Changeset 5968 for trunk/MagicSoft/GRB-Proposal
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trunk/MagicSoft/GRB-Proposal/GRB_proposal_2005.tex
r5967 r5968 54 54 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 55 55 \title{Proposal for the Observation of Gamma-Ray Bursts with the MAGIC Telescope \\ 56 {\it \Large DRAFT 0.0 }}56 {\it \Large DRAFT 1.0 }} 57 57 \author{ N. Galante\\ \texttt{<nicola.galante@pd.infn.it>}\\ 58 58 M. Garczarczyk\\ \texttt{<garcz@mppmu.mpg.de>}\\ … … 61 61 } 62 62 63 \date{ December, 2003\\}64 \TDAScode{MAGIC-TDAS 0 2-??\\ 0312??/NGalante}63 \date{January, 2005\\} 64 \TDAScode{MAGIC-TDAS 05-??\\ 0312??/NGalante} 65 65 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 66 66 %% title %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% … … 70 70 \begin{abstract} 71 71 We give a detailed plan for the observation of Gamma Ray Bursts for the year 72 2004. All observations will be triggered by alerts of the satellites \he, \ig, 73 \sw or by other circulars by the \g. Based on \he experience from the year 2002, 74 we expect an alert rate of a total of about 50 per year out of which only about 20 will 75 be followed by a position. 76 %FIXME 77 {\it \bf THIS HAS STILL TO BE UPDATED FOR 2003 !!} 78 The majority of these alerts will be based on ground analysis and 79 arrive with a delay of about an hour or more. 72 2005. All observations will be triggered mainly by alerts of the satellites \he, \ig 73 and above all \sw. we expect an alert rate of a total of about 74 \par 75 \ldots HOW MANY??? \ldots 76 \par 77 per year out of which only about 78 \par 79 \ldots HOW MANY??? \ldots 80 \par 81 will be followed by a position. 82 We give a detailed description of the observation procedures in La Palma and 83 propose to review the situation in half a year from now. 80 84 \end{abstract} 81 85 82 86 %% contents %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 83 %\thetableofcontents87 \thetableofcontents 84 88 85 89 \newpage 86 90 87 91 %% body %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 92 \include{Introduction} 93 \include{Alerts} 94 \include{Monitor} 95 \include{Strategies} 96 \include{Timing} 97 \include{Requirements} 98 88 99 89 100 %------------------------------------------------------------ 90 \section{Introduction} 91 The MAGIC telescope has been designed especially light with a special focus on 92 being able to react fastly to GRB alerts from the satellites. 93 In \cite{design} and~\cite{PETRY}, 94 the objective was set to turn the telescope to the burst position in 10-30~s 95 in order to have a fair chance of detecting a burst with the MAGIC telescope. 96 The current possible value is 20 sec. for full turn-around 97 %FIXME 98 {\it \bf THIS HAS TO BE CHECKED FROM THOMAS B. !!} 99 \par 100 Several attempts have been made in the past to observe GRBs at energies 101 from the GeV range upwards each indicating some excess over background but 102 without stringent evidence. The only secured detection was performed by EGRET 103 which detected seven GRBs emitting high energy photons in the 104 100~MeV to 18~GeV range~\cite{EGRET}. There have been 105 results suggesting gamma rays beyond the GeV range from the TIBET array~\cite{TIBET} and 106 from HEGRA-AIROBICC~\cite{HEGRA}. Evidence for TeV emission of one burst was claimed by 107 the MILAGRITO experiment~\cite{MILAGRO}. Recently, the GRAND array has reported some 108 excess of observed muons during seven BATSE bursts~\cite{GRAND}. In this context, note 109 especially a recent publication from the TASC detector on \eg~\cite{TASC}, 110 finding a high-energy spectral 111 component presumably due to ultra-relativistic acceleration of hadrons and 112 producing a spectral index of $-1$ with no cut-off up to the detector limit (200 MeV). 