00readme.txt -------- NSSDC contact: D. Bilitza ------------ Nov 20, 2001

This is the introductory file to the Student Nitric Oxide Explorer (SNOE)
spacecraft data directory.

Contents:
beta-angle_MLT.txt      An ancillary dataset containing the Beta Angle, 
                        Beta Hour Angle, MLT, and MLT Hour.

/NO_uvs 		Data from the Ultraviolet Spectrometer (UVS)  
/x_ray_irradiance_sxp 	Data from the Solar X-ray Photometer (SXP).

The following files are attached below:
APPENDIX_A.TXT defines acronyms used in SNOE documentation.
APPENDIX_B.TXT is a list of known anomalies in the data.
APPENDIX_C.TXT describes the SNOE orbit in the southern hemisphere.
APPENDIX_D.TXT is a list of hardware and software compatible with these datasets.

A brief description of the SNOE spacecraft and instruments can be found in the
NSSDC Master Catalog at http://nssdc.gsfc.nasa.gov/nmc

For help with the science instruments onboard the spacecraft, and
descriptions of the orbit and trajectory, visit the SNOE website.
http://lasp.colorado.edu/snoe/

For help with the data products produced by the spacecraft, and the
Ultraviolet Spectrometer in particular, visit the SNOE Data website.
http://lasp.colorado.edu/snoedata/

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APPENDIX_A.TXT

A.U.		Astronomical Unit
ADCS		Attitude Determination and Control System
		http://lasp.colorado.edu/snoe/lib/ADCS.html
Ap		geomagnetic activity index
C&DH		Command and Data Handling processor
		http://lasp.colorado.edu/snoe/lib/CDH.html
CDF		Common Data Format
		http://nssdc.gsfc.nasa.gov/cdf/
CGM		Corrected Geo Magnetic
		http://nssdc.gsfc.nasa.gov/space/cgm/cgm.html
cm		centimeter
doy		Day Of Year (1 through 366)
F10.7		10.7 cm radio flux
HCI		Horizon Crossing Indicator
		http://lasp.colorado.edu/snoe/lib/ADCS.html
IDL		Interactive Data Language
		http://www.rsinc.com
km		kilometer
LASP		Laboratory For Atmospheric and Space Physics
		http://lasp.colorado.edu
L1/2/3/4/5	Level One/Two/etc. data products from SNOE
		see PROCESSING.TXT, FILE_USAGE.TXT
LOS		Loss of Signal
m		meters
mW		milliWatts
NCDF		network Common Data Format
		http://www.unidata.ucar.edu/packages/netcdf/
NO		Nitric Oxide
nm		nanometer
NSSDC		National Space Science Data Center
		http://nssdc.gsfc.nasa.gov
p		photon
PMC		Polar Mesospheric Cloud
S/C		Spacecraft
sec		second (time unit)
SNOE		Student Nitric Oxide Explorer
		http://lasp.colorado.edu/snoe/
SNR		Signal to Noise Ratio
SXP		Solar X-ray Photometer
		http://lasp.colorado.edu/snoe/lib/instruments.html#SXP
URL		Universal Resource Locator (a web address)
UTC		Universal Coordinated Time
UVS		Ultraviolet Spectrometer
		http://lasp.colorado.edu/snoe/lib/instruments.html#UVS
YYYYDDD		A date format, Year Day-of-Year (January 1, 1998 = 1998001)

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APPENDIX_B.TXT

PURPOSE: Document all know anomalies in the SNOE data set
   NOTE: these anomalies are not listed in any particular order

A1: There are days with no data. The cause is one of two reasons. (a) The
S/C was not able to deliver sampled data to Earth due to computer resets
or ground station LOS. (b) The processing routines discarded the data that
was sampled because of extra noise, S/C pointing errors, etc.

A2: Daily average files are comprised of the average of all orbits made
during a given day. On occasion, only one orbit's worth of data is
'averaged' into the daily average files. The day average therefore has a
poor signal to noise (SNR) ratio. Day 1999.083 and 2000.044 (geo) are
examples of this type of data.

A3: yyyyddd 1998259 to 1998263 has the magnetic coordinates calculated
using equations 3 and 39 of Fraser-Smith (Rev Geophys, 1987). This differs
from the rest of the data that uses a CGM lookup table on a one degree
geographic grid.

A4: Partial data exists (missing latitudes) for numerous days. Note that
this anomaly is usually removed by the processing that creates the L4
data.

A5: PMCs are visible in the data. They typically appear in the northern
hemisphere from May through August, and in the southern hemisphere from
November through March. The location in the SNOE database is typically at
96.6 km, between 60 and 90 degrees latitude. Note that this is not
necessarily the actual location of a PMC, only where it appears in this
dataset.

============================================================================

APPENDIX_C.TXT

PURPOSE: Describe the SNOE orbit with respect to the southern 
	 auroral region

The SNOE spacecraft samples the southern auroral region during orbits 0
through 5 and 12 through 14 (inclusive). SNOE does not fly through the
southern auroral region on orbits 6 through 11.

This is due to the fact that the orbit does not take the spacecraft
poleward of -82.5 degrees.

============================================================================

APPENDIX_D.TXT

This file is a list of computers that the SNOE dataset is known to work
with. All processing has been done in the IDL language on various *nix
machines. 

The lines in this file are the output of the IDL command:
IDL> print, !version

The SNOE dataset has been decoded and viewed on the following systems:
{ x86 linux unix 5.4 Sep 25 2000      32      32}
{ x86 linux unix 5.3 Nov 11 1999}
{ x86 linux unix 5.2.1L Aug  2 1999}
{ sparc sunos unix 5.4 Sep 25 2000      64      64}
{ sparc sunos unix 5.4 Sep 25 2000      32      64}
{ sparc sunos unix 5.3 Nov 11 1999}
{ sparc sunos unix 5.2 Oct 30 1998}
{ sparc sunos unix 5.0.2 Aug 19 1997}