates object.
USER> add Important! Loads
object into TCS.
USER> remove {object_name} Removes object.
USER> out file {your_catalogue} Writes the contents
of the current TCS
catalogue to file.
Note that to add the object you must include the epoch. No error message will be shown if you
do not, but the object will not load properly.
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12. Setting up CCD parameters
In the ICS, check that the CCD readout speed, readout window and binning are
the desired ones. If not,
| SYS> rspeed slow |
Set CCD readout speed (choices: slow or fast).
|
| SYS> bin 1 1 |
Sets binning to 1 by 1.
|
| SYS> window 1 "[785:1150,1:4200]" |
Set readout window size (in pixels) from 755 to 1119 in the spatial direction,
from 1 to 4200 (the whole CCD) in the wavelength direction. These values are
independent of the binning set. |
For further information on commands regarding the CCD, refer to the
UltraDAS
documentation.
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13. Preparing for autoguiding
Suitable guide stars can be found using a graphical user interface
to the Guide Star Catalog. If the GSS2 interface is not already visible, open an
xterm in the ICS machine an
type:
| lpss7> ssh -X gss@intgss |
Login as gss (the password should be written on the whiteboard. If not, ask your support astronomer or the WHT telescope operator). |
| intgss> gss2 |
A new window with the graphic user interface for Guide Star Search will be displayed. This will be used later for
selecting appropriate guide stars
|
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14. Opening Up
- Check that the weather conditions allows for observations. Set the
humidity alarm to 75%.
- Ride
the lift down at least one floor and turn the lights off. Open the
south doors, latching them safely to the walls. If the humidity is
above 75%, set the humidity alarm to 90%, and DO NOT open the south
doors. If the wind speed is above 40km/h DO NOT open the south doors.
- Switch all dome lights off, as well as the lights in the far end of the control room.
- Rotate the dome towards the East (in the direction of the doors to the lift) using the DOME ROTATION CW
(clockwise) and CCW (counter clockwise) buttons found just right of the UPPER SHUTTER panel.
- On the UPPER SHUTTER panel (located on lower engineering rack), use
RAISE MICRO until the MAIN OVERTRAVEL light
underneath turns off and you hear a 'clunk'.
- On the UPPER SHUTTER panel, push RAISE MAIN
until the shutter stops moving.
- Push and hold the MIRROR COVER OPEN
button. The light below the MIRROR COVER buttons will change from green (closed) to red (open) when finished.
- Push the DOME VENT FAN ON button to
enable dome ventilation. The red light will go OFF when the ventilator is
on. If the humidity rises above 75%, the dome fans must be turned off.
- Close the control room blind.
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15. Single star calibrate of telescope pointing
Using a single star calibration will improve the pointing model, and should be sufficient to use for the rest of your
observing run, unless the TCS has to be restarted.
If you find the pointing on subsequent nights is poor, it could be
because the TCS has been restarted during maintenance checks. If this is the case, simply repeat the single star
calibrate procedure.
Begin with:
| USER> enter aperture 0 0 0 |
This centres the aperture on the slit centre. |
| USER> cal faint |
This sends the telescope to a suitable faint calibration star and begins the 7-star calibration procedure. |
Since we only want to do a single star calibrate, we must break out of the HANDSET menu when it appears in the TCS
window. To do this press <ctrl-Z>
Begin taking image frames with the TV acquisition camera by clicking the
TV button. Adjust the
exposure times if necessary using the top box, and pressing RETURN.
If the star appears directly on the green cross + (which marks the rotator centre), the pointing is fine and you can skip the rest
of this section. Otherwise, you need to use the 'HANDSET' button again to centre the star on the green cross
+.
USE OF THE HANDSET
- Press the 'HANDSET' button (F6) on the TCS keyboard to enter HANDSET mode. Pressing it again will exit HANDSET.
- Press "a" to select APOFF offset (important if telescope needs offsetting while autoguiding).
- The '<INC' and '>INC' keys will set the offset step
in arcseconds, from 0.3 to 100.
- Pressing the arrow keys will move
the telescope in the direction indicated - remember you are moving the cross towards the star, not the star
towards the cross. Wait for the acquisition TV to catch up with each movement before moving again.
|
Once the star is well centred on the green cross, exit the HANDSET (
F6) and type:
| USER> point calibrate (point calib) |
|
| USER> cal anal zero |
|
Unless the rms of the solution is very high (>0.05), type "Y" to accept.