113 \par 114 The nowadays most widely accepted model for gamma emission from GRB suggests a bursts 115 environment involving collisions of an ultra-relativistic e$^+$-e$^-$ 116 plasma fireball~\cite{PAZCYNSKI,GOODMAN,SARI}. These fireballs may produce 117 low-energy gamma rays either by ``internal'' collisions of multiple 118 shocks~\cite{XU,REES} or by ``external'' collisions of a single shock 119 with the ambient circum burst medium (CBM)~\cite{MESZAROS94}. 120 \par 121 In many publications, 122 the possibility that more energetic gamma-rays come along with the (low-energy) gamma-ray 123 burst, have been explored. 124 Proton-synchrotron emission~\cite{TOTANI} have 125 been suggested as well as photo-pion production~\cite{WAXMAN,BAHCALL,BOETTCHER} 126 and inverse-Comption 127 scattering in the burst environment~\cite{MESZAROS93,CHIANG,PILLA,ZHANG}. 128 Long-term high-energy gamma emission from accelerated protons in forward-shock 129 has been predicted in~\cite{LI}. 130 Even considering pure electron-synchrotron radiation predicts measurable GeV emission for a 131 significant fraction of GRBs~\cite{ZHANG}. 132 Implications of the observation of a high-energy gamma-ray component on 133 distance scale, energy production in the GRB and distinction between internal and 134 external shock models have been treated in~\cite{HARTMANN,MANNHEIM,SALOMON,PRIMACK}. 135 \par 136 In the year 2004, mainly three satellites will produce the bulk of the GRB alerts: The \he 137 satellite, launched in October 2000, the \ig satellite, launched October 2002 and the 138 \sw satellite, scheduled for launch in May, 2004. 139 \par 140 % HERE 141 We will give an overview of the types of alarms, we expect from the three satellites 142 and add then our proposal for observation strategies. Note that while there is already some 143 experience accumulated from the \he and \ig alarms, we do not know yet how \sw will perform 144 since it is still not launched. Because the observation of GRBs will differ 145 from conventional observations in several aspects, we also propose a detailed plan to test 146 and calibrate the system in order to meet our purposes. 147 \par 148 {\ldots \it \bf THIS IS TO BE CHECKED BY NICOLA G. !! \ldots \\} 149 \par 150 Concerning estimates about the MAGIC observability of GRBs, a very detailed study 151 of GRB spectra obtained from the third and fourth \ba catalogue has been made 152 in~\cite{ICRC,NICOLA}. The spectra were extrapolated to \ma energies with a simple continuation 153 of the observed high-energy power law behaviour and the calculated fluxes compared 154 with \ma sensitivities. Setting conservative cuts on observation times and significances, 155 and assuming an energy threshold of 15~GeV, a GRB detection rate of $0.5--2$ per year 156 was obtained for an assumed observation delay of 15~sec. and the \sw GRB trigger rate ($\sim 100/year$). 157 158 159 \section{\he Alarms} 160 161 {\it \bf THIS HAS TO BE UPDATED TO 2003 !!} 162 163 The HETE mission has three instruments on board which can generate burst triggers: 164 Fregate, the WXM, and the SXC. 165 Fregate data are examined in two broad energy channels: 166 5-80 keV and 30-400 keV. 167 The WXM data are from 2-30 keV, 168 and the SXC data are from 1.5 to 12 keV. 169 \par 170 The Fregate data are searched for counts excesses on four different timescales: 171 20 ms, 160 ms, 1.3 s, and 5.2 s. 172 The threshold for a count excess to be considered significant is generally around 5 sigma. 173 Such an excess must be seen in two of the four Fregate detectors on the same timescale 174 for a burst to be considered real. 175 \par 176 The WXM data are examined on multiple timescales between 80 ms and 10 s. 177 The thresholds are all near 5 sigma. This analysis is done on one of the on-board transputers. 178 \par 179 Fregate data are also analyzed on multiple timescales in a manner identical 180 to that for the WXM data on the same transputer the WXM data are analyzed by. 181 \par 182 SXC data can be used to create a continuous series of cross-correlation maps using a dedicated DSP, 183 and a burst is registered when the peak of the cross-correlation map exceeds a threshold. 