Subject: : Fact Book on Spikes in the LDEF IDE data set

From : John Oliver

Date : 14 November, 2023

## Introduction

The LDEF IDE data set contains a number of distinctive events. Perhaps
the most prominent are the Multiple-Orbit Event Sequences (MOES) and the
"spikes". This report presents the basic observational information for
the spikes, as well as some discussion of specific spike
characteristics.

## What is a Spike?

For the purpose of this study, a "spike" was defined as more than 10
impacts on high sensitivity sensors[^1] in a single 100 IDE tick
(approximately 20 minutes) wide bin. Spikes are distinguished from MOES
by being isolated from any other significant impact activity at the same
orbital phase over an interval of ±8 orbits (about ±one-half day). An
example of an MOES and a spike can be seen in Figure
1.![](media/image1.emf){width="5.346527777777778in"
height="2.6777777777777776in"}

Spikes were identified by a visual scan of the IDE data set using
IDEview with the ticks/bin parameter set to 100. The data set scanned
has had the buffer overflow events added (see TB930613A). Conversions to
UT from IDE ticks have been based on the IDE clock calibration given in
Oliver et al. A total of thirteen spikes have been identified ( see
Figure 2.).

![](media/image2.emf){width="0.9305555555555556in"
height="1.4340277777777777in"}![](media/image3.emf){width="0.9305555555555556in"
height="1.4131944444444444in"}![](media/image4.emf){width="0.9402777777777778in"
height="1.4131944444444444in"}![](media/image5.emf){width="0.9305555555555556in"
height="1.4222222222222223in"}![](media/image6.emf){width="0.9416666666666667in"
height="1.4131944444444444in"}![](media/image7.emf){width="0.9305555555555556in"
height="1.4222222222222223in"}![](media/image8.emf){width="0.9305555555555556in"
height="1.4222222222222223in"}![](media/image9.emf){width="0.9305555555555556in"
height="1.4131944444444444in"}![](media/image10.emf){width="0.9305555555555556in"
height="1.4131944444444444in"}![](media/image11.emf){width="0.9305555555555556in"
height="1.4118055555555555in"}![](media/image12.emf){width="0.9402777777777778in"
height="1.4222222222222223in"}![](media/image13.emf){width="0.93125in"
height="1.4131944444444444in"}![](media/image14.emf)\
Figure 2. \"Seismograph\" plots of the spikes. Each plot represents 20
minutes of time. Plots can be identified by IDE clock tick and day
number. Note that D155s is marked as 156 here.

## Basic Data:

The basic data for these spikes are summarized in Tables 1 and 2. The
spikes have been labeled by a "D" number based on the number of days
following LDEF deploy (which occurred April 7, 1984) and a suffix "s".

  ---- ------- -- -- -- --------- --------- ------------ --------- ------- ----- ------ -------- ---- ------ ---- ----- ------ ----- ----- ----- ---- ----- ----------- ---------- ---- ------ -------- ---- ------ ---- ---- ------ ---- ---- ----- --- ---- ---------- --------- -- --
                        start                            end                            0.4                                                                                                    1.0                                                                                    
                                                                                        micron                                                                                                 micron                                                                                 

  \#   Name             (ticks)                          (ticks)   bifur ?              N                    S                 E                 U                      Sum                    N                    S                E               U                   Sum          

  1    D002S            13330                            13352                          14                   0                 14                17                     45                                                           0                                   0            

  2    D010S            66692                            66712                          70                   0                 60                3                      133                    3                                     2                                   5            

  3    D016S            105937                           106012    x                    95                   0                 8                 35                     138                    4                                     1               4                   9            

  4    D063S            421297                           421316    x                    0                    0                 134               0                      134                                                          7                                   7            

  5    D079S            523170                           523205    x                    54                   0                 83                0                      137                    6                                     11                                  17           

  6    D110S            725485                           725555    x                    138                  0                 8                 1                      147                    21                                                                        21           

  7    D155S            1028731                          1028802   x                    77                   0                 7                 18                     102                    3                                                     2                   5            

  8    D158S            1047699                          1047711                        10                   0                 35                0                      45                     1                                     5                                   6            

  9    D162S            1072680                          1072701                        0                    4                 19                0                      23                                                           2                                   2            