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16. Focusing the telescope
To determine the best telescope focus select a suitable (mag 9-11)
flux
standard star from the "ING Spectrophotometric" catalog on the the ING webpages
(http://catserver.ing.iac.es/landscape/). Point the telescope to the star with
| USER> gocat SPXXXX+XXX |
Ensure you enter the ING name of the star, e.g SP1234+567 |
Use the HANDSET to centre the star on the centre of the
slit (blue cross). Then set the slit width to a large value, to ensure
the entire PSF of the star is included.
| SYS> slitarc 9.7 |
Sets the slit width to the 9.7 arcsecond maximum
|
Now we begin a manual focus run.
| USER> focus {focus.value} |
Set the focus to a value 0.2 mm below the nominal focus value |
| SYS> run 10 "focus {focus.value}" |
Take a 10 second exposure labelled with the current focus position. |
Repeat the above two steps, incrementing the focus value by 0.1 mm (or 0.05mm if the seeing is good). Display each
image in IRAF:
| cl> display r{run number}[1] 1; imexam |
Displays the image in the ds9. |
Measure the FWHM of the central spectrum in the spatial direction
by placing the cursor over the central spectrum and pressing the 'j'
key.
Keep incrementing the focus value and taking exposures until
the FWHM is clearly getting worse. Set the focus to the value with the
smallest FWHM.
Note: Ensure you are looking at the FWHM of the same point in the spectrum by creating a region in the
ds9 -
this can be done by a simple left-click.
Also, the focus may change significantly if you introduce a filter, in which case you will have to repeat this process.
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17. Observing
Here follows a list of the most commonly used commands throughout the
night.
See also the
ULTRADAS Dictionary for commands related to exposure definition
and CCD parameters settings.
Remember that the lower shutter starts vignetting at ZENITH DISTANCE
>57 degrees (ELEVATION <33 degrees) - the system does not warn you!
If you need to observe at ZENITH DISTANCE > 57 degrees, please follow
the instructions described in the troubleshooting guide.
Acquisition
Ensure your target is included in the catalogue loaded in to the TCS (see
Loading
Catalogues section). To slew to your target, simply type the command:
| SYS> gocat V458Vul |
This moves the telescope to the object called V458Vul in the catalogue. Note that spectrophotometric
standards and other lists of bright stars are included by default in
the system
catalogue. |
| SYS> rotate sky {mount PA value} |
This move CASS rotator to xx degrees, which corresponds to the position
angle (PA) of the slit in the sky.
|
DO NOT try to move to a rotator angle between 138 and 142
degrees, as it will push the rotator out of its limits. Instead use angles from 318 to 322
degrees.
Press
TV in the "SDSU Autoguider
on AG0" grey window to start the continuous readout mode of the slit-viewing
camera. You can adjust the exposure time for each frame in the top box -
press RETURN to initiate the new exposure
time
Use the
HANDSET mode (
F6) to move the target on to the slit
centre (blue cross
+).
TV camera filters:
There is a set
of filters dedicated to the acquisition TV camera. They are
particularly useful for bright objects, for a more accurate acquisition.
To use the filters type the
command:
| SYS> tvfilt 2
|
This will use the green (BG38) filter (which is in position 2)
|
The numbers associated to each TV filter are listed in the following table:
0
|
Clear
|
1
|
Green (BG38)
|
2
|
Blue (BG28)
|
3
|
Red (RG630)
|
Orientation of the sky with Cass TV slit-viewing
camera
sky PA = 0 sky PA=90 sky PA=180 sky PA=270
N <-------- N E --------> E
| ^ ^ |
| | | |
| | | |
| | | |
V | | V
E E <-------- ---------> N N
At the INT control room there is a hand made "graduated circle" that
can be used to determine the orientation at other sky PAs.
When a certain sky position angle is not required (for example for a
single point source), it is recommended that the sky PA matches that of
the parallactic angle of the target. Mounting a PA of this value puts the
slit along the longest axis of the star, elongated by atmospheric
refraction. As such,
this becomes ever more important towards low
elevation.
The
parallactic angle of the object can be seen on the TCS info display
underneath the information on the current mount PA. The value is
constantly changing with time, and a PA should be chosen which roughly
matches the parallactic angle the target will have in the middle of the
exposure.
The
parallactic angle of multiple targets can be calculated in advance
using the
STARALT
tool. Note that the parallactic angle option should be chosen instead of moon
distance.
Because the Cassegrain rotator is slow, overheads can be reduced by
calculating the required PA before each new target, and sending the
command to change the sky angle (see "rotate sky" above) immediately after
issuing the "gocat ..." command.
Acquisition of faint targets
If the desired target is too faint to be acquired directly into the slit, then a
blind offset should be used.