184 Because of the difficulties with the SXC hardware, SXC triggering is currently not operating. 185 \par 186 When a burst is detected, the real-time spacecraft notification will distribute 187 \begin{itemize} 188 \item the energy range of the burst (1.5-12 keV, 2-30 keV, 5-80 keV, or 30-400 keV) 189 \item the timescale of the trigger (from 20 ms to over 10 s) 190 \item the S/N or the peak count rate of the burst 191 \end{itemize} 192 \par 193 194 In the year 2002, about 630 internal \he triggers occurred, out of which about 75 were 195 considered as GRBs or possible GRBs by the ground analysis. About 50 of these bursts 196 were subsequently considered as real\cite{HETE-SUM}. Note that about 40 of 197 another species of bursts called ``X-ray bursts'' (XRB) were detected, mainly while the 198 satellite was looking towards the Galactic center. 199 \par 200 201 The real-time alerts sent to the \g by \he have the following signature~\cite{HETE}: 202 \begin{description} 203 \item[ALERT] If the burst is detected using photons in the 5-80 keV or 30-400 keV bands, 204 regardless whether a position has been determined or not. This type of alert has occurred 205 about 170 times in 2002. 206 \item[UPDATE] If a position is determined on board and it is considered significant enough, 207 the RA and declination of the burst will be distributed in this type to the \g. 208 Each additional position determined on board 209 (each with higher significance than all determined before) 210 will result in a new Notice of type UPDATE. In 2002, about 10 UPDATE's were sent to 211 the \g, two third of which had a position error of about 1 arcmin, one third with about 212 half an arcmin. 213 \item[LAST] Once the on-board processing of data near the time of the trigger is complete, 214 there will be no more immediate results from the spacecraft, 215 a summary Notice this type is distributed. In 2002, about 120 LAST's were sent out to the \g, 216 containing about 20 positions of bursts. 217 \end{description} 218 The quality of the real-time positions are assured by making a cut on the lightcurve S/N and the 219 image S/N in a way that with $>$90\% the real-time position is correct. 220 As a result, HETE positions distributed in real time from the spacecraft are in one of two categories: 221 \begin{itemize} 222 \item Category I: 223 The image and lightcurve S/N all exceed 3.0, 224 so the position is distributed with a 90\% error radius of 12-14 arcminutes. 225 \item Category II: 226 Not all of the image and lightcurve S/N exceeds 3.0, 227 but the quadrature sum of the image S/N from the WXM X and Y detectors is > 3.7, 228 and neither the X nor the Y incident angle exceeds 30 degrees, 229 so the position is distributed with a 90\% error radius of 30 arcminutes. 230 \end{itemize} 231 232 In order to accommodate those observers who would like to make their own estimate 233 of the quality of a real-time burst localization, also included in the \g message are: 234 \begin{itemize} 235 \item The image S/N from the X and Y modules of the WXM 236 \item The lightcurve S/N from the X and Y modules of the WXM 237 \item The longitude of the HETE spacecraft at the time of the trigger. 238 \end{itemize} 239 The higher the image and lightcurve S/N, 240 the more reliable the localization will be. 241 Low values of image and lightcurve S/N are typically associated with events 242 localized at the edge of the instrument FOV. 243 \par 244 This method of distribution of \g Notices results in a few common situations: 245 \begin{itemize} 246 \item If there is no significant position calculated in real time on board, 247 there will be no burst coordinates in any \g Notice. 248 If ground analysis reveals a position, 249 it will be sent out as a type GND\_ANALYSIS Notice. 