Gamma-ray Burst 090217

(All information courtesy of the instrument teams.)

Previous IAU Circulars

• none

• GCN Circular #8902
  A. von Kienlin (MPE) reports on behalf of the Fermi GBM Team:
  "At 04:56:42.56 UT on 17 February 2009, the Fermi Gamma-Ray Burst Monitor triggered and located GRB 090217 (trigger 256539404/ 090217206).
  The on-ground calculated location, using the GBM trigger data, is RA = 211.9, DEC = -2.8 (J2000 degrees, equivalent to 14h 08m, -02d 48'), with an uncertainty of 1.0 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which is currently estimated to be 2 to 3 degrees).
  The angle from the Fermi LAT boresight is 34 degrees.
  This burst was also independently detected by INTEGRAL SPI-ACS.
  The GBM light curve shows one major structured peak with a duration (T90) of about 32.8 s (8-1000 keV) and (T50) of about 4.6 s (8-1000 keV). The time-averaged spectrum from T0+0.003 s to T0+19.584 s is well fit by a power law function with an exponential high energy cutoff. The power law index is -0.85 +/- 0.02 and the cutoff energy, parameterized as Epeak, is 626 +/- 29 keV (chi squared 631.30 for 482 d.o.f.).
  The event fluence (8-1000 keV) in this time interval is (3.08 +/- 0.03)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+6.272 s in the 8-1000 keV band is 11.2 +/- 0.3 ph/s/cm^2.
  A Band function fits the spectrum equally well (chi squared 629.43 for 481d.o.f.) with Epeak= 610 +/- 32 keV, alpha = -0.845 +/- 0.023 and beta = -2.86 +/- 0.36.
  The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog."
• GCN Circular #8903
  Masanori Ohno(ISAS/JAXA), Julie McEnery(NASA/GSFC), and Veronique Pelassa(CNRS/IN2P3/LPTA) report on behalf of the Fermi LAT team:
  We report a detection by the Fermi Large Area Telescope of emission from a GRB at 04:56:51 UT with detection significance of more than 5 sigma. This burst is spatially and temporally correlated with a GBM detected burst (trigger 256539404, GCN 8902).
  This burst was found in a blind search in the LAT data, and also independently by follow up studies around the GBM location. The emission continues for up to 20 seconds after the GBM trigger, but commences several seconds after the GBM trigger.
  The best LAT on-ground localization is found to be (RA,Dec=204.9, -8.4) with a 90% containment radius of 0.52 deg (statistical; 68% containment radius: 0.36 deg).
  Further analysis is ongoing.
  The Fermi LAT point of contact for this burst is Masanori Ohno (ohno@astro.isas.jaxa.jp)
  The Fermi LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. This message can be cited.
• GCN Circular #8905
  I. G. Mitrofanov, D. Golovin, M. L. Litvak, and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,
  W. Boynton, C. Fellows, K. Harshman, C. Shinohara and R. Starr, on behalf of the GRS-Odyssey GRB team,
  S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team,
  K. Yamaoka, M. Ohno, Y. Fukazawa, T. Takahashi, M. Tashiro, Y. Terada, T. Murakami, K. Makishima, and Y. Hanabata on behalf of the Suzaku-WAM te= am,
  A. von Kienlin, G. Lichti, and A. Rau, on behalf of the INTEGRAL SPI-ACS and GRB team, and K. Hurley, on behalf of the INTEGRAL=20 SPI-ACS and Odyssey GRB teams, report:
  Suzaku-WAM, Konus-Wind, INTEGRAL-SPI-ACS, and Mars Odyssey observed the=20 long GRB 090217 at about 04:56:42 UT (corresponding to the Fermi/GBM trigger 256539404/ 090217206: von Kienlin, GCN 8902; also detected by=20 Fermi/LAT: Ohno et al., GCN 8903).
  The burst light curve shows a multipeaked structure with a total=20 duration of ~40 sec.
  Triangulation gives a MO-Konus annulus centered at RA(2000)=3D132.322 (08= h=20 49m 17s) Dec(2000)=3D+18.838 (+18d 50' 18"), whose radius is 76.132 +/-=20 0.104 deg (3 sigma), and a Konus-WAM annulus centered at=20 RA(2000)=3D135.708 (09h 02m 50s) Dec(2000)=3D+21.300 (+21d 17' 59"), whos= e=20 radius is 73.641 =B1 0.941 deg (3sigma). These annuli intersect at grazin= g=20 incidence to form two long error boxes, one of which may be eliminated=20 by the Konus ecliptic latitude response. The resulting error box has the coordinates:

