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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"

14823 results found.

  1. GRB 260909A: SVOM detection of a burst
  2. The EP-WXT trigger 01709306297 is likely the known LMXB 4U 1745-203
  3. GRB 260907A: Glowbug gamma-ray detection of a likely short burst
  4. GRB 260907B: Fermi GBM Final Real-time Localization
  5. GRB 260907A: Fermi GBM Final Real-time Localization
  6. EP260903a: EP-FXT follow-up observation
  7. GRB 260830A: GECAM-B detection of a burst
  8. EP260903a: EP-WXT detection of a fast X-ray transient
  9. GRB 260830A: Insight-HXMT/HE detection
  10. GRB 260903A: OHP/T193 optical afterglow detection
  11. NuSTAR Transient 260828: SOAR Optical Upper Limits
  12. GRB 260903A: Retraction of optical counterpart of GCN 45501
  13. GRB 260903A: LCO optical counterpart detection
  14. GRB 260827A: Insight-HXMT/HE detection
  15. GRB 260903A: SVOM detection of a soft faint burst
  16. EP260901a: EP-FXT follow-up observation
  17. Konus-Wind detection of GRB 260829A
  18. GRB 260818A: ATCA detection of a candidate radio counterpart
  19. EP260830a: EP-FXT follow-up observation
  20. NuSTAR Transient 260828: LCO Optical Upper Limits
  21. EP260901a: EP-WXT detection of a fast X-ray transient
  22. GRB 260829A: AstroSat CZTI detection
  23. GRB 260830A: NuSTAR detection of prompt emission
  24. EP260830a: EP-WXT detection of a fast X-ray transient
  25. NuSTAR 260828: a 1100s hard X-ray transient
  26. GRB 260831B: SVOM detection of a possible burst
  27. IPN triangulation of GRB 260829A
  28. GRB 260827A: Glowbug gamma-ray detection
  29. EP260727a: ATCA 10 GHz detection
  30. GRB 260831A: Fermi GBM Final Real-time Localization
  31. GRB 260829A: Fermi GBM Detection
  32. GRB 260825A: AstroSat CZTI detection
  33. GRB 260829A: Fermi GBM Final Real-time Localization
  34. GRB 260818B: VLT optical and nIR observations
  35. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  36. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  37. GRB 260827A: Fermi GBM Final Real-time Localization
  38. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  39. GRB 260822A: SVOM/VT optical upper limits
  40. GRB 260825A: Fermi GBM Final Real-time Localization
  41. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  43. EP260822a: EP-FXT non-detection and upper limit
  44. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  45. GRB 260822A: GOTO optical counterpart detection
  46. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  47. EP260822a: Einstein Probe detection of a fast X-ray transient
  48. The EP-WXT trigger 01709287395 is likely a flaring star
  49. GRB260822B: Fermi GBM Final Localization
  50. GRB 260822A: SVOM detection of a short burst
  51. GRB 260818B: SVOM/C-GFT optical upper limit
  52. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  53. GRB 260820A: Insight-HXMT/HE detection
  54. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260818B: SVOM/GRM observation
  56. EP detected a brightening of LMXB 1ES 1735-26.9
  57. GRB260820A: Fermi GBM Final Real-Time Localization
  58. GRB 260818B: Insight-HXMT detection
  59. GRB 260810A: SVOM/GRM observation
  60. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  61. GRB 260818B: SVOM detection of a short burst
  62. EP260806a: SAO RAS multicolor optical observations
  63. GRB 260810A: Insight-HXMT/HE detection
  64. GRB 260818A: SVOM possible detection of a long and faint GRB
  65. EP260806a: SVOM/ECLAIRs detection through targeted search
  66. EP260806a: NUTTELA-TAO optical observations
  67. EP260806a: WFST optical observations
  68. EP260812b: Optical upper limit with Kinder
  69. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  70. GRB 260813A: Fermi GBM Final Real-time Localization
  71. EP260812b: Liverpool Telescope observations
  72. EP260812b: GOTO detection of the optical counterpart
  73. EP260812b: Einstein Probe detection of an X-ray transient
  74. Fermi GBM Sub-Threshold Detection of GRB 260809A
  75. GRB 260810A: Glowbug gamma-ray detection
  76. GRB 260810A: AstroSat CZTI detection of a long burst
  77. EP260812a: Einstein Probe detection of an X-ray transient
  78. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  79. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  80. EP260806a: MAO/AZT-22 optical observations
  81. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  82. GRB 260806A: Glowbug gamma-ray detection
  83. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  85. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  86. GRB 260809A: SVOM detection of a faint burst
  87. GRB 260808A: NuSTAR detection of prompt emission
  88. EP260809a: LCO optical observation
  89. EP260809a: Einstein Probe detection of an X-ray transient
  90. GRB 260808C: Fermi GBM Final Real-time Localization
  91. GRB 260808B: SVOM detection of a faint burst
  92. GRB 260808A: Fermi GBM Final Real-time Localization
  93. EP260806a: ZTF serendipitous detection of ZTF26abmjjnm / AT 2026yeh
  94. GRB 260807A: SVOM possible detection of a faint burst
  95. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  96. EP260806a: COLIBRÍ optical observations
  97. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  98. EP260806a: SVOM/VT optical observation
  99. EP260806a: Liverpool Telescope observations of the counterpart show a blue colour
  100. EP260806a: OSIRIS+/GTC redshift z=0.089

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