250 \item Because the Burst Alert Station coverage is not always 100\%, 251 there can be gaps in the reception of burst data from the spacecraft. 252 If the flight analysis of a burst is over before a Burst Alert Station is seen, 253 the full analysis of the burst will be sent in two Notices, 254 one of type ALERT and the other of type LAST. 255 This means that a Notice of type ALERT could, in principle, 256 contain the coordinates of the burst. 257 \end{itemize} 258 Both the WXM and SXC search data from seconds before the burst trigger to minutes after, 259 looking for the image of the burst. The WXM software matches the shadow pattern on the detector 260 with template patterns, looking for a best fit; the SXC looks for peaks in the cross-correlation map. 261 In either case, if a significant position is found in either instrument, 262 its location is sent to the ground in real time. 263 Once the positions and their significances are received on the ground, 264 the RA and declination of the image are calculated and, 265 if the significances are high enough, transmitted to the \g. 266 At present, SXC positions are not sent to the \g automatically, 267 but rather only after ground analysis. 268 269 \par 270 Ground analysis of a burst begins as soon as the full burst data reach MIT after a 271 Primary Ground Station contact (from a few minutes to over an hour after the burst). 272 Automated software performs standard analyses of the downlinked data, 273 and a human is notified to make the final decisions. 274 A followup \g Notice, of type GND\_ANALYSIS, 275 will be distributed under the following circumstances: 276 \begin{itemize} 277 \item There was no position calculated on board, but ground analyses reveal a significant position. 278 \item There was a position calculated on board and ground analyses can improve the coordinates 279 and/or reduce the error box size. 280 \item There was a position calculated on board, but there is actually no significant position in the data. 281 \end{itemize} 282 In general, if there is a position in a real-time \g Notice, 283 it should be considered accurate. 284 If there is no position in a real-time \g Notice, 285 a position may be forthcoming within an hour or so of the original Notice. 286 If a burst position was distributed and it is wrong because of software or operator error, 287 a GND\_ANALYSIS message will be distributed; 288 if no position was distributed, no GND\_ANALYSIS message will be sent. 289 In 2002, about 25 ground analyses contained positions of GRB's and 5 further of XRB's. 290 \par 291 292 From the 30 bursts with position sent to the \g in 2002, \ma would have had 7 in its FOV 293 which are listed in the following table: 294 \begin{table}[h] 295 \label{tab:heteoverlap} 296 \begin{center} 297 {\small 298 \begin{tabular}{|c|c|c|c|c|c|c|c|c|c|} 299 \hline 300 \hline 301 GRB & date & UTC & RA & dec. & error & $\theta$ & $\phi$ & flag & comments\\ 302 name & (dd.mm)& & & & arc. & MA- & MA- & providing & \\ 303 & & & & & min. & GIC & GIC & position & \\ 304 \hline 305 -- & 27.11. & 1:20:39 & 53.78 & -15.84 & 60 & 48 & 198 & UPDATE & probable GRB \\ 306 & & & & & & & & & moon at:\\ 307 & & & & & & & & & $\theta= 77^\circ, \phi=77^\circ$\\ 308 \hline 309 GRB021113 & 13.11. & 06:38:57 & 23.47 & 40.4 & 28 & 85 & 314 & GND & no moon \\ 310 \hline 311 GRB021112 & 12.11. & 03:28:16 & 39.22 & 48.8 & 54 & 40 & 313 & GND & no moon \\ 312 \hline 313 GRB020813 & 13.08. & 02:44:19 & 296.66 & -19.6 & 28 & 67 & 229 & ALERT & no moon \\ 314 \hline 315 -- & 28.07. & 21:44:58 & 273.67 & -12.13 & 28 & 45 & 153 & UPDATE & probable GRB\\ 316 & & & & & & & & & no moon \\ 317 \hline 318 GRB020531 & 31.05. & 00:26:18 & 228.69 & -19.36 & 77 & 49 & 191 & GND & 319 moon at: \\ 320 & & & & & & & & & $\theta= 87^\circ, \phi=118^\circ$ \\ 321 \hline 322 GRB020127 & 27.01. & 20:57:24 & 123.77 & 36.74 & 240 & 51 & 64 & UPDATE & 323 moon at: \\ 324 & & & & & & & & & $\theta= 47^\circ, \phi=83^\circ$ \\ 325 \hline 326 \hline 327 \end{tabular} 328 } 329 \end{center} 330 \caption{\he bursts, which would have been in principle visible from the \ma telescope site at 331 night. No burst durations, alert delays, weather conditions, etc. are displayed. For more 332 detailed information on single bursts, see~\cite{NICOLAGRB}.