  -----------------------------------------------------
        RA(2000), deg              Dec(2000), deg
  -----------------------------------------------------
  Center:
    204.865 (13h 39m 28s)    -7.442 (-07d 26' 31")
  Corners:
    212.234 (14h 08m 56s)   +13.782 (+13d 46' 57")
    199.337 (13h 17m 21s)   -19.856 (-19d 51' 21")
    197.625 (13h 10m 30s)   -22.539 (-22d 32' 21")
    210.398 (14h 01m 36s)   + 8.568 (+08d 34' 06")
  -----------------------------------------------------
  

  The error box area is 7.2 sq. deg. This box may be improved.
  The box is consistent with the LAT location (Ohno et al., GCN 8903). The center line of the MO-Konus annulus passes 0.385 degrees from the center of the Fermi/LAT error circle, and the annulus intersects the 90% containment error circle at:

  -----------------------------------------------------
         RA(2000), deg         Dec(2000), deg
  -----------------------------------------------------
    204.800 (13h 39m 12s)    -7.890 (-07d 53' 22")
    204.505 (13h 38m 01s)    -8.057 (-08d 03' 24")
    204.471 (13h 37m 53s)    -8.701 (-08d 42' 04")
    204.375 (13h 37m 30s)    -8.379 (-08d 22' 45")
  ----------------------------------------------------
  

