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[vsnet-grb 395] Proposed additions to HETE Notices
TO: All GCN Sites 27 Mar 02
RE: Additions to HETE e-mail Notices and socket packets
A QUESTION TO GCN RECIPIENTS:
Several changes to the HETE email & socket packet formats are described below.
The question is: Are any of these changes going to disrupt your operations?
Specifically:
1) For email sites: Do you have hardwired parsing programs for the email
format that would break if extra "token: value" lines appear in the email
Notices?
2) For socket sites: Will any of the extra items in the socket packets
cause problems?
YOUR REPLY PLEASE:
Please reply if this is a problem; and include a description of how you are
processing the current formats and how this would cause a problem.
The explanation is important, because there may be alternative ways
to accomplish these additions to the format without breaking your operations.
This is important because a significant fraction of the community has asked
for these changes (at the Woods Hole town meeting).
Please reply quickly -- week to 10 days.
[Fear not; if there are problems with some sites, there can be adjustements
made to accomplish both group's needs.]
INTRO:
As per "town meeting" discussions and conclusions at the Woods Hole workshop,
several items will be added to the HETE messages (socket packet & email).
The changes are: 1) Lightcurve & image signal/noise rations, 2) s/c longitude,
and 3) ecliptic coordinates.
1) LIGHTCURVE and IMAGE SIG/NOISE RATIOS:
The signal/noise ratio values for the x & y light curve and the image
x & y location values from the WXM have been added. They appear in slot 38
in the socket packet format (remember counting is 0-39, not 1-40).
There are 4 values, 1 byte each, and they are:
WXM_X_LC_SN in the most significant byte,
WXM_Y_LC_SN in the next most significant byte,
WXM_X_IMAGE_SN in the third most significant byte, and
WXM_Y_IMAGE_SN in the least significant byte.
And for the email format, see the attached example below
for the TOKENs and the format.
WXM_X_LC_SN & WXM_Y_LC_SN describe the signal-to-noise of the excess
over background in the WXM light curve (LC) in each of the two modules (X & Y).
The WXM light curve is obtained by summing the data over all position bins
at 320ms time resolution. The flight software chooses background and
burst time intervals, and performs a standard background subtraction
in each detector. The resulting net signals are divided by their respective
root-variances, to yield the quantities reported here.
Note that WXM_*_LC_SN are not directly related to trigger SNR,
since the trigger operates on 80ms resolution data, and may in fact
come from FREGATE data rather than from WXM data. The light-curve SNR
is designed measure the overall signal-to-noise in the actual data used
to obtain the location, so as to complement WXM_*_IMAGE_SN.
The two values stored in the packet are in units of deci-sigma (ie they
have been multiplied by 10.0 and intergerized prior to storing, and thus
have a dynamic range of 0.0 to 25.5).
WXM_X_IMAGE_SN and WXM_Y_IMAGE_SN describe the peak signal-to-noise
in the cross-correlation of the background-subtracted image with the mask
in each of the two modules (X & Y).
The background-subtracted signal across each WXM detector is cross-correlated
with the mask. The resulting cross-correlation functions are mean-subtracted
and divided by their respective root-variances, yielding SNR as a function
of source projection angle in each detector. The quantities reported here
are the peak values of those functions.
The two values stored in the socket packet are in units of deci-sigma
(ie they have been multiplied by 10.0 and intergerized prior to storing, and
thus have a dynamic range of 0.0 to 25.5).
These individual X & Y IMAGE Signal/Noise values are related to the original
WXM_LOC_SN "token: value" line in the email format. The "LOC_SN" is just
the quadrature sum of the individual X & Y IMAGE_SN values. The WXM_LOC_SN
is being retained in the email formats for backwards compatibility reasons.
See the "Socket Packet Definition" document
http://gcn.gsfc.nasa.gov/gcn/sock_pkt_def_doc.html
for the details.
2) S/C LONGITUDE:
The longitude location of the s/c in its orbit has been added.
It appears in the most significant byte in the H_POS_FLAGS 4-byte word
in the socket packets. Due to space limitations only a single byte
is available, so the value stored is East Longitude divided by 2.
So the stored values 0-179 correspond to East Longitude values 0-358.
See the "Socket Packet Definition" document
http://gcn.gsfc.nasa.gov/gcn/sock_pkt_def_doc.html
for the details.
See the email example below for the TOKEN:value and location within
the email Notice. [The email format has the value multiplied by 2
so it appears in real degrees East longitude units.]
