Changeset 6548

Timestamp:

02/16/05 19:07:10 (20 years ago)

Author:

garcz

Message:

*** empty log message ***

File:

• trunk/MagicSoft/GRB-Proposal/Monitor.tex (modified) (9 diffs)

trunk/MagicSoft/GRB-Proposal/Monitor.tex

@@ -42 +42 @@
 inner pixel of the \ma camera.\\
 
-In case of an alert {\it gspot} stores the informations and enters
+In case of alert, {\it gspot} stores the informations and enters
 an {\bf Alarm State}. The duration of the alarm depends on the following parameters:
 
 \begin{itemize}
 \item {\bf Darkness of the sky}: The Sun has to be below 
-to the astronomical horizon at 108$^\circ$ zenith.
+the astronomical horizon or have a zenith angle larger than 108$^\circ$.
 \item {\bf Position of GRB}: The GRB equatorial
 coordinates are transformed into local horizontal coordinates.
-The resulting GRB zenith angle has to be smaller than 70$^\circ$. In case that the moon is
-shining, the zenith angle limit is reduced to 65$^\circ$.
-\item {\bf Position of moon}: The angular
+The resulting GRB zenith angle has to be smaller than 70$^\circ$. If the Moon is
+shining, the maximal zenith angle is reduced to 65$^\circ$.
+\item {\bf Position of Moon}: The angular
 distance from the GRB to the moon has to be at least 30$^\circ$.
 \end{itemize}
@@ -60 +60 @@
 Currently, the program does not calculate if and when the GRB will become observable for \ma.
 If all the  mentioned conditions are satisfied, 
-{\it gspot} enters into a \textcolor{red}{\bf Red Alarm State}, it means that the GRB is considered to be observable now.\\
-
-In both cases (in \textcolor{red}{\bf RED} and {\color[rgb]{0.9,0.75,0.}\bf YELLOW} Alarm State), {\it gspot} establishes the communication with the CC and sends the GRB equatorial coordinates (RA/DEC J2000).
+{\it gspot} enters into a \textcolor{red}{\bf Red Alarm State}, meaning that the GRB is observable.\\
+
+In both cases (\textcolor{red}{\bf RED} or {\color[rgb]{0.9,0.75,0.}\bf YELLOW} Alarm State), {\it gspot} establishes the communication with the CC and sends the GRB equatorial coordinates (RA/DEC J2000).
 For the communication with CC the format defined in~\cite{CONTROL} is used. At the same time,
 the shifters and the GRB-MAGIC group is contacted.
@@ -69 +69 @@
 
 An interface of {\it gspot} sends all the relevant information to the CC.
-In the case that {\it gspot} is not in alarm state, 
-the standard packages are continuously exchanged between CC and {\it gspot}, containing the main global status
-of the two subsystems.
-In the alert case, {\it gspot} starts to send  special alert packages to the CC,
-containing information about the GRB and the ''color'' of the alert.
+When {\it gspot} is not in alarm state, standard packages are continuously exchanged between CC and {\it gspot}.
+These packages contain the main global status of the two subsystems.
+In case of alert, {\it gspot} starts to send special alert packages to the CC,
+containing information about the GRB and the ``color'' of the alert.
 The exchange of the alert packages continues until:
 
@@ -88 +87 @@
 appears with all the alert information received by the burst monitor.
 The operator has to confirm the notice by closing the pop-up window.
-He can decide to stop the current scheduled observation and to point the GRB.
-A new button will be displayed in the CC and allows to point the telescope to
+He can decide whether to stop the current scheduled observation and to point the GRB.
+A new button will be displayed in the CC allowing to point the telescope to
 the GRB coordinates.
 
 \subsection{GRB Archive and Emails to the GRB-mailing List}
 
-In case of an alert -- even if it did not contain the necessary coordinates -- the
-information is  translated into ''human language'' and stored in ASCII files.
+In case of alert -- even if it did not contain the necessary coordinates -- the
+information is  translated into ``human language'' and stored in ASCII files.
 At the same time, an e-mail is sent to the MAGIC GRB-mailing list 
 {\it grb@mppmu.mpg.de}.
@@ -102 +101 @@
 
 The status of the GRB Alert System and relevant informations about the latest
-alert are displayed on a separate web page. The page is hosted at the web server in La Palma a
+alerts are displayed on a separate web page. The page is hosted at the web server in La Palma a
 and can be accessed under:\\
 
@@ -117 +116 @@
 even if the CC is switched off, so that persons in the counting house
 can be noticed about the alert situation. The signal will be on as long as
-{\it gspot} remains in alarm state, and for a minimum of 1 minute.
+{\it gspot} remains in alarm state for a minimum of 1 minute.
 The device features also a display with the status of the system and the alert.
 
