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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"

28856 results found.

  1. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  2. SVOM trigger sb26083106 is not a GRB
  3. GRB 260829A: AstroSat CZTI detection
  4. GRB 260831B: EP-FXT follow-up observation
  5. GRB 260831B: LCO optical upper limits
  6. EP260830a: Global MASTER-Net observations report
  7. GRB 260827A: SVOM/GRM observation
  8. GRB 260831B: SVOM detection of a possible burst
  9. IPN triangulation of GRB 260829A
  10. GRB 260827A: Glowbug gamma-ray detection
  11. EP260727a: ATCA 10 GHz detection
  12. GRB 260831A: Fermi GBM Final Real-time Localization
  13. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  14. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  15. GRB 260829A: GECAM-B observation of a long burst
  16. GRB 260825A: SVOM/GRM observation of a long burst
  17. GRB 260825A: GECAM-B observation
  18. GRB 260829A: Fermi GBM Detection
  19. GRB 260825A: AstroSat CZTI detection
  20. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  21. GRB 260829A: Fermi GBM Final Real-time Localization
  22. Fermi GBM trigger 809666623/260829141 is not a GRB
  23. GRB 260818B: Further EP-FXT observation
  24. GRB 260818B: VLT optical and nIR observations
  25. GRB 260818B: TNG NIR observations
  26. MAXI GRB260827.40: Global MASTER-Net observations report
  27. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  28. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  29. GRB 260827A: Fermi GBM Final Real-time Localization
  30. GRB 260818B: 6 GHz VLA observations
  31. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  32. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  33. EP260822a: Global MASTER-Net observations report
  34. EP Alert 260820.31: Global MASTER-Net observations report
  35. GRB 260807A: EP-FXT follow-up observations
  36. GRB 260822A: SVOM/ECLAIRs refined analysis
  37. GRB 260809A: SVOM/ECLAIRs refined analysis
  38. IceCube Alert 260825A: Global MASTER-Net observations report
  39. GRB 260825A: Fermi GBM Final Real-time Localization
  40. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  41. GRB 260822A: EP/FXT follow-up observations
  42. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  43. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  44. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  45. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  46. GRB 260822A: LCO optical upper limits
  47. The EP-WXT trigger 01709287395 is likely a flaring star
  48. GRB260822B: Fermi GBM Final Localization
  49. GRB 260822A: GROWTH-India Telescope Upper Limits
  50. GRB 260822A: GOTO optical upper limit
  51. GRB 260822A: SVOM detection of a short burst
  52. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  53. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  54. GRB 260818B: SVOM/C-GFT optical upper limit
  55. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  56. IceCube Alert 260821A: Global MASTER-Net observations report
  57. The EP-WXT trigger 01709286204 is likely a flaring star
  58. GRB 260820A: Insight-HXMT/HE detection
  59. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  60. GRB260820A: Fermi GBM Final Real-Time Localization
  61. GRB 260818B: EP-FXT follow-up observation
  62. GRB 260818A: J-band observations with WINTER
  63. GRB 260818B: SVOM/ECLAIRs refined analysis
  64. GRB 260818A: SVOM/ECLAIRs refined analysis
  65. GRB 260818B: NOT optical upper limits
  66. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  67. GRB260818A: EP-FXT follow-up observation
  68. GRB 260818B: LCO optical upper limits
  69. GRB 260818B: SVOM detection of a short burst
  70. SVOM trigger sb26081806 is not a GRB
  71. EP260806a: SAO RAS multicolor optical observations
  72. GRB 260818A: LCO optical upper limits
  73. EP260812a: AbAO optical upper limit
  74. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  75. GRB 260818A: SVOM possible detection of a long and faint GRB
  76. EP260806a: SVOM/ECLAIRs detection through targeted search
  77. The EP-WXT trigger 01709281429 is likely a flaring star
  78. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  79. EP260806a: WFST optical observations
  80. The EP-WXT trigger 01709280562 is likely a flaring star
  81. The EP-WXT trigger 01709279838 is likely a flaring star
  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. EP260812a: NOT and Liverpool Telescope upper limits:
  88. EP260812a: SVOM/C-GFT optical upper limit
  89. EP260812b: COLIBRÍ optical observations
  90. EP260812b: SVOM/VT optical observation
  91. GRB 260808A: SVOM/GRM observation
  92. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  93. Fermi GBM Sub-Threshold Detection of GRB 260809A
  94. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  95. GRB 260808B: SVOM/VT optical re-brightening at day 3
  96. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  97. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  98. GRB 260808A: GECAM-B observation
  99. GRB 260807A: SVOM/ECLAIRs refined analysis
  100. GRB260808B: MAO/AZT-22 optical observations

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