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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"

21467 results found.

  1. GRB 070107: Possible UVOT Afterglow
  2. GRB 070107, Swift-BAT refined analysis
  3. GRB 070107: Swift/XRT position
  4. GRB 070107: Swift detection of a burst
  5. VLA observation of GRB 061222B
  6. VLA detection of GRB 061222A
  7. GRB070103: APO SPIcam i' and z' limits
  8. GRB070103: KPNO 4m+FLAMINGOS J limit
  9. GRB 070103: Swift/UVOT Upper limits
  10. GRB070103: Swift XRT refined analysis
  11. GRB 070103, Swift-BAT refined analysis
  12. GRB 070103: TAROT Calern observatory optical observations
  13. GRB 070103: Swift detection of a burst
  14. Retractions of previous Swift-BAT triggers
  15. GRB061222a: optical observations
  16. Konus-Wind observation of GRB 061222A
  17. GRB 061210: Swift/XRT Astrometry Correction
  18. GRB 050826: MDM Redshift
  19. GRB 061222A: MITSuME Akeno optical upper limits
  20. GRB 061222A: Gemini Afterglow Candidate
  21. GRB 061222B, Swift-BAT refined analysis
  22. GRB061222A Swift/UVOT: Upper Limits
  23. GRB 061222B: Swift/UVOT Upper limits
  24. GRB061222B: Swift-XRT Refined Analysis
  25. GRB 061222A: Observation with the KANATA 1.5m telescope
  26. GRB 061222B: BOOTES-IR optical observations
  27. GRB 061222B: SARA upper limit
  28. GRB 061222A: Swift-XRT refined analysis
  29. GRB 061222A, Swift-BAT refined analysis
  30. GRB 061222B: TAROT La Silla observatory optical observations
  31. GRB 061222B: Swift detection of a burst
  32. GRB 061222b: optical afterglow
  33. GRB 061222A: Prompt ROTSE-III Optical Limits
  34. GRB 061222: Swift detection of a burst
  35. GRB 061217: Astrometry-Corrected XRT Position
  36. GRB 061217: Confirmation of host candidate
  37. GRB 061217: Object ib GCN 5948 is a star
  38. GRB 061217: Extended object in the revised XRT error circle
  39. GRB 061217, Candidate host galaxy
  40. GRB 061217 - Swift/XRT position correction
  41. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  42. GRB 061218: TAROT La Silla observatory optical observations
  43. GRB 061217: TAROT Calern observatory optical observations
  44. GRB 061218, Swift-BAT refined analysis
  45. GRB061217: VLT NIR observations
  46. Swift triggers (#251863) on a possible burst
  47. GRB061217: Swift/UVOT refined analysis.
  48. GRB 061217: optical observations at Calar Alto
  49. GRB061217 - Swift/XRT refined analysis
  50. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  51. GRB 061217, Swift-BAT refined analysis
  52. GRB 061217: ROTSE-III Optical Limits
  53. GRB 061217: Swift detection of a short hard burst
  54. GRB 061210: MDM Follow-up Observation
  55. GRB061210: Swift/UVOT observations
  56. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  57. GRB 061210: Optical sources near XRT positions
  58. GRB 061210: Swift XRT analysis - Possible counterparts
  59. GRB 061210 : Faulkes North Telescope optical limit
  60. GRB 061214(?): ROTSE-III Optical Limits
  61. GRB 061214(?): Swift detection of a possible burst
  62. Swift/BAT trigger #250033 is due to a known source during loss of
  63. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  64. GRB 061213: MASTER-VWF-Kislovodsk observations
  65. GRB 061210: MDM Observation
  66. GRB 061210, Swift-BAT refined analysis of the SHB
  67. GRB 061210: Swift-BAT detection of a short burst
  68. Optical Afterglow observations of GRB 061126
  69. GRB 060926: MASTER: discovery of the optical flare
  70. GRB061126: update on the Swift-XRT afterglow light curve
  71. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  72. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  73. GRB061126 : NMSU 1.0m observations
  74. GRB 061202: Swift XRT refined analysis
  75. GRB061202: FRAM early follow-up limit
  76. GRB061202 optical limit by "Pi of the Sky"
  77. Konus-Wind observation of GRB 061201
  78. GRB061202: optical/NIR observations with REM
  79. GRB061202: Swift/UVOT Upper Limits
  80. GRB 061202, Swift-BAT refined analysis
  81. GRB 061202: Swift detection of a burst
  82. GRB 061201: Swift XRT Team refined analysis
  83. GRB 061201: VLT optical observations
  84. GRB 061201: Initial UVOT Observations
  85. GRB 061201, Swift-BAT refined analysis of the SHB
  86. GRB 061201: Swift detection of a short hard burst
  87. GRB 061201: Coincidence with a Galaxy Cluster
  88. GRB 061126: RAPTOR Optical Detection During Gamma-Ray Emission
  89. Swift XRT on-board boresight update
  90. GRB 061126: Early Super-LOTIS Observations
  91. GRB061126: Optical afterglow observations from MIRO
  92. GRB061126: Optical afterglow observations from MIRO
  93. GRB 061126: Swift-XRT refined analysis
  94. GRB 061126: Swift/UVOT Observations
  95. GRB 061126, Swift-BAT refined analysis
  96. GRB 061126: Faulkes Telescope North Optical Observations
  97. GRB 061126: Swift/UVOT Afterglow Detection
  98. GRB 061126: XRT position
  99. GRB 061126: Swift detection of a burst
  100. GRB 061122: Confirmation of X-ray/Optical Afterglow

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