  10   D227S            1498320                          1498332                        1                    0                 19                0                      20                                                                                               0            

  11   D250S            1654051                          1654095   x                    151                  0                 36                0                      187                    21                                    1                                   22           

  12   D264S            1744342                          1744391   x                    63                   0                 40                0                      103                    6                                     2                                   8            

  13   D286S            1887719                          1887848                        0                    0                 20                0                      20                                                           2                                   2            

                                                                   Sums                 673                  4                 483               74                     **1234**               65                   0                33              6                   **104**      

                                  Total                                          2467                 3029              4540               380              **10416**                   1081                 1200             1542             155            **3978**                
                                  Impacts                                                                                                                                                                                                                                             
                                  on Panel:                                                                                                                                                                                                                                           

                                            Percentage                     27%                   0%               11%                19%              12%                          6%                   0%               2%               4%             3%                           
                                            in spikes:                                                                                                                                                                                                                                
  ---- ------- -- -- -- --------- --------- ------------ --------- ------- ----- ------ -------- ---- ------ ---- ----- ------ ----- ----- ----- ---- ----- ----------- ---------- ---- ------ -------- ---- ------ ---- ---- ------ ---- ---- ----- --- ---- ---------- --------- -- --

Table 1. Primary data for spikes. The starting and ending ticks
represent the extreme range for the **N**orth, **S**outh, **E**ast, and
**U**p (space) surfaces. Spike which have an apparent bifurcated
appearance are marked in the bifur ? column. The total number of impacts
and the sum are given for the 0.4 micron dielectric thickness (effective
particle diameter \> 0.2 micron) and 1.0 micron dielectric thickness
(effective particle diameter \> 0.4 micron) detectors. Also tabulated
are the total number of impacts on the specified surfaces over the 346
day high time-resolution IDE data recording period, and the fraction of
those impacts occurring in spikes. Note: These are raw counts. To
correct for nominal effective area, the U (space) 0.4 entries must be
multiplied by 1.3, and the U 1.0 entries must be multiplied by 1.5.

  ---- ------- --------- ---------- --------- ---- ---- ---------- ---- ---- --------- --- --- ---------- --- ---
               Tcenter              0.4                                      1.0                              
                                    micron                                   micron                           

               leading   trailing   leading             trailing             leading           trailing       

  \#   Name    (ticks)   (ticks)    N         E    U    N          E    U    N         E   U   N          E   U

  3    D016S   105954    105997     52        7    22   43         1    13   3         1   1   1          0   3

  4    D063S   421299    421309     0         49   0    0          85   0    0         0   0   0          7   0

  5    D079S   523175    523198     24        39   0    30         44   0    5         7   0   0          4   1

  6    D110S   725487    725552     69        7    0    69         1    1    12        0   0   9          0   0

  7    D155S   1028738   1028797    30        5    9    47         2    9    0         0   1   3          0   1

  11   D250S   1654056   1654092    108       28   0    43         8    0    17        1   0   4          0   0

  12   D264S   1744346   1744389    39        30   0    24         10   0    6         1   0   0          1   0
  ---- ------- --------- ---------- --------- ---- ---- ---------- ---- ---- --------- --- --- ---------- --- ---

> Table 2. Additional primary data for bifurcated spikes. The
> approximate time of the 1st and 2nd peaks of bifurcated spikes are
> tabulated as well as the number of impacts in each peak. Note: These
> are raw counts. To correct for nominal effective area, the U (space)
> 0.4 entries must be multiplied by 1.3, and the U 1.0 entries must be
> multiplied by 1.5.