3) ECLIPTIC COORDINATES:
The position of the burst location is now also reported in ecliptic
coordinates (email formats only). This convenience allows people
to quickly determine if the location is on the ecliptic plane or not, and
hence if there is a chance that some optical transient they might detect
might be due to a moving object (like an asteroid). [This addition is similar
to the addition of the Galactic coords that allows people to quickly
determine the optical extinction, field crowdedness, and if the location
is in the galactic bulge region with all of its (transient) sources.]
This Ecliptic coords "token: value" line is being added only
to the HETE email Notices. I would like to get some feedback
from the community about adding it to the other Notice types.
I am concerned that people have implemented procedures
that automatically parse these email messages, and therefore these format
changes might cause problems with those parsing procedures.
Sincerely,
Scott Barthelmy NASA-GSFC, Code 661, Greenbelt, MD 20771
PHONE: 301-286-3106 (work)
FAX: 301-286-1684 (1st choice, -1682 2nd choice)
EMAIL: scott@lheamail.gsfc.nasa.gov
PAGER: 3016472666@alphapage.airtouch.com (by email, ~200 characters/message)
WEB: http://gcn.gsfc.nasa.gov/gcn
//////////////////////////////email example //////////////////////////////////
TITLE: GCN/HETE BURST POSITION NOTICE
NOTICE_DATE: Sun 24 Mar 02 21:18:22 UT
NOTICE_TYPE: HETE Ground Analysis
TRIGGER_NUM: 1959, Seq_Num: 5
GRB_DATE: 12050 TJD; 141 DOY; 01/05/21
GRB_TIME: 65731.42 SOD {18:15:31.42} UT
TRIGGER_SOURCE: Trigger on the 6-120 keV band.
GAMMA_RATE: 428 [cnts/s] on a 1.300 [sec] timescale
SC_-Z_RA: 175 [deg]
SC_-Z_DEC: 1 [deg]
SC_LONG: 230 [deg East]
WXM_CNTR_RA: 143.283d {+09h 33m 08s} (J2000),
143.300d {+09h 33m 12s} (current),
142.677d {+09h 30m 42s} (1950)
WXM_CNTR_DEC: -11.594d {-11d 35' 38"} (J2000),
-11.600d {-11d 36' 01"} (current),
-11.372d {-11d 22' 18"} (1950)
WXM_CORNER1: 143.4740 -11.3180 [deg]
WXM_CORNER2: 143.5230 -11.7680 [deg]
WXM_CORNER3: 143.0430 -11.4200 [deg]
WXM_CORNER4: 143.0930 -11.8710 [deg]
WXM_MAX_SIZE: 36.00 [arcmin] diameter
WXM_LOC_SN: 5 sig/noise (pt src in image)
WXM_IMAGE_SN: X= 4.0 Y= 3.5 [sig/noise]
WXM_LC_SN: X= 3.2 Y= 3.7 [sig/noise]
SUN_POSTN: 58.60d {+03h 54m 25s} +20.31d {+20d 18' 28"}
SUN_DIST: 89.13 [deg]
MOON_POSTN: 42.48d {+02h 49m 56s} +11.96d {+11d 57' 38"}
MOON_DIST: 102.80 [deg]
MOON_ILLUM: 2 [%]
GAL_COORDS: 245.07,28.27 [deg] galactic lon,lat of the burst
ECL_COORDS: 149.78,-24.67 [deg] ecliptic lon,lat of the burst
COMMENTS: Definite GRB.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM error box is circular; not rectangular.
COMMENTS: Burst_Validity flag is true.
COMMENTS: WXM data refined since S/C_Last Notice.
////////////////////////// Your sites's configuration //////////////////////////
Site_name: VSNET
Lon,Lat= 135.75 35.00
Distribution_method: EMAIL
Address: vsnet-grb@kusastro.kyoto-u.ac.jp
Filter: ALL
Error_limit= 360.100 [deg, diameter]
Delta_T_limit= 999.900 [hr]
Sources & Notice Types/Subtypes:
RXTE-PCA_Alert_wont: Disabled
RXTE-PCA_Alert_will: Disabled
RXTE-PCA_nosaw: Disabled
RXTE-PCA_saw: Disabled
RXTE-ASM: Disabled
IPN_POS: Disabled
SAX-WFC_saw: Disabled
SAX-NFI_saw: Disabled
ALEXIS: Disabled
RXTE-ASM_TRANS: Disabled
HETE_S/C_ALERT: Enabled
HETE_S/C_UPDATE: Enabled
HETE_S/C_LAST: Enabled
HETE_GND_ANA: Enabled
HETE_Test_notices: Disabled
Test_type2_notices: Disabled
SRC2_FLAG: 0
GRB_CNTRPART: Disabled
Please note that the format has changed slightly.
All the CGRO-related fields (BATSE & COMPTEL) have been deleted.
vsnet-adm@kusastro.kyoto-u.ac.jp
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