About using MSSP-1 interface

This interface allows users to create one, or a series of,
spectral plots of energetic proton or alpha particle fluxes
from one or more data sources.

Users may scan the available data as time series plots to
find intervals of special interest by clicking on the desired
row of the interface's "Data Source, Plot/List" column.  This
yields an OMNIWeb-Plus plot/list interface for the selected
data set.

Users specify for which data set(s) they want to generate
spectral plots.

Users specify whether to generate spectral plots for protons or alpha 
particles.
(The Voyager/LECP ion fluxes are considered protons for this purpose.)

Users specify the time span over which the fluxes to be shown in the
first spectral plot will be created.  Note that this may be to hourly
or daily resolution.  Note also that the end hour or day specified will
be included in the flux averaging.


Data are held at various time resolutions for various data sets.
Users may create, on the fly, spectral plots for fluxes at
(a) the lower of (a1) hourly resolution or (a2) the resolution
of the lowest-resolution data set selected for display, or at
(b) any lower time resolution.
The averaging used in these flux determinations is discussed below.  
To create a plot, after having specified which species and data 
sets, the user specifies a start time and a stop time.  For 
plots spanning integral numbers of whole days, users should use 
the format YYYYMMDD in their time specification, otherwise they 
should use YYYYMMDDHH.

The horizontal error bars show energy bins, while the vertical
error bars show standard deviations in flux averages (see
discussion of averaging below).  Since we plot spectra on a
log-log scale, we fix a minimum flux value for plotting at 1.0E-06.
However, computed average values of fluxes (even if<1.0E-6) and
their standard deviations are listed via the "Listing of spectral
function points ..." option on the plot pages.

[In the flux vs. time plots reached with the "Data source, Plot/List" 
links on this MSSP page, the minimum flux plotted is either 1.E-5 or
1.E-6 according to which data set is involved.]
  
Having created a first plot, a user may generate similar
plots for contiguous intervals of the same duration by clicking
on the "Previous" or "Next" button of the spectral plot page.
Clicking on the "Home" button returns the user to the default
version of the interface page.

Users may ensure that all plots of a given series of plots
have a common Y-axis range by specifying a minimum and
maximum flux in the "Y scale range" option near the bottom
of the main interface page.  Otherwise IDL will fix the scale
range for each plot according to the data range on that plot.
(Bottom of the range should not be less than 1.0e-6.)

The page with the spectral plot offers the option to list digital
values associated with the plots, including energy bin minimum
and maximum values and geometric means (where spectral points
are plotted), the average fluxes and their standard deviations, 
and the numbers of individual fluxes in the flux averages.

The spectral points for each source for each output plot are
fitted to a power law, F = A * E ** b, where F and E are flux
and energy, and where A and b are the fit parameters.
A and b are determined by a linear least squares fit to
the relation Log(F) = Log(A) + b * Log(E).
The A and b values are also given on the digital output page.

Note that users may specify the energy range over which to include
data in plots and fits by using the "Enter energy range..." option
near the bottom of the interface page.  If this option is not
specified, the plot will span the minimum to maximum energy bins
of any of the data sets selected.

The interface page's "Advanced plot selections" allow users
control of the appearance of the output spectral plots.

Computing the lower resolution fluxes -

Ideally, one should determine a long-term flux using the total
number of relevant counts over the interval and the total 
time of counting over the interval.  However, since at least 
some of the data sets we hope to support with this interface 
provide fluxes and flux uncertainties but not all the counts 
and observing times for each such flux, we cannot determine 
longer term fluxes this way.  Accordingly, we take simple 
linear flux averages and their standard deviations to 
determine longer term fluxes and their uncertainties.

Note on plotted vertical error bars

To avoid the down legs of vertical error bars frequently
reaching to the bottom of the plot on our log scale, we fix the
bottom of the vertical error bar at F = Fmin = <F>**2/(<F>+sigma).
Thus the error bar goes up from Fmin to Fmax (=<F>+sigma),
with <F> half way up the error bar on the log scale.  We've used
Fmax/<F> = <F>/Fmin.  The numeric value of the linearly computed 
standard deviation, sigma, is given via the "Listing of spectral 
function points..." option on the plot page.
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This interface and its capabilities were developed by Natalia
Papitashvili and Joe King as part of the Virtual Energetic Particle
Observatory (VEPO) activity, John F. Cooper, Principal Investigator,
carried out within NASA/Goddard's Space Physics Data Facility.
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