Table of Contents
Preparing Observations
You can do observations using script generated from OBs, custom script and/or manually using command line. With TCS target catalogue you can have all your targets loaded in TCS for manual observations, but if you are using script the catalogue is not needed as the script will automatically add target to TCS.
Observing scripts
Observing scripts can be generated automatically through the
Observing Script Generator
or crafted manually. If done through the web, the script will be uploaded and within a few minutes available in
~obs/scripts/proposal-ID, where proposal-ID refers to the proposal ID entered in the web
form (e.g. 38-042). If the directory does no exist, it will be created. If you make your observing scripts manually,
first make the proposal ID directory (using mkdir) and place them therein.
The scripts are executed from the sequencer window, from the directory where they are placed.
Note that if you are saving scripts or files elsewhere in the ~obs account, the directory
will be cleaned up after every run and it will not be possible to recover them.
Create a TCS Target Catalogue
A source catalogue can be made well in advance of your observations by using the web interface,
NOT Source Catalogue Creation.
Note that it is also possible to enter targets on-the-fly and create a catalogue directly on the
TCS while observing (See section, Loading Target Catalogue).
Exposure Time Calculator
The Exposure Time Calculator
can be used to estimate the required exposure times for ALFOSC, NOTCam, FIES, MOSCA and StanCam (both in
imaging and spectroscopy mode, where it is available).
MOSCA CCDs
MOSCA CCDs are linear (better than 0.2%) up to
digital saturation (216ADU).
NOTE The full well of device (ext 3) W20-(0,0) has a strong position
dependence with a limiting level of only 40 kADU (/52 ke-)
in the bottom right corner, nearest the centre of the mosaic array.
Please find more information from
MOSCA general characteristics and
Detector pages.
MOSCA read out time
The read out time of the full mosaic is 36 seconds
with 2x2 binning.
Afternoon Preparations
Overview of everyday afternoon tasks
|
TCS access code
Any instrument computer which needs access to the TCS, for instance
to move the telescope during slit acquisition or dithering, will ask
for the current TCS access code at start-up. This
code is updated every day (around lunch time). When you are asked to
supply the TCS access code, do the following:
- On the TCS VT510 terminal, make sure that the brightness
is turned up
- On TCS type: Show-Page and then 1 (or type
sh-p 1 for short)
- The TCS access code is shown on the top part of the screen
as: AccessCode xxxxxxxxxx
Starting the MOSCA Observing Software
- Go to the computer called lisa.
- Click on the line
'selena.not.iac.es Willing to manage'
- Click on Accept.
- Log in with username obs. Password will be supplied
by the staff.
- To start the observing system in a terminal window type:
[obs@selena ~]$ startobssys mosca
and enter the TCS Access code of the night in a popup window.
- Wait until the Talker displays the text "MOSCA Sequencer READY TO USE"
or the UT is incrementing on the top right of the "CCD status" window.
The lisa-screen should look like this .
- Images are stored in the directory /data/mosca.
-
The automatic MOSCA observing log displays a listing of FITS headers for
incoming data files. The System Talker lists incoming messages from the
Sequencer. These two programs are displayed on the InfoSys monitor, and
are automatically reset every afternoon. If you change between instruments
you can change the obslog with the command e.g.:
[obs@selena][MOSCA]$ mosca.showlog
- Change directory to your working directory (e.g.):
[obs@selena ~][MOSCA]$ cd ~obs/scripts/43-999
- Start a new Sequencer terminal, if needed:
In a terminal window type
[obs@selena~]$ seqterm
and choose the MOSCA option.
The computer florence is used for image analysis using IRAF/MSCRED.
You can start iraf ecl by typing xgterm on a terminal window.
On
florence, images made by MOSCA are found in the directory
/data/mosca/. Be advised that this directory is read-only.
Loading the TCS Target Catalogue
Obtaining Calibration Frames
For many observing programs calibration frames can be secured in the afternoon. The type of
calibration frames needed depend very much on your science goals and the instrument mode you
are using. For further information see:
MOSCA
During the afternoon it is recommended to take some bias frames and *dark* frames.
The dark frames should have similar or longer integration time as your longest science exposures.
Please let your duty officer known that you are taking dark exposures in order to keep the dome dark.
In addition, it doesn't make any harm to take a set of dome flats however twilight flats do a
good job as well.
Acquire at least two bias frames before starting your observations in the afternoon/evening
and again in the end of your observing night. With two bias frames and with two flat fields of the
same intensity level, gain and readout noise can be determined, e.g. by using the IRAF task
findgain.
If there is a sudden large area of reduced sensitivity and
the area is moving most likely it is a bug or spider.
The only way to remove "a bug with wings" or a spider during
an observing run is to lower the instrument
and remove the offending bug.
Contact staff!!!
Start of the night
Overview of things to do at sunset
|
Telescope Startup Procedure
Return to the dome at least 30 minutes before twilight and follow the instructions below.
Weather precautions
| Humidity |
Wind |
Dusty Wind |
Temperature |
> 90% - Close telescope
After 20min < 90% the telescope can be reopened. |
12 m/s - Close sideports and lower hatch |
10 m/s - Close sideports and lower hatch |
If the humidity is > 90% and the temperature is
< 0° C close telescope and do not open until all ice has melted on the outside of the dome. |
| 15 m/s - Observe down wind: at least 85 degrees in AZ away from wind |
12 m/s - Close telescope |
| 20 m/s - Close telescope |
Telescope Control System (TCS)
- Turn up the brightness of the TCS screen (on right-hand side, below the screen).
- Look at the top-left of the TCS screen. If the item ST isincrementing, then the TCS is running, if
not - then the TCS needs rebooting
(rebooting the TCS
should be done under guidance of a staff member). Type refresh if the screen looks strange.
