IRIS+to+process+spectra

How to use IRIS to do initial processing of low resolution Spectra from fits files:-

When you take the spectrum check that the counts are ideally above 10000 but not saturated I use the 'line profile window tool' under the View menu in Maxim DL.

Open your fits file in IRIS and click the AUTO button to get rough contrast.



You then need to remove the sky to a 2D spectra... this is in the Spectro Menu as below.



Select the Median Method (default). No idea why but Dr Rees knows why........need to ask.



Click AUTO again to get the contrast back to approximate level.



Then select 4 point in the background that are not over faint stars or spectra.



Then draw a box around the spectrum as shown in the image below. Make sure you are not on 'Slice' from a pervious run (see below for 'Slice).



Then select from the pull down menue 2D -1D ... (Optimal Addition)... this is in the Spectro Menu. ..again Dr Rees knows why!



You should then have a 'Strip' spectra as shown below. But the blue end may be to the right. So it needs flipping. See next procedure.



Flip the Spectrum Vertically ... this is in the Geometry Menu. Do this to make sure your spectrum goes Left to Right ... Blue to Red



You can see the source star now to the left.



If you select Slice in the view menu you can then click and drag a line along the section of the spectrum that is of interest to produce a graph.



The white line below represents the slice.



The above graph is not yet calibrated for CCD response or frequency etc. That will be done in Vspec.

Save your spectrum in fits format with a different name otherwise it will overwrite your original fits file...

This file is then ready for VSPEC :-)