  The K-W light curve of this GRB and IPN triangulation map is available at http://www.ioffe.ru/LEA/GRBs/GRB090217_T17804/
• GCN Circular #8906
  S. Golenetskii, R.Aptekar, E. Mazets, V. Pal'shin, D. Frederiks, P. Oleynik, M. Ulanov, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, report:
  The long GRB 090217 (Fermi/GBM trigger 256539404/ 090217206: von Kienlin, GCN 8902) localized by Fermi/LAT (Ohno et al., GCN 8903) and IPN (Mitrofanov et al., GCN 8905) triggered Konus-Wind at T0=17804.799 s UT (04:56:44.799) .
  As observed by Konus-Wind the burst had a fluence of 3.13(-0.30, +0.35)x10^-5 erg/cm2, and a 256-ms peak flux measured from T0+4.592 s of 4.72(-0.81, +0.86)x10^-6 erg/cm2/s (both in the 20 keV - 4 MeV energy range).
  The time-integrated spectrum of the burst (from T0 to T0+24.832 s) is well fitted (in the 20 keV - 4 MeV range) by a power law with exponential cutoff model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.87(-0.14, +0.15), and Ep = 534(-78, +105) keV (chi2 = 71.5/73 dof). Fitting by GRB (Band) model yields: the low-energy photon index alpha = -0.80(-0.16, +0.18), the high energy photon index beta < -2.19, the peak energy Ep = 480(-82, +120) keV (chi2 = 70.0/72 dof).
  All the quoted errors are at the 90% confidence level.
• GCN Circular #8907
  O. Godet (U. Leicester) on behalf the Swift-XRT team
  The Swift-XRT started observing the field of GRB090217 (GCN Circ. 8903) 39ks after the LAT trigger (T0) using an early LAT position (RA,Dec (J2000) = 204.436 deg, -8.858 deg and a 90% confidence error radius of 0.454 deg) which is 39 arcmin away from that quoted in Ohno et al. (GCN Circ. 8903).
  We analysed 7.5ks of Photon Counting (PC) data collected from T0+39ks to T0+62.8ks. The LAT error circle is larger than the XRT field of view. Three X-ray sources with a signal-to-noise ratio larger than 3 were found at (J2000):
  S1: RA, Dec, err = 13 37 18.11, -08 45 28.5, 5.5 arcsec
  S2: RA, Dec, err = 13 37 40.35 -09 01 29.7, 4.5 arcsec
  S3: RA, Dec, err = 13 37 39.49 -09 02 26.6, 4.4 arcsec
  The XRT error radii are quoted at 90% confidence level.
  The position S3 is consistent with the AGN HE 1335-0847 previously detected by ROSAT. The position S2 is consistent with that of a star from the USNO-B1 catalog, while the position S1 is 6.7 arcsec away from a USNO-B1 source.
  The data for S1 and S2 are too sparse to check for any variability during the observation. Nevertheless, none of these sources are likely to be the X-ray afterglow of GRB 090217.
  This is an official product of the Swift-XRT team.
• GCN Circular #8908
  Y. Hanabata, Y. Fukazawa, T. Takahashi, T. Uehara, C. Kira (HiroshimaU.), Y. Terada, M. Tashiro, Y. Urata, A. Endo, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), M. Ohno, M. Kokubun, M. Suzuki, T. Takahashi (ISAS/JAXA), K. Yamaoka, S. Sugita (Aoyama Gakuin U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), Y.E. Nakagawa, T. Tamagawa (RIKEN), E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono, H. Hayashi (Univ. of Miyazaki), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech), on behalf of the Suzaku WAM team, report:
  The bright, long Fermi-LAT detected GRB 090217 (Fermi-GBM trigger #256539404 ; von Kielin et al., GCN 8902; Fermi-LAT detection ; Ohno et al., ; GCN 8903) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 04:56:42.98 UT (=T0). The observed light curve shows a multi-peaked structure starting at T0-3s, ending at T0+19s with a duration (T90) of about 14 seconds. The fluence in 100 - 1000 keV was 1.56(+0.05,-0.09)x10^-5 erg/cm^2. The 1-s peak flux measured from T0+7s was 3.0 (+0.2,-0.3) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-3s to T0+20s is well fitted by a power-law with exponential cutoff model:

   dN/dE ~  E^{-alpha} * exp(-(2-alpha)*E/Epeak) with
   alpha       0.81(+0.26,-0.31), and
   Epeak       780(+187,-126) keV (chi^2/d.o.f. = 41.0/24).
  

  The GRB Band model also gives a good fit with only an upper limit on the high-energy photon index as follows:
  the low-energy photon index alpha: -0.75(+0.50,-0.28), the high-energy photon index beta: < -2.33, and the peak energy Epeak: 748(+195,-175) keV (chi^2/d.o.f = 40.4/23).
  Please note that this GRB comes from the WAM 2 on-axis direction, which has a large uncertaintiy only in absolute flux. All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included.
  The light curves for this burst will be available soon at:
  http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html
• 1002.0228 from 2 Feb 10
  Masanori Ohno et al.: Fermi-LAT observations of GRBs with weak LAT emission
  We present the analysis results of three Gamma-Ray Bursts (GRBs) detected by the Gamma-ray Burst Monitor (GBM) and the Large Area Telescope (LAT) onboard Fermi: the two long GRB 080825C and GRB 090217, and the first short burst with GeV photons GRB 081024B. The emission from GRB 081024B observed by the LAT above 100 MeV is delayed with respect to the GBM trigger, and significantly extends after the low-energy episode. Some hints for spectral hardening was observed in this burst as well as in GRB 080825C, possibly related to a separate and harder component showing up at late times. Conversely, GRB 090217 does not exhibit any noticeable feature. Together with the other bright LAT detected bursts (e.g. GRB 080916C and GRB 090510), these observations help to classify the GRB properties and give new insight on the acceleration mechanisms responsible for their emission at the highest energies.