Telescope power-on and Dome Opening
- Check the safety system in the computer room.
Reset the system by turning the left key (marked as "First") and then the right key (marked as "Second"),
one at a time (See TCS Manual Sect. 10.1
for procedure). If you hear a repeated clanking sound then the system has not reset, check the red lights
above the keys to see if a safety stop or other item is set.
- After dinner power on the TCS by typing, power-on and confirm with y for yes. Look at the status page number 1 (type sh-p 1).
On this page the status of the power units for the telescope motors can be viewed. When the TopUnitPower
is on and the telescope is Idle, the telescope is ready to use. The power-on procedure takes about
one minute in total.
- Dome can be opened about an hour before sunset if you first turn telescope to the hoist position tcs.Building-Hoist-Position or point to a blank field which is away from the sun tcs.goto Blankxx+xx. Upper hatch and lower hatch can be opened normally, but leave north sideport closed tcs.open-side-ports-fully west south east. After sunset open north sideport as well tcs.open-side-ports-fully.
- At sunset, if weather conditions are OK, open the upper hatch with the mirror covers closed.
Press the key, START/STOP on the TCS and then the key Open Upper Hatch (7). Confirm by typing y
for yes. It takes about 3.5 minutes to open the upper hatch.
- In the dome (While the upper hatch opens) check that nothing is in the way of the telescope motion (altitude: 6.5° - 90°)
- Open the side ports (only if
weather conditions are OK and the sun is under the horizon).
Type on TCS, open-side-ports-fully. Look at the TCS status page number 3 (type sh-p 3). Status page 31 shows more
details, but is delayed in updating.
For manual opening procedure of the sideports see
Sideport Operation .
The side ports can be operated individually and opened before sunset by typing in TCS
open-side-ports-fully south or respectively east, west, north based on the sun position.
- Open the lower hatch (only if weather conditions are OK).
On the TCS, press the keys Start/Stop
and Open Lower Hatch (8). Confirm with a y. It takes about two minutes to open the lower hatch. The TCS
will not allow opening of the lower hatch before the upper hatch has completed opening. In case you can only open the
upper hatch, the maximum zenith distance for unvignetted observing is 55°, and at a zenith distance of about
70° roughly half of the mirror is vignetted.
- The mirror covers can be opened at the sunset or 1-2 degrees before if flats for narrow filters are needed. On the TCS, press the keys
Start/Stop and Open Mirror Covers (9). Confirm with a y. It takes about 50 seconds to open the
mirror covers. Please note that the power for hatches and mirror covers is completely independent of the telescope
power and the electronics in the control room.
Set default telescope parameters
- This should be done in any sequencer terminal with
[obs@selena]$ setup-tel-mosca
This sets amongst other items, the default telescope focus and rotator
angle, and auto-pos-full for fully automatic autoguiding when pointing
to an object. Note that after this command the telescope will stop tracking.
Field Rotator
In an alt-az telescope the field rotator is used to keep the orientation on
the sky fixed while tracking. When the field rotator is in automatic mode,
which is the default, the TCS command field-rotation value sets
the rotator such that value is the angle between the sky and
the instrument.
The default value of the Field Rotator is different for each
instrument and can be found in Table 1.
The field-rotation value will be set to the default angle when executing the script
setup-tel-mosca
The rotator-position is the physical position of the rotator
with respect to the telescope fork, and it has a limit at +- 200
degrees. Its current value is shown on the TCS status display together
with the time-to-reach-limit in minutes.
Before reaching the limit, the TCS will send a warning and suggest you
to turn the rotator 360 degrees at any convenient moment. This can be
done manually with the TCS command ro-tu-360 after switching
off autoguiding with ag-off. Note that this is possible only
in the overlapping ranges [-200,-160] and [160,200].
If the limit is reached, the TCS will eventually, after repeated
warnings, perform the full rotation automatically (whether or not an
observation is ongoing).
The exposure commands for ALFOSC, FIES, MOSCA
and StanCam check whether the rotator limit is reached within the exposure time,
if this is larger than 300 seconds. For NOTCam, where typically multiple short
exposures are made, this is not the case.
If you want to follow the same target continuously for
many hours, and you wish to avoid having to turn the rotator, for
instance because you want your target on exactly the same pixels all
the time (transit light curves), you might consider using a different
field-rotation value, based on the time-to-reach-limit value displayed
on the TCS UIF.
For the case that right after the telescope pointing the rotator will
start off in the overlapping rotator range, the telescope can be told
to automatically point using the rotator position that allows for
maximum tracking time, with tcs.set-rotator-standard, which is
the default behaviour. For details see
the TCS documentation.
If you have many pointings with relatively short exposures or you keep
pointing towards the same region of the sky, you may save some
pointing overheads by making the TCS choose the fastest rotator slew
to reach either of the overlapping rotator ranges: set the rotator to
fast mode using tcs.set-rotator-fast, which is a sticky
command. To go back to the default mode, use the command
tcs.set-rotator-standard .
Camera Probe
The Camera Probe is used for the standby Camera (StanCam) and for FIES and should be
put in park position for all other instruments. Put the Camera Probe in the correct position
by typing the TCS command as indicated in Table 1.
The correct Camera-Probe position will be set when executing the script
setup-tel-mosca
Sky Flats
If you are observing in imaging mode, obtain sky flats in the evening twilight
with the filters you are going to use. If you know before hand that you might be requested to perform
observations for a Target of Opportunity (ToO), it could be convenient to obtain sky flat fields in the
standard filters (U, B, V, R, i) already in the evening. The type of calibration frames needed depend very
much on your science goals and the instrument mode you are using. We recommend the documentation
on the instrument pages. Please, check the User Guides available
for:
MOSCA
Below is a short guide of how to obtain twilight flat fields for
optical imaging.