} 333 \end{table} 334 335 As one can see from table~\ref{tab:heteoverlap}, more overlap bursts 336 than expected from randomly superimposed fields of view ($\sim$1--2 bursts only), 337 have been found. As expected from the increase of covered solid angle at high 338 zenith angles, all bursts had rather larger zenith angles ($\theta \geq 40^\circ$) 339 culminating and cover the whole range of azimuths. 340 \par 341 Additionally, five bursts occurred during the day, but would have moved into the \ma FOV in a 342 delay of less than six hours (see table~\ref{tab:hetelongoverlap}): 343 \begin{table}[h] 344 \label{tab:hetelongoverlap} 345 \begin{center} 346 {\small 347 \begin{tabular}{|c|c|c|c|c|c|c|c|c|c|} 348 \hline 349 \hline 350 GRB & date & UTC & RA & dec. & error & $\theta$ & $\phi$ & flag & comments\\ 351 name & (dd.mm)& & & & arc. & MA- & MA- & providing & \\ 352 & & & & & min. & GIC & GIC & position & \\ 353 \hline 354 -- & 15.07. & 18:45:40 & 273.7 & -12.1 & 2.0 & 51 & 138 & UPDATE & XRB \\ 355 & & & & & & & & & $\theta$ and $\phi$ at 21:43:00 UTC \\ 356 & & & & & & & & & moon at:\\ 357 & & & & & & & & & $\theta= 69^\circ, \phi=252^\circ$\\ 358 \hline 359 -- & 09.06. & 20:45:37 & 275.9 & -30.4 & 1.4 & 88 & 126 & LAST & possible GRB \\ 360 & & & & & & & & & $\theta$ and $\phi$ at 21:43:00 UTC \\ 361 & & & & & & & & & no moon \\ 362 \hline 363 -- & 08.06. & 16:02:39 & 275.9 & -30.4 & 2.2 & 89 & 125 & GND & XRB \\ 364 & & & & & & & & & $\theta$ and $\phi$ at 21:43:00 UTC \\ 365 & & & & & & & & & no moon \\ 366 \hline 367 GRB020331 & 31.03. & 16:32:28 & 199.1 & -17.9 & 20 & 86 & 113 & GND & $\theta$ and $\phi$ at 21:49:00 UTC \\ 368 & & & & & & & & & no moon \\ 369 \hline 370 GRB020317 & 17.03. & 18:15:31 & 155.8 & 12.7 & 36 & 46 & 101 & GND & $\theta$ and $\phi$ at 21:40:00 UTC \\ 371 & & & & & & & & & moon at:\\ 372 & & & & & & & & & $\theta= 19^\circ, \phi=271^\circ$\\ 373 \hline 374 \hline 375 \end{tabular} 376 } 377 \end{center} 378 \caption{\he bursts, which would have been in principle visible from the \ma telescope site occurring 379 during the day but moving into the \ma FOV in less than six hours. 380 No burst durations, alert delays, weather conditions, etc. are displayed. For more 381 detailed information on single bursts, see~\cite{NICOLAGRB,GCNARCHIVE}. Two bursts are marked 382 as XRB (X-ray bursts) a phenomenon seen regularly by the \he WXM while looking into the Galactic Center.} 383 \end{table} 384 385 The \he field of view spans roughly 75$^\circ$ in DEC and and 5 hrs in RA. 386 Because \he is anti-solar pointing, its field-of view drifts along the ecliptic 387 at a rate of about one degree per day. Its maximum declination reaches 60$^\circ$ with the lower 388 border of its field of view at about -15$^\circ$. Its minimum declination reaches -60$^\circ$ 389 with the upper border at about +15$^\circ$~\cite{HETE}. 390 The best overlap between \ma and \he fields of view 391 is thus in the winter, between October and March. 392 393 \section{\ig Alarms} 394 395 {\ldots \it \bf THIS IS TO BE UPDATED TO 2003 !! \ldots \\} 396 \par 397 The \ig satellite was successfully commissioned in March 2003. 398 The use of INTEGRAL is planned for 2 years with a possible extension for up to 5 years. 