An inverse chronological list of ACE Real-Time Solar Wind Announcements
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October, 2012 New Pointing for the ACE Satellite to Improve SWEPAM data
The ACE satellite pointing is now being kept at larger angles with respect to the Sun in order to enable the SWEPAM instrument to expose more responsive channel electron multipliers (CEMs) to the solar wind. Prior to this time, the CEMs that had been exposed had done so for the life of the mission and they had degraded to where reliable solar wind parameters had become difficult to extract. The most significant impact will be improved, higher density values. In the weekly ACE reports that are available from the ACE Science the following description is available:
“The project has accepted the SWEPAM team proposal to keep the spacecraftat larger sun angles with weekly attitude maneuvers. The SWEPAM-Ion
instrument has a series of channel electron multipliers (CEMs) andlarger sun angles allows more responsive CEMs to measure the solar wind.
The maximum sun angle follows the Sun-Earth-Vehicle angle (SEV). TheSEV angle is determined by the size/shape of the orbit around L1. Whenthe spacecraft antenna ispointeddirectly towards earth, thespacecraft's sun angle will be equal to the Sun-Earth-Vehicle angle. With weekly maneuvers, the average sun angle can be kept 4-8deg morethan the SEV angle. This results in the spacecraft antenna aspect anglebeing kept between 5 and 9 degrees and neverpointingdirectly back atearth. For reference, the SWEPAM team prefers sun angles above 13degrees. With the current size of the L1 orbit, the sun angle will beabove 13 degrees for ~45% of the time.”
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October 19, 2010 EPAM Energy Range Now Corrected on SWPCWebsite
Based on the advice of the ACE EPAM science team, the EPAM FP6p proton channel energy range shown in headerswas corrected from 761-1220 keV to 795-1193 keV.
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June 1, 2006 ACE RTSW SWEPAM Data Improvement
The ACE RTSW SWEPAM data processing was updated at 0000 UTC June 1, 2006. This change will result in improved solar wind parameters (speed, density, and temperature) that more closely match ACE Science Center data.
ACE RTSW MAG, EPAM, and SIS data are unaffected.
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May 5, 2006 ACE RTSW SWEPAM Data Improvement
At 0000 UTC on June 1, 2006, the ACE RTSW SWEPAM data processingwill be updated. This change will result in improved solar wind parameters (speed, density, and temperature) that more closely match ACE Science Center data. The most significant impact will be higher RTSW density values during low-speed, low-density solar wind conditions. ACE RTSW MAG, EPAM, and SIS data are unaffected.
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May 15, 2006 ACE RTSW Data Timing Problem Resolved
From 1300UT May 12 to 1300 UT May 13 there was a problem in the SEC ACE RTSW data. Values were correct but the associated time tags were about 15 minutes earlier than the actual reading.
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April 3, 2006 Termination of ACE Solar Wind Data
A comment period for the proposed NWS Termination of ACE Solar Wind Data was April 3 - May 18, 2006
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May 19, 2005 SIS DATA noise
There is currently noise in the SIS RTSW proton rates. The SIS team is investigating the cause and expects it to be corrected
in the next few days.
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August 24, 2004 ACE MAG Data Processing Change
ACE MAG data processing was updated at 0000 UTC on 24 August, 2004. This update should result in improved RTSW magnetic field values that
more closely match ACE Science Center data.
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February 4, 2004 EPAMData Switched from LEMS30 to LEMS120
Real-time proton data from the EPAM LEMS30 instrument has been replaced with similar proton data from the LEMS120 sensor. The new proton channels cover the following energy ranges: 47-68 keV, 115-195 keV, 310-580 keV, and 1.06-1.9 MeV. Previous real-time electron (38-53, 175-315 keV)and proton (0.761-1.22 MeV) data from the EPAM CA60 telescope remainunchanged. Plots and Data Lists of 5-minute and 1-hour averaged data werebackfilled to January 29, 2004.
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January 15, 2004 SEC Planning to Switch EPAMSensors
SEC is proceeding to switch the ACE RTSW EPAM proton data processing to another sensor. The operational switch over to the new sensor data hasbeen reschedule to February 4, 2004. It is anticipated that the following proton energy ranges will be available: 47-68 keV (P1'), 115-195 keV (P3'), 321-587 keV (P5'), and 1060-1900 keV (P7').
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November 12, 2003 EPAM Data Problems Continue
As a result of the last two weeks of high solar activity several of the RTSWEPAM proton channels have become abnormally high and have shown excessivenoise. As a result the data from the 65-112 keV (P2), 112-187 keV (P3), and310-50 keV (P5) energy channels have been removed from the real-time plotsand lists. The 1060-1910 keV (P7) channel remains but has also begun toshow noise. The 761-1220 (W1) proton channel and electron channels, beingfrom another EPAM sensor, have been unaffected. SEC is investigating theswitch to another EPAM proton sensor for its RTSW data stream.
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November 3, 2003 ACE EPAM Data Problems
On October 29 the ACE EPAM 65-112 keV (P2) and 112-187 keV (P3) energy channels became spuriously high following the onset of a large solar energetic particle event and have not returned to nominal values. In addition, the 310-580 keV (P5) channel became elevated and erratic onNovember 1 and 2 during a second solar energetic particle event. The P5channel appears to have recovered; however, this does not precludesimilar problems in the future. The EPAM instrument team and SEC areinvestigating the cause of these problems and a possible cure. Look for more information here as information becomes available.
