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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 080805: Faulkes Telescope South optical observations
  2. GRB 080804: GROND observations
  3. GRB 080727B: Late VLT imaging
  4. GRB 080804: ATCA Radio Observations
  5. GRB 080805: Swift-XRT Refined Analysis
  6. GRB 080805: Swift/UVOT Upper Limits
  7. GRB 080804: Swift-XRT Refined Analysis
  8. GRB 080804: Swift/UVOT Refined Analysis
  9. GRB 080805, Swift-BAT refined analysis
  10. GRB 080804, Swift-BAT refined analysis
  11. GRB 080804: Enhanced Swift-XRT position
  12. GRB080804: Gemini South redshift confirmation
  13. GRB 080804: Faulkes Telescope South observations
  14. GRB080805 optical limit by "Pi of the Sky"
  15. GRB 080805: VLT redshift
  16. GRB 080805: Afterglow confirmation
  17. GRB 080805: GROND detection of possible afterglow
  18. GRB 080805: Swift detection of a burst
  19. GRB 080804: UVES redshift
  20. GRB 080804: Swift detection of a burst with optical afterglow
  21. GRB 080804: ROTSE-III Detection of Optical Counterpart
  22. GRB 080802: Swift/UVOT Upper Limits
  23. GRB 080802: Swift-XRT Refined Analysis
  24. GRB 080802: UVI Telescope Upper Limit
  25. GRB 080802, Swift-BAT refined analysis
  26. GRB 080802: Swift detection of a probable burst
  27. GRB 080727C: Suzaku WAM observation of the prompt emission
  28. GRB 080727B: IR photometry
  29. GRB 080727A: Early IR observations
  30. GRB 080727C: TAROT Calern observatory optical observations
  31. GRB 080727B: KAIT photometry and an early lightcurve break
  32. GRB 080727B: GROND redshift limit
  33. GRB 080727C, Swift-BAT refined analysis
  34. GRB 080727C: Swift/UVOT Upper Limits
  35. Konus-Wind observation of GRB 080727B
  36. GRB 080727C: Swift XRT refined analysis
  37. GRB 080727C: Liverpool Telescope observations
  38. GRB 080727A: VLT upper limits
  39. GRB 080727C: Enhanced Swift-XRT position
  40. GRB 080727B: REM NIR afterglow prompt detection
  41. GRB080727C: RTT150 optical observations
  42. GRB 080727C: Swift detection of a burst
  43. Swift detection of XTE J1701-407
  44. GRB 080727B: Swift/UVOT Upper Limits
  45. BAT Trigger 318150 is not a GRB
  46. GRB 080727B: Swift-XRT refined analysis
  47. GRB 080727B, Swift-BAT refined analysis
  48. GRB 080727A, Swift-BAT refined analysis
  49. GRB 080727A: Swift-XRT refined analysis
  50. GRB080727A: Swift/UVOT Upper Limits
  51. GRB 080727B: Enhanced Swift-XRT position
  52. GRB 080727A: Enhanced Swift-XRT position
  53. GRB 080727B: KAIT observations
  54. GRB 080727B: REM prompt observations
  55. GRB 080727B: Swift detection of a bright burst
  56. GRB 080727: Swift detection of a burst
  57. GRB 080726: GRB Localization by SuperAGILE
  58. GRB 080725, Swift-BAT refined analysis
  59. GRB 080723A: optical upper limit
  60. GRB080723B: Swift/UVOT Upper Limits
  61. GRB 080725: REM prompt observations
  62. Konus-Wind observation of GRB 080723B
  63. GRB 080725: Swift detection of a burst
  64. ATCA radio upper limit on GRB 080723B
  65. GRB 080723A: Swift/UVOT Upper Limits
  66. VLA radio upper limit on GRB 080721
  67. GRB 080723B - correction to flux conversion factor
  68. GRB 080723B - Swift-XRT refined analysis
  69. GRB 080723B - Swift-XRT position
  70. GRB 080723, Swift-BAT refined analysis
  71. GRB 080723B: AGILE GRID and MCAL results
  72. GRB 080723B : Planned XMM-Newton observation
  73. GRB 080723A: Swift-XRT refined analysis
  74. GRB 080723B: Detection and Localization by SuperAGILE
  75. GRB 080723B : a long GRB detected with INTEGRAL
  76. GRB 080723: Enhanced Swift-XRT position
  77. GRB 080723: Swift detection of a burst
  78. GRB 080721 : Lulin 2nd optical follow-ups
  79. GRB 080721: OA fading and redshift
  80. TNG/DOLORES redshift for GRB080721
  81. GRB 080721: UVOT Follow-Up Observations
  82. Konus-Wind observation of GRB 080721
  83. GRB 080721: Swift-XRT refined analysis
  84. GRB 080721: Enhanced Swift-XRT position
  85. GRB 080721, Swift-BAT refined analysis
  86. GRB 080721: Swift/UVOT Photometric Redshift
  87. GRB 080721 : Lulin Optical follow-ups
  88. GRB 080721: Swift-XRT correct position
  89. GRB 080721: Swift detection of a burst with a bright optical counterpart.
  90. Retraction of Swift Trigger 317393
  91. Trigger 317393: Swift detection of a possible GRB
  92. Trigger 317205: Swift detection of an outburst from XTE J1701-407
  93. GRB 080714: GROND confirmation of the optical/NIR afterglow
  94. Konus-Wind observation of GRB 080714
  95. GRB 080714: Swift/UVOT Detection of an Optical Afterglow
  96. GRB 080714: Swift-XRT refined analysis
  97. GRB 080714: Enhanced Swift-XRT position
  98. GRB 080714: Swift-BAT refined analysis
  99. GRB 080714: Swift detection of a burst
  100. GRB 080702A: optical upper limit

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