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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 080810: Liverpool Telescope observations
  2. GRB 080810: D50 optical observation
  3. GRB 080810: Kanazawa optical observation
  4. GRB 080810: OSN follow-up
  5. GRB 080810: Observations from NOT
  6. GRB 080810: RTT150 optical observations
  7. GRB 080810: Swift-XRT Team refined analysis
  8. GRB 080810: Enhanced Swift-XRT position
  9. GRB 080810: KANATA optical-NIR observation, update
  10. GRB 080810: ROTSE-III Prompt Detection of Optical Counterpart
  11. GRB 080810: Keck/HIRES Spectroscopy
  12. GRB 080810, Swift-BAT refined analysis
  13. GRB 080810 : optical observation with KANATA
  14. GRB 080810: Swift detection of a burst with a bright optical afterglow
  15. GRB 080723B: GROND upper limits
  16. GRB 080723B: XMM-Newton observation
  17. GRB 080805: VLT redshift update
  18. GRB 080805: Faulkes Telescope South optical observations
  19. GRB 080804: GROND observations
  20. GRB 080727B: Late VLT imaging
  21. GRB 080804: ATCA Radio Observations
  22. GRB 080805: Swift-XRT Refined Analysis
  23. GRB 080805: Swift/UVOT Upper Limits
  24. GRB 080804: Swift-XRT Refined Analysis
  25. GRB 080804: Swift/UVOT Refined Analysis
  26. GRB 080805, Swift-BAT refined analysis
  27. GRB 080804, Swift-BAT refined analysis
  28. GRB 080804: Enhanced Swift-XRT position
  29. GRB080804: Gemini South redshift confirmation
  30. GRB 080804: Faulkes Telescope South observations
  31. GRB080805 optical limit by "Pi of the Sky"
  32. GRB 080805: VLT redshift
  33. GRB 080805: Afterglow confirmation
  34. GRB 080805: GROND detection of possible afterglow
  35. GRB 080805: Swift detection of a burst
  36. GRB 080804: UVES redshift
  37. GRB 080804: Swift detection of a burst with optical afterglow
  38. GRB 080804: ROTSE-III Detection of Optical Counterpart
  39. GRB 080802: Swift/UVOT Upper Limits
  40. GRB 080802: Swift-XRT Refined Analysis
  41. GRB 080802: UVI Telescope Upper Limit
  42. GRB 080802, Swift-BAT refined analysis
  43. GRB 080802: Swift detection of a probable burst
  44. GRB 080727C: Suzaku WAM observation of the prompt emission
  45. GRB 080727B: IR photometry
  46. GRB 080727A: Early IR observations
  47. GRB 080727C: TAROT Calern observatory optical observations
  48. GRB 080727B: KAIT photometry and an early lightcurve break
  49. GRB 080727B: GROND redshift limit
  50. GRB 080727C, Swift-BAT refined analysis
  51. GRB 080727C: Swift/UVOT Upper Limits
  52. Konus-Wind observation of GRB 080727B
  53. GRB 080727C: Swift XRT refined analysis
  54. GRB 080727C: Liverpool Telescope observations
  55. GRB 080727A: VLT upper limits
  56. GRB 080727C: Enhanced Swift-XRT position
  57. GRB 080727B: REM NIR afterglow prompt detection
  58. GRB080727C: RTT150 optical observations
  59. GRB 080727C: Swift detection of a burst
  60. Swift detection of XTE J1701-407
  61. GRB 080727B: Swift/UVOT Upper Limits
  62. BAT Trigger 318150 is not a GRB
  63. GRB 080727B: Swift-XRT refined analysis
  64. GRB 080727B, Swift-BAT refined analysis
  65. GRB 080727A, Swift-BAT refined analysis
  66. GRB 080727A: Swift-XRT refined analysis
  67. GRB080727A: Swift/UVOT Upper Limits
  68. GRB 080727B: Enhanced Swift-XRT position
  69. GRB 080727A: Enhanced Swift-XRT position
  70. GRB 080727B: KAIT observations
  71. GRB 080727B: REM prompt observations
  72. GRB 080727B: Swift detection of a bright burst
  73. GRB 080727: Swift detection of a burst
  74. GRB 080726: GRB Localization by SuperAGILE
  75. GRB 080725, Swift-BAT refined analysis
  76. GRB 080723A: optical upper limit
  77. GRB080723B: Swift/UVOT Upper Limits
  78. GRB 080725: REM prompt observations
  79. Konus-Wind observation of GRB 080723B
  80. GRB 080725: Swift detection of a burst
  81. ATCA radio upper limit on GRB 080723B
  82. GRB 080723A: Swift/UVOT Upper Limits
  83. VLA radio upper limit on GRB 080721
  84. GRB 080723B - correction to flux conversion factor
  85. GRB 080723B - Swift-XRT refined analysis
  86. GRB 080723B - Swift-XRT position
  87. GRB 080723, Swift-BAT refined analysis
  88. GRB 080723B: AGILE GRID and MCAL results
  89. GRB 080723B : Planned XMM-Newton observation
  90. GRB 080723A: Swift-XRT refined analysis
  91. GRB 080723B: Detection and Localization by SuperAGILE
  92. GRB 080723B : a long GRB detected with INTEGRAL
  93. GRB 080723: Enhanced Swift-XRT position
  94. GRB 080723: Swift detection of a burst
  95. GRB 080721 : Lulin 2nd optical follow-ups
  96. GRB 080721: OA fading and redshift
  97. TNG/DOLORES redshift for GRB080721
  98. GRB 080721: UVOT Follow-Up Observations
  99. Konus-Wind observation of GRB 080721
  100. GRB 080721: Swift-XRT refined analysis

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