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Introduction:
The IRAF interface on the Data Reduction System (intdrpc) is used to
examine the data. To start it, go to the /home/intguest directory and type
$> ecl <
When in IRAF, help on any command can be obtained by typing
cl> help name_of_the _command
The command parameter can be changed with
cl> epar name_of_the _command
(Ctrl D to leave the parameter menu)
or reset to the deafulat values with
cl> unlearn name_of_the _command
Make sure you are in the directory where the fits frames are stored,
i.e.
cl> cd /obsdata/inta/20020712 <
Displaying 2-D spectra:
Displaying frame in a proper way is essential for a correct
assessment of the content of a frame! It is usually convenient to
use a log scale, which allows a larger dynamic range of the
intensity levels to be displayed. Depending on the type of the frame,
it might be convenient that the minimum and maximum image intensity
levels z1 and z2 are automatically chosen (.eg. for a
bias or flatfield image), like in the following example
cl> display r242645[1] 1 zs+ zr+ zfill+
or that z1 is set at approximately the bias value, and
z2 at a significantly higher value for a larger dynamic range, e.g.
cl> display r242645[1] 1 zs- zr- zfill+ z1=2700 z2=10000
Once displayed on ds9, different type of analysis can be done
using
cl> imexam
Within imexam, moving the cursor over the desired area and typing
one of the following keys will produce:
| a | Aperture sum, moment parameters, and profile fit /td> |
| j | Gaussian fit along lines /td> |
| k | Gaussian fit along columns /td> |
| m | Statistics of a rectangular region /td> |
| h | Histogram of a rectangular region centered on the cursor /td> |
| e | Contour plot |
| s | Surface plot |
| l | Plot of a line or average of lines /td> |
| c | Plot of a column or average of columns /td> |
| v | Plot of a vector defined by two cursor positions (v and v again) /td> |
| q | quit imexam /td> |
Extracting 1-D spectra of point sources and plotting them:
Extracting:
cl> apall input=input_2D_spectrum.fits
output=output_1D_spectrum nfind=1
type ? to see the varios options for the choice of the aperture
for extraction, then b to check and change the apertures for sky
subtraction (? again for its menu, e.g. t s
to define new windows), and then press f to fit.
and to plot it:
cl> splot output_1D_spectrum
k for gaussian fit, l for linear wavelenght claic
a and a for.....
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Last Updated: 1 August 2006
Romano Corradi rcorradi@ing.iac.es |