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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: APO SPIcam i' and z' limits
  2. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  3. GRB070103: KPNO 4m+FLAMINGOS J limit
  4. GRB 070103: Swift/UVOT Upper limits
  5. GRB070103: Swift XRT refined analysis
  6. GRB 070103, Swift-BAT refined analysis
  7. GRB 070103: NOT observations
  8. GRB 070103: TAROT Calern observatory optical observations
  9. GRB 070103: Swift detection of a burst
  10. Retractions of previous Swift-BAT triggers
  11. GRB061222a: optical observations
  12. erratum : SDSS Pre-burst Observations of GRB061126
  13. Konus-Wind observation of GRB 061222A
  14. GRB 061210: Swift/XRT Astrometry Correction
  15. GRB 050826: MDM Redshift
  16. GRB 061222B: TAROT La Silla observatory early optical observations
  17. GRB 061218: TAROT La Silla observatory early optical observations
  18. GRB 061222A: MITSuME Akeno optical upper limits
  19. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  20. GRB 061222B: MITSuME Akeno optical upper limits
  21. GRB 061222A: Xinglong Optical Limit
  22. GRB 061222A: Gemini Afterglow Candidate
  23. GRB 061222B, Swift-BAT refined analysis
  24. GRB061222A Swift/UVOT: Upper Limits
  25. GRB 061222B: Swift/UVOT Upper limits
  26. GRB 061222B: Observation with the KANATA 1.5m telescope
  27. GRB061222B: Swift-XRT Refined Analysis
  28. GRB 061222A: Observation with the KANATA 1.5m telescope
  29. GRB 061222B: BOOTES-IR optical observations
  30. GRB 061222B: SARA upper limit
  31. GRB 061222A: Swift-XRT refined analysis
  32. GRB 061217: Magellan host galaxy redshift
  33. GRB 061222A, Swift-BAT refined analysis
  34. GRB 061222B: REM NIR/optical observations
  35. GRB 061222b: Refined redshift
  36. GRB 061222b, SMARTS optical/IR afterglow observations
  37. GRB 061222B: TAROT La Silla observatory afterglow observation
  38. GRB 061222B: TAROT La Silla observatory optical observations
  39. GRB 061222b: Magellan redshift
  40. GRB 061222B: Swift detection of a burst
  41. GRB 061222b: optical afterglow
  42. GRB 061222A: Prompt ROTSE-III Optical Limits
  43. GRB 061222: Swift detection of a burst
  44. GRB 061217: Astrometry-Corrected XRT Position
  45. GRB 061201: Magellan redshift of nearby galaxy
  46. GRB 061217: Confirmation of host candidate
  47. GRB 061217: Object ib GCN 5948 is a star
  48. GRB 061217: Extended object in the revised XRT error circle
  49. GRB 061217, Candidate host galaxy
  50. GRB 061217 - Swift/XRT position correction
  51. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  52. GRB 061201: Correction to GCN 5944
  53. GRB 061201: Magellan Redshift of nearby Abell cluster
  54. GRB 061218: TAROT La Silla observatory optical observations
  55. GRB 061217: TAROT Calern observatory optical observations
  56. GRB 061218: TORTOREM optical upper limits
  57. GRB 061218, Swift-BAT refined analysis
  58. GRB061217: VLT NIR observations
  59. GRB 061218, SMARTS optical/IR observations
  60. GRB 061218: REM prompt observations
  61. Swift triggers (#251863) on a possible burst
  62. GRB 061217, SMARTS optical observations
  63. GRB061217: Swift/UVOT refined analysis.
  64. GRB 061217: optical observations at Calar Alto
  65. GRB061217 - Swift/XRT refined analysis
  66. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  67. GRB 061217, Swift-BAT refined analysis
  68. GRB 061217: Magellan Observations
  69. GRB 061217: REM prompt observations
  70. GRB 061217: ROTSE-III Optical Limits
  71. GRB 061217: Swift detection of a short hard burst
  72. GRB 061210: MDM Follow-up Observation
  73. GRB061210: Swift/UVOT observations
  74. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  75. GRB 061210: Optical sources near XRT positions
  76. GRB 061210: Swift XRT analysis - Possible counterparts
  77. GRB 061210 : Faulkes North Telescope optical limit
  78. GRB 061214(?): ROTSE-III Optical Limits
  79. GRB 061214(?): Swift detection of a possible burst
  80. GRB 061210: Suzaku WAM observation of the prompt emission
  81. Swift/BAT trigger #250033 is due to a known source during loss of
  82. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  83. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  84. GRB 061213: MASTER-VWF-Kislovodsk observations
  85. GRB 061210: Gemini/GMOS Observations
  86. GRB 061126: Radio Observations
  87. GRB061210: Radio Observations
  88. GRB061201, VLT optical decay: correction
  89. GRB 061126: a GRB detected off-axis by INTEGRAL
  90. GRB 061202: Suzaku WAM observation of the prompt emission
  91. GRB 061210: MDM Observation
  92. GRB 061210, Swift-BAT refined analysis of the SHB
  93. GRB 061210: Swift-BAT detection of a short burst
  94. Optical Afterglow observations of GRB 061126
  95. GRB061126: optical observations
  96. GRB 060926: MASTER: discovery of the optical flare
  97. GRB061126: update on the Swift-XRT afterglow light curve
  98. Corrections for Swift/UVOT Exposure Times for GRBs 061110B and 061121
  99. GRB 061201: UVOT Observations of a Fading Optical Afterglow
  100. GRB 061202: TORTOREM optical upper limits

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