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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 080506, Swift-BAT refined analysis
  2. GRB080503, RIMOTS optical upper limit
  3. GRB 080506: Observations from NOT
  4. GRB 080506: optical observation from Ondrejov
  5. GRB 080506: TLS afterglow detection in VRIZ
  6. GRB 080506: Enhanced Swift-XRT position
  7. GRB 080506: Optical observation with KANATA/TRISPEC
  8. GRB 080506: Swift detection of a burst with optical afterglow
  9. GRB 080503: VLA radio upper limit
  10. GRB 080503: Observations from NOT
  11. GRB 080503: Slow-rise optical AG ?
  12. GRB 080430: TLS imaging one day after the GRB
  13. GRB 080503: No further optical rebrightening
  14. GRB 080503: Late-time Optical rebrightening (possible mini-SN) - correction
  15. GRB 080503: Late-time Optical rebrightening (possible mini-SN)
  16. GRB 080503, Swift-BAT lag and time-resolved spectral analysis
  17. GRB 080503: MITSuME Ishigakijima optical upper limits
  18. GRB080503: Swift/UVOT Upper Limits
  19. GRB080503 XRT refined analysis
  20. GRB 080503, Swift-BAT refined analysis
  21. GRB 080430
  22. GRB 080430
  23. GRB 080430
  24. GRB 080503: Enhanced Swift-XRT position
  25. GRB 080503: MITSuME Akeno optical upper limits
  26. GRB 080503: New candidate afterglow/host in Gemini imaging
  27. GRB 080503: Optical afterglow candidate and LRIS spectroscopy of the short burst
  28. GRB 080503: Swift detection of a short burst
  29. GRB 080411: Continued Swift Monitoring
  30. GRB 080430: Optical observations
  31. GRB 080430: Shallow decay
  32. GRB080430: RTT150 Optical Observations
  33. GRB080430: Swift/UVOT observations
  34. VLA radio upper limit on GRB 080430
  35. GRB 080430 - multicolor observations of the afterglow
  36. GRB 080430 optical observations
  37. GRB 080430, Swift-BAT refined analysis
  38. GRB080430: optical observations
  39. GRB 080430: Hobby-Eberly Telescope Absorption Redshift
  40. GRB 080430: Swift-XRT refined analysis
  41. GRB 080430: Enhanced Swift-XRT position
  42. GRB080430: Optical observation in AsU CAS Ondrejov & Brno
  43. GRB 080430: Spectroscopy from CAHA
  44. GRB 080430 - SDSS Pre-Burst Observations
  45. GRB 080430: Bootes observation
  46. GRB 080430: Swift detection of a burst with optical afterglow
  47. GRB 080430: TAROT Calern observatory optical observations
  48. GRB960202B - on the association with SN 1996cr
  49. GRB080426: Observations from CAHA
  50. GRB 080426: Swift-XRT refined analysis
  51. GRB080426: Swift/UVOT upper limits
  52. GRB 080426: Enhanced Swift-XRT position
  53. GRB 080426, Swift-BAT refined analysis
  54. GRB 080426: Swift detection of a possibly short burst
  55. Possible GRB 080315: XRT non-detection of afterglow
  56. GRB 080320 : Faulkes Telescope North Observations
  57. GRB 080319A : Liverpool and Faulkes Telescopes Observations
  58. GRB080319A: MAGIC telescope GeV observation
  59. Swift-BAT trigger 309665 is not a GRB
  60. GRB 080420A: ROTSE-III Optical Limits on a possible short burst
  61. GRB 080420?: Swift detection of a possible short burst
  62. GRB080310, BVRcIc field calibration
  63. GRB 080413A: Suzaku/WAM and Swift/BAT joint spectral analysis
  64. GRB 080413B: Rapid PROMPT Observations
  65. Swift XRT and UVOT observations of GRB080414
  66. GRB 080319B: Jet Break, Energetics, Supernova
  67. GRB 080413B: Faulkes Telescope South optical afterglow observations
  68. GRB 080413A: Liverpool Telescope and Faulkes Telescope South optical observations
  69. GRB 080413A: Suzaku WAM observation of the prompt emission
  70. GRB 080413B: Suzaku WAM observation of the prompt emission
  71. GRB 080413A: MOA-II optical afterglow observations
  72. GRB 080319B: Continued Gemini-N monitoring
  73. GRB 080414: RTT150 optical observations
  74. GRB 080414 Watcher observations
  75. GRB 080414: A long GRB detected by INTEGRAL
  76. VLA radio observations of GRB 080413B
  77. GRB 080413A: Gemini-South Spectroscopy
  78. GRB 080413B: Gemini-South Spectroscopy
  79. VLA radio observations of GRB 080413A
  80. IBAS Alert n. 5257 : not a GRB
  81. GRB 080413B: Ep,i-Eiso correlation
  82. GRB080413B
  83. Swift-BAT spectral lag analysis of GRB 080413B
  84. GRB 080413a, SMARTS optical/IR afterglow observations
  85. GRB 080413B: Swift XRT refined analysis
  86. GRB080413A: Swift/UVOT observations
  87. GRB 080413B, Swift-BAT refined analysis
  88. GRB 080413A: Swift-XRT refined analysis
  89. GRB 080413A, Swift-BAT refined analysis
  90. GRB 080413A Bootes observation
  91. GRB 080413A: VLT/UVES redshift
  92. GRB 080413B: VLT redshift
  93. GRB080413B: REM NIR & Optical Observation
  94. GRB 080413B: GROND detection of afterglow in all bands
  95. GRB 080413B: Swift detection of a possibly short burst with optical counterpart
  96. GRB 080413A: REM detection of the NIR Afterglow
  97. GRB 080413: Enhanced Swift-XRT position
  98. GRB 080413: TAROT Calern observatory optical observations
  99. GRB 080413: Swift detection of a burst with an optical afterglow
  100. GRB 080413: ROTSE-III Detection of Optical Counterpart

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