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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"

14831 results found.

  1. GRB 260913A: SVOM detection of a faint burst
  2. GRB 260909A: OSN 1.5m, CAHA 2.2m and GTC 10.4m optical upper limits
  3. GRB 260910B: GOTO tentative optical counterpart candidates
  4. GRB 260910B: Fermi GBM Final Real-time Localization
  5. EP260806a: VLA+ALMA radio detections
  6. GRB 260910A: Fermi GBM Final Real-time Localization
  7. EP260806a: NOEMA detection
  8. EP260623a: NOEMA detections
  9. GRB 260909A: SVOM detection of a burst
  10. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  11. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  12. GRB 260907B: Fermi GBM Final Real-time Localization
  13. GRB 260907A: Fermi GBM Final Real-time Localization
  14. EP260903a: EP-FXT follow-up observation
  15. GRB 260830A: GECAM-B detection of a burst
  16. EP260903a: EP-WXT detection of a fast X-ray transient
  17. GRB 260830A: Insight-HXMT/HE detection
  18. GRB 260903A: OHP/T193 optical afterglow detection
  19. NuSTAR Transient 260828: SOAR Optical Upper Limits
  20. GRB 260903A: Retraction of optical counterpart of GCN 45501
  21. GRB 260903A: LCO optical counterpart detection
  22. GRB 260827A: Insight-HXMT/HE detection
  23. GRB 260903A: SVOM detection of a soft faint burst
  24. EP260901a: EP-FXT follow-up observation
  25. Konus-Wind detection of GRB 260829A
  26. GRB 260818A: ATCA detection of a candidate radio counterpart
  27. EP260830a: EP-FXT follow-up observation
  28. NuSTAR Transient 260828: LCO Optical Upper Limits
  29. EP260901a: EP-WXT detection of a fast X-ray transient
  30. GRB 260829A: AstroSat CZTI detection
  31. GRB 260830A: NuSTAR detection of prompt emission
  32. EP260830a: EP-WXT detection of a fast X-ray transient
  33. NuSTAR 260828: a 1100s hard X-ray transient
  34. GRB 260831B: SVOM detection of a possible burst
  35. IPN triangulation of GRB 260829A
  36. GRB 260827A: Glowbug gamma-ray detection
  37. EP260727a: ATCA 10 GHz detection
  38. GRB 260831A: Fermi GBM Final Real-time Localization
  39. GRB 260829A: Fermi GBM Detection
  40. GRB 260825A: AstroSat CZTI detection
  41. GRB 260829A: Fermi GBM Final Real-time Localization
  42. GRB 260818B: VLT optical and nIR observations
  43. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  44. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  45. GRB 260827A: Fermi GBM Final Real-time Localization
  46. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  47. GRB 260822A: SVOM/VT optical upper limits
  48. GRB 260825A: Fermi GBM Final Real-time Localization
  49. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  50. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  51. EP260822a: EP-FXT non-detection and upper limit
  52. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  53. GRB 260822A: GOTO optical counterpart detection
  54. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  55. EP260822a: Einstein Probe detection of a fast X-ray transient
  56. The EP-WXT trigger 01709287395 is likely a flaring star
  57. GRB260822B: Fermi GBM Final Localization
  58. GRB 260822A: SVOM detection of a short burst
  59. GRB 260818B: SVOM/C-GFT optical upper limit
  60. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  61. GRB 260820A: Insight-HXMT/HE detection
  62. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 260818B: SVOM/GRM observation
  64. EP detected a brightening of LMXB 1ES 1735-26.9
  65. GRB260820A: Fermi GBM Final Real-Time Localization
  66. GRB 260818B: Insight-HXMT detection
  67. GRB 260810A: SVOM/GRM observation
  68. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  69. GRB 260818B: SVOM detection of a short burst
  70. EP260806a: SAO RAS multicolor optical observations
  71. GRB 260810A: Insight-HXMT/HE detection
  72. GRB 260818A: SVOM possible detection of a long and faint GRB
  73. EP260806a: SVOM/ECLAIRs detection through targeted search
  74. EP260806a: NUTTELA-TAO optical observations
  75. EP260806a: WFST optical observations
  76. EP260812b: Optical upper limit with Kinder
  77. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  78. GRB 260813A: Fermi GBM Final Real-time Localization
  79. EP260812b: Liverpool Telescope observations
  80. EP260812b: GOTO detection of the optical counterpart
  81. EP260812b: Einstein Probe detection of an X-ray transient
  82. Fermi GBM Sub-Threshold Detection of GRB 260809A
  83. GRB 260810A: Glowbug gamma-ray detection
  84. GRB 260810A: AstroSat CZTI detection of a long burst
  85. EP260812a: Einstein Probe detection of an X-ray transient
  86. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  87. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  88. EP260806a: MAO/AZT-22 optical observations
  89. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  90. GRB 260806A: Glowbug gamma-ray detection
  91. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  93. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  94. GRB 260809A: SVOM detection of a faint burst
  95. GRB 260808A: NuSTAR detection of prompt emission
  96. EP260809a: LCO optical observation
  97. EP260809a: Einstein Probe detection of an X-ray transient
  98. GRB 260808C: Fermi GBM Final Real-time Localization
  99. GRB 260808B: SVOM detection of a faint burst
  100. GRB 260808A: Fermi GBM Final Real-time Localization

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