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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 080430 optical observations
  2. GRB 080430, Swift-BAT refined analysis
  3. GRB080430: optical observations
  4. GRB 080430: Hobby-Eberly Telescope Absorption Redshift
  5. GRB 080430: Swift-XRT refined analysis
  6. GRB 080430: Enhanced Swift-XRT position
  7. GRB080430: Optical observation in AsU CAS Ondrejov & Brno
  8. GRB 080430: Spectroscopy from CAHA
  9. GRB 080430 - SDSS Pre-Burst Observations
  10. GRB 080430: Bootes observation
  11. GRB 080430: Swift detection of a burst with optical afterglow
  12. GRB 080430: TAROT Calern observatory optical observations
  13. GRB960202B - on the association with SN 1996cr
  14. GRB080426: Observations from CAHA
  15. GRB 080426: Swift-XRT refined analysis
  16. GRB080426: Swift/UVOT upper limits
  17. GRB 080426: Enhanced Swift-XRT position
  18. GRB 080426, Swift-BAT refined analysis
  19. GRB 080426: Swift detection of a possibly short burst
  20. Possible GRB 080315: XRT non-detection of afterglow
  21. GRB 080320 : Faulkes Telescope North Observations
  22. GRB 080319A : Liverpool and Faulkes Telescopes Observations
  23. GRB080319A: MAGIC telescope GeV observation
  24. Swift-BAT trigger 309665 is not a GRB
  25. GRB 080420A: ROTSE-III Optical Limits on a possible short burst
  26. GRB 080420?: Swift detection of a possible short burst
  27. GRB080310, BVRcIc field calibration
  28. GRB 080413A: Suzaku/WAM and Swift/BAT joint spectral analysis
  29. GRB 080413B: Rapid PROMPT Observations
  30. Swift XRT and UVOT observations of GRB080414
  31. GRB 080319B: Jet Break, Energetics, Supernova
  32. GRB 080413B: Faulkes Telescope South optical afterglow observations
  33. GRB 080413A: Liverpool Telescope and Faulkes Telescope South optical observations
  34. GRB 080413A: Suzaku WAM observation of the prompt emission
  35. GRB 080413B: Suzaku WAM observation of the prompt emission
  36. GRB 080413A: MOA-II optical afterglow observations
  37. GRB 080319B: Continued Gemini-N monitoring
  38. GRB 080414: RTT150 optical observations
  39. GRB 080414 Watcher observations
  40. GRB 080414: A long GRB detected by INTEGRAL
  41. VLA radio observations of GRB 080413B
  42. GRB 080413A: Gemini-South Spectroscopy
  43. GRB 080413B: Gemini-South Spectroscopy
  44. VLA radio observations of GRB 080413A
  45. IBAS Alert n. 5257 : not a GRB
  46. GRB 080413B: Ep,i-Eiso correlation
  47. GRB080413B
  48. Swift-BAT spectral lag analysis of GRB 080413B
  49. GRB 080413a, SMARTS optical/IR afterglow observations
  50. GRB 080413B: Swift XRT refined analysis
  51. GRB080413A: Swift/UVOT observations
  52. GRB 080413B, Swift-BAT refined analysis
  53. GRB 080413A: Swift-XRT refined analysis
  54. GRB 080413A, Swift-BAT refined analysis
  55. GRB 080413A Bootes observation
  56. GRB 080413A: VLT/UVES redshift
  57. GRB 080413B: VLT redshift
  58. GRB080413B: REM NIR & Optical Observation
  59. GRB 080413B: GROND detection of afterglow in all bands
  60. GRB 080413B: Swift detection of a possibly short burst with optical counterpart
  61. GRB 080413A: REM detection of the NIR Afterglow
  62. GRB 080413: Enhanced Swift-XRT position
  63. GRB 080413: TAROT Calern observatory optical observations
  64. GRB 080413: Swift detection of a burst with an optical afterglow
  65. GRB 080413: ROTSE-III Detection of Optical Counterpart
  66. GRB 080411: Swift/UVOT refined analysis
  67. GRB 080411, Swift-BAT refined analysis
  68. GRB 080411: Swift-XRT Refined Analysis
  69. Konus-Wind observation of GRB 080411
  70. GRB 080411: Enhanced Swift-XRT position
  71. GRB 080411: VLT redshift
  72. GRB 080411: GROND detection of optical afterglow candidate
  73. GRB080330: MAGIC telescope GeV observation
  74. GRB 080411: Swift detection of a bright burst
  75. GRB 080330: Swift-XRT refined position retraction
  76. GRB 080409: Swift-BAT refined analysis
  77. GRB 080408: GROND detection of optical/NIR afterglow candidate
  78. GRB 080330 optical observations
  79. Swift/UVOT observations of GRB080409
  80. GRB 080409: Swift XRT refined analysis
  81. UVOT/Swift Observations of GRB080408
  82. GRB 080408: Swift-XRT position of a possible afterglow
  83. GRB 080409: Enhanced Swift-XRT position
  84. GRB 080409: REM optical/NIR observations
  85. GRB 080409: Swift detection of a burst
  86. GRB 080408: Analysis of AGILE Gamma-ray data
  87. GRB 080408: GRB Localization by SuperAGILE
  88. GRB 080319A: Early RAPTOR optical limits
  89. GRB 080319B: HST observations
  90. GRB 080330: RAPTOR detection of prompt optical flash
  91. GRB 080319B: Potential Jet Break Observed by Swift-XRT and UVOT
  92. GRB 080405: Swift-BAT refined analysis
  93. GRB 080405: Swift-XRT position
  94. GRB 080405: Mars Oddysey and Swift-BAT detection, possible host galaxy
  95. GRB 080325: optical upper limit
  96. GRB 080328: GAO 150cm telescope Optical Observation
  97. GRB080330: Improved Swift XRT Position
  98. GRB 080330: Prompt PROMPT Observations
  99. GRB080330: optical observations
  100. GRB 080319B: TORTORA light curve (Correction)

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