 \subsection{Summary of Alerts Received Until Now}
 
-Since July 15$^{th}$, 2004, {\it gspot} has been working stably at La Palma.
-It has received about 100 alerts from HETE-2 and INTEGRAL, out of which
+Since July 15$^{\mathrm{th}}$, 2004, {\it gspot} has been working stably at La Palma.
+It received about 100 alerts from HETE-2 and INTEGRAL, out of which
 21 contained GRB's coordinates. Time delays to the onset of the burst 
 were of the order of several minutes to tens of minutes. The Burst Monitor can be considered stable 
@@ -137 +136 @@
 \subsection{Experience from SWIFT GRBs until now}
 
-According to the \sw home page~\cite{SWIFT}, the satellite has detected 16 GRBs since mid-December last year.
-The bursts were detected by chance during the commissioning phase. Since 15th of February the satellite sends
-burst allerts to the \g in real time. The current sample contains three bursts
-which could have been observed by \ma. The coordinates of the last burst from 15th February were send via an
-alert within few seconds. The weather conditions did not allow any observation in this nights.\\
+According to the \sw home page~\cite{SWIFT}, the satellite has detected 12 GRBs since mid-December last year.
+The bursts were detected by chance during the commissioning phase. The satellite did not send
+the coordinates to the \g on time. The current sample contains two bursts
+which could have been observed by \ma:\\
 
 \begin{tabular}{lllcc}
 19th & December & 2004 & 1:42 am & Zd $\sim 65^\circ$ \\
-26th & December & 2004 & 8:34 pm & Zd $\sim 52^\circ$ \\
-15th & Februar & 2005 & 2:33 am & Zd $\sim 17^\circ$ \\ \\
+26th & December & 2004 & 20:34 am & Zd $\sim 52^\circ$ \\ \\
 \end{tabular}
 
@@ -177 +174 @@
 
 The Burst Alarm System is currently able to provide the minimum
-features needed to point and to observe a GRB. However, in order to improve our efficiency
+features needed to point and to observe a GRB. However, in order to improve the efficiency
 to point and observe GRBs, several procedures have to be defined:
 
