-
Notifications
You must be signed in to change notification settings - Fork 0
/
about_ace_page.html
207 lines (172 loc) · 7 KB
/
about_ace_page.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
<HTML>
<HEAD>
<TITLE>About ACE Monitoring </TITLE>
<!-- Changed by: Scott J. Wolk, 22-Apr-1998 -->
<META NAME="GENERATOR" CONTENT="Mozilla/3.0Gold (X11; I; SunOS 5.5 sun4m) [Netscape]">
</HEAD>
<BODY TEXT="#DDDDDD" BGCOLOR="#000000" LINK="#FF0000" VLINK="#FFFF22"
ALINK="#7500FF">
<center>
<H2>
About ACE Monitoring
</h2>
</center>
<br>
<br>
<a href="http://cxc.cfa.harvard.edu/acis/reb/OnRadiation.html"> ACIS Ops Response to Radiation Events</a><br />
<h3>The Science Operations Team has two proton monitoring systems.</h3>
<ol>
<li> Orbit Monitor:<br>
The fluence of ACE protons in the 115-195 keV energy range is
integrated over each Chandra orbit, while Chandra is above 70,000 km
geocentric distance. The fluence measurement is reset to 0 while
Chandra is below 70,000 km.
<p>
If the fluence exceeds a threshold, SOT and FOT members are alerted
via pagers and via email. The alert message provides the measured
fluence and the integrated time.
<p>
The latest ACE proton flux, and the integrated fluence, are on the
top line of the
Chandra snapshot </a>display (f_ACE and F_CRM respectively),
and on the SOT's <a href="http://cxc.harvard.edu/mta/ace.html">
ACE page</a>.
<p>
<!--- Regarding EPHIN data, our P4GM channel threshold in these OBC units is 118.08 cts/sample.
The E1300 threshold is 1318.56 cts/sample and the P41GM trigger is 100
cts/sample FYI. -->
<p>
ACE proton energy range: 130 - 214 keV
<p>
An open-ended series of thresholds,
at 1E9, 3E9, 9E9, 27E9, 81E9, 243E9 etc.
For each threshold, issue 3 alerts at 30 minute intervals,
then increase threshold to next level.
Reset orbit fluence to zero, and reset threshold to 1E9
at the end of each orbit.
<p>
<ul>
<li>Alert list:
<ul>
<li> sot_red_alert
</ul>
</ul>
Details of operation: see /proj/rac/ops/ACE/README on the HEAD LAN.
<HR>
<li> Two Hour Monitor:
<h4><font color=FF0000> A violation of this limit is more serious than the orbital limit
since it implies a similar flux in a shorter time scale.</h4> </font>
<p>
The fluence of ACE protons in the 115-195 keV energy range is
integrated as a runing average over each 2 hour period.
This is 24 measurments during each period. Bad measurments are
dropped and the average Flux particles/cm2-s-ster-MeV is calculated.
<p>
If the fluence exceeds a threshold, SOT and FOT members are alerted
via pagers and via email. The alert message provides the measured
fluence and the integrated time.
<p>
ACE proton energy range: 130 - 214 keV
<p>
Fluence threshold = 50,000 protons/cm2-s-ster-MeV average over a 2
hour window (3.6e8 protons/cm2-ster-MeV).
<br><br>
An ACE instrument swap occurred in February 2004. The FP6p (761-1220 keV)
channel stayed the same but the P3 channel (112-187 keV) changed somewhat.
Therefore we now alert first if the fluence derived from FP6p*36.0
is greater than 1.2e8 p/cm2-ster-MeV. An alert is also sent if the new
P3 channel (115-195 keV) exceeds 3.6e8 p/cm2-ster-MeV and P3/FP6f < 36.
