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Example Analysis of a MAGIC GRB Observation at CALP

Example Analysis of a MAGIC GRB Observation at CALP. Markus Gaug (IAC Tenerife). Introduction. Gamma Ray Burst observations can happen at any time during the night (incl. during twilight) and at any zenith angle up to 60 deg.

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Example Analysis of a MAGIC GRB Observation at CALP

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  1. Example Analysis of a MAGIC GRB Observation at CALP Markus Gaug(IAC Tenerife)

  2. Introduction Gamma Ray Burst observations can happen at any time during the night (incl. during twilight) and at any zenith angle up to 60 deg. Observation conditions can cover everything from dark night to clouds and/or moon light and/or twilight. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  3. Introduction Expected signals can be fast (up to variations <1 s) and/or slow (emission during >1 h). VHE gamma-ray emission can be correlated with -ray, X-ray or optical emission peaks or not! Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  4. Introduction The earlier the telescope observes, the higher the chance to catch a signal. For this reason, MAGIC observes fully automatically in GRB observation mode, even if the quality of the observation could improve by adjusting the telescope to the conditions found at the new sky position. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  5. Introduction Multi-wavelength observations are triggered by GCN circulars to which also MAGIC sends reports. The reports by MAGIC should arrive as soon as possible, at best within days. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  6. Introduction For this reason, an automatic analysis has been set up at CALP (Centro Astrofisica en La Palma) - to which all members of the GRB WG have access. The analysis consists of the MARS analysis software, with the inclusion of the mtemp/mgrb directory and a couple of perl-scripts found in the mtemp/mcalp directory of MARS. This documentation was obtained with Mars_V1-7-13. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  7. Introduction • The GRB data is usually calibrated at the Roque on the muxana machine. The data are transferred to CALP automatically via a permanent link to: /datm1/magic/INCOMING/YYYY_MM_DD/ • The automatic analysis takes these data and copies them to: /datm1/magic/GRB/GRBYYMMDD/Calibrated • From there, star files, melibea files, celestina output and upper limits are created. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  8. Introduction • An OFF database has been created at CALP: /datm1/magic/OFFData/PSF_XXmm • A MC database can be found at: /datm1/magic/MonteCarlo/M1/PSF_XX.Xmm • All RF and DISP matrices have been produced for all zenith angle ranges: /datm1/magic/OFFData/PSF_XXmm/Theta_XX_YY/NoMoon/RandomForest/ • Two standard image cleanings are used so far: ”Abs” and “Diego” (at PIC the corresping names are:“notime” and “time”)

  9. Introduction This presentation should be used as a manual to run and understand the automatic analysis. As exemplary data the especially difficult to analyze data of GRB071112C was used. The analysis was launched (automatically) via: $MARSSYS/mtemp/mcalp/analyze <GRB> <author> e.g.: $MARSSYS/mtemp/mcalp/analyze GRB071112C Gaug Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  10. Introduction The automatic analysis will do everything including a draft for an analysis report and a GCN circular. However you have to check every step for correctness and complete the analysis report. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  11. Introduction PLEASE DO NOT RUN THE ANALYSIS ON ALREADY ANALYZED GRB DATA! IT MIGHT OVERWRITE EXISTING DATA…. INSTEAD APPOINT YOURSELF AS A BURST ADVOCATE AND TRY OUT A NEW BURST Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  12. Introduction For further information about the (general) analysis framework MARS, see: http://magic.pic.es/wiki In case of problems with anything related to the GRB analysis, do not hesitate to contact Markus Gaug (markus@iac.es) At the beginning, this will be the normal case… Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  13. The Data Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  14. The Data • We start our example analysis with the output of the star-files of GRB01112C, runs 299332-299437 • Additionally the star file from run 299331 (last file from previous run taken before this burst occurred) has been used to calculate the reaction times Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  15. STAR Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  16. The output of STAR The STAR program can be run with the following script: $MARSSYS/mtemp/mcalp/runstar.pl <GRBname> <cleaning> (this script is launched automatically by the analyze program, with the cleanings “Abs” and “Diego”) STAR removes spurious noise from the night sky (image cleaning) and calculates suitable parameters of the remaining camera images. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  17. The star.root file We check first the output of star: showplot/datm1/magic/GRB/GRB071112C/Star/Star_Diego/star.root or showplot/datm1/magic/GRB/GRB071112C/Star/Star_Abs/star.root Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  18. The star.root file Increase in event rate after 10 min. of data. A GRB? Short period with no events Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  19. The star.root file A closer look reveals 3 peak in event rate… Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  20. The star.root file [2007-11-12 19:44:06] We have a GRB alert. We follow the established procedure and contact Daniel Kranich in order to modify the schedule. Nicola Galante contacts us also to inform about the nature of this GRB. [2007-11-12 20:20:33] Car flashes in runs number 299343, 299344 and 299345. We have a look in that nights runbook available at:http://magic.pic.es/datacenter/CCdata/2007_11/2007_11_13/CC_2007_11_12_18_07_50.rbk Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  21. The star.root file The gap in obs. time occurs during 4.5 minutes Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  22. The star.root file [2007-11-12 21:46:13] We stop GRB datataking in order to restart it and take pedestal and calibration files, as suggented by Markus Garcz. We also set extragalactic DT. We continue observing. We have again a look in that nights runbook available at:http://magic.pic.es/datacenter/CCdata/2007_11/2007_11_13/CC_2007_11_12_18_07_50.rbk Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  23. The star.root file Several drops in rate Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  24. The star.root file Generally, rate increases with time showing two more peaks right after observation gap Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  25. The star.root file Before the observation gap: Moon Discriminator thresholds After the observation gap: NoMoon Discriminator thresholds Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  26. The star.root file -------------------------------------------------------------------- Source Kind Time Evts Rate Zd HD-spc (min) (Hz) (deg) (GB) -------------------------------------------------------------------- 0851+202-W0.40+000 59 772k 218 10->30 43.1 0851+202-W0.40+180 72 972k 224 8->33 54.3 Crab-SUM 81 3983k 822 7->22 222.5 GRB071112-18 158 1557k 165 22->57 87.0 GRB071112-18 Moon 12 100k 137 57->59 5.6 We have again a look in that nights runbook available at:http://magic.pic.es/datacenter/CCdata/2007_11/2007_11_13/CC_2007_11_12_18_07_50.rbk Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  27. The star.root file Mean event rate >100 Hz: OK Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  28. Conclusions from the rate plots • At the beginning the moon was still shining and therefore the operators had “moon” discriminator thresholds (DTs) set. These DTs are too high for normal data taking resulting in a low rate. --> take into account for efficiency correction of the upper limits • After two hours, the shifters stopped the observation to take a pedestal and calibration run, and reset the DTs to correct (lower) values. --> From that time on the efficiency correction becomes smaller • 3 car flashes and 3 (not understood) smaller increases in rate --> At these times, be careful with patterns in the light curve • 3 drops in event rate are found --> have to check if clouds are responsible