399 400 \par 401 The satellite contains four main instruments: 402 \begin{description} 403 \item[IBIS:\xspace] The imager IBIS (Imager on Board the INTEGRAL Satellite) 404 will achieve an angular resolution of 12 arcmin over an energy range between 15 keV and 10 MeV. 405 \item[SPI:\xspace] The spectrometer SPI (SPectrometer on INTEGRAL) 406 will provide spectral analysis of gamma-ray point sources 407 as well as extended sources over an energy range between 20 keV and 8 MeV. 408 \item[JEM-X:\xspace] 409 Two identical X-ray monitors, JEM-X (Joint European X-ray Monitor) will work 410 simultaneously with the other instruments in the energy range between 3 and 35 keV 411 and with an angular resolution of one arcmin. 412 \item[OMC:\xspace] 413 The optical monitoring camera, OMC, covers a field of 17.6 x 17.6 arcsec. 414 The total field of view of the OMC camera will be of 5 x 5 degrees. 415 \end{description} 416 417 \par 418 Alerts with the coordinates of GRBs will be distributed via internet 419 with a small delay with respect to the GRB occurrence. 420 It is expected that this delay will be smaller than a few minutes. The alerts as 421 such can be delivered to the recipient within 1 second. 422 The expected rate of GRBs that will be localized with an accuracy of a few arcminutes 423 is of the order of 1-2 per month~\cite{GOTZ}. 424 \par 425 The IBAS alerts are sent via internet, using the UDP transport protocol. The Client Software 426 made available by \ig together with the first real alerts are currently being tested in Barcelona. 427 Five Alert Types have been defined so far~\cite{IBAS}: 428 \begin{description} 429 \item[POINTDIR] Gives the \ig pointing direction (e.g. to obtain reference images of the pre-GRB sky). No 430 alert is attached with this type. 431 \item[SPIACS] 432 SPIACS alert packets will be sent after positive triggers detected with the 433 SPI Anti-Coincidence Shield (ACS). No position information will be available, 434 unless the same GRB also triggers some of the imaging instruments 435 and in such a case the position will come through other packet types. 436 \item[WAKEUP] 437 WAKEUP packets are generated only once for each GRB 438 and only if the GRB position information is available. 439 They contain the preliminary position derived for the GRB. 440 These are the alerts with the shortest time delay. 441 Any (potential) GRB will generate only one WAKEUP packet. 442 \item[REFINED] 443 REFINED packets provide refined information on a GRB event. 444 Zero to several REFINED packets can be generated for a given GRB. 445 \item[OFFLINE] 446 OFFLINE packets are generated manually after interactive analysis of the data has been performed 447 offline by a Duty Scientist. 448 The time delay might be from one to a few hours (or even longer in some cases). 449 \end{description} 450 451 One \ig burst was delivered to the GCN up to now. It would have been visible 452 by \ma with a delay of about 1.5 hours (see table~\ref{tab:integraloverlap}). 453 454 \begin{table}[ht] 455 \begin{center} 456 {\small 457 \begin{tabular}{|c|c|c|c|c|c|c|c|c|c|} 458 \hline 459 \hline 460 GRB & date & UTC & RA & dec. & error & $\theta$ & $\phi$ & flag & comments\\ 461 name & (dd.mm)& & & & arc. & MA- & MA- & providing & \\ 462 & & & & & min. & GIC & GIC & position & \\ 463 \hline 464 GRB021125 & 25.11. & 17:58:30 & 19.78 & 28.1 & 30 & 51 & 280 & --- & no moon \\ 465 & & & & & & & & & $\theta$ and $\phi$ at 19:37:00 UTC \\ 466 \hline 467 \hline 468 \end{tabular} 469 } 470 \end{center} 471 \label{tab:integraloverlap} 472 \caption{\ig bursts, which would have been in principle visible from the \ma telescope site at 473 night. No burst durations, alert delays, weather conditions, etc. are displayed. For more 474 detailed information on single bursts, see~\cite{NICOLAGRB,GCNARCHIVE}.} 475 \end{table} 476 477 The period of the INTEGRAL orbit is 3 sideral days, 478 so that the perigee occurs always above the same geographical point on Earth. 479 480 %It is a highly eccentric orbit, 481 %with a perigee height of 10'000 km and 482 %an apogee height of 152'600 km 483 %with an inclination of 51.6 degrees with respect to the equatorial plane. 