@@ -215 +212 @@
 %%% TeX-master: "GRB_proposal_2005"
 %%% End: 
+\section{The Burst Alarm System at La Palma}
+
+{\bf Current status:}
+
+\par
+
+The Burst Alarm System {\it gspot} (Gamma
+Sources Pointing Trigger) is working in La Palma since last summer. 
+It performs a full-time survey of the {\it GRB Coordinates Network} (\g) alerts~\cite{GCN}.
+Different satellite experiments 
+send GRB coordinates to the \g which distributes 
+the alerts to registered users.
+The Burst Alarm System is composed of a core program which 
+manages the monitoring of the \g and the communication with the Central Control (CC). 
+It also handles three communication channels to notice the shifters
+about an alert. It is a C based daemon running 24
+hours a day on the {\it www} machine, our external server, in a
+{\it stand alone} mode. It does not need to be operated and is
+fully automatic. It manages network disconnections
+within the external net and/or the internal one.
+
+
+\subsection{The Connection to the GCN}
+
+The connection to the \g is performed by {\it gspot} through a
+TCP/IP connection to a computer at the Goddard Space Flight Center (GSFC).
+This computer distributes the alerts from the satellite
+experiments through an internet socket connection. {\it gspot} 
+acts as a server while the client, running at the GSFC,
+manages the communication of the data concerning the GRBs
+and concerning the status of the connection. \\
+
+The format of the data distributed through the \g differ between the individual satellites
+and the kind of package. Currently, three satellites participate in the GRB survey:
+HETE-2~\cite{HETE}, INTEGRAL~\cite{INTEGRAL} and SWIFT~\cite{SWIFT}. 
+The alerts include the UTC, the GRB coordinates (not always), error on coordinates
+(not always) and intensity (photon counts) of the burst.
+The first notices from HETE-2 and INTEGRAL usually do not include the coordinates.
+In few cases only coordinates are distributed in refined notices.
+The \sw alerts are predicted to arrive with coordinates between 30-80 sec after the onset of the burst.
+The error on the coordinates from the BAT detector will be 4 arcmin which is smaller than the size of one
+inner pixel of the \ma camera.\\
+
+In case of alert, {\it gspot} stores the informations and enters
+an {\bf Alarm State}. The duration of the alarm depends on the following parameters:
+
+\begin{itemize}
+\item {\bf Darkness of the sky}: The Sun has to be below 
+the astronomical horizon or have a zenith angle larger than 108$^\circ$.
+\item {\bf Position of GRB}: The GRB equatorial
+coordinates are transformed into local horizontal coordinates.
+The resulting GRB zenith angle has to be smaller than 70$^\circ$. If the Moon is
+shining, the maximal zenith angle is reduced to 65$^\circ$.
+\item {\bf Position of Moon}: The angular
+distance from the GRB to the moon has to be at least 30$^\circ$.
+\end{itemize}
+
+If one or more of these conditions fail, {\it gspot} enters into a
+{\color[rgb]{0.9,0.75,0.}\bf Yellow Alarm State}: The GRB is not observable at the moment.
+Currently, the program does not calculate if and when the GRB will become observable for \ma.
+If all the  mentioned conditions are satisfied, 
+{\it gspot} enters into a \textcolor{red}{\bf Red Alarm State}, meaning that the GRB is observable.\\
+
+In both cases (\textcolor{red}{\bf RED} or {\color[rgb]{0.9,0.75,0.}\bf YELLOW} Alarm State), {\it gspot} establishes the communication with the CC and sends the GRB equatorial coordinates (RA/DEC J2000).
+For the communication with CC the format defined in~\cite{CONTROL} is used. At the same time,
+the shifters and the GRB-MAGIC group is contacted.
+
+\subsection{The Interface to the Central Control}
+
+An interface of {\it gspot} sends all the relevant information to the CC.
+When {\it gspot} is not in alarm state, standard packages are continuously exchanged between CC and {\it gspot}.
+These packages contain the main global status of the two subsystems.
+In case of alert, {\it gspot} starts to send special alert packages to the CC,
+containing information about the GRB and the ``color'' of the alert.
+The exchange of the alert packages continues until:
+
+\begin{itemize}
+\item {\it gspot} receives from the CC the confirmation
+that the alert notice has been received; The CC must send back the alert in order
+to perform a cross-check of the relevant data.
+\item the alarm state expires after {\bf 5 hours}
+\end{itemize}
+
+The CC informs the shift crew about the alert and undertakes
+further steps only in case of a \textcolor{red}{\bf red alerts}. 
+In this case, a pop-up window
+appears with all the alert information received by the burst monitor.
+The operator has to confirm the notice by closing the pop-up window.
+He can decide whether to stop the current scheduled observation and to point the GRB.
+A new button will be displayed in the CC allowing to point the telescope to
+the GRB coordinates.
+
+\subsection{GRB Archive and Emails to the GRB-mailing List}
+
+In case of alert -- even if it did not contain the necessary coordinates -- the
+information is  translated into ``human language'' and stored in ASCII files.
+At the same time, an e-mail is sent to the MAGIC GRB-mailing list 
