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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"

38923 results found.

  1. Fermi GBM trigger 809666623/260829141 is not a GRB
  2. GRB 260818B: Further EP-FXT observation
  3. GRB 260818B: VLT optical and nIR observations
  4. GRB 260818B: TNG NIR observations
  5. MAXI GRB260827.40: Global MASTER-Net observations report
  6. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  7. GRB 260827A: Fermi GBM Final Real-time Localization
  8. GRB 260818B: 6 GHz VLA observations
  9. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  10. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  11. GRB 260808B: SAO RAS observations of the optical rebrightening
  12. EP260822a: Global MASTER-Net observations report
  13. EP Alert 260820.31: Global MASTER-Net observations report
  14. GRB 260807A: EP-FXT follow-up observations
  15. GRB 260822A: SVOM/ECLAIRs refined analysis
  16. GRB 260809A: SVOM/ECLAIRs refined analysis
  17. GRB 260822A: SVOM/VT optical upper limits
  18. IceCube Alert 260825A: Global MASTER-Net observations report
  19. GRB 260825A: Fermi GBM Final Real-time Localization
  20. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  21. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  22. GRB 260822A: EP/FXT follow-up observations
  23. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  24. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  25. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  26. GRB 260822A: GOTO optical counterpart detection
  27. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  28. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  29. EP260822a: Einstein Probe detection of a fast X-ray transient
  30. GRB 260822A: LCO optical upper limits
  31. The EP-WXT trigger 01709287395 is likely a flaring star
  32. GRB260822B: Fermi GBM Final Localization
  33. GRB 260822A: GROWTH-India Telescope Upper Limits
  34. GRB 260822A: GOTO optical upper limit
  35. GRB 260822A: SVOM detection of a short burst
  36. GRB 260818B: VLA radio observations
  37. GRB 260818B: SVOM/C-GFT optical upper limit
  38. IceCube Alert 260821A: Global MASTER-Net observations report
  39. GRB 260820A: Insight-HXMT/HE detection
  40. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 260818B: SVOM/GRM observation
  42. GRB260820A: Fermi GBM Final Real-Time Localization
  43. GRB 260818B: Insight-HXMT detection
  44. GRB 260818B: EP-FXT follow-up observation
  45. GRB 260818A: J-band observations with WINTER
  46. GRB 260818B: SVOM/ECLAIRs refined analysis
  47. GRB 260818A: SVOM/ECLAIRs refined analysis
  48. GRB 260818B: NOT optical upper limits
  49. GRB 260810A: SVOM/GRM observation
  50. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  51. GRB260818A: EP-FXT follow-up observation
  52. GRB 260818B: LCO optical upper limits
  53. GRB 260818B: SVOM detection of a short burst
  54. SVOM trigger sb26081806 is not a GRB
  55. EP260806a: SAO RAS multicolor optical observations
  56. GRB 260818A: LCO optical upper limits
  57. EP260812a: AbAO optical upper limit
  58. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  59. GRB 260810A: Insight-HXMT/HE detection
  60. GRB 260818A: SVOM possible detection of a long and faint GRB
  61. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  62. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  63. GRB 260808B: Liverpool Telescope further optical observations
  64. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  65. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  66. GRB 260813A: Fermi GBM Final Real-time Localization
  67. EP260812a: NOT and Liverpool Telescope upper limits:
  68. EP260812a: SVOM/C-GFT optical upper limit
  69. EP260812b: COLIBRÍ optical observations
  70. GRB 260808A: SVOM/GRM observation
  71. Fermi GBM Sub-Threshold Detection of GRB 260809A
  72. GRB 260810A: Glowbug gamma-ray detection
  73. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  74. GRB 260810A: AstroSat CZTI detection of a long burst
  75. GRB 260809A: SAO RAS optical observations
  76. GRB 260808B: SAO RAS optical observations
  77. GRB 260808B: SVOM/VT optical re-brightening at day 3
  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. GRB 260808A: GECAM-B observation
  81. GRB 260807A: SVOM/ECLAIRs refined analysis
  82. GRB260808B: MAO/AZT-22 optical observations
  83. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  84. GRB 260809A: J-band upper limit with WINTER
  85. GRB 260806A: Glowbug gamma-ray detection
  86. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  89. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  90. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  91. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  92. GRB 260809A: NOT optical observations
  93. GRB260809A: MAO/AZT-22 optical observations
  94. GRB260809A: OHP/T193 optical observations
  95. GRB 260809A: SVOM/VT optical counterpart
  96. GRB 260808B: J-band upper limit with WINTER
  97. GRB 260808B: SVOM/ECLAIRs refined analysis
  98. GRB 260809A: SVOM detection of a faint burst
  99. GRB 260808B: Liverpool Telescope optical observations
  100. GRB 260808B: NOT optical observations

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