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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 070110: Ep,i - Eiso correlation
  2. GRB 070107: Suzaku WAM observation of the prompt emission
  3. GRB 070110: VLT R-band photometry
  4. GRB 070110 declared a "Burst of Interest" by Swift team
  5. Further Retractions of previous Swift-BAT triggers
  6. Swift-BAT Trigger 255685 is not a GRB
  7. Trigger 255685: Swift detection of a possible burst
  8. GRB 070110: VLT absorption redshift
  9. GRB 070110: UVOT Observations of a Candidate Afterglow
  10. GRB070110: Swift XRT Team refined analysis
  11. GRB 070110, Swift-BAT refined analysis
  12. GRB070107 Swift/UVOT Observations of a Fading Optical Afterglow
  13. GRB 070110: Swift detection of a burst with a possible optical afterglow
  14. IBAS Alert n. 4047: Not a GRB
  15. GRB070107: Swift/XRT refined analysis
  16. GRB 070107: Possible UVOT Afterglow
  17. GRB 070107, Swift-BAT refined analysis
  18. GRB 070107: Swift/XRT position
  19. GRB 070107: Swift detection of a burst
  20. VLA observation of GRB 061222B
  21. VLA detection of GRB 061222A
  22. GRB070103: APO SPIcam i' and z' limits
  23. GRB 061201: Nearby Galaxy Cluster Abell 995 is at z=0.0865
  24. GRB070103: KPNO 4m+FLAMINGOS J limit
  25. GRB 070103: Swift/UVOT Upper limits
  26. GRB070103: Swift XRT refined analysis
  27. GRB 070103, Swift-BAT refined analysis
  28. GRB 070103: NOT observations
  29. GRB 070103: TAROT Calern observatory optical observations
  30. GRB 070103: Swift detection of a burst
  31. Retractions of previous Swift-BAT triggers
  32. GRB061222a: optical observations
  33. erratum : SDSS Pre-burst Observations of GRB061126
  34. Konus-Wind observation of GRB 061222A
  35. GRB 061210: Swift/XRT Astrometry Correction
  36. GRB 050826: MDM Redshift
  37. GRB 061222B: TAROT La Silla observatory early optical observations
  38. GRB 061218: TAROT La Silla observatory early optical observations
  39. GRB 061222A: MITSuME Akeno optical upper limits
  40. GRB 061222A: Confirmation of Gemini Afterglow Candidate
  41. GRB 061222B: MITSuME Akeno optical upper limits
  42. GRB 061222A: Xinglong Optical Limit
  43. GRB 061222A: Gemini Afterglow Candidate
  44. GRB 061222B, Swift-BAT refined analysis
  45. GRB061222A Swift/UVOT: Upper Limits
  46. GRB 061222B: Swift/UVOT Upper limits
  47. GRB 061222B: Observation with the KANATA 1.5m telescope
  48. GRB061222B: Swift-XRT Refined Analysis
  49. GRB 061222A: Observation with the KANATA 1.5m telescope
  50. GRB 061222B: BOOTES-IR optical observations
  51. GRB 061222B: SARA upper limit
  52. GRB 061222A: Swift-XRT refined analysis
  53. GRB 061217: Magellan host galaxy redshift
  54. GRB 061222A, Swift-BAT refined analysis
  55. GRB 061222B: REM NIR/optical observations
  56. GRB 061222b: Refined redshift
  57. GRB 061222b, SMARTS optical/IR afterglow observations
  58. GRB 061222B: TAROT La Silla observatory afterglow observation
  59. GRB 061222B: TAROT La Silla observatory optical observations
  60. GRB 061222b: Magellan redshift
  61. GRB 061222B: Swift detection of a burst
  62. GRB 061222b: optical afterglow
  63. GRB 061222A: Prompt ROTSE-III Optical Limits
  64. GRB 061222: Swift detection of a burst
  65. GRB 061217: Astrometry-Corrected XRT Position
  66. GRB 061201: Magellan redshift of nearby galaxy
  67. GRB 061217: Confirmation of host candidate
  68. GRB 061217: Object ib GCN 5948 is a star
  69. GRB 061217: Extended object in the revised XRT error circle
  70. GRB 061217, Candidate host galaxy
  71. GRB 061217 - Swift/XRT position correction
  72. GRB 061210: Possible Host Galaxy (S2-G2) Keck Spectrum
  73. GRB 061201: Correction to GCN 5944
  74. GRB 061201: Magellan Redshift of nearby Abell cluster
  75. GRB 061218: TAROT La Silla observatory optical observations
  76. GRB 061217: TAROT Calern observatory optical observations
  77. GRB 061218: TORTOREM optical upper limits
  78. GRB 061218, Swift-BAT refined analysis
  79. GRB061217: VLT NIR observations
  80. GRB 061218, SMARTS optical/IR observations
  81. GRB 061218: REM prompt observations
  82. Swift triggers (#251863) on a possible burst
  83. GRB 061217, SMARTS optical observations
  84. GRB061217: Swift/UVOT refined analysis.
  85. GRB 061217: optical observations at Calar Alto
  86. GRB061217 - Swift/XRT refined analysis
  87. GRB 061217, Further Swift-BAT refined analysis of the short hard burst
  88. GRB 061217, Swift-BAT refined analysis
  89. GRB 061217: Magellan Observations
  90. GRB 061217: REM prompt observations
  91. GRB 061217: ROTSE-III Optical Limits
  92. GRB 061217: Swift detection of a short hard burst
  93. GRB 061210: MDM Follow-up Observation
  94. GRB061210: Swift/UVOT observations
  95. Swift-BAT Trigger 250908 is a Cosmic Ray Shower event
  96. GRB 061210: Optical sources near XRT positions
  97. GRB 061210: Swift XRT analysis - Possible counterparts
  98. GRB 061210 : Faulkes North Telescope optical limit
  99. GRB 061214(?): ROTSE-III Optical Limits
  100. GRB 061214(?): Swift detection of a possible burst

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