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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"

28054 results found.

  1. SGR 1806-20 and extragalactic short-duration GRBs
  2. Further ATCA observations of SGR 1806-20
  3. Fourth Epoch VLA observations of SGR 1806-20
  4. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  5. ATCA observations of SGR 1806-20
  6. SGR 1806-20, RHESSI observations of the 041227 giant flare
  7. Third epoch observations of SGR 1806-20 with VLA
  8. Second Epoch VLA observations of SGR 1806-20
  9. Second-epoch VLA observations of SGR 1806-20
  10. SGR1806 VLA Observations
  11. SGR1806-20: RXTE-PCA observation of the 041227 super-flare
  12. GRB 041217: Optical observations
  13. GRB041228: Swift-BAT detection of a burst
  14. GRB041219; RXTE ASM Observations
  15. NIR Observations of GRB 041219
  16. GRB041226: Swift-BAT detection of a burst
  17. GRB041223: decay of the afterglow
  18. GRB 041224: near-infrared observations with REM
  19. GRB 041223 Fluence measured by Swift-BAT
  20. GRB041223: optical and NIR observations with REM
  21. Swift-BAT Time History of GRB041219
  22. GRB 041219: TAROT optical observations
  23. GRB 041218: TAROT optical observations
  24. GRB 041223: J-band observations of the afterglow
  25. GRB 041219c: PROMPT Observations
  26. GRB041223: Swift-BAT detection of a bright long burst
  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. GRB041219: Continued NIR Observations
  32. GRB 041219 ,optical observation
  33. GRB 041219: Radio Afterglow Detection
  34. GRB 041218 : Radio Observations
  35. GRB 041218: R-band optical observations
  36. GRB041218: optical observations
  37. GRB041219: Confirmed NIR Afterglow
  38. Swift-BAT detection of the bright long burst GRB041219
  39. GRB 041219: Infrared Afterglow Candidate
  40. GRB041219, BVRcIc field calibration
  41. GRB 041219: Infrared Afterglow Candidate
  42. GRB041218, BVRcIc field calibration
  43. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  44. GRB 041219 - A long GRB detected by INTEGRAL
  45. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  46. GRB 041217: PROMPT Observations
  47. GRB 041217: LCO40 Optical Observations and Possible Candidates
  48. GRB 041218 - A long GRB detected by integral
  49. GRB041217: NIR and optical observations with REM
  50. GRB041217: Infrared Observations
  51. GRB041217: The First GRB Located On-Board Swift
  52. GRB041211: Faulkes Telescope continued optical monitoring
  53. Optical Transient in Lynx not a GRB
  54. Optical transient (GRB?) in Lynx
  55. GRB041211: RAPTOR observations
  56. GRB041211: Ashra Prototype optical observation
  57. GRB041211, BVRcIc field calibration
  58. GRB041211,optical observation
  59. GRB 041211: Infrared Observations
  60. GRB 041211: KAIT observations
  61. GRB 041211: Optical follow-up in East Asian region
  62. Triangulation of short GRB 041116 (large error box)
  63. GRB 040924: Afterglow Color
  64. GRB 041006: GETS Optical Afterglow Observation
  65. Summary of the recent bursts from SGR 1806-20
  66. GRB 041006: Optical Observations
  67. GRB041006, late-time optical photometry
  68. GRB041006: RTT150 Optical Observations
  69. HST Observations: XRF 040701 and 040812
  70. Bright bursts from SGR1806-20
  71. GRB 041016: BOOTES-2 simultaneous observation
  72. GRB041006: RTT150 Optical Observations
  73. GRB041016,optical observation
  74. GRB 041016: Optical limits
  75. GRB 041016:Optical limit during first minute
  76. GRB 041015: Optical Observations at Rikubetsu
  77. GRB 041016: Optical limit
  78. GRB 041015 R band observations
  79. GRB040924, BVRcIc field calibration
  80. GRB041015,optical observation
  81. GRB041006: Fading X-ray Afterglow Observed with Chandra
  82. GRB 041015 - A long GRB detected by INTEGRAL
  83. GRB041006: VLT observations of the afterglow and host galaxy
  84. GRB041006: Optical observations and Potential host galaxy
  85. GRB041006, BVRcIc field calibration
  86. GRB 040924: VLT spectroscopy
  87. GRB 041006: SARA afterglow observations
  88. GRB041006, optical observation in CrAO
  89. Search for SN light in XRF 040912 with MEGACAM
  90. GRB 041006: BR observations with VATT
  91. GRB 041006: Redshift confirmed
  92. GRB 041006: Radio Observations
  93. GRB 041006 : optical follow-up observation at Lulin Observatory
  94. GRB041006: Optical photometry and spectroscopy at TNG
  95. GRB 041006: presice astrometry
  96. GRB041006, optical I observation
  97. GRB041006 (=HETE3570): optical observations
  98. ROTSE-IIIa Observations of GRB 041006
  99. GRB041006: MASTER optical observations
  100. GRB041006,optical observation

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