The limiting magnitude for an effective acquisition is around V
= 17 mag, for dark/grey sky brightness and bad seeing conditions (~ 2
arcsecs). If the seeing is good, it can be possible to go a little bit fainter.
Note
that the acquisition of fainter targets is possible, but the longer
exposure times (>15 secs) on the acquisition TV makes it not
practical.
The steps for a blind offset are:
- Select a nearby bright target.
Note: Up to 8 arcminutes, the blind offset should be perfect, and still good (within 0.5" shift) up
to 15 arcminutes. For more than 20 arcminutes shift, the difference becomes noticeable and is
not recommended unless with a large slit width (the shift can be ~ 1-1.5").
- Add the bright target (bright_object) to the catalog (using source and add commands).
- Acquire the bright_object following the above acquisition procedure
(using the gocat command).
- The faint target (faint_object) can be blindly brought into the slit using the command:
USER> blind faint_object
Note: Coordinates of both the bright_object and the faint_object must be in the same astrometric system and both with precision 2 decimal seconds in RA and 1 decimal arcsec in Dec.
Guiding
- In the Guide Star Search Interface window enter the coordinates of the target.
- Select INTCass from the Configuration menu.
- Fill in the Rotator Sky PA box with the Mount PA shown on the TCS DISPLAY screen (not the parallactic angle).
- Ensure the aperture offset values are 0 0 0 and click SEARCH.
- The GSS2 Interface will now display a list of potential guide stars. Select a guide star ideally between
11-13th mag and highlight the X/Y position (automatically copies text). Now execute the following commands:
| SYS> autoxy 430000 58000 |
This centres the autoguiding probe at the X/Y position 430000 58000. This is the position copied from the
GSS2. To paste them just press mouse middle button. |
| SYS> field |
This searches for potential guide stars at this position (careful that some could be hot pixels and not
real stars!). |
| SYS> guide on star 1 |
This will guide on the star marked as star 1. |
Note: If small corrections of the telescope position are needed while guiding, use the
HANDSET (F6 on the TCS keyboard) in
APOFF offset mode ("a" on the TCS keyboard).
It is strongly recommended that you use guiding if the time on the target is longer than two minutes.
Exposing
| SYS> glance 10 |
Takes
a 10 second exposure which is saved as s1.fit. New glances will
overwrite previous ones. Glance can be used for instance to check
exposure times. |
Calibration frames
Sky flat exposures:
It is advisable to point the telescope to a blank field
before taking sky flats. A print-out of blank fields can be found on
the engineering console, and the catalog containing them can be loaded
into the TCS by typing:
USER> include blank38
If you are using a high resolution grating, you can begin
taking sky flats before sunset. Sky flats for lower resolution gratings
can commence shortly after sunset.
| SYS> sky 10 |
Takes a 10 second sky flat. Aim for approximately 30,000 - 40,000 counts in any single exposure.
|
| SYS> offset arc 10 10 |
Dither
the telescope by 10 arcseconds in the x and y direction (this is
recommended between each sky flat exposure). Note that offsets are all
absolute with respect to 0,0 and not relative to the last offset
position.
|
In general it is not recommended to use sky flats, because there are
many absorption lines from the atmosphere. Tungsten lamp flats should
be used instead, see below.
Arc / Tungsten exposures:
| SYS> compmirror in |
Places the comparison mirror in the beam. |
| SYS> complamps CuAr |
Turns on Arc lamp, options: CuAr/CuNe/CuAr+CuNe. |
| SYS> arc 30 "CuAr V458Vul" |
Takes an arc frame of 30 seconds. |
| SYS> complamps W |
Turns on Tungsten (white) lamp. |
| SYS> flat 5 "W flat V458Vul" |
Takes a 5 seconds flat with the tungsten light. |
| SYS> complamps off |
Turns off lamps. |
| SYS> compmirror out |
Removes comparison mirror from beam. |
If the counts are too high (for example with the tungsten lamp) and the
exposure times are already short (less than 1 sec), then you might need
to use the neutral density filters dedicated to the lamps (0 to 7,
where 0 is no filter and 7 is the strongest).
