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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"

37518 results found.

  1. GRB 260827A: Insight-HXMT/HE detection
  2. GRB 260903A: SVOM detection of a soft faint burst
  3. Konus-Wind detection of GRB 260829A
  4. GRB 260829A: SVOM/GRM observation
  5. GRB 260818A: ATCA detection of a candidate radio counterpart
  6. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  7. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  8. SVOM trigger sb26083106 is not a GRB
  9. GRB 260829A: AstroSat CZTI detection
  10. GRB 260831B: EP-FXT follow-up observation
  11. GRB 260830A: NuSTAR detection of prompt emission
  12. GRB 260831B: LCO optical upper limits
  13. GRB 260827A: SVOM/GRM observation
  14. GRB 260831B: SVOM detection of a possible burst
  15. IPN triangulation of GRB 260829A
  16. GRB 260827A: Glowbug gamma-ray detection
  17. GRB 260831A: Fermi GBM Final Real-time Localization
  18. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  19. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  20. GRB 260829A: GECAM-B observation of a long burst
  21. GRB 260825A: SVOM/GRM observation of a long burst
  22. GRB 260825A: GECAM-B observation
  23. GRB 260829A: Fermi GBM Detection
  24. GRB 260825A: AstroSat CZTI detection
  25. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  26. GRB 260829A: Fermi GBM Final Real-time Localization
  27. Fermi GBM trigger 809666623/260829141 is not a GRB
  28. GRB 260818B: Further EP-FXT observation
  29. GRB 260818B: VLT optical and nIR observations
  30. GRB 260818B: TNG NIR observations
  31. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  32. GRB 260827A: Fermi GBM Final Real-time Localization
  33. GRB 260818B: 6 GHz VLA observations
  34. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  35. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  36. GRB 260808B: SAO RAS observations of the optical rebrightening
  37. GRB 260807A: EP-FXT follow-up observations
  38. GRB 260822A: SVOM/ECLAIRs refined analysis
  39. GRB 260809A: SVOM/ECLAIRs refined analysis
  40. GRB 260822A: SVOM/VT optical upper limits
  41. GRB 260825A: Fermi GBM Final Real-time Localization
  42. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  43. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  44. GRB 260822A: EP/FXT follow-up observations
  45. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  46. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  47. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  48. GRB 260822A: GOTO optical counterpart detection
  49. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  50. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  51. GRB 260822A: LCO optical upper limits
  52. GRB260822B: Fermi GBM Final Localization
  53. GRB 260822A: GROWTH-India Telescope Upper Limits
  54. GRB 260822A: GOTO optical upper limit
  55. GRB 260822A: SVOM detection of a short burst
  56. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  57. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  58. GRB 260818B: VLA radio observations
  59. GRB 260818B: SVOM/C-GFT optical upper limit
  60. GRB 260820A: Insight-HXMT/HE detection
  61. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  62. GRB 260818B: SVOM/GRM observation
  63. GRB260820A: Fermi GBM Final Real-Time Localization
  64. GRB 260818B: Insight-HXMT detection
  65. GRB 260818B: EP-FXT follow-up observation
  66. GRB 260818A: J-band observations with WINTER
  67. GRB 260818B: SVOM/ECLAIRs refined analysis
  68. GRB 260818A: SVOM/ECLAIRs refined analysis
  69. GRB 260818B: NOT optical upper limits
  70. GRB 260810A: SVOM/GRM observation
  71. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  72. GRB260818A: EP-FXT follow-up observation
  73. GRB 260818B: LCO optical upper limits
  74. GRB 260818B: SVOM detection of a short burst
  75. SVOM trigger sb26081806 is not a GRB
  76. EP260806a: SAO RAS multicolor optical observations
  77. GRB 260818A: LCO optical upper limits
  78. EP260812a: AbAO optical upper limit
  79. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  80. GRB 260810A: Insight-HXMT/HE detection
  81. GRB 260818A: SVOM possible detection of a long and faint GRB
  82. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  83. GRB 260808B: Liverpool Telescope further optical observations
  84. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  85. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  86. GRB 260813A: Fermi GBM Final Real-time Localization
  87. GRB 260808A: SVOM/GRM observation
  88. Fermi GBM Sub-Threshold Detection of GRB 260809A
  89. GRB 260810A: Glowbug gamma-ray detection
  90. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  91. GRB 260810A: AstroSat CZTI detection of a long burst
  92. GRB 260809A: SAO RAS optical observations
  93. GRB 260808B: SAO RAS optical observations
  94. GRB 260808B: SVOM/VT optical re-brightening at day 3
  95. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  96. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  97. GRB 260808A: GECAM-B observation
  98. GRB 260807A: SVOM/ECLAIRs refined analysis
  99. GRB260808B: MAO/AZT-22 optical observations
  100. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search

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