Twilight flat exposure prediction

(see also)

       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 (