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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"

27767 results found.

  1. GRB 260915A: 10.4m GTC deep optical limits
  2. GRB 260915A: SVOM/VT optical upper limits from VHF data
  3. Fermi GBM Sub-Threshold Detection of GRB 260915A
  4. GRB 260915A: SVOM detection of a burst
  5. Fermi GBM Sub-Threshold Detection of GRB 260914A
  6. GRB 260914A: SVOM detection of a burst
  7. GRB 260818A: Continued ATCA observations
  8. GRB 260913A: SVOM detection of a faint burst
  9. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  10. GRB 260910B: GOTO tentative optical counterpart candidates
  11. GRB 260909A: Swift ToO observations
  12. GRB 260910B: Fermi GBM Final Real-time Localization
  13. GRB 260903A: Swift-XRT observations
  14. EP260806a: VLA+ALMA radio detections
  15. GRB 260910A: Fermi GBM Final Real-time Localization
  16. EP260806a: NOEMA detection
  17. EP260623a: NOEMA detections
  18. GRB 260909A: SVOM detection of a burst
  19. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  20. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  21. GRB 260903A: Swift ToO observations
  22. GRB 260907B: Fermi GBM Final Real-time Localization
  23. GRB 260907A: Fermi GBM Final Real-time Localization
  24. EP260903a: EP-FXT follow-up observation
  25. GRB 260830A: GECAM-B detection of a burst
  26. EP260903a: EP-WXT detection of a fast X-ray transient
  27. GRB 260830A: Insight-HXMT/HE detection
  28. GRB 260903A: OHP/T193 optical afterglow detection
  29. NuSTAR Transient 260828: SOAR Optical Upper Limits
  30. GRB 260903A: Retraction of optical counterpart of GCN 45501
  31. GRB 260903A: LCO optical counterpart detection
  32. GRB 260827A: Insight-HXMT/HE detection
  33. GRB 260903A: SVOM detection of a soft faint burst
  34. EP260901a: EP-FXT follow-up observation
  35. Konus-Wind detection of GRB 260829A
  36. GRB 260818A: ATCA detection of a candidate radio counterpart
  37. EP260830a: EP-FXT follow-up observation
  38. NuSTAR Transient 260828: LCO Optical Upper Limits
  39. EP260901a: EP-WXT detection of a fast X-ray transient
  40. GRB 260829A: AstroSat CZTI detection
  41. GRB 260830A: NuSTAR detection of prompt emission
  42. EP260830a: EP-WXT detection of a fast X-ray transient
  43. NuSTAR 260828: a 1100s hard X-ray transient
  44. GRB 260831B: SVOM detection of a possible burst
  45. IPN triangulation of GRB 260829A
  46. GRB 260827A: Glowbug gamma-ray detection
  47. EP260727a: ATCA 10 GHz detection
  48. GRB 260831A: Fermi GBM Final Real-time Localization
  49. GRB 260829A: Fermi GBM Detection
  50. GRB 260825A: AstroSat CZTI detection
  51. GRB 260829A: Fermi GBM Final Real-time Localization
  52. GRB 260818B: VLT optical and nIR observations
  53. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  54. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  55. GRB 260827A: Fermi GBM Final Real-time Localization
  56. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  57. GRB 260822A: SVOM/VT optical upper limits
  58. GRB 260825A: Fermi GBM Final Real-time Localization
  59. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  61. EP260822a: EP-FXT non-detection and upper limit
  62. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  63. GRB 260822A: GOTO optical counterpart detection
  64. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  65. EP260822a: Einstein Probe detection of a fast X-ray transient
  66. The EP-WXT trigger 01709287395 is likely a flaring star
  67. GRB260822B: Fermi GBM Final Localization
  68. GRB 260822A: SVOM detection of a short burst
  69. GRB 260818B: SVOM/C-GFT optical upper limit
  70. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  71. GRB 260820A: Insight-HXMT/HE detection
  72. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  73. EP detected a brightening of LMXB 1ES 1735-26.9
  74. GRB260820A: Fermi GBM Final Real-Time Localization
  75. GRB 260818B: Insight-HXMT detection
  76. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  77. GRB 260818B: SVOM detection of a short burst
  78. GRB 260810A: Insight-HXMT/HE detection
  79. GRB 260818A: SVOM possible detection of a long and faint GRB
  80. EP260806a: SVOM/ECLAIRs detection through targeted search
  81. EP260806a: WFST optical observations
  82. EP260812b: Optical upper limit with Kinder
  83. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  84. GRB 260813A: Fermi GBM Final Real-time Localization
  85. EP260812b: Liverpool Telescope observations
  86. EP260812b: GOTO detection of the optical counterpart
  87. EP260812b: Einstein Probe detection of an X-ray transient
  88. Fermi GBM Sub-Threshold Detection of GRB 260809A
  89. GRB 260810A: Glowbug gamma-ray detection
  90. GRB 260810A: AstroSat CZTI detection of a long burst
  91. EP260812a: Einstein Probe detection of an X-ray transient
  92. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  93. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  94. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  95. GRB 260806A: Glowbug gamma-ray detection
  96. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  98. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 260809A: SVOM detection of a faint burst
  100. GRB 260808A: NuSTAR detection of prompt emission

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