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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"

36180 results found.

  1. GRB050128 Swift-BAT observations
  2. GRB 050128: Swift XRT prompt afterglow position
  3. GRB 050124: K-band afterglow observations
  4. GRB050126: MASTER optical limit for KECK OT
  5. GRB050126: MASTER optical observations
  6. GRB 050126: Detection of NIR afterglow with Keck/NIRC
  7. GRB 050126: Prompt XRT detection and localization
  8. GRB 050124: NIR afterglow confirmed with Keck/NIRC
  9. GRB 050124, SMARTS optical/IR observations
  10. GRB 050117a: Radio Observations
  11. GRB 050124 I-band observation
  12. GRB 050124: NIR Candidates from Keck/NIRC
  13. GRB050124,optical observation
  14. GRB 050124 : Lulin R-band follow-up observation
  15. GRB 050124: Swift XRT Detection of X-ray Afterglow Emission
  16. GRB 050123 : I-band follow-up observation
  17. GRB050123: optical limit 1.8h before GRB
  18. GRB050123,optical observation
  19. GRB 050123: KAIT observations
  20. GRB050123: P60 Observations
  21. GRB 050123(=H3666): A GRB Localized in Real Time by HETE
  22. CFHTLS optical transient unlikely to be a GRB
  23. Unusual optical transient (GRB ???)
  24. GRB050117a: Radio Observations
  25. GRB 041224 and GRB 041226: BOOTES-2 simultaneous observations
  26. GRB 050117, I-band observations
  27. GRB 050117: Optical observation
  28. GRB050117: Refined XRT position
  29. GRB050117: MASTER optical observations
  30. MASTER:GRB050117 SWIFT
  31. GRB050117: Swift-BAT detection of a long multi-peaked burst
  32. Triangulation of Short Hard GRB050112 (large error box)
  33. SGR1806: Optical Transient Candidates in SOHO/LASCO Images
  34. SGR 1806-20 and extragalactic short-duration GRBs
  35. SGR 1806-20: Low frequency GMRT results; submission to GCN circulars
  36. SGR 1806-20: Temporal and Spectral behavior of radio transient
  37. SGR 1806-20, RHESSI observations of the 041227 giant flare
  38. SGR1806: Detection of a Sudden Ionospheric Disturbance
  39. GRB 041217: Optical observations
  40. GRB041219, early time observations
  41. IPN localization of giant flare from SGR1806-20
  42. GRB041219; RXTE ASM Observations
  43. NIR Observations of GRB 041219
  44. GRB041223: decay of the afterglow
  45. GRB 041224: near-infrared observations with REM
  46. GRB 041223: XRT afterglow spectrum and light curve
  47. GRB 041223 Fluence measured by Swift-BAT
  48. GRB041223: optical and NIR observations with REM
  49. GRB 041219: TAROT optical observations
  50. GRB 041218: TAROT optical observations
  51. GRB 041223: J-band observations of the afterglow
  52. GRB 041223: Detection of Optical Transient with LCO40
  53. GRB 041219c: PROMPT Observations
  54. GRB 041218: optical observations
  55. GRB 041219: Second Epoch WSRT Radio Observations
  56. GRB 041219: WSRT Radio Afterglow Detection
  57. GRB 041219: Keck IR Observations and Astrometric Refinement of the
  58. GRB 041218: Optical observations
  59. GRB 041219 : optical follow-up observations
  60. Deep RAPTOR observations during GRB 041219
  61. GRB 041218 Optical Observations
  62. GRB 041219 Optical Observations
  63. GRB041219c: Third Burst in One Day from Swift-BAT
  64. GRB041219: Optical Afterglow Detection
  65. GRB041219: Continued NIR Observations
  66. GRB 041219 ,optical observation
  67. GRB 041219: Radio Afterglow Detection
  68. GRB 041218 : Radio Observations
  69. GRB 041218: R-band optical observations
  70. GRB041219: Confirmed NIR Afterglow
  71. GRB041218: Continued P60 Optical Observations
  72. GRB 041218: Optical Observation
  73. GRB 041219: Infrared Afterglow Candidate
  74. GRB041219, BVRcIc field calibration
  75. GRB 041219: Infrared Afterglow Candidate
  76. GRB041218, BVRcIc field calibration
  77. GRB041219: Prompt Optical Observations from ROTSE-IIIb
  78. GRB041219: P60 Optical Observations
  79. GRB 041219 - A long GRB detected by INTEGRAL
  80. GRB 041219: PAIRITEL IR Observations, < 3 minutes after trigger
  81. GRB 041217: PROMPT Observations
  82. GRB041218: optical observations
  83. GRB041217: optical limit 30 min after GRB
  84. GRB 041218; optical candidate
  85. GRB 041218: Optical observations
  86. GRB 041217: LCO40 Optical Observations and Possible Candidates
  87. GRB 041218 - A long GRB detected by integral
  88. GRB041217: Optical Observations
  89. GRB041217: P60 Optical Observations
  90. GRB041217: Infrared Observations
  91. GRB041217: The First GRB Located On-Board Swift
  92. GRB041211: Faulkes Telescope continued optical monitoring
  93. Optical Transient in Lynx not a GRB
  94. Optical transient (GRB?) in Lynx
  95. Optical transient (GRB?) in Lynx, UT Dec 11.4436
  96. GRB041211: Continued P60 Observations
  97. GRB041211: RAPTOR observations
  98. GRB041211: Ashra Prototype optical observation
  99. GRB041211, Faulkes Telescope optical observation
  100. GRB041211, BVRcIc field calibration

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