- Remember to set tv-off on the TCS before making sky flat fields (adequate for
morning flat fields, the TV monitor is often already off in the evening).
- Choose a proper blank field from
the blanks catalogue.
A useful blank field target in the eastern sky that is not too low (i.e. RA 1-4 hours more than current ST).
- point the telescope to the blank field:e.g.
tcs.goto-object Blank03+31 from the sequencer terminal or
goto-object Blank03+31 from the TCS.
- You can also read the full catalogue:
- Load a catalogue containing empty fields by typing read blanks on the TCS. Access the
catalogue by pressing the key CAT and select an empty field with the keys 1, 7, or
Prev, Next. Preset the telescope by pressing the key Preset to selected (4).
-
It is recommended to be close to the focus for each filter. Type foc-pos value where
value is the default focus for the instrument and can be found in Table 1.
Then type foc-del value where value is the focus offset (focus delta) for the filter, see
full focus offset table and
remember to change the value of the focus delta when you are changing filter.
-
Choose the desired filter
-
Make an exposure by typing expose t in the
sequencer window where t is the exposure time in seconds. It is recommended to make a small
offset between each image in order to be able to remove stars from the frames. To make an offset, choose
the move mode Telescope RA/DEC of the TCS by pressing 5 on the numerical key pad
until the right move mode is selected. Then make sure that the offset size is put to a suitable value by typing
o-s x y on the TCS, where the value of x and y is in arcseconds (it is
recommended to use an offset size of ten times the size of the FWHM of the seeing disk in order to easily
filter out the stars). Make the actual offset while the CCD is reading out by pressing down AltFunc
together with any of the arrow keys (make the offsets in the same direction). One keystroke
corresponds to the value of the offset size. Repeat for next filter.
Focusing the Telescope
Focusing the Telescope
with MOSCA
The telescope focus depends on temperature and zenith distance. These
relations have been measured to a high accuracy and the corresponding
corrections are applied in real time by the TCS (note
that you will not see these corrections in the focus value displayed on
the TCS since this value is kept constant to avoid confusing the observer).
Focusing with MOSCA
To focus the telescope with MOSCA is done easiest if you
use scripts focusexpose,
mosca.focus-auto (from a sequencer terminal)
and select a
focus star field
close to the meridian and make sure both FASU A and FASU B are "Open".
If you will use filter without known focus offsets you need to
determine the focus offset.
[obs@selena 42-999][MOSCA]$focusexpose [focus-startvalue] [focus stepsize] [tint]
which make 5 images, e.g. focusexpose 22000 75 12
!!!NOTE Do not autoguide and make sure the
'field-rotation' is set to -90!!!!
[obs@selena 42-999][MOSCA]$focus-auto [focus step-size]
[file name]
For the focusexpose-script you have to give
the initial TCS focus value and the
focus step size, e.g. focus-auto 75
(for the last obtained image).
If the exposure time is not provided the script will
use the MOSCA default integration time ( tint).
The "mosca.focus-auto"-sequencer script analyses the image and
estimates the best focus value.
A good first guess for the focus script is
focusexpose 22000 75 12
Set the telescope focus e.g.
tcs.focus-position 22120
or on the TCS by (e.g.)"foc-pos 22120".
!!!NOTE the smallest meaningful focus offset
is about 20-30 TCS focus units.
A
The full documentation and other methods of estimating the telescope focus
can be found from
MOSCA www-pages.
See also the
focus offsets between the filters
and the
focus offsets between the CCDs .
AutoGuiding
It is recommended to have the telescope autoguide on an optical source
close to your target object. The TCS is automatically selecting a star
from the HST guide star catalogue. The guide probe is then
automatically placed at the correct position to auto-guide on this
star.
- After obtaining sky flats, switch on the two Guide
TV monitors above the TCS monitor. When it is dark outside, type
tv-on on the TCS to power on the TV guide camera.
Alternatively, use in any Sequencer window
[obs@selena]$ tcs.tv-on
The TCS command tv-off switches the TV camera off.
- On the TCS, type auto-pos-full to choose the fully automatic guiding mode.
Note that this is the default guiding mode as set in
tcs.setup-tel-<inst>.
In this mode, a guide
star will be automatically found, centered on the screen and
autoguiding will be switched on (ag-on).
If the guiding
does not start automatically but you see a guide star on the TV
monitor, type auto-pos-retry.
- The TV filter can be adjusted to the intensity
of the guide star by typing tv-filt name on the TCS,
where the options for name is Open, Closed, Grey, Red,
Yellow or Blue. Choose an appropriate TV filter based on
the brightness of the guiding object and keep an eye on the guide
monitors during your observations so you can change TV filter after weather conditions and
brightness of the guide stars.
- The autoguider TV focus is also set by the script
tcs.setup-tel-<inst>. The TV focus is depending on
instrument and can be adjusted by typing tv-foc value on
the TCS, where the value for default focus is found in Table 1.
If you wish the TV-focus to follow the telescope focus type
au-t-f (Automatic-TV-Focus, default setting) on the TCS, else
to restrict to only manual TV-focus settings type ma-t-f
(Manual-TV-Focus).
In automatic mode, after every pointing of the telescope the TV-focus
will be set to a default value that takes the telescope-focus position
into account. If that value is not adequate, you can recalibrate the
TV-focus on the spot: after adjusting the tv-focus type
calibrate-tv-focus in the TCS interface.
Note, do not change the TV-focus while integrating or while placing
an object on a slit. For example, the position of a star on ALFOSC CCD
can move up to 1 second of arc by adjusting the TV focus by 25 units.