484 485 486 \section{\sw Alarms} 487 488 {\ldots \it \bf THIS IS TO BE UPDATED !! \ldots \\} 489 490 The \sw satellite~\cite{SWIFT} is scheduled for launch in May, 2004 for a nominal two-years mission. 491 \par 492 It contains three instruments: 493 \begin{description} 494 \item[BAT:\xspace] The BAT has an large field of view (1.4~sr) in an energy range of 15-150~keV. 495 It has an angular resolution of 22 arcmin. and is itself able to determine GRB source locations (of 496 5$\sigma$ or higher) to a resolution of 4 arcmin. It is predicted to locate more than 100 sources 497 per year. 498 \item[XRT:\xspace] The X-Ray Telescope on \sw provides afterglow positions of 5 arcsec. accuracy within 499 100 sec. of the burst alert from BAT in an energy range of 0.2-10~keV. 500 \item[UVOT:\xspace] 501 The UVOT is designed for optical images of the GRB field 20-60 sec. after the GRB alert and 502 in a wavelength range between 170 and 650~nm. 503 \end{description} 504 505 1--4 arcmin. position estimates of the GRB coordinates are predicted to arrive at ground within 506 15 seconds~\cite{SWIFT2}. 507 \par 508 \sw autonomously sends preliminary information to the GCN, including a crude optical finding chart 509 populated with postage stamp images around detected stars in UVOT, and BAT and XRT source positions 510 and spectra. Within hours of the next ground pass, the Swift Science Data Center (SDC) 511 initiates autonomous pipeline processing of the telemetry and serves it immediately 512 to the community on its Quick-Look area, available to the community (FITS-files). 513 514 \section{Further Possible Alarms} 515 516 \subsection{IPN position notices} 517 518 These notices are sent out by the GCN itself with GRB positions obtained 519 after triangulation of at least three satellites 520 using the individual arrival times and positions of the spacecrafts \he, \ig, 521 KONUS, NEAR, MARS and ULYSSES. 522 Usually, these messages arrive 523 after previous alerts by the satellites themselves and refine the GRB position determination. 524 525 There are two types of messages: 526 \begin{description} 527 \item[IPN\_SEG:\xspace] 528 These Notices use the data from two different spacecrafts. 529 Triangulation 530 yields an annulus for possible GRB positions. 531 The annulii segments are long (2-10deg) and narrow (2-30armin). 532 %yielding an error box area of 4 sq.arcmin to 5 sq.deg. 533 %The range of time delays is on average 24 to 48 hours (with the shortest being 11 hours to date). 534 These message will not be considered further here 535 because their position uncertainties are too large. 536 \item[IPN\_POS:\xspace] 537 For IPN\_POS Notices, the error boxes will be in the several arcmin and above range. 538 For about 55\% of the Notices there will be only a single error box, 539 but because 3 sources yield only 2 unique annuli and these 2 annuli cross in 2 locations, 540 there can be 2 error boxes reports (~25\% of the cases). 541 Depending on the relative timing of the GRB and the data dumps through the DSN, 542 the wait can be 1-25 hours (more on the weekends). 543 In 2002, 22 such messages were sent out with errors in the range of usually 544 5--30 arcmin. There were no messages before the May 5$^{th}$, however. 545 \end{description} 546 547 Only one burst would have been announced by an IPN\_POS in less than 12 hours after the burst 548 (see table~\ref{tab:ipnoverlap}). 549 550 \begin{table}[ht] 551 \label{tab:ipnoverlap} 552 \begin{center} 553 {\small 554 \begin{tabular}{|c|c|c|c|c|c|c|c|c|c|} 555 \hline 556 \hline 557 GRB & date & UTC & RA & dec. & error & $\theta$ & $\phi$ & flag & comments\\ 558 name & (dd.mm)& & & & arc. & MA- & MA- & providing & \\ 559 & & & & & min. & GIC & GIC & position & \\ 560 \hline 561 GRB021016 & 16.10. & 10:29:00 & 8.43 & 46.8 & 22 & 61 & 43 & IPN\_POS & 562 $\theta$ and $\phi$ at 22:06:48 UTC \\ 563 & & & & & & & & & moon at: \\ 564 & & & & & & & & & $\theta= 87^\circ, \phi=118^\circ$ \\ 565 \hline 566 \hline 567 \end{tabular} 568 } 569 \end{center} 570 \caption{\ip bursts, which would have been in principle visible from the \ma telescope site at 571 night. Only bursts which have been announced with less than 12 hours are taken into account. 