Soft Gamma Repeater 1627-41

This SGR was discovered with BATSE....

Previous IAU Circulars

• IAUC 6944 BATSE detection of 3 bursts on June 15, 1998
• IAUC 6945 BeppoSAX detection of two bursts on June 17/18, 1998
• IAUC 6948 BATSE Earth-occultaion and Ulysses IPN location; SNR G337.0-0.1
• IAUC 6950 RXTE/ASM detection of 3 bursts consistent with G337.0-0.1 location
• IAUC 6956 Corrigendum for >IAUC 6950
• IAUC 6962 RXTE/PCA detection of 1 burst on June 26
• IAUC 6966 Ulysses/Konus-Wind triangulation of 7 events

• astro-ph/9909334 Corbel etal: The Distance to the Soft Gamma Repeater SGR 1627-41
• astro-ph/9909355 Hurley etal: ASCA Observation of the quiescent X-ray counterpart to SGR1627-41
• ApJ 526 (1999) L29

• GCN notice #107
  C. Kouveliotou, Universities Space Research Association, M. Kippen, P. Woods, G. Richardson, University of Alabama in Huntsville, V. Connaughton, National Research Council, report on behalf of the BATSE team at NASA/Marshall Space Flight Center:
  BATSE has detected repeated soft gamma-ray bursts consistent with the same (previously unknown) location. We recorded three bursts on June 15.109, 15.296, 15.411 UT (BATSE triggers 6825, 6826, 6827, respectively) with an average duration of ~ 200 milliseconds. Preliminary spectral analysis of the data indicates that the events are very soft, with power law spectral indices varying between -3.0 and -7.0. BATSE triggered 5 more times, on June 17.873, 17.901, 18.004, 18.035, and 18.071 UT (BATSE trigger numbers 6833, 6834, 6835, 6836 and 6837, respectively). The last trigger had a peak count rate of over 300000 counts/sec above background (integrated over 4 detectors between 20-1000 keV, in 1 second interval) and a duration of ~ 3 seconds. Due to its very high peak intensity, deadtime effects prevent us from using it for localization, until we receive more data types. The weighted location of the 7 remaining triggers is centered on R.A. = 16h27m12.0s and dec = -41d06.0' with an error radius of about 2 degrees. This location does not correspond to any previously known SGR source; we conclude that we have discovered a new source, SGR1627-41. We have initiated an RXTE ToO and we strongly encourage wide field observations at other wavelengths.
• GCN notice #110
  K. Hurley, Space Sciences Laboratory, on behalf of the Ulysses Gamma-Ray Burst Team and C. Kouveliotou, Universities Space Research Association, on behalf of the Gamma-Ray Observatory BATSE team, report: "This soft gamma repeater (IAUC 6944) has been observed by Ulysses. Triangulation gives a preliminary annulus whose center is at (equinox 2000.0) R.A. = 22h01m40s, Decl. = -10o09'.8, and whose radius is 76.771 +/- 0.05 deg. This annulus intersects the BATSE error circle and forms an error box with an area of approximately 1700 sq. arcmin. Further refinement of this position is possible. An image may be found at http://ssl.berkeley.edu/ipn3/sgr1627-41/"
• GCN notice #111
  M. Feroci, E. Costa, L. Amati, L. Piro and B. Martino, Istituto di Astrofisica Spaziale (CNR, Rome), L. Di Ciolo and A. Coletta, BeppoSAX Science Operation Center (Rome), F. Frontera, Istituto Tecnologie e Studio Radiazioni Extraterrestri (CNR, Bologna), report:
  "The Gamma Ray Burst Monitor (GRBM) onboard BeppoSAX has detected bursts from a direction consistent with the new Soft Gamma-ray Repeater SGR1627-41 (Kouveliotou et al., GCN #107 and IAUC 6944). Two events were triggered on June 17.90091 (consistent with BATSE trigger n. 6834) and 18.15556. The duration of the events is about 90 and 40 milliseconds respectively. The spectral index, assuming a power law function, is (3.0+/-0.3) and (2.5+/-0.3) respectively in the 40-700 keV energy band. These detections are in agreement with those reported by BATSE and with the harder energy range of the GRBM. Data analysis is in progress to find out other bursts from the same source."
• GCN notice #113
  P. Woods, M. Kippen, Jan van Paradijs, University of Alabama in Huntsvile, C. Kouveliotou, M. McCollough, Universities Space Research Association, K. Hurley, Space Sciences Laboratory, report: " BATSE Earth limb considerations limit the possible position of this SGR to declinations along the IPN annulus reported in GCN # 110, which are between -43 and -49 degrees. This is slightly outside the BATSE 1 sigma error circle reported in GCN # 107. However, due to the soft spectrum of the source systematic errors were larger than usual. A preliminary search through the MOST SNR catalog (Whiteoak and Green, A&A Suppl. Ser. 118, 329, 1996) reveals only one candidate within the error box reported here, G337.0-0.1. The peculiar nothermal structure core reported for G337.0-0.1 is entirely within the IPN annulus width. We strongly encourage follow-up observations of the SNR source.
• GCN notice #115
  K. Hurley, Space Sciences Laboratory, on behalf of the Ulysses Gamma-Ray Burst Team and C. Kouveliotou, USRA, M. Kippen, P. Woods, UAH, on behalf of the Gamma-Ray Observatory BATSE team, report:
  "We have obtained a refined IPN annulus for this soft gamma repeater (IAUC 6944 and GCN 110). Its center is at (equinox 2000.0) R.A. = 22h01m40s, Decl. = -10o09'.8, and its radius is 76.769 +/- 0.028 deg. This annulus is contained within the previous one. Considerable further refinement of this position is possible. An image may be found at http://ssl.berkeley.edu/ipn3/sgr1627-41/
• GCN notice #116
  D. A. Smith and A. M. Levine, on behalf of the RXTE/ASM teams at MIT and NASA/GSFC, report:
  "Although the ASM did not observe any of the BATSE-detected events from SGR 1627-41, during the interval from Jun 15 to Jun 19, three short (<~1 s) burst events were detected in SSC 3 at May 17.943917, 17.954243, and 18.010803 (UTC). During the first event, the original BATSE location (GCN 107) was outside the FOV of the ASM. The full width of the FOV of SSC 3 during the first event restricts the range of declination values along the IPN annulus (GCN 115) between -44.4 and -56.4 degrees. This is fully consistent with the revised BATSE position reported in GCN 113. Due to low signal-to-noise, our standard cross-correlation technique was unable to isolate these events in our position data, but given the IPN annulus, we were able to search along it for a best-fit location. We find a minimum reduced chi-squared at R.A. = 16h35m50s, Decl.= -47o32' for event 1 and R.A. = 16h35m50s, Decl.= -47o39' for event 2 (1-sigma error of 4' in Decl. in both cases). Both positions are consistent with the location of the SNR (g337.0-0.1) mentioned in GCN 113. If we assume these bursts are coming from SNR G337.0-0.1, we can use its location to measure the burst fluxes:

  Event           Fluence                 Peak Flux (2-12 keV)
                  (10^{-7} erg/cm^2)      (10^{-7} erg/cm^2/s)
          1.5-3    3-5    5-12 kev        (1-s averages)
  1       <0.6    <0.4    2.1 (+- 0.3)            1.1
  2       <0.8    <0.4    2.9 (+- 0.5)            2.8 

  Upper limits are 2-sigma. We do not yet have pointing information for the observation of the third burst."
• GCN notice #121
  D. A. Frail, National Radio Astronomy Observatory and S. R. Kulkarni, California Institute of Technology report:
  The recent renewed activity from SGR1900+14 (GCN #94) and the newly-discovered SGR1627-41 (GCN #107) prompted VLA radio observations at 8.46 GHz on 1998 June 25. For SGR1900+14 we observed a field centered on the proposed X-ray/infrared counterpart (Hurley et al. ApJ, 463, L13, 1996, Vrba et al. ApJ, 468, 225, 1996). For SGR1627-41 we observed the 95 arcsec diameter supernova remnant CTB33 (IAU Circ. 6948), most recently studied by Sarma, Goss, Green & Frail (ApJ, 483, 335, 1997). The synthesized beam was approximately 1 arcsec. The interferometer is insensitive to extended structure on angular scales larger than 20 arcsec. No point sources were visible above 200 microJy and 345 microJy (4-sigma) for the SGR1900+14 and SGR1627-41, respectively. These interferometer observations are less sensitive to angular scales larger than 20 arcsec.
• GCN notice #122
  K. Hurley, Space Sciences Laboratory, T. Cline, P. Butterworth, NASA GSFC, E. Mazets and S. Golenetskii, Ioffe Institute, on behalf of the Ulysses and Konus-Wind teams, report: "We have triangulated the position of this soft gamma repeater using 7 Konus-Ulysses events between 17 and 22 June. A typical annulus has a center at (equinox 2000.0) R.A.=22h03m04s, Decl.=-9o49'.8, and a radius 77.247 +/- 0.013 degrees. Around the position of the supernova remnant G337.0-0.1, this annulus nests within the one reported previously (IAUC 6948), but is considerably narrower. Around this position, the 7 annuli give results which are mutually consistent to better than 10 arcseconds. The positions of the annuli suggest that if the source of the bursts is indeed within the SNR, it lies between the two radio lobes. An image may be found at http://ssl.berkeley.edu/ipn3/sgr1627-41/. These preliminary annuli can be refined further."