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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"
  1. EP260830a: Global MASTER-Net observations report
  2. EP260830a: EP-WXT detection of a fast X-ray transient
  3. GRB 260827A: SVOM/GRM observation
  4. NuSTAR 260828: a 1100s hard X-ray transient
  5. GRB 260831B: SVOM detection of a possible burst
  6. IPN triangulation of GRB 260829A
  7. GRB 260827A: Glowbug gamma-ray detection
  8. EP260727a: ATCA 10 GHz detection
  9. GRB 260831A: Fermi GBM Final Real-time Localization
  10. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  11. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  12. GRB 260829A: GECAM-B observation of a long burst
  13. GRB 260825A: SVOM/GRM observation of a long burst
  14. GRB 260825A: GECAM-B observation
  15. GRB 260829A: Fermi GBM Detection
  16. GRB 260825A: AstroSat CZTI detection
  17. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  18. GRB 260829A: Fermi GBM Final Real-time Localization
  19. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  20. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  21. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  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. GRB 260808B: SAO RAS observations of the optical rebrightening
  34. EP260822a: Global MASTER-Net observations report
  35. EP Alert 260820.31: Global MASTER-Net observations report
  36. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  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. IceCube Alert 260825A: Global MASTER-Net observations report
  42. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  43. GRB 260825A: Fermi GBM Final Real-time Localization
  44. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  45. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  46. GRB 260822A: EP/FXT follow-up observations
  47. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  48. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  49. EP260822a: EP-FXT non-detection and upper limit
  50. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  51. GRB 260822A: GOTO optical counterpart detection
  52. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  53. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  54. EP260822a: Einstein Probe detection of a fast X-ray transient
  55. GRB 260822A: LCO optical upper limits
  56. The EP-WXT trigger 01709287395 is likely a flaring star
  57. GRB260822B: Fermi GBM Final Localization
  58. GRB 260822A: GROWTH-India Telescope Upper Limits
  59. GRB 260822A: GOTO optical upper limit
  60. GRB 260822A: SVOM detection of a short burst
  61. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  62. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  63. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 260818B: VLA radio observations
  65. GRB 260818B: SVOM/C-GFT optical upper limit
  66. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  67. IceCube Alert 260821A: Global MASTER-Net observations report
  68. The EP-WXT trigger 01709286204 is likely a flaring star
  69. GRB 260820A: Insight-HXMT/HE detection
  70. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  71. GRB 260818B: SVOM/GRM observation
  72. EP detected a brightening of LMXB 1ES 1735-26.9
  73. GRB260820A: Fermi GBM Final Real-Time Localization
  74. GRB 260818B: Insight-HXMT detection
  75. GRB 260818B: EP-FXT follow-up observation
  76. GRB 260818A: J-band observations with WINTER
  77. GRB 260818B: SVOM/ECLAIRs refined analysis
  78. GRB 260818A: SVOM/ECLAIRs refined analysis
  79. GRB 260818B: NOT optical upper limits
  80. GRB 260810A: SVOM/GRM observation
  81. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  82. GRB260818A: EP-FXT follow-up observation
  83. GRB 260818B: LCO optical upper limits
  84. GRB 260818B: SVOM detection of a short burst
  85. SVOM trigger sb26081806 is not a GRB
  86. EP260806a: SAO RAS multicolor optical observations
  87. GRB 260818A: LCO optical upper limits
  88. EP260812a: AbAO optical upper limit
  89. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  90. GRB 260810A: Insight-HXMT/HE detection
  91. GRB 260818A: SVOM possible detection of a long and faint GRB
  92. EP260806a: SVOM/ECLAIRs detection through targeted search
  93. EP260806a: NUTTELA-TAO optical observations
  94. The EP-WXT trigger 01709281429 is likely a flaring star
  95. EP260812a: AZT-22 optical upper limit
  96. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  97. EP260806a: WFST optical observations
  98. The EP-WXT trigger 01709280562 is likely a flaring star
  99. EP260812b: Optical upper limit with Kinder
  100. The EP-WXT trigger 01709279838 is likely a flaring star

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