DOI: 10.48322/9pz0-sj43
title: PSP Solar Wind Electrons Alphas and Protons (SWEAP) SPAN-A Electron Energy Spectra, Level 2 (L2), 1.74 s Data

description: SPAN-E Level 2 ELectron Energy Spectra Data
-------------------------------------------

File Naming Format: psp_swp_spa_sf1_L2_32E_YYYYMMDD_v01.cdf

The SF1 product is an energy spectrum produced on the spacecraft by summing over the Theta and Phi directions. The units are differential energy flux and eV. The sample filename above includes 32 Energies.

The larger Theta angles (deflection angles) are artificially enhanced in the "sf1" energy spectra data products due to the method of spectra production on the SPAN-E instrument (straight summing). Thus, SF1 energy spectra are not recommended for rigid statistical analysis.

Parker Solar Probe SWEAP Solar Probe Analyzer, SPAN, Electron Data Release Notes
--------------------------------------------------------------------------------

November 19, 2019 Initial Data Release
--------------------------------------

Overview of Measurements
------------------------

The SWEAP team is pleased to release the data from Encounter 1 and Encounter 2. The files contain data from the time range October 31, 2018 - June 18, 2019.

The prime mission of Parker Solar Probe is to take data when within 0.25 AU of the Sun during its orbit. However, there has been some extended campaign measurements outside of this distance. The data are available for those days that are within 0.25 AU as well as those days when the instruments were operational outside of 0.25 AU.

Each SWEAP data file includes a set of a particular type of measurements over a single observing day. Measurements are provided in Common Data Format (CDF), a self-documenting data framework for which convenient open source tools exist across most scientific computing platforms. Users are strongly encouraged to consult the global metadata in each file, and the metadata that are linked to each variable. The metadata includes comprehensive listings of relevant information, including units, coordinate systems, qualitative descriptions, measurement uncertainties, methodologies, links to further documentation, and so forth.

SPAN-E Level 2 Version 01 Release Notes
---------------------------------------

The SPAN-Ae and SPAN-B instruments together have fields of view covering >90% of the sky; major obstructions to the FOV include the spacecraft heat shield and other intrusions by spacecraft components. Each individual SPAN-E has FOV of ±60° in Theta and 240° in Phi. The rotation matrices to convert into the spacecraft frame can be found in the individual CDF files, or in the instrument paper.

This data set covers all periods for which the instrument was turned on and taking data in the solar wind in ion mode. This includes maneuvers affecting the spacecraft attitude and orientation. Measurements taken by SPAN-B when the spacecraft is pointed away from the sun are taken in sunlight.

The data quality flags for the SPAN data can be found in the CDF files as: QUALITY_FLAG (0=good, 1=bad)

General Remarks for Version 01 Data
-----------------------------------

Users interested in field-aligned electrons should take care regarding potential blockages from the heat shield when B is near radial, especially in SPAN-Ae. Artificial reductions in strahl width can result.

Due to the relatively high electron temperature in the inner heliosphere, many secondary electrons are generated from spacecraft and instrument surfaces. As a result, electron measurements in this release below 30 eV are not advised for scientific analysis.

The fields of view in SPAN-Ae and SPAN-B have many intrusions by the spacecraft, and erroneous pixels discovered in analysis, in particular near the edges of the FOV, should be viewed with skepticism. Details on FOV intrusion are found in the instrument paper, forthcoming, or by contacting the SPAN-E instrument scientist.

The instrument mechanical attentuators are engaged during the eight days around perihelia 1 and perihelia 2, which results in a factor of about 10 reduction of the total electron flux into the instrument. During these eight days, halo electron measurements are artificially enhanced in the L2 products as a result of the reduced instrument geometric factor and subsequent ground corrections.

A general note for Encounter 1 and Encounter 2 data: a miscalculation in the deflection tables loaded to both SPAN-Ae and SPAN-B resulted in over-deflection of the outermost Theta angles during these encounters. As such, pixels at large Thetas should be ignored. This error was corrected by a table upload prior to Encounter 3.

Lastly, when viewing time gaps in the SPAN-E measurements, be advised that the first data point produced by the instrument after a power-on is the maximum value permitted by internal instrument counters. Therefore, the first data point after powerup is erroneous and should be discarded, as indicated by quality flags.

SPAN-E Encounter 1 Remarks
--------------------------

SPAN-E operated nominally for the majority of the first encounter. Exceptions to this include: a few instances of corrupted, higher-energy sweep tables, and an instrument commanding error for the two hours surrounding perihelion 1. These and other instrument diagnostic tests are indicated with the QUALITY_FLAG variable in the CDFs.

The mechanical attentuator was engaged for the 8 days around perihelion 1: as a result the microchannel plate, MCP, noise due to thermal effects and cosmic rays are artificially enhanced and are particularly obvious at higher energies. Exercise caution with this data release if looking for halo electrons when the mechanical attenuator is engaged.

SPAN-E Cruise Phase Remarks
---------------------------

The cruise mode rates of SPAN-E are greatly reduced compared to the encounter mode rates. When the PSP spacecraft is in a communications slew, the SPAN-B instrument occasionally reaches its maximum allowable operating temperature and is powered off by SWEM.

Timing for the SF1 products in cruise phase is not corrected in v01, and thus it is not advised to use the data at this time for scientific analysis. The typical return of SF0 products is one spectrum out of every 32 survey spectra is returned every 15 minutes or so. One out of every four 27.75 s SF1 spectra is produced every 111 s.

SPAN-E Encounter 2 Remarks
--------------------------

SPAN-E operated nominally for the majority of the second encounter. Exceptions include instrument diagnostic and health checks and a few instances of corrupted high-energy sweep tables. These tests and corrupted table loads are indicated with the QUALITY_FLAG parameter.

The mechanical attentuator was engaged for the 8 days around perihelion 2: as a result the MCP noise due to thermal effects and cosmic rays are artificially enhanced and are particularly obvious at higher energies. Exercise caution in this data release if looking for halo electrons when the mechanical attenuator is engaged.

Parker Solar Probe SWEAP Rules of the Road
------------------------------------------

As part of the development of collaboration with the broader Heliophysics community, the mission has drafted a "Rules of the Road" to govern how PSP instrument data are to be used.

* 1) Users should consult with the PI to discuss the appropriate use of instrument data or model results and to ensure that the users are accessing the most recently available versions of the data and of the analysis routines. Instrument team Science Operations Centers, SOCs, and/or Virtual Observatories, VOs, should facilitate this process serving as the contact point between PI and users in most cases.

* 2) Users should heed the caveats of investigators to the interpretations and limitations of data or model results. Investigators supplying data or models may insist that such caveats be published. Data and model version numbers should also be specified.

* 3) Browse products, Quicklook, and Planning data are not intended for science analysis or publication and should not be used for those purposes without consent of the PI.

* 4) Users should acknowledge the sources of data used in all publications, presentations, and reports: "We acknowledge the NASA Parker Solar Probe Mission and the SWEAP team led by J. Kasper for use of data.".

* 5) Users are encouraged to provide the PI a copy of each manuscript that uses the PI data prior to submission of that manuscript for consideration of publication. On publication, the citation should be transmitted to the PI and any other providers of data.