| SYS> compfilta 1 |
Moves the comparison filter wheel A to position 1. |
| SYS> compfilta 0 |
Takes off the comparison filter. |
Bias:
| SYS> bias Takes a bias exposure. |
| SYS> multbias n Takes n bias exposures. |
Science exposures
| SYS> run 1200 "V458Vul" |
Exposes for 1200 seconds and name the image V458Vul. Note that if you don't specify a comment, the
observing log automatically applies a comment of the target name is written in your catalogue. |
| SYS> multrun 3 120 "V458Vul" |
Takes 3 consecutive exposures of 120 seconds each. |
At the end of the exposure, if you want to move to another target:
| SYS> guide off |
Stops guiding (SYS>guide on would later recover
the same guide star if telescope is not moved). |
| Press Stop in the "SDSU Autoguider on
AG0" |
Stops readout of acquisition camera. |
Neutral density and colour filters:
If the target is too bright, one of the
above slit neutral density filters can be put in position, by issuing the command:
| SYS> asnd 2 |
Moves the ND filter tray to position 2. The possibilities are 0 to 5, being 5 the strongest. |
| SYS> asnd 0 |
Takes off the ND filter. |
Note: These ND filters are common to the science target and lamp
beams, and are different from the ND filters described in the
Arc/tungsten exposure subsections, which are dedicated only to the
lamps.
Several
colour filters are also available for use (e.g. for
order
sorting or other wavelength discrimination purposes) in the other
filter tray above the slit. The filters that are currently mounted at each tray position are:
1
|
BG28
|
2
|
RG630
|
3
|
GG495
|
4
|
GG395
|
5
|
WG360
|
There are more available filters that can be placed in the above slit tray, as
UG1, GG385, RG695, and RG830. Ask your support astronomer if you require a filter which is not currently mounted. The wavelength dependence of transmission
of these filters is given
here.
The filter can be positioned by issuing the command:
| SYS> ascf 2 |
Moves the filter tray to position 2. The possibilities are 0 to 5. |
| SYS> ascf 0 |
Takes off the colour filter. |
Note that the use of filters above the slit introduces an offset to the telescope focus.
If you are going to observe with and without filter (or with various filters) in the same
night, the best would be to focus the telescope with/without filters at the beginning of the night, and calculate
the offset in the focus value.
Examining Data
First, close any active IRAF sessions on the INTDRPC1 computer. Then issue the command iraf in a terminal
window. This will open an xgterm window, a ds9 window and execute IRAF automatically.
The IRAF interface on the Data Reduction System (INTDRPC1) is
used to examine the data. From the IRAF prompt, make sure you are in
today's directory, e.g. for 05/10/2011
ecl> cd /obsdata/inta/20111005
Today's directory can be found at the bottom of the EEV10@lpss7 - udas_camera_mimic on the ICS.
Use the following IRAF command to display the image:
| cl> display r242645[1] 1 ; imexam |
Loads the 2D spectrum of image number r242645 in to the ds9 window. Wavelength runs from red at
the bottom of the screen to blue at the top. The imexam command allows for quick examination of the data. |
Useful imexam commands include:
'v' for vector cut; click start and end
'c' for column cut
'l' for line
'e' for elliptical plot
's' for surface plot
'm' to obtain pixel statistics on section around cursor
'r' for radial profile
'q' to quit imexam
Note:
If you plan to reduce your data on the INTDRPC1 remember that you must
not operate on the images stored in the /obsdata directory (in
particular, NEVER move or delete the image files). You can create
a directory in the /scratch folder (e.g. /scratch/inta/20111005) or in
the /reduction/local folder on INTDRPC1, and copy the images there to
proceed with your own data processing. This should not be a substitute
for backing up your data as these files are periodically wiped
clean.
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18. Closing down at end of night
- Check that the acquisition camera AG0 and the autoguider are not
reading out (press Stop in both windows).
- Bring the Telescope to zenith and the rotator to a convenient position
by typing:
USER> park zenith
USER> rotate sky 0
- Push and hold the MIRROR COVER CLOSE button. Check the mirror petals
close fully (the light will also change from red (open) to green (closed)).
- Push the DOME VENT FAN STOP button to turn off dome ventilation.
The red light will go on when ventilator is stopped.
- Once the telescope is STOPPED, switch the TCS to engineering mode
by typing:
USER> eng
The ENG/COMP push button should now be illuminated with a yellow
light.
- On the Engineering Rack, close the dome shutter pushing LOWER MAIN until the shutter stops
moving.
- Push LOWER MICRO to fully close the shutter. If the lower shutter is open, it must be closed and
lowered before the upper shutter.
- Turn off OIL PUMP from the engineering rack. The light will show green when off.
- Close the south doors if open.
- Fill the IDS cryostat following the same procedures as at the start
of the night. Leave the telescope parked at zenith.
