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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"

27777 results found.

  1. GRB 260302A: Fermi GBM Final Real-time Localization
  2. GRB 260228A: CAHA 2.2m telescope optical upper limit
  3. EP260227a: Mephisto optical detection
  4. GRID detection of GRB 260225D
  5. EP260227A: 3.6m DOT optical afterglow detection
  6. GRB 260228A: SVOM detection of a burst
  7. GRB 260226A: Asiago r-band upper limit
  8. EP260227a: Liverpool Telescope observations
  9. GRID detection of GRB 260223A
  10. EP260227a: Einstein Probe detection of an X-ray transient and refined analysis
  11. IceCube cascade alert 142200_1517143 retraction
  12. GRB 260226A: Insight-HXMT/HE detection of the very bright burst
  13. Konus-Wind detection of GRB 260226A
  14. GRB 260223A: 7DT detection and Medium-band SED of Afterglow
  15. GRB 260226A: CALET Gamma-Ray Burst Monitor detection
  16. GRB 260225D: Glowbug gamma-ray detection of a likely short burst
  17. GRB 260226A: Glowbug gamma-ray detection
  18. GRB 260226A: NuSTAR detection of bright prompt emission
  19. GRB 260226A: AstroSat CZTI detection of bright long burst
  20. EP260214a: VLA 6 GHz detection
  21. GRB 260226A: Fermi-LAT detection of a bright burst
  22. GRB 260226A: Fermi GBM Final Real-time Localization
  23. GRB 260225A: SVOM/COLIBRÍ (FM-GFT) Detection of an Optical Counterpart Candidate
  24. GRB 260225C: Fermi GBM Final Real-time Localization
  25. GRB 260225A: SVOM/VT optical upper limits
  26. GRB 260225B: Fermi GBM Final Real-time Localization
  27. EP260126a: VLA 6 GHz detection
  28. EP260223a: Liverpool Telescope upper limits
  29. GRB 260225A: SVOM detection of a burst
  30. EP260224a: Einstein Probe detection of an X-ray transient
  31. EP260223a: Xinglong optical upper limit
  32. GRB 260223A: Glowbug gamma-ray detection
  33. EP260213a: Mephisto optical upper limits
  34. EP260223a: EP-FXT follow-up observation
  35. sb26021801: SVOM/VT optical upper limits
  36. EP260223a: Einstein Probe detection of an X-ray transient
  37. EP260221a: Optical upper limit with Kinder observations
  38. GRB 260223A: Fermi GBM Final Real-time Localization
  39. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  40. EP260221a: COLIBRÍ optical counterpart candidate
  41. EP260221a: Gemini South z-band upper limit
  42. GRB 260222A: Fermi GBM Final Real-time Localization
  43. GRB 260221B: Fermi GBM Final Real-time Localization
  44. EP-WXT01709258519: Xinglong optical upper limit
  45. EP260221a: Xinglong optical upper limit
  46. GRB 260221A: Fermi GBM Final Real-time Localization
  47. EP260221a: Einstein Probe detection of an X-ray transient
  48. GRB 260219A: AstroSat CZTI detection
  49. GRB 260219A: Fermi GBM Final Real-time Localization
  50. GRB 260217A: Fermi GBM Final Localization
  51. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  52. sb26021801: SVOM detection of a long faint X-ray transient
  53. EP260214b: 1.3m DFOT optical upper limit
  54. Konus-Wind detection of GRB 260212A
  55. IPN triangulation of GRB 260212A
  56. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  57. GRB 260216A: Fermi GBM Final Real-time Localization
  58. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  59. EP260214b: Optical upper limit with Kinder observations
  60. EP260214a: Optical upper limits with Kinder observations
  61. EP260214b: EP-FXT follow-up observation
  62. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  63. EP260214b: DDOTI Optical Detection
  64. EP260214b: LCO optical counterpart detection
  65. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  66. EP260214b: NOT optical counterpart detection
  67. EP260214b: Einstein Probe detection of a fast X-ray transient
  68. EP260214a: Einstein Probe detection of an X-ray transient
  69. GRB 260212A: AstroSat CZTI detection
  70. EP260213a: Liverpool Telescope optical upper limits
  71. EP260213a: Optical upper limits with Kinder observations
  72. EP260213a: Einstein Probe detection of a fast X-ray transient
  73. GRB 260213B: Fermi GBM Final Localization
  74. GRB 260204A: SVOM/ECLAIRs refined analysis
  75. GRB 260213A: Fermi GBM Final Localization
  76. GRB 260212A: Glowbug gamma-ray detection
  77. GRB 260212A: Fermi GBM Final Real-time Localization
  78. Fermi GBM Sub-Threshold Detection of GRB 260211A
  79. Konus-Wind detection of GRB 260207B
  80. GRID detection of GRB 260207B
  81. GRB260131A/B: 3.6m DOT Optical Observations
  82. GRB 260211A: SVOM detection of a burst
  83. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  84. Konus-Wind detection of GRB 260209B
  85. GRB 260208A: Swift UVOT detection
  86. Konus-Wind detection of GRB 260127B
  87. GRB 260208A: LCO detection of the optical counterpart
  88. EP260209a: Einstein Probe detection of a fast X-ray transient
  89. IPN triangulation of GRB 260207B (short/hard with EE)
  90. GRB 260210C: Fermi GBM Final Real-time Localization
  91. GRB 260210A: Glowbug gamma-ray detection
  92. GRB 260210B: Fermi GBM Final Real-time Localization
  93. GRB 260210A: AstroSat CZTI detection
  94. GRB 260208C: AstroSat CZTI detection
  95. GRB 260208B: refined analysis of the EP-FXT observation
  96. EP260210a: Einstein Probe detection of an X-ray transient
  97. GRB 260207B: AstroSat CZTI detection
  98. GRB 260204A: Swift-XRT afterglow detection
  99. GRB 260208B: AstroSat CZTI detection of a bright long burst
  100. GRB 260208A: Glowbug gamma-ray detection

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