!!!EIS Object Methods

An EIS data object is created with

IDL> data=obj_new('eis_data',filename)

where filename is the name of the EIS FITS file (either level-0 or level-1).

To extract information from an object or manipulate the data it is necessary to use methods. A list of all methods for 'data' is available by doing:

IDL> data->display_methods 

We list below some useful methods.

!!Extracting a data window (getvar)

This extracts a data window from the object.

IDL> wd=data->getvar(iwin)

where iwin is either the index of the window you want (beginning with 0), or the wavelength of the line you are interested in (e.g., 195.12).

The output is an array whose dimensions will vary depending on the type of data. For a standard raster it will be a 3D array.

!!Pointing coordinates (getxpos, getxcen, etc.)

The heliocentric coordinates for the data are given by

IDL> xpos=data->getxpos()\\
IDL> ypos=data->getypos()

XPOS gives the X-coordinate for each slit position and YPOS gives the position for each pixel in the Y direction.

In addition if you want the coordinates of the center of the raster do:

IDL> xcen=data->getxcen()\\
IDL> ycen=data->getycen()

Note that each of these is an array of same size as the number of exposures. This is because the center of the raster moves with time due to the spacecraft jitter.

!!Exposure times

The exposure time for each exposure of the raster is given by

IDL> exp_time=data->getexp()

!!Extracting the data header

The header is extracted into an object with

IDL> hdr_obj=data->gethdr()

there are then a number of methods for extracting information from the header which can be listed by doing:

IDL> hdr_obj->display_methods

If you just want to extract the full header into a text array, then do:

IDL> text=hdr_obj->getbte_hdr() 

You can then use the standard routine FXPAR for extracting particular parameters, e.g.,

IDL> date_obs=fxpar(text,'DATE_OBS')