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19. Closing Down in a Hurry
If it starts to rain or snow, the humidity rises above 90% or the winds above 80km/h you will
be forced to shut down in a hurry. If this is the case:
- Stop the current exposure and read out. To do this break out of the
command and return the SYS prompt using <ctrl-z>. Then type:
SYS> finish
- Park the telescope using the command:
USER> park zenith
- While the telescope is moving hit the DOME SHUTTERS button below to the Engineering Console, so the dome shutters may be moved at the same time as the telescope.
- Close the mirror and the dome in that order (as in the section Closing down at the End of the Night), remembering to close the lower shutter before the upper if it is open.
- Shut off the fans.
- Close the South Doors.
- If you were using a 'mult' command then typing finish will not have
stopped the remaining exposures from being taken, and the run
must be aborted. This can be done by typing:
SYS> abort
- Release the DOME SHUTTERS button on the Engineering Console for the dome shutters. If you
forget to do this the dome will not track with the telescope.
- If the telescope is shut down for a long period of time then turn
off the oil pumps. Do not forget to turn them back on before you move
the telescope again.
- If abandoning the telescope due to bad weather then fill the cryostat before leaving, and
fill out a fault report
with the time you filled it so that the Operations Team can refill it
first thing in the morning. Note that only time lost due for technical
reasons should be
included in the fault report. If abandoning due to high humidity turn
the alarm off (middle setting) to stop it going off all night.
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20. Saving Data
With IDS, you can save your data either on DVD, on a DAT tape, or
directly to your laptop or hard-drive. You only need to write your copy
disk/tape, there is no need to write an archive tape. DVDs can be burnt
on either of the two Linux public computers in the control room
(INTDRPC1 and INTDRPC2).
Recording data on DVDs:
Please refer for details to the following document (also shown on the wall to the right of INTDRPC1):
http://www.ing.iac.es/Astronomy/computing/recording.html.
Direct to Laptop:
Data can be transferred directly to your laptop through
the INGEXT network. This can be done file by file using the scp command
from your laptop:
$> scp intobs@lpss7:/obsdata/inta/yyyymmdd/r{number}.fit /your/directoryOf
course the * can always be used as a wildcard.
Alternatively the rsync command can be used to copy all the files from
the directory on lpss7 to a directory on your laptop. Running the
command another time then updates your laptop's directory only with the
new data.
$> rsync -av intobs@lpss7:/obsdata/inta/yyyymmdd/ /your/directory
The password can be found on the screen of the computer.
Writing tapes:
Insert the DDS3 (125m) tape in the drive
/dev/nst0, on top of the data reduction
machine
INTDRPC1. A DDS3 tape (12GB) should be able to store 150 runs in
fits format, or about 300 using tar.
Open a new xterm on the Data Reduction machine and change directory
to where the data are stored:
e.g.
$>cd /obsdata/inta/20040419
$> tar cvf /dev/nst0 *.fit
this writes all '.fit' files in that directory to tape. If you
expect that this will take long time, leave a note on the keyboard to prevent
the day-time staff from closing the window, stopping the tar before it is completed.
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21. Creating the Night Log
Fill in the nightlog which is accessed from the
observing logger window. It is important to include the breakdown of
observing time: Fill in any downtime that was encountered (bad weather,
technical problems, etc.) and note the
time lost. Don't forget to click "create".
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22. Filling the Operations Logbook
The printed logbook in the control room contains fields which
must
be filled out during the night:
CCD cryostats: Initials and local time for filling the CCD(s).
Telescope focus and reference temperature (Internal Temp in
the meteorological data screen)
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23. Leaving the Building
Before leaving the building, please switch off all major lights in the
control room and in the kitchen area. Check that no electrical devices are
left on in the kitchen, i.e. sandwich toaster, coffee machine, etc.
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24. Observers handover check
Ready to do it alone? Please check you are familiar with the following tasks:
- use of intercom and telephone
- safety precautions when using liquid nitrogen
- weather precautions, knowing when the dome must be closed
- observing at zenith distance between 57 and 70 degrees
- opening and closing the dome
- moving the telescope in engineering mode
- starting up and shutting down the observing system
- knowing about the most common faults and how to solve them
- writing your data to disc/tape at the end of every night
- filling in fault reports
- filling in log book in control room
- producing the observing log
- filling in observing feedback form at the end of your run
If, after reading through this guide, the troubleshooter and the fault database, you are still having problems that
you cannot solve, contact your support astronomer on the first night of your run. On subsequent nights, or if the
support astronomer is unavailable, call the WHT Telescope Operator using the phone number on the whiteboard.
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25. Acknowledgements
Credits should be
given to the ING students Lee Patrick, Liam Hardy, Hugo Ledo, Dora
Fohring, Mansour Karami and Hassan Fathivavsari
who are contributing to improve this manual.
