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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 080310: Swift-XRT refined analysis
  2. GRB 080310: Swift/UVOT Refined Analysis
  3. GRB 080310: Redshift from Keck/DEIMOS Spectra
  4. GRB 080310 - SDSS Pre-Burst Observations
  5. GRB080310 : Lulin optical observation
  6. GRB 080310: Enhanced Swift-XRT position
  7. GRB 080310: RRM optical photometry with the VLT
  8. GRB080310, detection of break in optical
  9. GRB 080310: VLT/UVES spectroscopy
  10. GRB080310, optical observations with LBT
  11. GRB 080310: Magellan redshift revision
  12. GRB 080310: Lick/Kast Spectroscopy
  13. GRB080310: Super-LOTIS suggestion of brightening
  14. GRB 080310, SMARTS optical/IR afterglow observations
  15. GRB 080310: REM observations
  16. GRB 080310: Magellan redshift
  17. GRB 080310 afterglow candidate (correction to UT time)
  18. GRB 080310: Swift detection of a burst with optical afterglow
  19. GRB 080310 afterglow candidate
  20. GRB080229, optical upper limit (Correction)
  21. GRB080307, optical upper limit
  22. GRB080307 BOAO optical afterglow observation - detection of a possible OT
  23. GRB080229, optical upper limit
  24. GRB 080307: Swift-XRT Team refined analysis
  25. GRB 080307: Swift/UVOT Upper Limits
  26. GRB 080307: Early RAPTOR Limits
  27. GRB 080307, Swift-BAT refined analysis
  28. GRB080307 - SDSS Pre-Burst Observations
  29. GRB 080307: TNT optical observation
  30. GRB080307: Optical upper limits
  31. GRB 080307: Gemini-N i-band observations - candidate afterglow
  32. GRB 080307: BOAO imaging - retraction and new limit
  33. GRB 080307: retraction of UVOT candidate
  34. GRB 080307: Enhanced Swift-XRT position
  35. GRB 080307, Preliminary Swift-BAT refined analysis
  36. GRB 080307 : BOAO optical afterglow observation
  37. GRB 080307: Optical observation with DMC/KANATA
  38. GRB 080307: Swift detection of a burst
  39. VLA possible radio detection of GRB 080229
  40. GRB 080303: Swift/UVOT follow-up of afterglow detection
  41. GRB 080303, Swift-BAT refined analysis
  42. GRB 080303: Rapid PROMPT Detections
  43. GRB080303: Swift XRT refined analysis
  44. GRB 080303: Enhanced Swift-XRT position
  45. Swift UVOT observations of GRB080229B
  46. GRB080229B: Swift XRT afterglow observation
  47. GRB 080303A: Faulkes Telescope South optical afterglow observations
  48. GRB 080303
  49. GRB 080303: Swift detection of a burst with optical afterglow
  50. GRB 080303: REM NIR afterglow candidate
  51. GRB 080303A: ROTSE-III Optical Limits
  52. GRB 080229: I-band observations from OSN
  53. GRB 080229: VLT NIR observations
  54. GRB080229: Swift XRT refined analysis
  55. GRB 080229: TNG NIR observations
  56. GRB 080229: Deep Gemini/GMOS optical observations
  57. GRB 080229: Enhanced Swift-XRT position
  58. GRB 080229: REM NIR observations
  59. GRB080229: Possible optical afterglow
  60. GRB 080229B: Gamma Ray Burst Localization by SuperAGILE
  61. UVOT analysis for GRB080229
  62. GRB 080229, Swift-BAT refined analysis
  63. GRB 080229: Faulkes Telescope South optical limit
  64. GRB 080229A: ROTSE-III Optical Limits
  65. GRB 080229: Swift detection of a bright burst
  66. Early optical shallow decay in GRB 071112C
  67. GRB080207: optical observations
  68. GRB080205: optical observations
  69. GRB080211: optical observations
  70. XRF 080109/SN2008D : GMRT upper limit at 1.28 GHz
  71. GRB 071010B : Early optical brightening detected by TAOS
  72. Swift-XRT improved positions, and new redshift limits.
  73. ESO optical and NIR observations of GRB 080218B
  74. GRB 080204: Suzaku WAM observation of the prompt emission
  75. GRB 080218B, Swift-BAT refined analysis
  76. GRB 080218B: Swift-XRT refined analysis
  77. Swift/UVOT observations of GRB080218B
  78. GRB 080218B: REM NIR early upper limits
  79. GRB 080212: Mount Abu NIR observations
  80. GRB 080218B: Enhanced Swift-XRT position
  81. GRB 080218B: GROND upper limits
  82. GRB 080218b, SMARTS optical/IR limits
  83. GRB 080218A, Swift-BAT refined analysis
  84. GRB080218B: Watcher prompt limit
  85. GRB 080211: Suzaku WAM observation of the prompt emission
  86. GRB 080218B: Swift detection of a burst
  87. GRB 080218: Swift detection of a burst
  88. Swift-XRT and UVOT observations of the IPN burst GRB 080211
  89. GRB 080212: VLT optical rapid decay
  90. GRB 080212: REM refined analysis
  91. Konus-Wind observation of GRB 080211
  92. VLA radio upper limit on GRB 080212
  93. Swift/UVOT refined analysis of GRB080212
  94. GRB 080212, Swift-BAT refined analysis
  95. GRB080212: Optical afterglow candidate observed by MITSuME Telescope
  96. GRB 080212: Gemini-South optical observations
  97. GRB 080212: GROND detects afterglow
  98. GRB 080212: REM NIR afterglow?
  99. GRB 080212: optical observations
  100. GRB 080212: Enhanced Swift-XRT position

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