The first step to obtaining calibrated EIT data is to run EIT_PREP:
IDL> eit_prep, file, hdr, image
IDL> read_eit, file, index, data
IDL> eit_prep, index, hdr, image, data = data
This will give you a dark current subtracted, flat fielded, degridded, exposure time normalized, a first order response normalized image.
The next series of steps is complicated because of the various assumptions discussed in the previous section. Interpretation of this is not straightforward and it is recommended that the user consult with an EIT team member!
In order to obtain bandpass information use the routine EIT_PARMS. Please read the header information for all keywords.
IDL> bandpass = eit_parms(waves, band, units=units)
Band being equal to 171, 195, 284 or 304. One can visualize the bandpass by:
IDL> plot_io, waves, bandpass
In order to convert observed DN to real units, now one must choose the pathways described above. To obtain the simplest upper limit one can simply use: (remember the poor assumptions in this)
IDL> peak_calib = 1.0/interpol(bandpass, waves, wave_of_interest)
IDL> calib_image = image * peak_calib
If one assumes the structure you are looking at is an isothermal plasma then you can use the EIT_FLUX and EIT_TEMP routines discussed in Chapter 3 in order to obtain an emission measure.
If one has a DEM curve, either from CHIANTI or another source put in the same format as CHIANTI, then one can use the CHIANTI package to obtain absolutely calibrated lines by:
IDL> SYNTHETIC, Wmin, Wmax, Fwhm, Pressure, Lambda, Spectrum, List_wvl, List_ident
Last revised: Tuesday, December 25, 2001 2:16 PM - F. Auchère