  29. The star.root file Number of correctly focused mirrors must always be on thereference line (otherwise this analysis is not valid!) Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  30. The star.root file There are also clusters with NO signal : If these were inner pixels, we could not analyze these data without special MonteCarlo!!! Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  31. The star.root file We see clusters with much higher signal than other pixels Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  32. The star.root file In the plot with “Used pixels”, the clusters of excess signal have disappeared. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  33. Conclusions from the camera plots • Two clusters of not working outer pixels are found. Fortunately, only outer pixels are affected… --> take into account for efficiency correction of the upper limits • Three clusters of pixels with high average signal are found, however the pixels are not part of an image more frequently --> From experience we know that these are pixels sparking at a rate of ~1 Hz. A dedicated spark-cut is used later in the analysis, however this cut is not 100% efficient. --> If at the end of the analysis, more events in these regions are found, be careful Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  34. The star.root file Correlated with the decrease of discriminator thresholds the inhomogeneity of the camera response becomes better. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  35. The star.root file Correlated with the car flashes, the image reconstruction efficiency becomes worse (car flash events are above all very small events). Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  36. The star.root file Number of photo-electrons plot should follow a power-law with low- and high-energy cutoffs. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  37. The star.root file Distance of shower center from center of camera should rise linearly until end of trigger region Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  38. The star.root file Distribution of center of gravity should be uniform in azimuth (--> strong inhomogeneity here!) Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  39. The star.root file Distribution of Alpha parameter should be flat (--> strong inhomogeneity here!) Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  40. The star.root file Distribution of number of core pixels should show a power law with cut-off (--> tail of events with many core pixels found!) Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  41. Conclusions from the Hillas parameters • Strong inhomogeneity of the camera has been found, above all in the first part of the observation with high DT values --> take into account for efficiency correction of the upper limits • The distribution of core pixels show a not expected tail at high numbers of core pixels --> We will investigate this now Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  42. Test of the strange distribution of variable MImagePar.fNumSinglePixels: • We go to the Star directory of GRB071112C: > cd /datb/magic/GRB/GRB071112C/Star • We start ROOT: > root • We load the MARS library: > .x $MARSSYS/macros/rootlogon.C • We create a TChain object: > TChain *c = new TChain(“Events”); • We load the GRB data: > c->Add(“2007*.root”); • We check if files have been loaded: > c->GetEntries(); > (const Long64_t)1098087 • We draw the variable over time: > c->Draw("MImagePar.fNumSinglePixels:MTime.fTime.fMilliSec/1000.","MImagePar.fNumSinglePixels>5",”colz”) The output ----> Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  43. Checking variable MImagePar.fNumSinglePixels High values coincide with the car flashes, for the moment nothing to worry about the rest of data… Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  44. The star.root file The cloudiness parameter (blue line) is generally very high and sometimes > 50% Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  45. The star.root file Very clear anti-correlations of cloudiness with event rate are visible. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  46. Conclusions from the Pyrometer plots It seems that the sky was cloudy over some periods We cannot produce a reasonable upper limit in the cases when the cloudiness was >50%. We simply do not know at which height the clouds were and therefore do not know anything about the absorption of gamma-ray showers! Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  47. MELIBEA Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  48. The output of MELIBEA The MELIBEA program can be run with the following script: $MARSSYS/mtemp/mcalp/runmelibea.pl <GRBname> <cleaning> <PSF> 0 (this script is launched automatically by the analyze program, with the cleanings “Diego” and “Abs” and a corresponding simulated point-spread-function (PSF) for MC images (typically “10.6mm”). The “0” stands for ON/OFF observation) MELIBEA performs an energy reconstruction, makes an estimate of the arrival direction (the DISP) and calculates a hadronness parameter for each event. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  49. The output of MELIBEA MELIBEA stores also the distribution of pointing offsets, obtained from the starguider. The runmelibea.pl scripts will use this distribution to apply the same pointing offsets to OFF data in a second melibea loop. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

  50. The melibea.root files If the zenith angle range is large, the automatic analysis will: • remove runs with average cloudiness > 50%. • split the data into parts which match reasonable zenith angles ranges with MC zbins. • select MC azimuth angles which minimize the differences of the effects of geomagnetic field between MC and ON data. Example Analysis of a MAGIC GRB Observation Markus Gaug MAGIC GRB meeting, La Palma, 6. December 2007

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