- If you want to choose a new guide star, type
get-guide-star 2 (or 3,4,5, etc.) to get a new guide star from the guide server
at the current pointing, followed by auto-pos-retry.
- On the TCS, the signal strength from
the autoguider is shown as a number. A guiding value between 1 and 23
is useful. Put in a filter if the signal is above 24, otherwise the TV
filter will be set to grey automatically.
If the signal is close to 1 the autoguiding is not reliable
(e.g. clouds and/or bad seeing).
Set tv-filt open and check for
clouds.
- Make sure that the smaller box, the sky box is
placed outside the star box. If needed, move the sky box by selecting
the function Sky Box with Change move mode (5) and move
the box with the keystroke combination, Alt Function + arrow
keys.
Always turn-off autoguiding (ag-off) before moving
the telescope.
Hints for manual guiding and tweaking of telescope pointing
If guiding mode is set to auto-pos-off, the guiding has to be activated
manually. Furthermore, in case that the pointing is not optimal, some
manual tweaking may be required.
For manual choosing of a guide star, start with preseting to
target. Find a guide star on the screen and move the star box to the star
by pressing the key change move mode (5) on the TCS several times until
the option Star Box is shown. Move the box by using the keystroke
combination Alt Funtion + arrow keys. Alternatively, choose the move mode
Guide Probe to move the star into the box, or use the command move-g.
To set the step size of the Guide Probe, type probe-step-size x y on the
TCS, where x and y are in arcseconds.
In case the telescope pointing is not optimal, in particular if the guide star
ends up outside the screen, a pointing correction can be made with the move
mode called Telescope: press the key change move mode (5) on the TCS several
times until the option Telescope is shown, and move the star by using the
keystroke combination Alt Funtion + arrow keys. The step size of the
Telescope is set with the command offset-size on the TCS UIF.
Alternatively, if no guide star can be found on the screen, use get-guide-star
2 (or 3,4,5, etc.) to get a new guide star from the guide server at the
current pointing.
If still no guide-star is seen on the guide TV,
the Aladin@NOT
tool allows to identify suitable guide stars:
in "Guide probe" view, use the pointer
to read off (GP_X, GP_Y) coordinates of a suitable guide star inside the red-lined GP area,
and then use the TCS UIF to move the guide-probe to those coordinates with commands
x GP_X and y GP_Y.
When the star is placed in the starbox, type ag-on on the TCS
to switch on autoguiding. To switch off the autoguiding, type ag-off.
Guiding on moving targets
If you are observing moving targets, view the page Tracking of Moving Targets, in the Appendix.
Start Observing
When the telescope is focused it is time to start the observations.
Visit the individual pages for instrument specific information:
MOSCA
The software interfaces for the instruments are very similar looking, however MOSCA
has still non-sequencer BIAS CCD Control-software.
However, all the
tcs commands ,
tcs scripts
and
postprocessing commands
are available from the sequencer window.
For instance,
type tcs.setup-tel-mosca to set up the telescope for for observing with MOSCA.
See the list of the most
commonly used TCS sequencer commands. For a complete list of all sequencer commands,
view the Sequencer Reference Manual.
If you are observing moving targets, view the page Tracking of Moving Targets.
Overview: observing an object at night
- Point the telescope using the TCS terminal, or use the tcs.append-object
and tcs.goto-object
commands in a Sequencer window.
- Make sure the telescope is autoguiding (auto-pos-full or ag-on)
- Choose the desired filter by clicking on the
FASU User Interface button or with script/command line
[obs@selena 42-999][MOSCA]$ fasua 1
or giving a command with the filter id
[obs@selena 42-999][MOSCA]$mosca.wheels -f 111
- Adjust the telescope focus
[obs@selena 42-999][MOSCA]$mosca.focus-offset
or using the "focus-delta"-command (e.g. for filter #111)
[obs@selena 42-999][MOSCA]$tcs.focus-delta 100
- Start integrating e.g.
[obs@selena 42-999][MOSCA]$expose 120
- Note the bias levels of the CCDs can be variable. It is recommended to
keep on eye of the bias levels during the night.
- The easiest way to observe with MOSCA is using a
script
(
MOSCA commands,
TCS commands) and to run a script type e.g.
[obs@selena 42-999][MOSCA]$my_script
-
Switch-off autoguiding
from the TCS terminal ag-off
or from the sequencer window
[obs@selena 42-999][MOSCA]$ tcs.ag-off
before pointing the telescope to the next object
- In case of a FIES override:
|
Start Observing - With MOSCA
In most cases one has more than one pointing per filter per object. The possibility is to type (all) the
commands (exp, object, teloffset) on the command line (Sequencer terminal) and change the filters
by clicking on the "FASU User Interface" or write a
a
script
(MOSCA commands,
TCS commands).
The script
can include TCS-commands like: tcs.append-object, tcs.goto-object,
tcs.focus-delta etc and MOSCA-commands like:
fasua, fasub (to change filter), teloffset, expose etc.
All saved images are automatically loaded into the MOSCA DS9 display
and can be examined interactively
(see MOSCA SEQUENCER
Script Reference):
- on seqterm type
[obs@selena 42-999][MOSCA]$ imexam
- If you want to offset the telescope to move a target from one position on
the mosaic to another use
targetoff-script
[obs@selena 42-999][MOSCA]$ targetoff
- If you want to disply an image from the same night as you are observing
(from "/data/mosca" -directory)
[obs@selena 42-999][MOSCA]$ display MOtk020010.fits
or from other night (e.g. "/data/mosca/MOta15" -directory)
[obs@selena 42-999][MOSCA]$ display MOta15/MOta150010.fits
Unfortunately the bias level of CCD[im4] is variable, hence it is recommended to take a bias frame every
now and then in order to monitor the bias level changes. After the commissioning the instrument the top right
CCD (W19) has shown to have variable bias level. The change of thirty ADUs in 30 minutes have been seen.