  ---- ------- --------------- --------------- --------- ---------- ----------
                                                         Initial    

               UT Start        UT End          Dur (min) DaD        DoY

  1    D002S   4/9/84 14:46    4/9/84 14:50    4.8       2.0214     100.6154

  2    D010S   4/17/84 16:58   4/17/84 17:02   4.4       10.1131    108.7072

  3    D016S   4/23/84 15:47   4/23/84 16:04   16.4      16.0642    114.6583

  4    D063S   6/10/84 11:30   6/10/84 11:34   4.1       63.8852    162.4792

  5    D079S   6/25/84 22:15   6/25/84 22:22   7.6       79.3332    177.9272

  6    D110S   7/26/84 14:32   7/26/84 14:48   15.3      110.0121   208.6061

  7    D155S   9/10/84 14:09   9/10/84 14:25   15.5      155.9961   254.5901

  8    D158S   9/13/84 11:11   9/13/84 11:14   2.6       158.8724   257.4664

  9    D162S   9/17/84 6:06    9/17/84 6:11    4.6       162.6605   261.2545

  10   D227S   11/20/84 19:09  11/20/84 19:12  2.6       227.2043   325.7983

  11   D250S   12/14/84 9:55   12/14/84 10:04  9.6       250.8192   349.4133

  12   D264S   12/28/84 2:31   12/28/84 2:41   10.7      264.5109   363.1049

  13   D286S   1/18/85 20:19   1/18/85 20:47   28.2      286.2525   384.8465
  ---- ------- --------------- --------------- --------- ---------- ----------

Table 3. Derived data for spikes. The times are calculated based on the
IDE clock calibration of Oliver, et al. The start and end times (and
durations) refer to the stating and ending ticks of Table 1. Also
tabulated are the Day after Deploy (DaD) and Day of Year 1984 (DoY) for
the beginning of each spike.

Each spike is illustrated in Appendix A. Two figures are displayed for
each spike. The first covers 20 minutes of time, the second covers eight
LDEF orbits or about 12.5 hours. Scales marked in LDEF orbits are shown
on the 8 orbit figures.

## Spike Locations in Time and Space

During our meeting we discussed the apparent concentration of spike
activity on the north surface of LDEF, and over the northern hemisphere
and terrestrial longitudes from 120° to 180° east. While examining the
event times of the bifurcated spikes, I noticed an apparent
concentration in time as well. Appendix B contains plots of Right
Ascension versus time and terrestrial latitude versus terrestrial
longitude for the north, east, and space LDEF IDE data sets. The RA vs.
time plots have been overlaid with a grid fitting the ephemeris[^2]\
DaD (days after deploy)=1.167 + 15.541\*epoch; epoch ranging from 0 to
22.

It is apparent that many of the spikes (which have been labeled on these
plots) fall on, or close to, the indicated epochs.

## Appendix A:

\"Seismograph\" plots of spikes. These plots were generated by IDEview.
Two figures are displayed for each spike. The first covers 20 minutes of
time, the second covers eight LDEF orbits or about 12.5 hours. Scales
marked in LDEF orbits are shown on the 8 orbit figures.

## Appendix B:

Plots of Right Ascension versus time and terrestrial latitude versus
terrestrial longitude for the north, east, and space LDEF IDE data sets.
These plots were generated with Stanford Graphics.

**Appendix C:**

A complete tabulation of the data events for the spikes. The columns are
as follows:

Data Point Each IDE clock tick during which one or more impacts occurred
is a data point.

Tick IDE clock tick (each tick is approximately 13.1 seconds).

DaD Days after LDEF DEploy, April 7, 1984.

DoY Day of Year 1984 (may exceed 365 since data run over in to 1985).

P LDEF/IDE surface: N4 = north 0.4, N1 = north 1.0, etc.

hits number of impacts counted.

RA(hr) Geocentric Right Ascension of LDEF, in hours.

RA(deg) Geocentric Right Ascension of LDEF, in degrees.

Dec Geocentric declination of LDEF, in degrees.

subL sub-LDEF terrestrial longitude, in degrees.

L-Lsun LDEF ecliptic longitude - ecliptic longitude of sun, in degrees.

L LDEF ecliptic longitude, in degrees.

B LDEF ecliptic latitude, in degrees.

LES LDEF-Earth-Sun central angle, in degrees.

Lsun ecliptic longitude of sun, in degrees.

Event Event designation (\"D\" number). Based on DaD at start of event.

L-Max dRA difference between Right Ascensions of LDEF and Solar Max
satellite, in degrees.

L-E-Max LDEF-Earth-Solar Max central angle, in degrees.

[^1]: in practice, on the north, space, and leading edge.

[^2]: This ephemeris was generated by a linear least squares fit to the
    starting point epochs of the bifurcated spikes.