<ul>
<li>Alert list:
<ul>
<li> sot_red_alert
</ul>
</ul>
Alert scheme: 1 alert. Once this alert
triggers it is disabled for 24-48 hours or until manually rearmed by the
MTA scientist.<br>
<hr>
<li> Kp Monitor:
<h4><font color=FF0000> A violation of this limit indicate the general
radiation state near the Earth is high.</h4> </font>
<p>
If the value of Kp (projected) exceeds the threshold a
yellow alert is generated, SOT and FOT members are alerted
via email and pager. The alert message provides the measured
Kp, current S/C configuration and comm schedule. The threshold is
variable on a matrix of time (by month) and configuration (grating and sim
position).
<p>
<ul>
<li>Alert list: sot_yellow_alert
</ul>
Alert scheme: 1 alerts, Once this alert
triggers it is disabled in 24 hours.<br>
<p>
The latest ACE proton flux, the integrated fluence, and Kp are on the
top line of the
<a href="http://cxc.harvard.edu/mta/Snapshot/snap.cgi?action=Latest">
Chandra snapshot </a> display (f_ACE, F_CRM and Kp respectively),
and on the SOT's <a href="http://asc.harvard.edu/mta/ace.html">
ACE page</a>.
<p>
<hr>
<li><a name="RADMON"> Chandra RADMON trigger levels</a>
<p>
RADMON will trigger SCS 107 (SI safing) if ANY of the following three
EPHIN channels exceeds the on-board threshold for 10 consecutive samples.
EPHIN samples are sent to the OBC each 65.6 seconds.
<pre>
AS OF DEC 09, 2008:
- No discrimination among electrons, protons, and nuclei will be made
- All four proton channels will show 0 counts
- All four electron channels will become combinations of electrons, protons
and nuclei (e.g. the new E150 will be E150 + P4GM + H4GM)
- The overall geometric factor will be change but will be constant (i.e. it
will not toggle between large and small)
- The safing channels will be E150, E1300, HRC MCP Total Rate with the
following thresholds:
E150 800000 counts/sample
E1300 1000 counts/sample
MCP Total 30 counts/sample (the relevant MSID is 2DETART)
The previous thresholds (now obsolete) were:
THRESHOLDS
LARGE Geom SMALL Geom
cts/cm^2-s-sr cts/sample cts/sample
------------- ---------- ----------
E1300 (electrons, 2.64 - 6.18 MeV): 10.0 1318.56 78.72
P4GM (protons, 5.0 - 8.3 MeV): 300.0 3542.4 3542.4
P41GM (protons, 41 - 53 MeV): 8.47 100.0 100.0
</pre>
<HR>
<B>Other links:</B>
<ol>
<li> <B> Travel Time of CME vs. Initial Speed.</b>- this is a link to
a plot which proports to be able to calculate the travel time of a CME<P>
<li> <B> Costello Geomagnetic Activity Index</b> - The Costello
home page withe full details about this predictive index <P>
<li> <B> Magnetospheric Specification Model Latest MSM Output</b><P>
<li> <B> 3-day archive of the latest ACE data.</b><P>
<li> <B> Latest orbital fluence when CHANDRA is above 70kkm. </b><P>
<li> <B> History of fluence when CHANDRA has been above 70kkm. </b><P>
<li> <B>Fluence on ACIS per orbit (current.dat)</B> - This is the
fluence only when ACIS is in the Focal plane, corrected for grating
blockage. A combination of ACE/ACIS fluence files with the
data presented in scientific notation so that it is easier to read.
<p>
<li> <B>Archival fluence in the ACE P3 channel (proton.dat)</B> -
this feeds off my archive file and produces a file that
is again easier to read. Moreover, it tallies the fluence in the ACE P3
channel to date to the extent of my archive. I intend to have my fluence
scripts backtrap and determine the fluence for each orbit since
SSD-opening. Once that is done, this file will provide us with the
observed ACE proton fluence for each orbit and for the mission to date
(which we can compare against our budget of 2E10).
<p>
<li> <B>Archival fluence of all ACE channels (all.dat)</B> - same as 2 but does it for all ACE channels that we monitor.
<p>
<li> <B> About our ACE Monitoring and Alerts.</b><P>
</ol>
Last updated: 04/19/04
</body>
</html>