+{\it grb@mppmu.mpg.de}.
+
+\subsection{The GRB Web Page}
+
+The status of the GRB Alert System and relevant informations about the latest
+alerts are displayed on a separate web page. The page is hosted at the web server in La Palma a
+and can be accessed under:\\
+
+\qquad \qquad http://www.magic.iac.es/site/grbm/\\
+
+The web page updates itself automatically every 10 seconds. In this way
+the status of the Burst Alarm System can be checked by the shifters and from outside.
+
+\subsection{The Acoustic Alert}
+
+A further CC-independent acoustic alarm called {\it phava}
+(PHonetic Alarm for Valued Alerts) will be installed
+in La Palma soon. It will provide a loud acoustic signal
+even if the CC is switched off, so that persons in the counting house
+can be noticed about the alert situation. The signal will be on as long as
+{\it gspot} remains in alarm state for a minimum of 1 minute.
+The device features also a display with the status of the system and the alert.
+
+\subsection{Summary of Alerts Received Until Now}
+
+Since July 15$^{\mathrm{th}}$, 2004, {\it gspot} has been working stably at La Palma.
+It received about 100 alerts from HETE-2 and INTEGRAL, out of which
+21 contained GRB's coordinates. Time delays to the onset of the burst 
+were of the order of several minutes to tens of minutes. The Burst Monitor can be considered stable 
+since November, 2004. Since then, we have received the following two significant alerts:\\
+
+\begin{tabular}{lllcccl}
+19th & December & 2004 & 1:44 am & INTEGRAL satellite & Zd $\sim 60^\circ$ & Time delay 71 sec.\\
+28th & January & 2005 & 5:36 am & HETE-2 satellite & Zd $\sim 65^\circ$ & Time delay 73 min. \\ \\
+\end{tabular}
+
+In both cases the weather conditions at La Palma were bad.
+
+\subsection{Experience from SWIFT GRBs until now}
+
+According to the \sw home page~\cite{SWIFT}, the satellite has detected 12 GRBs since mid-December last year.
+The bursts were detected by chance during the commissioning phase. The satellite did not send
+the coordinates to the \g on time. The current sample contains two bursts
+which could have been observed by \ma:\\
+
+\begin{tabular}{lllcc}
+19th & December & 2004 & 1:42 am & Zd $\sim 65^\circ$ \\
+26th & December & 2004 & 20:34 am & Zd $\sim 52^\circ$ \\ \\
+\end{tabular}
+
+\subsection{Comparison between the Satellite Orbits}
+
+Figure~\ref{fig:orbit} shows the orbits of the \sw, \he and \ig satellites.
+The \sw and \he satellites are situated in a circular orbit with 
+20.6$^\circ$ and 2$^\circ$ inclination, respectively.
+One revolution of the \sw and \he satellites last about 100\,min. 
+The \ig satellite has a 
+highly eccentric orbit with a revolution period of three sidereal days around the Earth.
+
+\par
+
+It is difficult to draw strong conclusions from the individual satellites' orbits. 
+The orientation of the satellites' FOV is influenced by the scheduled targets. 
+However, \sw is the satellite with the largest inclination and overlaps mostly with the FOV of \ma. 
+This increases the chance to receive {\bf Red Alarms} from this satellite.
+
+\begin{figure}[htp]
+\centering
+\includegraphics[width=0.7\linewidth]{GCNsatellites.eps}
+\caption{Orbits of the \sw (top), \he (center) and \ig (bottom) satellites: The pointed lines 
+show the orbit while the drawn lines show the horizon of the Sun. Here, a typical night at 
+La Palma is shown. The \sw satellite passes over the Roque seven times each night.}
+\label{fig:orbit}
+\end{figure}
+
+\subsection{Routines to Be Defined}
+
+The Burst Alarm System is currently able to provide the minimum
+features needed to point and to observe a GRB. However, in order to improve the efficiency
+to point and observe GRBs, several procedures have to be defined:
+
+\begin{itemize}
+\item {\bf Yellow Alarm strategy}:
+The strategy to follow a {\bf Yellow Alarm} is not defined yet.
+In such a case, the CC does not undertake any steps,
+except confirming the alarm notice to the Burst Monitor. We have not
+calculated yet if and when the GRB will become observable.
+It would make sense to check if we could point to the burst during the period of 5 hours.
+The Alarm System should change to a {\bf Red Alarm State}, then.
+
+\item {\bf Sequence of alerts}:
+How to deal with new alerts that are distributed during the time
+that {\it gspot} is in alarm state? Currently, {\it gspot}
+locks its alert status until it exits the alarm state (see session 2.2).
+This feature was implemented to avoid any loss of GRB information.
+Such a situation can occur for example if more than one burst alert is sent before
+the shift crew launches the CC. 
+To solve this problem, we will change the {\it gspot} routine 
+by implementing a list of all available GRB alerts.
+
+
+\par
+
+If more than one alert is present in the list, the program
+will weight the possible GRBs according to the following criteria:
+(1) the total time of observability within the canonical 5 hours,
+(2) the intensity of the burst and
+(3) the time until the GRB becomes observable.
+The information of the best GRB will be sent to the CC.
+
+\end{itemize}
+
+%%% Local Variables: 
+%%% mode: latex
+%%% TeX-master: "GRB_proposal_2005"
+%%% End: