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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"

36149 results found.

  1. Triangulation of Short Hard GRB050112 (large error box)
  2. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  3. SGR 1806-20 and extragalactic short-duration GRBs
  4. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  5. SGR 1806-20: Temporal and Spectral behavior of radio transient
  6. SGR 1806-20, RHESSI observations of the 041227 giant flare
  7. SGR1806: Detection of a Sudden Ionospheric Disturbance
  8. GRB 041217: Optical observations
  9. GRB041219, early time observations
  10. IPN localization of giant flare from SGR1806-20
  11. GRB041219; RXTE ASM Observations
  12. NIR Observations of GRB 041219
  13. GRB041223: decay of the afterglow
  14. GRB 041224: near-infrared observations with REM
  15. GRB 041223: XRT afterglow spectrum and light curve
  16. GRB 041223 Fluence measured by Swift-BAT
  17. GRB041223: optical and NIR observations with REM
  18. GRB 041219: TAROT optical observations
  19. GRB 041218: TAROT optical observations
  20. GRB 041223: J-band observations of the afterglow
  21. GRB 041223: Detection of Optical Transient with LCO40
  22. GRB 041219c: PROMPT Observations
  23. GRB 041218: optical observations
  24. GRB 041219: Second Epoch WSRT Radio Observations
  25. GRB 041219: WSRT Radio Afterglow Detection
  26. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  27. GRB 041218: Optical observations
  28. GRB 041219 : optical follow-up observations
  29. Deep RAPTOR observations during GRB 041219
  30. GRB 041218 Optical Observations
  31. GRB 041219 Optical Observations
  32. GRB041219c: Third Burst in One Day from Swift-BAT
  33. GRB041219: Optical Afterglow Detection
  34. GRB041219: Continued NIR Observations
  35. GRB 041219 ,optical observation
  36. GRB 041219: Radio Afterglow Detection
  37. GRB 041218 : Radio Observations
  38. GRB 041218: R-band optical observations
  39. GRB041219: Confirmed NIR Afterglow
  40. GRB041218: Continued P60 Optical Observations
  41. GRB 041218: Optical Observation
  42. GRB 041219: Infrared Afterglow Candidate
  43. GRB041219, BVRcIc field calibration
  44. GRB 041219: Infrared Afterglow Candidate
  45. GRB041218, BVRcIc field calibration
  46. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  47. GRB041219: P60 Optical Observations
  48. GRB 041219 - A long GRB detected by INTEGRAL
  49. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  50. GRB 041217: PROMPT Observations
  51. GRB041218: optical observations
  52. GRB041217: optical limit 30 min after GRB
  53. GRB 041218; optical candidate
  54. GRB 041218: Optical observations
  55. GRB 041217: LCO40 Optical Observations and Possible Candidates
  56. GRB 041218 - A long GRB detected by integral
  57. GRB041217: Optical Observations
  58. GRB041217: P60 Optical Observations
  59. GRB041217: Infrared Observations
  60. GRB041217: The First GRB Located On-Board Swift
  61. GRB041211: Faulkes Telescope continued optical monitoring
  62. Optical Transient in Lynx not a GRB
  63. Optical transient (GRB?) in Lynx
  64. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  65. GRB041211: Continued P60 Observations
  66. GRB041211: RAPTOR observations
  67. GRB041211: Ashra Prototype optical observation
  68. GRB041211, Faulkes Telescope optical observation
  69. GRB041211, BVRcIc field calibration
  70. GRB 041211: Infrared Observations
  71. GRB 041211: KAIT observations
  72. GRB 041211: Optical follow-up in East Asian region
  73. GRB 041211(=H3622): A Long GRB Localized by the HETE WXM and SXC
  74. GRB041211: P60 optical imaging
  75. GRB970815: Discovery of Optical Afterglow
  76. Distribution of IBAS Alerts for NON-GRB sources
  77. Triangulation of short GRB 041116 (large error box)
  78. GRB 040924: Afterglow Color
  79. GRB 041006: GETS Optical Afterglow Observation
  80. Summary of the recent bursts from SGR 1806-20
  81. GRB 041006: Optical Observations
  82. GRB041006, late-time optical photometry
  83. IBAS GRB Alert # 2034
  84. GRB041006: RTT150 Optical Observations
  85. Bright bursts from SGR1806-20
  86. GRB 041016: BOOTES-2 simultaneous observation
  87. GRB041006: RTT150 Optical Observations
  88. GRB 041016: Optical limits
  89. GRB 041016: Optical limits in V, R, I
  90. GRB 041016:Optical limit during first minute
  91. GRB041016: MASTER: Optical observations
  92. GRB 041015: Optical Observations at Rikubetsu
  93. GRB041006: Near Infrared observations
  94. GRB 041016: Optical limit
  95. GRB 041015 R band observations
  96. GRB040924, BVRcIc field calibration
  97. GRB041015: MASTER: Optical observations
  98. GRB041015,optical observation
  99. GRB 041015: Optical limit at Osaka University
  100. GRB041015 : Optical follow-up at Kiso

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