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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"

38919 results found.

  1. MAXI GRB260827.40: Global MASTER-Net observations report
  2. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 260827A: Fermi GBM Final Real-time Localization
  4. GRB 260818B: 6 GHz VLA observations
  5. GRB 2600818B: SVOM/VT optical upper limit and continuous observations
  6. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  7. GRB 260808B: SAO RAS observations of the optical rebrightening
  8. EP260822a: Global MASTER-Net observations report
  9. EP Alert 260820.31: Global MASTER-Net observations report
  10. GRB 260807A: EP-FXT follow-up observations
  11. GRB 260822A: SVOM/ECLAIRs refined analysis
  12. GRB 260809A: SVOM/ECLAIRs refined analysis
  13. GRB 260822A: SVOM/VT optical upper limits
  14. IceCube Alert 260825A: Global MASTER-Net observations report
  15. GRB 260825A: Fermi GBM Final Real-time Localization
  16. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  17. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  18. GRB 260822A: EP/FXT follow-up observations
  19. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  20. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  21. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  22. GRB 260822A: GOTO optical counterpart detection
  23. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  24. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  25. EP260822a: Einstein Probe detection of a fast X-ray transient
  26. GRB 260822A: LCO optical upper limits
  27. The EP-WXT trigger 01709287395 is likely a flaring star
  28. GRB260822B: Fermi GBM Final Localization
  29. GRB 260822A: GROWTH-India Telescope Upper Limits
  30. GRB 260822A: GOTO optical upper limit
  31. GRB 260822A: SVOM detection of a short burst
  32. GRB 260818B: VLA radio observations
  33. GRB 260818B: SVOM/C-GFT optical upper limit
  34. IceCube Alert 260821A: Global MASTER-Net observations report
  35. GRB 260820A: Insight-HXMT/HE detection
  36. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  37. GRB 260818B: SVOM/GRM observation
  38. GRB260820A: Fermi GBM Final Real-Time Localization
  39. GRB 260818B: Insight-HXMT detection
  40. GRB 260818B: EP-FXT follow-up observation
  41. GRB 260818A: J-band observations with WINTER
  42. GRB 260818B: SVOM/ECLAIRs refined analysis
  43. GRB 260818A: SVOM/ECLAIRs refined analysis
  44. GRB 260818B: NOT optical upper limits
  45. GRB 260810A: SVOM/GRM observation
  46. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. GRB260818A: EP-FXT follow-up observation
  48. GRB 260818B: LCO optical upper limits
  49. GRB 260818B: SVOM detection of a short burst
  50. SVOM trigger sb26081806 is not a GRB
  51. EP260806a: SAO RAS multicolor optical observations
  52. GRB 260818A: LCO optical upper limits
  53. EP260812a: AbAO optical upper limit
  54. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  55. GRB 260810A: Insight-HXMT/HE detection
  56. GRB 260818A: SVOM possible detection of a long and faint GRB
  57. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  58. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  59. GRB 260808B: Liverpool Telescope further optical observations
  60. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  61. GRB 260813A: BALROG localization (Fermi Trigger 808341387 / GRB 260813803)
  62. GRB 260813A: Fermi GBM Final Real-time Localization
  63. EP260812a: NOT and Liverpool Telescope upper limits:
  64. EP260812a: SVOM/C-GFT optical upper limit
  65. EP260812b: COLIBRÍ optical observations
  66. GRB 260808A: SVOM/GRM observation
  67. Fermi GBM Sub-Threshold Detection of GRB 260809A
  68. GRB 260810A: Glowbug gamma-ray detection
  69. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  70. GRB 260810A: AstroSat CZTI detection of a long burst
  71. GRB 260809A: SAO RAS optical observations
  72. GRB 260808B: SAO RAS optical observations
  73. GRB 260808B: SVOM/VT optical re-brightening at day 3
  74. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  75. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  76. GRB 260808A: GECAM-B observation
  77. GRB 260807A: SVOM/ECLAIRs refined analysis
  78. GRB260808B: MAO/AZT-22 optical observations
  79. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  80. GRB 260809A: J-band upper limit with WINTER
  81. GRB 260806A: Glowbug gamma-ray detection
  82. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  83. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  84. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  85. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  86. GRB 260809A: SVOM/COLIBRÍ (FM-GFT) optical observation
  87. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) optical observation
  88. GRB 260809A: NOT optical observations
  89. GRB260809A: MAO/AZT-22 optical observations
  90. GRB260809A: OHP/T193 optical observations
  91. GRB 260809A: SVOM/VT optical counterpart
  92. GRB 260808B: J-band upper limit with WINTER
  93. GRB 260808B: SVOM/ECLAIRs refined analysis
  94. GRB 260809A: SVOM detection of a faint burst
  95. GRB 260808B: Liverpool Telescope optical observations
  96. GRB 260808B: NOT optical observations
  97. GRB 260808B: LCO optical observations
  98. GRB 260808A: NuSTAR detection of prompt emission
  99. EP260809a: COLIBRÍ optical observations
  100. EP260809a: LCO optical observation

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