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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. GRB070103: KPNO 4m+FLAMINGOS J limit
  2. GRB 070103: Swift/UVOT Upper limits
  3. GRB070103: Swift XRT refined analysis
  4. GRB 070103, Swift-BAT refined analysis
  5. GRB 070103: NOT observations
  6. GRB 070103: TAROT Calern observatory optical observations
  7. GRB 070103: Swift detection of a burst
  8. Retractions of previous Swift-BAT triggers
  9. GRB061222a: optical observations
  10. erratum : SDSS Pre-burst Observations of GRB061126
  11. Konus-Wind observation of GRB 061222A
  12. GRB 061210: Swift/XRT Astrometry Correction
  13. GRB 050826: MDM Redshift
  14. GRB 061222B: TAROT La Silla observatory early optical observations
  15. GRB 061218: TAROT La Silla observatory early optical observations
  16. GRB 061222A: MITSuME Akeno optical upper limits
  17. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  18. GRB 061222B: MITSuME Akeno optical upper limits
  19. GRB 061222A: Xinglong Optical Limit
  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. GRB 061222B: Observation with the KANATA 1.5m telescope
  25. GRB061222B: Swift-XRT Refined Analysis
  26. GRB 061222A: Observation with the KANATA 1.5m telescope
  27. GRB 061222B: BOOTES-IR optical observations
  28. GRB 061222B: SARA upper limit
  29. GRB 061222A: Swift-XRT refined analysis
  30. GRB 061217: Magellan host galaxy redshift
  31. GRB 061222A, Swift-BAT refined analysis
  32. GRB 061222B: REM NIR/optical observations
  33. GRB 061222b: Refined redshift
  34. GRB 061222b, SMARTS optical/IR afterglow observations
  35. GRB 061222B: TAROT La Silla observatory afterglow observation
  36. GRB 061222B: TAROT La Silla observatory optical observations
  37. GRB 061222b: Magellan redshift
  38. GRB 061222B: Swift detection of a burst
  39. GRB 061222b: optical afterglow
  40. GRB 061222A: Prompt ROTSE-III Optical Limits
  41. GRB 061222: Swift detection of a burst
  42. GRB 061217: Astrometry-Corrected XRT Position
  43. GRB 061201: Magellan redshift of nearby galaxy
  44. GRB 061217: Confirmation of host candidate
  45. GRB 061217: Object ib GCN 5948 is a star
  46. GRB 061217: Extended object in the revised XRT error circle
  47. GRB 061217, Candidate host galaxy
  48. GRB 061217 - Swift/XRT position correction
  49. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  50. GRB 061201: Correction to GCN 5944
  51. GRB 061201: Magellan Redshift of nearby Abell cluster
  52. GRB 061218: TAROT La Silla observatory optical observations
  53. GRB 061217: TAROT Calern observatory optical observations
  54. GRB 061218: TORTOREM optical upper limits
  55. GRB 061218, Swift-BAT refined analysis
  56. GRB061217: VLT NIR observations
  57. GRB 061218, SMARTS optical/IR observations
  58. GRB 061218: REM prompt observations
  59. Swift triggers (#251863) on a possible burst
  60. GRB 061217, SMARTS optical observations
  61. GRB061217: Swift/UVOT refined analysis.
  62. GRB 061217: optical observations at Calar Alto
  63. GRB061217 - Swift/XRT refined analysis
  64. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  65. GRB 061217, Swift-BAT refined analysis
  66. GRB 061217: Magellan Observations
  67. GRB 061217: REM prompt observations
  68. GRB 061217: ROTSE-III Optical Limits
  69. GRB 061217: Swift detection of a short hard burst
  70. GRB 061210: MDM Follow-up Observation
  71. GRB061210: Swift/UVOT observations
  72. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  73. GRB 061210: Optical sources near XRT positions
  74. GRB 061210: Swift XRT analysis - Possible counterparts
  75. GRB 061210 : Faulkes North Telescope optical limit
  76. GRB 061214(?): ROTSE-III Optical Limits
  77. GRB 061214(?): Swift detection of a possible burst
  78. GRB 061210: Suzaku WAM observation of the prompt emission
  79. Swift/BAT trigger #250033 is due to a known source during loss of
  80. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  81. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  82. GRB 061213: MASTER-VWF-Kislovodsk observations
  83. GRB 061210: Gemini/GMOS Observations
  84. GRB 061126: Radio Observations
  85. GRB061210: Radio Observations
  86. GRB061201, VLT optical decay: correction
  87. GRB 061126: a GRB detected off-axis by INTEGRAL
  88. GRB 061202: Suzaku WAM observation of the prompt emission
  89. GRB 061210: MDM Observation
  90. GRB 061210, Swift-BAT refined analysis of the SHB
  91. GRB 061210: Swift-BAT detection of a short burst
  92. Optical Afterglow observations of GRB 061126
  93. GRB061126: optical observations
  94. GRB 060926: MASTER: discovery of the optical flare
  95. GRB061126: update on the Swift-XRT afterglow light curve
  96. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  97. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  98. GRB 061202: TORTOREM optical upper limits
  99. GRB 061201: VLT optical decay
  100. GRB 061201: SOAR Confirmation of Candidate Afterglow

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