572 No burst durations, weather conditions, etc. are displayed. For more 573 detailed information on single bursts, see~\cite{NICOLAGRB,GCNARCHIVE}.} 574 \end{table} 575 576 \section{Proposed Observation Strategies} 577 578 {\ldots \it \bf THIS IS TO BE UPDATED !! \ldots \\} 579 \par 580 One can see from tables~\ref{tab:heteoverlap},~\ref{tab:hetelongoverlap},~\ref{tab:integraloverlap} 581 and~\ref{tab:ipnoverlap} that observing GRBs 582 at moon periods will significantly increase the chance to observe some. 583 Three out of the seven bursts from table~\ref{tab:heteoverlap} 584 would have occurred in astronomical twilight 585 or very close to the start or end of observation 586 (GRB021113 half an hour after usual closing of the telescope and 587 GRB020127 and the one on 28.7. each three quarters of an hour after usual 588 start). If we want to have a realistic chance to observe bursts, it is therefore 589 important to use all available time {\it including moon periods, periods of astronomical 590 twilight and putting the telescope as soon as possible in GRB-alert position}. 591 592 \subsection{What to do at alerts without position (yet)} 593 594 {\ldots \it \bf THIS IS TO BE REWRITTEN !! \ldots \\} 595 596 \begin{verbatim} 597 suggestion email Martin Kestel: \\ 598 \\ 599 When you put the telescope in Alt=90 degrees (zenith) and Az=90 degrees east, 600 you have at most 90 degrees to move in either 601 axis in order to reach any position on the sky, either in normal tracking mode 602 or in reverse tracking mode. The actual speed will most probably be different 603 in the two axes and the elevation will probably be slower, as it has only one 604 motor attached. Now, the maximum elevation movement from zenith will 605 correspond to the maximum zenith angle you want your GRB to have, so, 606 this number will be certainly smaller than 90 degrees. 607 \end{verbatim} 608 609 \subsection{What to do at alerts with position} 610 611 612 \section{Timing considerations} 613 614 {\ldots \it \bf HAS TO BE UPDATED AND COMPLETED!! \ldots \\} 615 {\it Here, all possible models should go in with reasonning why certain time 616 or flux estimates are proposed. We have now only estimates on extrapolations 617 of the \eg power-laws. Maybe we should include: IC (in many possible combinations), 618 hadronic emission models (see~\cite{TASC}), Cannonball model. } 619 \par 620 621 The EGRET~\cite{EGRET} instrument on the CGRO 622 has detected GeV emission of GRB940217 promptly and 90 sec. after 623 the burst onset. 624 \\ 625 \par 626 In~\cite{DERMER}, two peaks in the GeV light curve are calculated. An early maximum coincident 627 with the MeV eak is the high-eneryg extension of the synchrotron component, some seconds 628 after the burst onset. The second maximum peaking at $\approx$ 1.5 hours is due primarily to 629 SSC radiation with significant emission of up to $10^5$ sec. ($\approx 25$ hours) after the burst. 630 \\ 631 \par 632 Li, Dai and Lu~\cite{LI} suggest GeV emission after pion production and some thermalization of the 633 UHE component with radiation maxima of up to one day or even one week (accompanied by long-term 634 neutrino emission). 101 102 635 103 636 104 \subsection{Determine a reasonable upper time delay limit for the onset of an observation} … … 670 138 671 139 {\ldots \it \bf STILL TO BE WRITTEN \ldots \\} 672 673 \subsection{Observing neutrino events below the horizon}674 675 {\ldots \it \bf CAN BE MAYBE GO INTO A SEPARATE PROPOSAL \ldots \\}676 140 677 141 \subsection{Observing XRFs}
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