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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"
  1. GRB 061210: Swift/XRT Astrometry Correction
  2. GRB 050826: MDM Redshift
  3. GRB 061222B: TAROT La Silla observatory early optical observations
  4. GRB 061218: TAROT La Silla observatory early optical observations
  5. GRB 061222A: MITSuME Akeno optical upper limits
  6. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  7. GRB 061222B: MITSuME Akeno optical upper limits
  8. GRB 061222A: Xinglong Optical Limit
  9. GRB 061222A: Gemini Afterglow Candidate
  10. GRB 061222B, Swift-BAT refined analysis
  11. GRB061222A Swift/UVOT: Upper Limits
  12. GRB 061222B: Swift/UVOT Upper limits
  13. GRB 061222B: Observation with the KANATA 1.5m telescope
  14. GRB061222B: Swift-XRT Refined Analysis
  15. GRB 061222A: Observation with the KANATA 1.5m telescope
  16. GRB 061222B: BOOTES-IR optical observations
  17. GRB 061222B: SARA upper limit
  18. GRB 061222A: Swift-XRT refined analysis
  19. GRB 061217: Magellan host galaxy redshift
  20. GRB 061222A, Swift-BAT refined analysis
  21. GRB 061222B: REM NIR/optical observations
  22. GRB 061222b: Refined redshift
  23. GRB 061222b, SMARTS optical/IR afterglow observations
  24. GRB 061222B: TAROT La Silla observatory afterglow observation
  25. GRB 061222B: TAROT La Silla observatory optical observations
  26. GRB 061222b: Magellan redshift
  27. GRB 061222B: Swift detection of a burst
  28. GRB 061222b: optical afterglow
  29. GRB 061222A: Prompt ROTSE-III Optical Limits
  30. GRB 061222: Swift detection of a burst
  31. GRB 061217: Astrometry-Corrected XRT Position
  32. GRB 061201: Magellan redshift of nearby galaxy
  33. GRB 061217: Confirmation of host candidate
  34. GRB 061217: Object ib GCN 5948 is a star
  35. GRB 061217: Extended object in the revised XRT error circle
  36. GRB 061217, Candidate host galaxy
  37. GRB 061217 - Swift/XRT position correction
  38. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  39. GRB 061201: Correction to GCN 5944
  40. GRB 061201: Magellan Redshift of nearby Abell cluster
  41. GRB 061218: TAROT La Silla observatory optical observations
  42. GRB 061217: TAROT Calern observatory optical observations
  43. GRB 061218: TORTOREM optical upper limits
  44. GRB 061218, Swift-BAT refined analysis
  45. GRB061217: VLT NIR observations
  46. GRB 061218, SMARTS optical/IR observations
  47. GRB 061218: REM prompt observations
  48. Swift triggers (#251863) on a possible burst
  49. GRB 061217, SMARTS optical observations
  50. GRB061217: Swift/UVOT refined analysis.
  51. GRB 061217: optical observations at Calar Alto
  52. GRB061217 - Swift/XRT refined analysis
  53. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  54. GRB 061217, Swift-BAT refined analysis
  55. GRB 061217: Magellan Observations
  56. GRB 061217: REM prompt observations
  57. GRB 061217: ROTSE-III Optical Limits
  58. GRB 061217: Swift detection of a short hard burst
  59. GRB 061210: MDM Follow-up Observation
  60. GRB061210: Swift/UVOT observations
  61. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  62. GRB 061210: Optical sources near XRT positions
  63. GRB 061210: Swift XRT analysis - Possible counterparts
  64. GRB 061210 : Faulkes North Telescope optical limit
  65. GRB 061214(?): ROTSE-III Optical Limits
  66. GRB 061214(?): Swift detection of a possible burst
  67. GRB 061210: Suzaku WAM observation of the prompt emission
  68. Swift/BAT trigger #250033 is due to a known source during loss of
  69. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  70. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  71. GRB 061213: MASTER-VWF-Kislovodsk observations
  72. GRB 061210: Gemini/GMOS Observations
  73. GRB 061126: Radio Observations
  74. GRB061210: Radio Observations
  75. GRB061201, VLT optical decay: correction
  76. GRB 061126: a GRB detected off-axis by INTEGRAL
  77. GRB 061202: Suzaku WAM observation of the prompt emission
  78. GRB 061210: MDM Observation
  79. GRB 061210, Swift-BAT refined analysis of the SHB
  80. GRB 061210: Swift-BAT detection of a short burst
  81. Optical Afterglow observations of GRB 061126
  82. GRB061126: optical observations
  83. GRB 060926: MASTER: discovery of the optical flare
  84. GRB061126: update on the Swift-XRT afterglow light curve
  85. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  86. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  87. GRB 061202: TORTOREM optical upper limits
  88. GRB 061201: VLT optical decay
  89. GRB 061201: SOAR Confirmation of Candidate Afterglow
  90. GRB061126 : NMSU 1.0m observations
  91. GRB 061202: Swift XRT refined analysis
  92. GRB061202: FRAM early follow-up limit
  93. GRB061202 optical limit by "Pi of the Sky"
  94. Konus-Wind observation of GRB 061201
  95. GRB061202: optical/NIR observations with REM
  96. GRB061202: Swift/UVOT Upper Limits
  97. GRB 061202, Swift-BAT refined analysis
  98. GRB 061202: Swift detection of a burst
  99. GRB 061201: Swift XRT Team refined analysis
  100. GRB 061201: VLT optical observations

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