This behaviour is under investigation. The other CCDs have shown little (a few ADUs) or no intra-night bias
level changes.
Adjusting integration time
If you want to adjust the integration time while integrating
use "addtime" command from the sequencee terminal. This can be used
in either increasing (positive value)
or reducing the given integration time (negative value).
The FITS-header keyword 'EXPTIME' will have the correct shutter
opening time.
Teloffset
Offsets the telescope in seconds of arc in detector x and y direction.
This command is used, typically, when dithering or small (less than
about one arc minute) offsets of the telescope.
If you want to move a star from the
centre of the FOV (the cross) to the centre of a given CCD,
it is recommended to use
mosca.targetoff.
Note that teloffset works with any field angle.
Focus offsets
Most 100mm filters are about 5mm thick and are expected to have
similar telescope focus values.
The estimated focus offset is 19 units per millimetre, i.e. the estimated focus offset between filters
#108 (I_int 817_163) and #116 (b_Str 468_19) is +19 TCS focus units.
See the thickness
of filters
StanCam and MOSCA together
You can use
StanCam and
MOSCA together, if needed.
End of the night
Overview of things to do at the end of the night
|
Closing the telescope
- When observations finish and the sky is brightening turn the guide TV off
by typing tv-off on the TCS, i.e. before potentially taking morning skyflats.
- Put the telescope to zenith by typing zenith or pressing the key
Start/Stop and then Zenith (0). This will park the guide probe and it also sets
rot-man. Wait for Rotator -90°.
- Park the building by pressing the key Start/Stop and then the
key 4, Park Building. This process can take up to 8 minutes. Building will stop at Az
≈ 119°, Alt ≈ 90°.
- Close the mirror covers with the TCS command c-m-c or by pressing
key 3, Close Mirror Covers (if you are in the Start/Stop menu).
This takes 42 seconds.
- Close the lower hatch by typing c-l-h or pressing key 2, Close
Lower Hatch. This takes about 3 minutes.
- Close the upper hatch by typing c-u-h or pressing key 1, Close
Upper Hatch. This takes about 5 minutes. If timeout occurs or hatch does not move, see
TCS Manual p. 43.
NB: When the upper hatch has closed the dome cooling
will start and the staircase cooling will stop.
- Close the side ports by typing on the TCS UIF close-side-ports.
Check that all sideports did close by checking status in TCS page 3, type sh-p 3. If a
sideport does not close, go to the dome and flip the black knob from remote to local and press
the green button to move the sideport in question. For more details, see
Sideport Operation.
- Power down the telescope. After all of the above have been completed and the telescope is "Idle", type
power-off on the TCS, then type sh-p 1 to display the telescope power units.
Wait until all the telescope power displays show "off".
- Have a look in the dome at hatches and telescope, to check for any faults that
might have occurred.
- Run the calibration script (if you observe with ALFOSC or NOTCam),
i.e. alfosc-calibs ALxxxx or notcam-calibs NCxxxx, where xxxx refer to the file prefix
for the night.
- Turn down the TCS screen brightness. Use the knob on the right-hand side of the TCS
monitor, near the power switch. Never turn the TCS monitor off.
- Turn off monitors. Turn off the two autoguider monitors and dome TV camera monitor.
- Turn on the control room webcam and the dome webcams. Make sure that the webcams in
the control room as well as in the dome are turned on before you leave.
- Complete the WWW report forms. Fill in and submit Internet
NOT End-of-Night Report.
Be sure to include any faults that occurred and submit a
fault report,
so we can attend to problems promptly. If it is the last night of the observing run, also fill in and submit
Internet NOT End-of-Run Report.
- Lockup the dome. Lock the outer dome door when you leave the building.
- Clean up the kitchen/lounge area in the service building and switch
off all lights when you leave.
- Lockup the outer door in the service building before leaving for the Residencia.
Stopping the MOSCA observing system
- To shutdown the observing system type in a terminal window
[obs@selena ~]$ shutdownobssys mosca
- To exit the MOSCA Obs Log, click on the close icon in the frame of
the MOSCA Obs Log window.
Data saving and retrieval
Instructions on how to retrieve data from ALFOSC, NOTCam, StanCam, MOSCA and
FIES are found in
Data Download instructions.
Only principal investigators have direct access to their data on the data server.
The principal investigators can grant access to their data by generating and
distributing a shared link. Details on how to do so can be found in the instructions.
General information on NOT FITS-headers can be found
here.
Accessing raw and reduced data at night
The computer called florence is setup for you to make a quicklook analysis of
the incoming data, e.g. by starting up DS9 and IRAF:
> cd newiraf
> ds9
> xgterm -sb -fn 9x15 -sl 400 -cr red -title IRAF -e ecl &
For the different instruments we have on-line reduction programs running, that
deposit the reduced products on a disk accessible on florence.
The raw and reduced data files can be found on florence under directories
/data/<instrument-name>/
/data/reduced/<instrument-name>/
Copying data products from florence over the wifi in the NOT control room to your
own mobile computer is no longer feasible. Use the
Data Download tool.
Archival requests
To obtain NOT data from our archive, first compile a list of file
names of the calibration and science data to be retrieved, using our FITS archive.
Note that this archive does not show the
data obtained in the latest twelve months, due to the propriatary
period.
Then please contact staff and send the list of file names to be
retrieved, such that we can locate the data in our archive and make
them available through FTP.
