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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
  1. GRB 040812: Second epoch CXO Observations
  2. GRB040823,optical observation
  3. XRF040812: GMRT observations
  4. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  5. XRF 040812: optical observation at VLT
  6. GRB 040812: Optical counterparts of CXO sources
  7. XRF040812: possible afterglow
  8. CXO observation of GRB 040812
  9. Bursting activity from SGR 1806-20 detected with IBAS
  10. IPN/HETE localizations of GRB040810 (=H3489)
  11. GRB 040812: Keck and LCO optical observations
  12. GRB 040812: Keck and LCO observations
  13. GRB 040812: radio observations
  14. GRB040812, optical/IR observations
  15. Konus-Wind observation of GRB040810 (=H3489)
  16. GRB 040812: a long GRB detected by INTEGRAL
  17. GRB 040810: Optical observations of a limited region
  18. XRF040701: Optical Observations at ESO
  19. IPN/HETE triangulation of GRB040802 (=H3485)
  20. GRB 040730, infrared observations
  21. GRB 040730: Optical observations
  22. GRB 040730: a long GRB detected with INTEGRAL
  23. Ongoing activity of SGR 1806-20
  24. GRB040624: optical monitoring at TNG
  25. XRF 040701 - optical observations of the decaying Chandra source
  26. XRF040701: Second-Epoch Chandra Observations
  27. Cancellation of IBAS/INTEGRAL GRB alerts
  28. XRF040701: VLA Observations
  29. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  30. XRF040701: First-Epoch Chandra Observations
  31. IBAS Alert 1836: NOT a real GRB
  32. GRB040709 J,H-band observations
  33. Subject: GRB040624, optical observations
  34. GRB040706:observation at University of Miyazaki
  35. XRF 040701, optical observations
  36. XRF040701 (=U11548): a bright XRF detected by HETE
  37. GRB 040624: optical observations
  38. Optical Observations of GRB040624
  39. GRB 040624: optical observations at TNG and VLT
  40. MASTER: GRB 040624 optical observation after 0,48d
  41. GRB 040624: R-band observations
  42. GRB 040624, optical observations
  43. GRB 040624 - A long GRB detected with INTEGRAL
  44. GRB 030329: Rebrightening of hyperluminal ejecta.
  45. IPN Summary of SGR1806-20 Activity in 2004
  46. GRB040511: Retraction of redshift identification
  47. SGR 1806-20: no IR variability of the proposed counterparts
  48. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  49. SGR 1806-20, potential NIR counterpart
  50. GRB 040606: Optical observations
  51. MASTER: HETE Alert 3274 optical observation
  52. Activivty of SGR 1806-20
  53. IPN triangulation of an intense intermediate burst from SGR1806-20
  54. GRB 040511, very fast decay?
  55. GRB 030324: Detection and Color of Host Galaxy
  56. GRB 040511: NIR observations with REM
  57. GRB040511: Redshift identifcation
  58. GRB 040511: Optical limit
  59. GRB040511: Candidate optical/NIR afterglow
  60. IBAS GRB Alerts n.1785 to 1791
  61. GRB 040511: ROTSE-III Rapid Optical Upper Limits
  62. GRB 040511: Second Epoch Optical Observations
  63. IBAS GRB Alerts 1781-4
  64. GRB 040511: Optical observations
  65. GRB 040511: Optical Observations
  66. GRB040511: Optical Observations
  67. GRB040511: Optical Observations
  68. GRB040511 (=H3218): A Long GRB Localized by HETE WXM and SXC
  69. IBAS GRB Alert number 1774: NOT a real GRB
  70. Type Ic SN2001em (off-axis GRB jet?), optical spectrum
  71. IBAS Alerts 1771 and 1772: NOT a real GRB
  72. GRB and XRF on April 27, 2004. Detection by Konus-Wind and Helicon (Coronas-F)
  73. IPN triangulation of GRB040425 (=H3183)
  74. On Line Availability of Archival HETE Fregate Data and Lightcurves
  75. GRB040422: optical observations at Xinglong Observatory
  76. GRB040422: optical observations at CrAO
  77. GRB 040423 (=H3175): A Long GRB Localized by HETE
  78. GRB040422, optical observations at Loiano
  79. GRB040422 : I-band follow-up observation at Lulin Observatory
  80. GRB 040422: ROTSE-IIIb Prompt Optical Limits
  81. GRB040422, BVRcIc field calibration
  82. GRB 040422,optical observation
  83. GRB040422: optical and NIR observations at the VLT
  84. GRB 040422: a long GRB detected with INTEGRAL
  85. GRB 040403, deep optical observations
  86. MASTER: HETE Alert 3163, 3167 technical optical observation
  87. INTEGRAL-SPI/ACS GRB data: timing correction
  88. IBAS GRB alerts 1739, 1740, 1741
  89. HETE/IPN localization of GRB040403A (=H3143, a long burst) and GRB040403B(=H3144, a short/hard burst)
  90. GRB 040403: Optical Observations
  91. GRB 040403 Optical Observations
  92. GRB 040403: Optical observations
  93. GRB 040403: optical observations
  94. GRB 040403: Optical Observations
  95. GRB 040403: a long GRB detected with INTEGRAL
  96. Summary of recent bursts from SGR 1806-20 detected by INTEGRAL
  97. GRB 040329: hard burst detected by Konus-Wind and Helicon - Coronas-F
  98. IBAS GRB Alert 1694
  99. GRB040323: NIR Observations and Variable Object
  100. GRB 040319 (=H3128): An X-Ray-Rich GRB Localized by the HETE-2 WXM and SXC

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