Twiflat is a fortran program with which we can calculate the
integration time for twilight flats and optimize a sequence. The
starting point is a first exposure from which we know the amount of
counts/sec we get with the instrument, filter, optics, etc... we are
using. Also it takes into account the readout time of the CCD.
To run twiflat, just type "twiflat" in ultra1, ultra2 or ultra3.
The program will give us the information for the present date :
Twilight data for CALAR ALTO Observatory -- example --
Latitud 37 13 25 N
Longitud 2 32 46 W
Date : 19-Jul-1999 FJ(OhTU) : 2451379.4
-------------------------------------------------------------------
UT LST Azimut
-------------------------------------------------------------------
Beginning morning twilight : 3h 5.7m 22h 41.4m
Sunrise : 4h 55.7m 0h 31.7m 222.1
Sunset : 19h 36.8m 15h 15.3m 137.9
End evening twilight : 21h 26.4m 17h 5.1m
-------------------------------------------------------------------
We can change the date or plot the data.
The first graphic show several sequences of integration time
versus the starting moment of the exposures. Once the observer have
done the first flat, he can choose the appropriate sequence and
follow it.
More options are available clicking the buttons :
- Morning, Evening
The sequences can be displayed for the dawn or for dusk.
- 1st Flat
Maybe the most useful. After click on it, we'll click on the
plot to give the integration time and starting moment of the
exposure. The program will plot the sequence calculated for
the next exposures and list these values.
A new button is available:
- CCD Script
To create a file "CCDscript" with commands for an automatic
exposures sequence.
This script is apropiate for any CCD. Only when observing
with TWIN (double spectrograph), "camera" should be changed
for "red_camera" or "blue_camera" depending on which arm are
you using.
Also, it can be cuted if you only want to run part of it.
Otherwise, to run it as is, click the new button :
- Run Script
- Move Seqe.
Sequences can be moved in UT for a better set at the
present moment. We have to click on two different positions
of the plot and the sequences will move from the first to
the second.
- Zoom
We can zoom in clicking twice to select a box. To get the
initial scale click on the morning or evening button.
- Date
To change the date.
- Quit
Comments and suggestions -> Santos Pedraz (pedraz@caha.es)