Changeset 6256 for trunk

Timestamp:

02/04/05 14:50:47 (20 years ago)

Author:

gaug

Message:

*** empty log message ***

Location:

trunk/MagicSoft/GRB-Proposal

Files:

• Strategies.tex (modified) (3 diffs)
• make_ps.sh (modified) (1 diff)

trunk/MagicSoft/GRB-Proposal/Strategies.tex

@@ -48 +48 @@
 overlap with $F_{overlap}(SWIFT) = 1$ yielding $N_{obs}^{max} \sim 1.6$/month.
 
-\subsection{GRB observations in case of moon shine}
+\subsection{Determine the Maximum Zenith Angle}
+
+We determine the maximum zenith angle for GRB observations by requiring that the overwhelming 
+majority of possible GRBs will have an in principle observable spectrum. Figure~\ref{fig:grh}
+shows the gamma-ray horizon (GRH) as computed in~\cite{KNEISKE,SALOMON}. The GRH is defined as the
+gamma-ray energy at which a part of $1/e$ of a hypothetical mono-energetic flux gets absorbed after
+travelling a distance, expressed in redshift $z$, from the source. One can see that at typical
+GRB distances of $z=1$, all gamma-rays above 100\,GeV get absorbed before they can reach the earth.
+
+\par
+
+Even the closest GRB with known redshift ever observed, GRB030329~\cite{GRB030329}, lies at a redshift
+of $z=0.1685$. In this case $\gamma$-rays above 200\,GeV get entirely absorbed.
+
+\begin{figure}[htp]
+\centering
+\includegraphics[width=0.85\linewidth]{f4.eps}
+\caption{Gamma Ray Horizon as derived in~\cite{KNEISKE}}
+\label{fig:grh}
+\end{figure}
+
+\par
+
+We assume now a current energy threshold of 50\,GeV for \ma at a zenith angle of
+$\theta = 0$\footnote{As this proposal is going to be reviewed in a couple of months, improvements of the energy threshold will be taken into account then.}. According to~\cite{ecl}, the energy threshold of a Cherenkov telescope scales with zenith angle like:
+
+\begin{equation}
+E_{thr}(\theta) = E_{thr}(0) \cdot \cos(\theta)^{-2.7}
+\label{eq:ethrvszenith}
+\end{equation}
+
+Eq.~\ref{eq:ethrvszenith} leads to an energy threshold of about 5.6\,TeV at $\theta = 80^\circ$,
+900\,GeV at $\theta = 70^\circ$ and 500\,GeV at $\theta = 65^\circ$.
+Inserting these results into the GRH (figure~\ref{fig:grh}), one gets a maximal observable GRB 
+distance of $z = 0.1$ at $\theta = 70^\circ$ and $z = 0.2$ at $\theta = 65^\circ$.
+We think that the probability for GRBs to occur at these distances is sufficiently small in order to 
+neglect the very difficult observations beyond these limits.
+
+\subsection{GRB Observations in Case of Moon Shine}
 
 {\it gspot} allows only GRBs with an angular distance of $> 30^\circ$ from the moon.
@@ -80 +118 @@
 $\theta_{max} = 70^\circ$ to $\theta_{max} = 65^\circ$, there.
 
-\subsection{Active Mirror Control behaviour}
+\subsection{Active Mirror Control Behaviour}
 
 To reduce the time before the start of the observation, the use of the look-up tables (LUTs) is necessary.
@@ -98 +136 @@
 We would like to continue taking the interlaced calibration events when a GRB alert is launched, but leave out the pedestal and calibration run in order not to loose valuable time.
 
-\subsection{Determine the maximum zenith angle}
-
-We determine the maximum zenith angle for GRB observations by requiring that the overwhelming majority of possible GRBs will have an in principle observable spectrum. Figure~\ref{fig:grh}
-shows the gamma-ray horizon (GRH) as computed in~\cite{KNEISKE,SALOMON}. The GRH is defined as the
-gamma-ray energy at which a part of $1/e$ of a hypothetical mono-energetic flux gets absorbed after
-travelling a distance, expressed in redshift $z$, from the source. One can see that at typical
-GRB distances of $z=1$, all gamma-rays above 100\,GeV get absorbed before they can reach the earth.
-
-\par
-
-Even the closest GRB with known redshift ever observed, GRB030329~\cite{GRB030329}, lies at a redshift
-of $z=0.1685$. In this case $\gamma$-rays above 200\,GeV get entirely absorbed.
-
-\begin{figure}[htp]
-\centering
-\includegraphics[width=0.85\linewidth]{f4.eps}
-\caption{Gamma Ray Horizon as derived in~\cite{KNEISKE}}
-\label{fig:grh}
-\end{figure}
-
-\par
-
-We assume now a current energy threshold of 50\,GeV for \ma at a zenith angle of
-$\theta = 0$\footnote{As this proposal is going to be reviewed in a couple of months, improvements of the energy threshold will be taken into account then.}. According to~\cite{ecl}, the energy threshold of a Cherenkov telescope scales with zenith angle like:
-
-\begin{equation}
-E_{thr}(\theta) = E_{thr}(0) \cdot \cos(\theta)^{-2.7}
-\label{eq:ethrvszenith}
-\end{equation}
-
-Eq.~\ref{eq:ethrvszenith} leads to an energy threshold of about 5.6\,TeV at $\theta = 80^\circ$,
-900\,GeV at $\theta = 70^\circ$ and 500\,GeV at $\theta = 65^\circ$.
-Inserting these results into the GRH (figure~\ref{fig:grh}), one gets a maximal observable GRB distance of $z = 0.1$ at $\theta = 70^\circ$ and $z = 0.2$ at $\theta = 65^\circ$.
-We think that the probability for GRBs to occur at these distances is sufficiently small in order to neglect the very difficult observations beyond these limits.
-
-\subsection{In case of follow-up: Next steps}
+\subsection{In case of Follow-up: Next Steps}
 
 We propose to analyze the GRB data at the following day in order to tell whether a follow-up observation during the next night is useful. We think that a limit of 3\,$\sigma$ significance should be enough to start such a follow-up observation of the same place. This follow-up observation can then be used in two ways:

trunk/MagicSoft/GRB-Proposal/make_ps.sh

@@ -2 +2 @@
 
 rm    GRB_proposal_2005.aux
-#latex GRB_proposal_2005.tex
+latex GRB_proposal_2005.tex
 #bibtex GRB_proposal_2005
 latex GRB_proposal_2005.tex