Document title: Readme.doc for NDADS DE NACS_ASCII datatype
Project: DE
NDADS Datatype: NACS_ASCII         
Super-EID: DOCUMENT                      
There may be other documents also identified by this super-EID.
NDADS filename: NACS_READ_ME_DE.DOC
TRF entry B46555.txt in NSSDC's controlled digital document library. Feb. 1998.
Document text follows:
----------------------

        DE-2 Neutral Atmosphere Composition Spectrometer data on NDADS
        ______________________________________________________________
        
The Dynamics Explorer 2 Neutral Atmosphere Composition Spectrometer (NACS)
ASCII files contain the ambient densities averaged over one second and their
percent error for atomic oxygen, molecular nitrogen, helium, atomic nitrogen,
and argon.  The ASCII files also contain the most important DE-2 orbit
parameters.  NSSDC-developed software was used to read the binary NACS data
and create the ASCII files.  The orbit parameters were added using PI-provided
software.  For more on DE-2, NACS, and the binary data, see NACS_FORMAT_DE.SFD
and NACS_VOLDESC_DE.SFD.

The NACS ASCII daily files are requested with the DATA_TYPE = NACS_ASCII and
the ENTRY_ID yyddd.  They are then staged as yydddsssc_NACS_DE_1S_V01.ASC;
yy is the year, ddd is the day of the year, sss is the high order of seconds
of the first data point, and c is 0 or some other arbitrarily assigned integer
to ensure unique file names.  The date range for the NACS files is 
81215-83049 with most days represented.

----------------------------------------------------------------------------
              Format of the yydddsssc_NACS_DE_1S_V01.ASC Files
----------------------------------------------------------------------------

Each record in the ASCII file contains the following data.

UT                       (ms)
O density                (cm-3)
% error
N2 density               (cm-3)
% error
He density               (cm-3)
% error
N density                (cm-3)
% error
Ar density               (cm-3)
% error
orbit number
altitude                 (km)
latitude                 (deg)
longitude                (deg)
local solar time         (hr)
local magnetic time      (hr)
L shell
invariant latitude       (deg)
solar zenith angle       (deg)