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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').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"
  1. GRB040827: analysis of the XMM-Newton observation
  2. GRB040903, REM near-IR observation
  3. GRB 040903 - INTEGRAL data analysis
  4. IBAS Alert 1974. Not a real GRB
  5. Very bright burst detected from SGR 1806-20
  6. ROTSE-III Rapid Response to possible GRB 040903 (INTEGRAL #1972)
  7. Possible GRB 040903 - further analysis
  8. Possible GRB 040903 detected with INTEGRAL
  9. GRB 040827 - Radio Observations
  10. XMM-Newton Images of GRB 040827
  11. GRB040825A: Optical observations
  12. GRB040825A: Optical observations
  13. GRB 040827: optical and NIR observations at the VLT
  14. GRB 040827: UKIRT - 2nd epoch K-band imaging
  15. GRB 040827: 2nd epoch of Magellan K-band imaging
  16. GRB 040827: K imaging - no evidence of variability
  17. GRB 040827: Detection of NIR afterglow
  18. GRB 040827: Possible detection of optical afterglow
  19. GRB 040827: RTT150 optical observations
  20. GRB040827 XMM-Newton observation
  21. GRB040825A: optical limit before GRB
  22. MASTER: GRB040827 possible OT
  23. GRB 040825B: Optical observations
  24. GRB040827 optical observations
  25. GRB 040827 : Planned XMM-Newton observation
  26. GRB 040827 - Refined position
  27. GRB 040827 : peak flux
  28. GRB 040827 - A long GRB detected by INTEGRAL
  29. GRB040825B, BVRcIc field photometry
  30. GRB040825A, BVRcIc field photometry
  31. GCN GRB OBSERBATION REPORT
  32. GRB 040825A,optical observations
  33. Increase of SGR 1806-20 activity
  34. GRB040825A: optical observations
  35. GRB040825B: optical observations
  36. GRB040825B (=H3510): An XRF Localized in Real Time by HETE
  37. GRB 040825A: Optical observations.
  38. MASTER: GRB040825a optical observation
  39. MASTER: GRB040825b optical observation
  40. GRB040825B: Correction to GCN 2657
  41. GRB 040825: Optical observations
  42. XRF040812: possible afterglow second Chandra observation
  43. GRB 040812: Second epoch CXO Observations
  44. GRB040823,optical observation
  45. XRF040812: GMRT observations
  46. Triangulation of GRB 040816 (Konus-Wind - Helicon-Coronas-F)
  47. XRF 040812: optical observation at VLT
  48. GRB 040812: Optical counterparts of CXO sources
  49. XRF040812: possible afterglow
  50. CXO observation of GRB 040812
  51. Bursting activity from SGR 1806-20 detected with IBAS
  52. IPN/HETE localizations of GRB040810 (=H3489)
  53. GRB 040812: Keck and LCO optical observations
  54. GRB 040812: Keck and LCO observations
  55. GRB 040812: radio observations
  56. GRB040812, optical/IR observations
  57. Konus-Wind observation of GRB040810 (=H3489)
  58. GRB 040812: a long GRB detected by INTEGRAL
  59. GRB 040810: Optical observations of a limited region
  60. XRF040701: Optical Observations at ESO
  61. IPN/HETE triangulation of GRB040802 (=H3485)
  62. GRB 040730, infrared observations
  63. GRB 040730: Optical observations
  64. GRB 040730: a long GRB detected with INTEGRAL
  65. Ongoing activity of SGR 1806-20
  66. GRB040624: optical monitoring at TNG
  67. XRF 040701 - optical observations of the decaying Chandra source
  68. XRF040701: Second-Epoch Chandra Observations
  69. Cancellation of IBAS/INTEGRAL GRB alerts
  70. XRF040701: VLA Observations
  71. XRF040701: Magellan Spectroscopy of Chandra Source #2 Associated Galaxy
  72. XRF040701: First-Epoch Chandra Observations
  73. IBAS Alert 1836: NOT a real GRB
  74. GRB040709 J,H-band observations
  75. Subject: GRB040624, optical observations
  76. GRB040706:observation at University of Miyazaki
  77. XRF 040701, optical observations
  78. XRF040701 (=U11548): a bright XRF detected by HETE
  79. GRB 040624: optical observations
  80. Optical Observations of GRB040624
  81. GRB 040624: optical observations at TNG and VLT
  82. MASTER: GRB 040624 optical observation after 0,48d
  83. GRB 040624: R-band observations
  84. GRB 040624, optical observations
  85. GRB 040624 - A long GRB detected with INTEGRAL
  86. GRB 030329: Rebrightening of hyperluminal ejecta.
  87. IPN Summary of SGR1806-20 Activity in 2004
  88. GRB040511: Retraction of redshift identification
  89. SGR 1806-20: no IR variability of the proposed counterparts
  90. MASTER:HETE Alert 3259 (SRG1806-20) optical observation
  91. SGR 1806-20, potential NIR counterpart
  92. GRB 040606: Optical observations
  93. MASTER: HETE Alert 3274 optical observation
  94. Activivty of SGR 1806-20
  95. IPN triangulation of an intense intermediate burst from SGR1806-20
  96. GRB 040511, very fast decay?
  97. GRB 030324: Detection and Color of Host Galaxy
  98. GRB 040511: NIR observations with REM
  99. GRB040511: Redshift identifcation
  100. GRB 040511: Optical limit

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