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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 080727B: Swift-XRT refined analysis
  2. GRB 080727B, Swift-BAT refined analysis
  3. GRB 080727A, Swift-BAT refined analysis
  4. GRB 080727A: Swift-XRT refined analysis
  5. GRB080727A: Swift/UVOT Upper Limits
  6. GRB 080727B: Enhanced Swift-XRT position
  7. GRB 080727A: Enhanced Swift-XRT position
  8. GRB 080727B: KAIT observations
  9. GRB 080727B: REM prompt observations
  10. GRB 080727B: Swift detection of a bright burst
  11. GRB 080727: Swift detection of a burst
  12. GRB 080726: GRB Localization by SuperAGILE
  13. GRB 080725, Swift-BAT refined analysis
  14. GRB 080723A: optical upper limit
  15. GRB080723B: Swift/UVOT Upper Limits
  16. GRB 080725: REM prompt observations
  17. Konus-Wind observation of GRB 080723B
  18. GRB 080725: Swift detection of a burst
  19. ATCA radio upper limit on GRB 080723B
  20. GRB 080723A: Swift/UVOT Upper Limits
  21. VLA radio upper limit on GRB 080721
  22. GRB 080723B - correction to flux conversion factor
  23. GRB 080723B - Swift-XRT refined analysis
  24. GRB 080723B - Swift-XRT position
  25. GRB 080723, Swift-BAT refined analysis
  26. GRB 080723B: AGILE GRID and MCAL results
  27. GRB 080723B : Planned XMM-Newton observation
  28. GRB 080723A: Swift-XRT refined analysis
  29. GRB 080723B: Detection and Localization by SuperAGILE
  30. GRB 080723B : a long GRB detected with INTEGRAL
  31. GRB 080723: Enhanced Swift-XRT position
  32. GRB 080723: Swift detection of a burst
  33. GRB 080721 : Lulin 2nd optical follow-ups
  34. GRB 080721: OA fading and redshift
  35. TNG/DOLORES redshift for GRB080721
  36. GRB 080721: UVOT Follow-Up Observations
  37. Konus-Wind observation of GRB 080721
  38. GRB 080721: Swift-XRT refined analysis
  39. GRB 080721: Enhanced Swift-XRT position
  40. GRB 080721, Swift-BAT refined analysis
  41. GRB 080721: Swift/UVOT Photometric Redshift
  42. GRB 080721 : Lulin Optical follow-ups
  43. GRB 080721: Swift-XRT correct position
  44. GRB 080721: Swift detection of a burst with a bright optical counterpart.
  45. Retraction of Swift Trigger 317393
  46. Trigger 317393: Swift detection of a possible GRB
  47. Trigger 317205: Swift detection of an outburst from XTE J1701-407
  48. GRB 080714: GROND confirmation of the optical/NIR afterglow
  49. Konus-Wind observation of GRB 080714
  50. GRB 080714: Swift/UVOT Detection of an Optical Afterglow
  51. GRB 080714: Swift-XRT refined analysis
  52. GRB 080714: Enhanced Swift-XRT position
  53. GRB 080714: Swift-BAT refined analysis
  54. GRB 080714: Swift detection of a burst
  55. GRB 080702A: optical upper limit
  56. GRB 080603A: CrAO optical observations
  57. GRB 080603B: optical observations in MAO
  58. GRB 080603B: optical observations in CrAO
  59. GRB 080710: Optical observation with MITSuME Okayama
  60. GRB 080710: TLS observations, steepening afterglow decay
  61. GRB 080702B: Swift XRT confirmation of the afterglow
  62. GRB 080710: Lick IR detection
  63. GRB 080710, Swift-BAT refined analysis
  64. GRB 0800707: optical observations
  65. GRB 080710: Rapid PROMPT Observations
  66. GRB 080710: Swift-XRT refined analysis
  67. GRB080710: Swift/UVOT observations
  68. GRB 080710: Enhanced Swift-XRT position
  69. GRB 080710: Faulkes Telescope North observations
  70. GRB 080710: Gemini spectroscopy and probable redshift
  71. UVOT white band observations of GRB080710
  72. GRB 080710: REM afterglow confirmation & brightening
  73. GRB 080710: KAIT OA candidate
  74. GRB 080710: Swift XRT position
  75. GRB 080710: Swift detection of a burst
  76. GRB 080707: possible break in the X-rays
  77. New Swift-XRT GRB products available online.
  78. GRB 080707: GROND Confirmation of the Optical Afterglow
  79. UVOT observations of GRB080707
  80. GRB 080707, Swift-BAT refined analysis
  81. GRB 080707: Swift XRT refined analysis
  82. GRB 080707: Enhanced Swift-XRT position
  83. GRB 080707: VLT redshift
  84. GRB 080707: GROND Detection of the Optical Afterglow Candidate
  85. GRB 080707: Swift detection of a burst
  86. Refined analysis of Swift Trigger 316063, is IGR J08408-4503
  87. Trigger 316063: Swift detection of a transient
  88. GRB 080703: GROND Upper Limits
  89. GRB 080702B: GROND Upper Limits
  90. GRB 080703: Swift-XRT refined analysis
  91. GRB 080703: UVOT Follow-Up Observation
  92. GRB 080703: VLT observations of the afterglow
  93. GRB 080703: Enhanced Swift-XRT position
  94. GRB 080703, Swift-BAT refined analysis
  95. GRB 080702B Swift-BAT refined analysis
  96. GRB 080703: Swift detection of a burst with optical afterglow
  97. GRB 080703A: ROTSE-III Detection of Optical Counterpart
  98. No radio detection from the short GRB 080702A
  99. GRB 080702b: LCO optical observations
  100. Swift/UVOT observation of GRB080702A

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