Compensation for override observations
If your program was interrupted by a Target-of-Opportunity or
another override observing program, you are entitled to payback
time. Such compensation for time lost during your allocated
observing run (whether in visitor or service mode), is claimed
back through the submission of Observing Blocks (OBs) using our
OB Generator. The observations will be executed accordingly
in service mode by staff during Nordice Service nights, and you
will be informed by email when observations are made and where
to retrieve the data.
Using the OB generator to claim payback time
Access the
Observing Block Generator and login to your account, or if
you are a new user, please register. When you are logged in, add
your proposal for which you claim compensation time.
There are help buttons at every level of the OB generator, and you
can also get support and give feedback through
obsupport@not.iac.es.
If you have questions about how to define OBs and/or Observing
Sequences, please contact
service@not.iac.es.
For your OBs to be carried out as compensation for time lost to
overrides, please make sure to select OB Group type "Payback".
Troubleshooting
If you have ...
- ... cannot reset the safety system:
- ... no light on the CCD -- check:
- Dome open, mirror cover open
- Lower hatch not obstructing at low altitude
- Guide probe out of light path
- Camera probe in correct position
- FASU shutter open (if using ALFOSC)
- Correct filter in instrument
- Correct telescope focus
- If it is cloudy
- Check all the above again. If there still is a problem, then phone duty staff.
- If MOSCA or StanCam image has a count level of 0, this can actually mean saturation and you should reduce the
amount of light falling on the detector.
- StanCam shutter controller has power (if using StanCam)
- ... wrong field on CCD -- check:
- Coordinates of field
- Epoch of coordinates
- No typos in entering coordinates in TCS
- Field rotation is correct
- ... no guide star on guide probe screen -- check:
- Dome open, mirror cover open
- Guide probe in correct position
- Field and rotator angle
- TV switched on
- TV filter open
- TV focus correct
- Try typing in the X and Y values of another Guide Star fromthe
The 10 brightest currently available Guide Stars
- If it is cloudy
- ... lost tracking/guiding:
- How close to the zenith are you? (Good guiding and tracking is guaranteed only 5 degrees
or more from zenith).
- ... changing tv filter does not work:
- at TCS type in the command 'Initialize-TV-Filter'.
- ... ctrl x', 'ctrl g', 'ctrl t' and 'ctrl v' commands on the TCS give incorrect functionality,
e.g. telescope offset rather than star box movement.
- wrong function key menu on the TCS keyboard press keypad key 5.
- ... "building crash":
- ... other TCS problems
- Press the keypad key labelled Log and then keypad 2 to see the latest entries in the
TCS log.
- ... acquisition: slitoff/fiboff unresponsive
- Using the mouse to set the contrast while image is loading?
Using the mouse to set the contrast while this process takes place can cause DS9 to crash. Best procedure is to wait tuning the contrast level until the image has been fully loaded into DS9, and zoom / contrast levels set.
A DS9 crash while in 'imexam' while leave the postprocessing system in a non-workable state.
Rather than shutting down the whole observing system to recover, it is in most cases sufficient to run the sequencer command 'killimexam'.
See also next item.
- ... ds9 shutting down while doing acquisition
- Using the mouse to set the contrast while image is loading?
Using the mouse to set the contrast while this process takes place can cause DS9 to crash. Best procedure is to wait tuning the contrast level until the image has been fully loaded into DS9, and zoom / contrast levels set.
A DS9 crash while in 'imexam' while leave the postprocessing system in a non-workable state. Rather than shutting down the whole observing system to recover, it is in most cases sufficient to run the sequencer command 'killimexam'.
- ... "sequencer/obssys" does not respond or behaves badly:
- Standard procedure in such circumstances is to restart the observing system using 'shutdownobssys'
(from a terminal window) followed by 'startobssys'.
- ... lisa frozen, not responding, e.g. can not log out using the foot icon
- if you have a working terminal, try "$ killall panel", wait until the panel restarts and then logout as usual
- if there's no terminal available, you can use florence to ssh as obs into the observing computer you've been using,
and type the killall command.
- if you have no terminal available, etc. press the "Ctrl" and "Alt" keys and then press "Backspace".
That will kill the X server and force a logout
If you encounter a fault or a problem with the instrument, the computers or the telescopeduring the night, then fill in a
Fault Report.
A sudden large area of reduced sensitivity
If the area is moving most likely it is a bug or spider.
The only way to remove "a bug with wings" or a spider during
an observing run is to lower the instrument
and remove the offending bug.
Contact staff!!!
Appendix
Tables for Instrument Settings
| instrument |
field-rot |
i-p-a |
camera probe |
foc-pos |
tv-foc |
orientation |
c-w-h |
| ALFOSC |
+90 |
0 (horizontal slits)±90 (vertical slits) |
c-p-p |
26630 |
510 |
North ↑ East ← Horizontal slits: E-W (P.A. = ±90) |
0.75 |
| FIES |
0 |
N/A |
c-p-s |
26880 |
510 |
North ↓ East ← |
N/A |
| NOTCam |
-90 |
-90 |
c-p-p |
26750 |
500 |
North → East ↑ |
0.95 |
| MOSCA |
-90 |
N/A |
c-p-p |
27160 |
450 |
North ↑ East ← |
0.55 |
| StanCam |
0 |
N/A |
c-p-c |
26330 |
500 |
North ↑ East ← |
N/A |
| SOFIN |
0 |
-90 |
c-p-p |
26950 |
510 |
N/A |
0.9 |
| TurPol |
0 |
N/A |
c-p-p |
29450 |
650 |
North ↑ East → |
0.12 |
Table 1a shows the values of the: field rotation(field-r), instrument-parallactic-angle (i-p-a),
camera probe, focusposition (foc-pos), TV focus (tv-foc), field orientation andcounter weight height (c-w-h) for
the different instruments. On the TCS, type thecommand followed by the value, for instance field-r -90.
