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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 070107, Swift-BAT refined analysis
  2. GRB 070107: Swift/XRT position
  3. GRB 070107: Swift detection of a burst
  4. VLA observation of GRB 061222B
  5. VLA detection of GRB 061222A
  6. GRB070103: APO SPIcam i' and z' limits
  7. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  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: NOT observations
  13. GRB 070103: TAROT Calern observatory optical observations
  14. GRB 070103: Swift detection of a burst
  15. Retractions of previous Swift-BAT triggers
  16. GRB061222a: optical observations
  17. erratum : SDSS Pre-burst Observations of GRB061126
  18. Konus-Wind observation of GRB 061222A
  19. GRB 061210: Swift/XRT Astrometry Correction
  20. GRB 050826: MDM Redshift
  21. GRB 061222B: TAROT La Silla observatory early optical observations
  22. GRB 061218: TAROT La Silla observatory early optical observations
  23. GRB 061222A: MITSuME Akeno optical upper limits
  24. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  25. GRB 061222B: MITSuME Akeno optical upper limits
  26. GRB 061222A: Xinglong Optical Limit
  27. GRB 061222A: Gemini Afterglow Candidate
  28. GRB 061222B, Swift-BAT refined analysis
  29. GRB061222A Swift/UVOT: Upper Limits
  30. GRB 061222B: Swift/UVOT Upper limits
  31. GRB 061222B: Observation with the KANATA 1.5m telescope
  32. GRB061222B: Swift-XRT Refined Analysis
  33. GRB 061222A: Observation with the KANATA 1.5m telescope
  34. GRB 061222B: BOOTES-IR optical observations
  35. GRB 061222B: SARA upper limit
  36. GRB 061222A: Swift-XRT refined analysis
  37. GRB 061217: Magellan host galaxy redshift
  38. GRB 061222A, Swift-BAT refined analysis
  39. GRB 061222B: REM NIR/optical observations
  40. GRB 061222b: Refined redshift
  41. GRB 061222b, SMARTS optical/IR afterglow observations
  42. GRB 061222B: TAROT La Silla observatory afterglow observation
  43. GRB 061222B: TAROT La Silla observatory optical observations
  44. GRB 061222b: Magellan redshift
  45. GRB 061222B: Swift detection of a burst
  46. GRB 061222b: optical afterglow
  47. GRB 061222A: Prompt ROTSE-III Optical Limits
  48. GRB 061222: Swift detection of a burst
  49. GRB 061217: Astrometry-Corrected XRT Position
  50. GRB 061201: Magellan redshift of nearby galaxy
  51. GRB 061217: Confirmation of host candidate
  52. GRB 061217: Object ib GCN 5948 is a star
  53. GRB 061217: Extended object in the revised XRT error circle
  54. GRB 061217, Candidate host galaxy
  55. GRB 061217 - Swift/XRT position correction
  56. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  57. GRB 061201: Correction to GCN 5944
  58. GRB 061201: Magellan Redshift of nearby Abell cluster
  59. GRB 061218: TAROT La Silla observatory optical observations
  60. GRB 061217: TAROT Calern observatory optical observations
  61. GRB 061218: TORTOREM optical upper limits
  62. GRB 061218, Swift-BAT refined analysis
  63. GRB061217: VLT NIR observations
  64. GRB 061218, SMARTS optical/IR observations
  65. GRB 061218: REM prompt observations
  66. Swift triggers (#251863) on a possible burst
  67. GRB 061217, SMARTS optical observations
  68. GRB061217: Swift/UVOT refined analysis.
  69. GRB 061217: optical observations at Calar Alto
  70. GRB061217 - Swift/XRT refined analysis
  71. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  72. GRB 061217, Swift-BAT refined analysis
  73. GRB 061217: Magellan Observations
  74. GRB 061217: REM prompt observations
  75. GRB 061217: ROTSE-III Optical Limits
  76. GRB 061217: Swift detection of a short hard burst
  77. GRB 061210: MDM Follow-up Observation
  78. GRB061210: Swift/UVOT observations
  79. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  80. GRB 061210: Optical sources near XRT positions
  81. GRB 061210: Swift XRT analysis - Possible counterparts
  82. GRB 061210 : Faulkes North Telescope optical limit
  83. GRB 061214(?): ROTSE-III Optical Limits
  84. GRB 061214(?): Swift detection of a possible burst
  85. GRB 061210: Suzaku WAM observation of the prompt emission
  86. Swift/BAT trigger #250033 is due to a known source during loss of
  87. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  88. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  89. GRB 061213: MASTER-VWF-Kislovodsk observations
  90. GRB 061210: Gemini/GMOS Observations
  91. GRB 061126: Radio Observations
  92. GRB061210: Radio Observations
  93. GRB061201, VLT optical decay: correction
  94. GRB 061126: a GRB detected off-axis by INTEGRAL
  95. GRB 061202: Suzaku WAM observation of the prompt emission
  96. GRB 061210: MDM Observation
  97. GRB 061210, Swift-BAT refined analysis of the SHB
  98. GRB 061210: Swift-BAT detection of a short burst
  99. Optical Afterglow observations of GRB 061126
  100. GRB061126: optical observations

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