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March 18, 2001 ACE EPAM Data Processing Changed
ACE EPAM data processing was updated. The visible change was replacingthe noisy Proton 47 to 65 keV data with the 65 to 112 keV data in EPAM lists and plots.
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March 5, 2002 EPAM Data Processing Change
On March 18, 2002 EPAM data processing will be updated. On data lists,the header line changes to show the new energy range for the first Protonchannel. On data plots, the legend changes.
EPAM data processing update:
In late November and early December 2001 the P1 channel (47 to 65 keV) data increased during an energetic particle event (small radiation storm) and never returned to nominal levels. The channel became "noisy" and after monitoring for a few weeks the decision was made to replace theP1 channel with the P2 channel (65 to 112 keV) data, the next higher energychannel within the same detector on EPAM.
During the later part of December 2001 the P5 channel (310 to 580 keV) showed anomalous periods of increased particle flux. The instrument PI from JHU/APL determined that when the detector was pointed in the general direction of the sun, the sector pointed toward the sun showed large increases in particle flux. This is believed to be due to solar contamination and only happens during limited times between each set ofspacecraft maneuvers. The decision was to change the processing of all channels from this detector to eliminate the solar noise problem. A third problem was induced by the solar noise problem: Whenever the P5 channel became noisy the P1 and P3 data would drop out. The cause of the drop out was a programming filter designed to eliminate "bad" data. Since not all of the data were "bad", only the sunward directed sector, a decision was made to eliminate all data from the sunward sector. Problems two and three were solved by the removal of the data from the sunward sectors for all channels. The only impact from removing the sunward sector data is larger fluctuations in the data when the flux is near background levels.
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January 25, 2002 EPAMP1 Channel Data Update
EPAM lowest energy channel (P1) 47-65 keV data are suspect since late November. This channel will bereplaced by late February. Possible cures are being investigated by the instrument team and SEC.
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December 20, 2001 ACE EPAM P1 Channel Data Suspect
Data from the ACE EPAM lowest energy channel (P1) 47-65 keV are suspect since late November, following the large proton event that ended on the 24th. The cause and possible cure are being investigated by the instrument team and SEC. Look for further messages here as more information becomes available.
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July 26, 2000 ACE EPAM Data Lists Header Line Changes
The ACE EPAM 5-min data lists, had incorrect Differential Proton Flux ranges. The header lines were changed beginning 26 July 2000.
CORRECTED:
# -- Differential Flux --------------------------
# UT Date Time ------------------ Protons keV ----------------
# YR MO DA HHMM 47-65 112-187 310-580 761-1220 1060-1910
INCORRECT:
# -- Differential Flux --------------------------
# UT Date Time ------------------ Protons keV ----------------
# YR MO DA HHMM 56-78 130-214 337-594 761-1220 1073-1802
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July 30, 1998 ACE Hourly Averaged data
SEC creates monthly files of hourly averaged data from eachof the ACE instruments. The files are updated every 3 hoursbeginning at 0010UT. The current month's files are recreatedat each run. The previous month's files is created for the last time on the first day of the new month.
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July 28, 1998 EPAMAlgorithm Updated
The EPAM 761-1220 MeV Proton algorithm was adjusted at 7/28 1600UT. There was factor of 3 decrease which matches expected values.
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April 3, 1998 Update on Quality of ACE RTSWData Sets
MAG: All data nominal
SWEPAM: All data nominal. When the velocity of the solar wind falls tolow values the current algorithm will often set a flag indicating aproblem exists. SEC flags the data in the data base and does not plotthe data on the web site. The end result is a number of missing data atthe one minute cadence.
EPAM: All differential flux channels nominal, except for W1. Thischannel is impacted by above normal temperatures on ACE. APL is lookingat this issue. The only impact is the anisotropy index is not valid. The energy range of this channel is covered by the other existingchannels.
SIS: Both integral channels nominal. Integral flux is at backgrounduntil a large event is detected
Update on tracking:
RAL, NASA, and AFSCN are fully operational. CRL is down for antennarepair and is expected up in two months. AFSCN has added extra trackingcoverage during the time period normally covered by CRL. Occasionallyshort dropouts occur during a tracking pass, usually due to datatransmission problems. Bad data records are received during sometracking passes. Software eliminates most of the problem data, but notall problem data.
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2/9/98 - A software solution to the SWEPAM instrument problem was installed on Feb 5. Density, Bulk Speed and Ion Temperature data now appear nominal.
2/2/98 - The Spacecraft Location files will not be available until March.
2/2/98 - The Magnetometer data is still in spacecraft coordinates (RTN). Will not be switched to GSM coordinates in March.
2/2/98 - Lists of hourly average will not be available until March.
2/2/98 - The limits shown below for Mag component magnitude, SWEPAM bulk speed, SWEPAM X vector velocity, and Xgse location were corrected 2/2/98.
1/21/98 - Operational ACE data lists began running.
