TRACE Analysis Guide

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TRACE analysis guide

Getting started

To download TRACE data to NRL from IDL, log on to gravity and enter Solarsoft. For your time period do:

IDL> get_trace_data,'11-APR-2010 11:00','11-APR-2010 14:00'

and the data will automatically be downloaded.

Reading data

Via the TRACE catalog

The TRACE catalogue is stored in \$SSWDB and comes in three forms: tcl (standard catalogue), tcs (short catalogue) and tce (engineering catalogue).

Reading and displaying the catalogue files is done as follows:

trace_cat,'31-may-98','1-jun-98',cat
more, trace_list_index(cat)

and the index and data arrays can be loaded as follows:

trace_cat2data,cat,index
ss=trace_sswhere(cat)
trace_cat2data,cat(ss),index,data

Via read_trace

The first step is to create an array of filenames, e.g.:

files=trace_files('31-may-98','1-jun-98')

The data can then be read into IDL as follows

read_trace,files,-1,index
ss=trace_sswhere(index)
read_trace,files,ss,index,data

If you only want to extract images every 5 minutes, then try doing:

read_trace,files,-1,index
ss=trace_sswhere(cat)
ss_out=trace_5min_files(ss,index)

(this is one of my routines). The output ss\_out can then be used in place of ss in the call to read\_trace.

Avoiding bad data

Quite a large proportion of TRACE data is almost unusable because of the spikes in the data. One can avoid choosing this data by making use of the .img_dev tag in the index structure, e.g.,

ss=where( index.img_dev le 70. )

Calibrating

To use trace_prep, you need to have the dark current files. These are distributed through $SSWDB.

The standard call to trace_prep is

IDL> trace_prep,index,data,outindex,outdata,/unspike,/destreak,/deripple

Co-aligning images

This can be done with

IDL> trace_align_cube, itrace, dtrace, index, data

where itrace and dtrace are the initial index and data fields, and index and data are the outputs.