The default focus value stated for NOTCam is for the K band in imaging mode using the WF camera (internal camera
focus of 5650).
| From |
To |
foc-delta |
| ALFOSC no filter |
StanCam R-filter (#10) |
-260 |
| MOSCA R-filter (#106) |
StanCam R-filter (#10) |
-155 |
| NOTCam Ks-filter (WF) |
StanCam R-filter (#10) |
-380 |
Table 1b shows the default focus offsets between the instruments.
Commonly Used TCS Commands
| Command |
Comments |
| ag-on |
Turns autoguiding on |
| ag-off |
Turns autoguiding off |
| auto-positioning-full |
Turns the guide star auto positioning to full-automatic |
| auto-positioning-retry |
Try again to bring the guide star in the guide box |
camera-probe-stancam
camera-probe-ccd |
Moves the camera probe to ccd position (for StanCam) |
| camera-probe-park |
Moves the camera probe to park position (for ALFOSC) |
camera-probe-fies
camera-probe-split |
Moves the camera probe to split position (for FIES) |
| field-rotation fieldangle |
Sets the field rotation to fieldangle |
| focus-position n |
Moves the telescope to focus position n |
| focus-delta n |
Applies a focus offset to the current telescope focus |
| get-guide-star 2 |
Find another guide star |
| instrument-parallactic-angle n |
Defines the parallactic angle for following presets |
| read-catalogue name.cat |
Reads the catalogue |
| tv-on |
Turns on the guide TV |
| tv-filter name |
Selects the guide TV filter where name can be either closed, grey, open, red,
yellow or blue |
| tv-foc pos |
Changes the guide TV focus to position pos |
|
|
| append-object string |
appends an object to the TCS catalog |
| goto-object Object |
moves telescope to "Object" |
| find-object |
selects an object in the TCS catalog |
| preset-with-parallactic-angle-to-selected |
moves telescope to the selected object, with parallactic angle |
Tracking of Moving Targets
At the NOT there are two main modes of tracking a moving object (planet, comet, asteroid, satellite):
1) differential tracking with auto-guiding and 2) differential tracking without
auto-guiding. Which of these to use, depends in practice on the target speed and how long the
observations take. We have been working with speeds as high as 700"/hour with auto-guiding.
For targets faster than 1000"/hour we recommend blind tracking with updating of differential
rates to the TCS (currently under testing).
Since September 2019 the OB generator
allows for non-sidereal tracking.
The differential rates are given in the FITS headers in the keywords DTRCK_RA and DTRCK_DE.
Differential tracking with auto-guiding
In this mode, the telescope tracking is set to the differential rates, and in addition,
the auto-guider is used with the star-box set in motion with the same rates. This works for
as long as the box stays within the auto-guider TV-screen (approximately 70" field). When
the limit is reached, auto-guiding is no longer working. It is possible to reposition the
star-box and guide probe without affecting the telescope tracking, but there is a limit to
how many times this can be done before reaching the limit of the available guide probe area.
This depends
on the RA/DEC rates, the field-rotator angle, and the initial location of the guide star
inside the guide probe area. If this happens, you have to repoint to the target again.
If your target moves less than 70" over the execution time of your observations, you
can relax. If it moves more, you need to keep an eye on the star-box and manually re-position
it as described below.
Both the telescope tracking rate and the box-motion rate are given in RA/DEC coordinates,
i.e. dDEC/dt and dRA/dt (in arcsec per hour), and the cos(DEC) correction is taken care
of internally by the TCS. (In other words, if your RA-rate is given as dRA*cos(DEC), you
have to divide by cos(DEC) before entering its value.)
The two modes "optimal-ll" and "optimal-lr" are intended for fast objects or long
observations where auto-guiding is required. They give the maximum amount of guide-probe
repositionings.
Using ASTEPH
The sequencer script tcs.asteph is a wrapper script that connects to a tool made
for the NOT by Grigori Fedorets to access the ephemerides of targets, see also
Fedorets' howto. The most recent version of asteph
is an upgrade in October 2024 that allows for more options.
For known targets and the majority of cases it looks up JPL Horizons to find position
and rates at the location of the NOT (Z23), converts from dRA/dt*cos(DEC) to dRA/dt,
as required by our TCS, and lists the sequencer commands you need to point to target
and start differential tracking AND potentially differential auto-guiding.
We recommend to test tcs.asteph in the afternoon to see that
it understands your target name.
See example below (in green). Type tcs.asteph to get a listing of input parameters.
New! It is no longer needed to use escape double
quotes for a target name with space in it! (but it can also be used)
These are the steps to follow:
- Start your "moving object" OB in one sequencer terminal. This sets FITS headers correctly.
- In another terminal run asteph to get pointing and differential tracking information.
tcs.asteph [ -t asteroid|comet|planet|unconfirmed|horizons] [ -m ima|para|along-slit|optimal-ll|optimal-lr ]
[ -r full|half ] [ -g on|blind|update] [-e INTIME] -n TARGET
-t default type is "asteroid"
option "planet" selects for instance the Jovian satellite Europa instead of the asteroid Europa
option "comet"
option "unconfirmed" for new objects not yet in the JPL database
option "horizons" allows for a free search in JPL Horizons (NB! only for experts)
-m default mode is "ima" using the default field rotation for imaging for current instrument
option "para" for spectroscopy orients the slit along the parallactic angle
option "along-slit" ALFOSC horizontal slit along the tracking direction
option "optimal-ll" orients the field to maximize the number of guide-probe repositions
option "optimal-lr" 180 degrees rotatated to above, both recommended for fast targets or long observations
-r default tracking rate is "full"
option "half" gives the half-rates of the differential tracking (sometimes requested for photometric calibration)
-g default is "on"
option "blind" will simply use blind tracking
option "update" outputs ephemerides to be used with "hitandrun" to update rates for very fast objects
-e default is current UT
option "INTIME" to give a requested time for today on the format HH:MM
-n targetname (mandatory, if it contains a space, use escape double quotes)
EXAMPLE (with autoguiding):
[obs@selena ~]$ tcs.asteph -n 2024 S1
3 -n 2024 S1
1 S1
cd /home/postprocess/asteph; source /home/postprocess/asteph/.venv/bin/activate; bash JPLHOR_to_NOTcat.sh -n " 2024 S1 "
Running tcs.asteph...
