P72-008 Characterising Earth's next imminent impactor
PI: G. Fedorets
One ToO trigger.
Either ALFOSC photometry or spectroscopy, depending on the target speed.
Fast target that will need hitandrun.
Instrument setup required for ALFOSC:
- Filters: SDSS g'r'i'z'
- Grism #4
- Slit: 2.5" or 1.8"
Observing instructions using hitandrun:
Note that tcs.asteph used for these observations will output an
ephemeride file called "hitandrun.input", stored in the current directory
(where asteph is running, overwriting old files).
For more information see the author's ASTEPH documentation.
The file is used by the sequencer script hitandrun for TCS pointing and
updating of the differential tracking rates.
- Open 3 seqterms and to the directory
cd ~/scripts/72-008
In all of them. List the available OB scripts
ls -lrt
- In the first window start the target OB script, when it tells you to do the pointing,
go to step 3.
- In the second window run tcs.asteph is indicated by the PI.
For completeness
we show below the usage with all possible options (the first option in each flag is the default)
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
The PI is responsible for giving you the the exact input for asteph (see OB comments).
Either of the two will be used:
- tcs.asteph -t unconfirmed -g update -n targetname (OpenOrb ephemerides for unconfirmed
targets to be used with script hitandrun)
- tcs.asteph -t asteroid -g update -n targetname (JPL ephemerides to be used with hitandrun)
EXAMPLE:
> tcs.asteph -t asteroid -g update -n 68548
...
Your input target is - 68548
Your observatory is Nordic Optical Telescope, La Palma.
Retrieving data from JPL Horizons...
Data retrieved successfully from JPL Horizons.
The object being searched for is 68548_2001_XR31
Prefix for file names will be 2023-Oct-04.68548_2001_XR31
Today is 2023-10-04
Your computer says time is 11:53 UTC.
***************************
These tasks should be given to the TCS:
***************************
tcs.append-object 68548_2001_XR31-1 17 06 18.91 +78 39 35.7 2000.0 0.0 0.0 17.314
tcs.ag-off
tcs.guide-object 68548_2001_XR31-1
tcs.reposition-guide-probe 193.864 41.25260
Remember to switch on the hit and run script
tmp.hitandrun.input 100% |********************************************************************|
Next, go to step 4 for imaging or 5 for spectroscopy.
- If imaging, you now start
PRE IMAGING as follows:
- In the second window, cut and paste only the 3 first TCS command lines output from asteph
- when autoguiding is ok, run the script griz-calib-images
It takes 4 ALFOSC griz images (120s, 40s, 40s, 120s). Go to step 6.
- If spectroscopy, there is no PRE IMAGING, but the PI
will probably ask for asteph mode -m along-slit and in that case the output lines
from asteph
will give an angle in the line "tcs.guide-object -f *** objectname"
and this angle must give given as the last parameter (field-rot) to the hitandrund script.
Go to step 6.
- In the third window use hitandrun for pointing and tracking with differential
rates and rate-updating as follows:
hitandrun targetname hitandrun.input 'UT-string' update-rate N-updates field-rot
targetname (give a name without space)
UT-string (use the exact format as shown in the example below, a future time)
update-rate (given by the PI, if not, use 10, means update every 10 seconds)
N-updates (given by the PI, must be enough to last for whole observation)
field-rot (given by the PI, see options below)
EXAMPLE: hitandrun CAXA292 hitandrun.input '2024-Oct-02 20:24:00.000' 10 300 ima
Here the rates are updated every 10 seconds a total of 300 times, i.e. it goes on for 3000 sec.
Can be Ctrl-C'ed.
The UT-string must be exactly on the format above
and given a minute or two into the future, to let the telescope arrive in time!
The field-rot values are either ima for default N up E left orientation,
para for parallactic angle, fixed for current rotator position,
or an angle
xx.x degrees for setting a specific field-rotation angle, used if tcs.asteph is
requested with the -m flag set to "along-slit"
to have the tracking direction along slits
(for ALFOSC horizontal slits).
NB! Press return when auto-guiding is on,
the script then waits for the "right moment" (your UT input),
the playphone rings when this happens, the target is now supposedly in the FOV,
differential tracking is started, and at this moment you are ready for step 7.
- Go back to the first window where the OB was started and press return to start data acquisition.
When the OB finishes with an astrowakeup, and if you did imaging, go to step 8.
- If you did imaging with modes B) or C) then do POST IMAGING: as follows:
- Ctrl-C the hitandrun script (switches to sidereal tracking)
- TCS UIF: g-g-s 1
- TCS UIF: auto-pos-retry
- in the second window start again the script griz-calib-images
- If you did spectroscopy, there will most likely be another OB of a solar analog to be
observed. This is just a normal OB.
At this point, all is done!
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