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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. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  2. GRB 070110: Swift detection of a burst with a possible optical afterglow
  3. IBAS Alert n. 4047: Not a GRB
  4. GRB070107: Swift/XRT refined analysis
  5. GRB 070107: Possible UVOT Afterglow
  6. GRB 070107, Swift-BAT refined analysis
  7. GRB 070107: Swift/XRT position
  8. GRB 070107: Swift detection of a burst
  9. VLA observation of GRB 061222B
  10. VLA detection of GRB 061222A
  11. GRB070103: APO SPIcam i' and z' limits
  12. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  13. GRB070103: KPNO 4m+FLAMINGOS J limit
  14. GRB 070103: Swift/UVOT Upper limits
  15. GRB070103: Swift XRT refined analysis
  16. GRB 070103, Swift-BAT refined analysis
  17. GRB 070103: NOT observations
  18. GRB 070103: TAROT Calern observatory optical observations
  19. GRB 070103: Swift detection of a burst
  20. Retractions of previous Swift-BAT triggers
  21. GRB061222a: optical observations
  22. erratum : SDSS Pre-burst Observations of GRB061126
  23. Konus-Wind observation of GRB 061222A
  24. GRB 061210: Swift/XRT Astrometry Correction
  25. GRB 050826: MDM Redshift
  26. GRB 061222B: TAROT La Silla observatory early optical observations
  27. GRB 061218: TAROT La Silla observatory early optical observations
  28. GRB 061222A: MITSuME Akeno optical upper limits
  29. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  30. GRB 061222B: MITSuME Akeno optical upper limits
  31. GRB 061222A: Xinglong Optical Limit
  32. GRB 061222A: Gemini Afterglow Candidate
  33. GRB 061222B, Swift-BAT refined analysis
  34. GRB061222A Swift/UVOT: Upper Limits
  35. GRB 061222B: Swift/UVOT Upper limits
  36. GRB 061222B: Observation with the KANATA 1.5m telescope
  37. GRB061222B: Swift-XRT Refined Analysis
  38. GRB 061222A: Observation with the KANATA 1.5m telescope
  39. GRB 061222B: BOOTES-IR optical observations
  40. GRB 061222B: SARA upper limit
  41. GRB 061222A: Swift-XRT refined analysis
  42. GRB 061217: Magellan host galaxy redshift
  43. GRB 061222A, Swift-BAT refined analysis
  44. GRB 061222B: REM NIR/optical observations
  45. GRB 061222b: Refined redshift
  46. GRB 061222b, SMARTS optical/IR afterglow observations
  47. GRB 061222B: TAROT La Silla observatory afterglow observation
  48. GRB 061222B: TAROT La Silla observatory optical observations
  49. GRB 061222b: Magellan redshift
  50. GRB 061222B: Swift detection of a burst
  51. GRB 061222b: optical afterglow
  52. GRB 061222A: Prompt ROTSE-III Optical Limits
  53. GRB 061222: Swift detection of a burst
  54. GRB 061217: Astrometry-Corrected XRT Position
  55. GRB 061201: Magellan redshift of nearby galaxy
  56. GRB 061217: Confirmation of host candidate
  57. GRB 061217: Object ib GCN 5948 is a star
  58. GRB 061217: Extended object in the revised XRT error circle
  59. GRB 061217, Candidate host galaxy
  60. GRB 061217 - Swift/XRT position correction
  61. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  62. GRB 061201: Correction to GCN 5944
  63. GRB 061201: Magellan Redshift of nearby Abell cluster
  64. GRB 061218: TAROT La Silla observatory optical observations
  65. GRB 061217: TAROT Calern observatory optical observations
  66. GRB 061218: TORTOREM optical upper limits
  67. GRB 061218, Swift-BAT refined analysis
  68. GRB061217: VLT NIR observations
  69. GRB 061218, SMARTS optical/IR observations
  70. GRB 061218: REM prompt observations
  71. Swift triggers (#251863) on a possible burst
  72. GRB 061217, SMARTS optical observations
  73. GRB061217: Swift/UVOT refined analysis.
  74. GRB 061217: optical observations at Calar Alto
  75. GRB061217 - Swift/XRT refined analysis
  76. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  77. GRB 061217, Swift-BAT refined analysis
  78. GRB 061217: Magellan Observations
  79. GRB 061217: REM prompt observations
  80. GRB 061217: ROTSE-III Optical Limits
  81. GRB 061217: Swift detection of a short hard burst
  82. GRB 061210: MDM Follow-up Observation
  83. GRB061210: Swift/UVOT observations
  84. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  85. GRB 061210: Optical sources near XRT positions
  86. GRB 061210: Swift XRT analysis - Possible counterparts
  87. GRB 061210 : Faulkes North Telescope optical limit
  88. GRB 061214(?): ROTSE-III Optical Limits
  89. GRB 061214(?): Swift detection of a possible burst
  90. GRB 061210: Suzaku WAM observation of the prompt emission
  91. Swift/BAT trigger #250033 is due to a known source during loss of
  92. GRB 061213: MASTER-VWF-Kislovodsk OT candidate retraction
  93. GRB 061213: MASTER-VWF-Kislovodsk optical candidate
  94. GRB 061213: MASTER-VWF-Kislovodsk observations
  95. GRB 061210: Gemini/GMOS Observations
  96. GRB 061126: Radio Observations
  97. GRB061210: Radio Observations
  98. GRB061201, VLT optical decay: correction
  99. GRB 061126: a GRB detected off-axis by INTEGRAL
  100. GRB 061202: Suzaku WAM observation of the prompt emission

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