Your input target is - 2024 S1
Your observatory is Nordic Optical Telescope, La Palma.
Today is 2024-10-15
Your computer says time is 12:20 UTC.
Retrieving data from JPL Horizons...
Data retrieved successfully from JPL Horizons.
The object being searched for is ATLAS_C-2024_S1
Prefix for file names will be 2024-Oct-15.ATLAS_C-2024_S1
***************************
These tasks should be given to the TCS:
***************************
tcs.append-object ATLAS_C-2024_S1-12 11 01 42.10 -17 51 55.9 2000.0 0.0 0.0 14.038
tcs.ag-off
tcs.guide-object ATLAS_C-2024_S1-12
tcs.reposition-guide-probe 377.67 -46.3062
- Cut and paste the three first sequencer commands listed by tcs.asteph (or point to your
target in the normal way), wait until guiding, and then cut and paste the fourth command or run it
as:
tcs.reposition-guide-probe RA-rate DEC-rate
This is a script which will 1) stop auto-guiding and box motion (if it was set in motion), 2) move
the star box to an optimal position on the TV screen, 3) set the telescope tracking rates to RA-rate
and DEC-rate, 4) start the box motion to the same rates, 5) move the guide probe to put the star in
the box, and 6) start differential auto-guiding.
- If this is a relatively fast target, i.e. moving more than 70" during the
time your observations take, you will have to keep an eye on the star box.
When it reaches the other edge of the TV screen, it will stop guiding. The
TCS will send warning beeps when there is 120, 90 and 60 seconds left.
Make sure you take action before guiding stops by re-running the command:
tcs.reposition-guide-probe RA-rate DEC-rate
in another sequencer window. You can do this while exposing, although it is
optimal during readout, in between exposures. This
repositions the box and the guide probe and continues differential autoguiding
without affecting the telescope tracking.
There is a limit to how many times you can reposition the guide probe due to the
limited guide probe area. If this happens, you have to start again from point 1.
- UNDER TESTING: If you used -g update you will not cut and paste the first commands listed. You get
an output filed called "hitandrun.input" which you will use for pointing and differential
tracking with updating of rates.
EXAMPLE (updating rates):
[obs@selena 70-508]$ tcs.asteph -t asteroid -g update -n 363027
6 -t asteroid -g update -n 363027
4 -g update -n 363027
2 -n 363027
cd /home/postprocess/asteph; source /home/postprocess/asteph/.venv/bin/activate; bash JPLHOR_to_NOTcat.sh -t asteroid -g update -n " 363027 "
Running tcs.asteph...
Your input target is - 363027
Your observatory is Nordic Optical Telescope, La Palma.
Today is 2024-10-15
Your computer says time is 12:53 UTC.
Retrieving data from JPL Horizons for rate updates...
Retrieving data from JPL Horizons...
Data retrieved successfully from JPL Horizons.
The object being searched for is 363027_1998_ST27
Prefix for file names will be 2024-Oct-15.363027_1998_ST27
Writing hitandrun file for update
***************************
These tasks should be given to the TCS:
***************************
tcs.append-object 363027_1998_ST27-1 18 29 52.76 -50 03 56.4 2000.0 0.0 0.0 16.376
tcs.ag-off
tcs.guide-object 363027_1998_ST27-1
tcs.reposition-guide-probe -1770.36 -380.005
tmp.hitandrun.input 100% |************************************************************************************| 7451 KB 00:00
- THIS STEP IS UNDER TESTING.
The telescope resets to the sidereal tracking rates at every new telescope preset/pointing so nothing
is needed at the end of the observation.
However, for your information, you may stop the differential
guiding by tcs.box-motion-stop (or in short on the TCS UIF b-m-sto). This does not reset
the telescope tracking rates, and if you wish to stop the differential tracking, going back to normal
tracking rates, then on the TCS UIF type set-rate 0 0.
Tracking without auto-guiding. Rapidly Moving Targets
The upgraded tcs.asteph allows for this! with or without updating of the
rates. See above. Below are old manual TCS instructions.
For more rapidly moving targets, use the set-rate command on the TCS to continuously move
the telescope from a pre-calculated change in position. RA-rate and DEC-rate as above. In this mode
auto-guiding is not used.
We are also upgrading the possibilities for very fast tracking (without autoguiding), and the
software speed limit has been increased from 17"/s to more than 5000"/s. Observations were made of
fast satellites where the RA/DEC rates were updated every second.
- Preset to your object.
- Set the rate of change by set-rate RA-rate DEC-rate (rate in arcsec per hour). The
maximum differential rate is 20 000 0000 arcsec/hour (≈ 5500 arcsec/s).
- Make the exposure.
- Reset by typing set-rate 0 0 on the TCS.
For Experts Only
If the target has an unknown or rapidly changing motion, you might
want to adjust the rate of change in RA and DEC while tracking. Use
the set-rate command on the TCS and use command recall with the
up/down keys and edit the set-rate.
- Preset to object.
- Guess the starting set-rate RA-rate DEC-rate values.
- Do as described above with command recall.
- Do set-rate 0 0 or just preset to another object.
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