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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"

23403 results found.

  1. short/hard GRB 050202, optical observations
  2. GRB050209: REM optical observations
  3. GRB 050209 I-band observation
  4. GRB 050209 Optical observations
  5. GRB050209: P60 Optical Observations
  6. GRB 050128: Radio observations
  7. GRB 050129: Optical observations
  8. GRB 050202: Short burst detected by Swift-BAT
  9. GRB 050128 Optical observation with REM
  10. GRB 050128: near-infrared observations with REM
  11. GRB050128,optical observations
  12. GRB050128 Swift-BAT observations
  13. GRB 050128: Swift XRT prompt afterglow position
  14. GRB050126: MASTER optical limit for KECK OT
  15. GRB050126: Burst Parameters Measured by BAT
  16. GRB050126: MASTER optical observations
  17. GRB050124: No Swift UVOT Detection of Afterglow Emission
  18. GRB 050124 I-band observation
  19. GRB050124,optical observation
  20. GRB050124: Updated Swift XRT Position and Fluxes
  21. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  22. GRB050124: Refined BAT position, spectral and fluence information
  23. GRB050124: Swift-BAT position of a double-peaked burst
  24. GRB 050123 : I-band follow-up observation
  25. GRB050123: optical limit 1.8h before GRB
  26. GRB050123,optical observation
  27. GRB 050123: KAIT observations
  28. CFHTLS optical transient unlikely to be a GRB
  29. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  30. GRB050117b: Swift-BAT detection of a weak burst
  31. GRB050117: MASTER optical observations
  32. MASTER:GRB050117 SWIFT
  33. GRB050117: Swift-BAT detection of a long multi-peaked burst
  34. GRB050117: Swift XRT Position
  35. Triangulation of Short Hard GRB050112 (large error box)
  36. SGR1806-20: Swift-BAT observations of two additional bursts
  37. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  38. Further VLA observations of SGR 1806-20
  39. SGR 1806-20 and extragalactic short-duration GRBs
  40. Further ATCA observations of SGR 1806-20
  41. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  42. SGR 1806-20, RHESSI observations of the 041227 giant flare
  43. Second-epoch VLA observations of SGR 1806-20
  44. SGR1806 VLA Observations
  45. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  46. GRB 041217: Optical observations
  47. GRB041228: ROTSE-III Optical Observations
  48. GRB041228: Swift-BAT detection of a burst
  49. GRB041219; RXTE ASM Observations
  50. GRB041226: ROTSE-III Optical Observations
  51. GRB041226: Swift-BAT detection of a burst
  52. GRB041223: decay of the afterglow
  53. GRB041224: ROTSE-III Optical Observations
  54. GRB 041224: near-infrared observations with REM
  55. GRB041224: Swift-BAT detection of a soft burst
  56. GRB041223: optical and NIR observations with REM
  57. GRB 041219: TAROT optical observations
  58. GRB 041218: TAROT optical observations
  59. GRB 041223: J-band observations of the afterglow
  60. GRB 041219c: PROMPT Observations
  61. GRB041223: ROTSE-III Optical Observations
  62. GRB041223: Swift-BAT detection of a bright long burst
  63. GRB 041218: optical observations
  64. GRB 041219 : optical follow-up observations
  65. GRB 041218 Optical Observations
  66. GRB041219: Continued NIR Observations
  67. GRB 041219 ,optical observation
  68. GRB 041219: Radio Afterglow Detection
  69. GRB 041218 : Radio Observations
  70. GRB 041218: R-band optical observations
  71. GRB041218: optical observations
  72. GRB041219: Confirmed NIR Afterglow
  73. Swift-BAT detection of the bright long burst GRB041219
  74. GRB 041219: Infrared Afterglow Candidate
  75. GRB041219, BVRcIc field calibration
  76. GRB 041219: Infrared Afterglow Candidate
  77. GRB041218, BVRcIc field calibration
  78. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  79. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  80. GRB 041217: PROMPT Observations
  81. GRB041217: optical limit 30 min after GRB
  82. GRB 041217: LCO40 Optical Observations and Possible Candidates
  83. GRB 041218 - A long GRB detected by integral
  84. GRB041217: NIR and optical observations with REM
  85. GRB041217: P60 Optical Observations
  86. GRB041217: Infrared Observations
  87. GRB041217: The First GRB Located On-Board Swift
  88. GRB041211: Faulkes Telescope continued optical monitoring
  89. Optical transient (GRB?) in Lynx
  90. GRB041211: RAPTOR observations
  91. GRB041211: Ashra Prototype optical observation
  92. GRB041211, BVRcIc field calibration
  93. GRB041211,optical observation
  94. GRB 041211: Infrared Observations
  95. GRB 041211: KAIT observations
  96. GRB 041211: Optical follow-up in East Asian region
  97. Triangulation of short GRB 041116 (large error box)
  98. GRB 040924: Afterglow Color
  99. GRB 041006: GETS Optical Afterglow Observation
  100. Summary of the recent bursts from SGR 1806-20

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