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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. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  2. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  3. Fermi GBM trigger 809666623/260829141 is not a GRB
  4. GRB 260818B: Further EP-FXT observation
  5. GRB 260818B: VLT optical and nIR observations
  6. GRB 260818B: TNG NIR observations
  7. MAXI GRB260827.40: Global MASTER-Net observations report
  8. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  9. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  10. GRB 260827A: Fermi GBM Final Real-time Localization
  11. GRB 260818B: 6 GHz VLA observations
  12. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  13. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  14. GRB 260808B: SAO RAS observations of the optical rebrightening
  15. EP260822a: Global MASTER-Net observations report
  16. EP Alert 260820.31: Global MASTER-Net observations report
  17. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  18. GRB 260807A: EP-FXT follow-up observations
  19. GRB 260822A: SVOM/ECLAIRs refined analysis
  20. GRB 260809A: SVOM/ECLAIRs refined analysis
  21. GRB 260822A: SVOM/VT optical upper limits
  22. IceCube Alert 260825A: Global MASTER-Net observations report
  23. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260825A: Fermi GBM Final Real-time Localization
  25. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  26. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  27. GRB 260822A: EP/FXT follow-up observations
  28. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  29. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  30. EP260822a: EP-FXT non-detection and upper limit
  31. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  32. GRB 260822A: GOTO optical counterpart detection
  33. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  34. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  35. EP260822a: Einstein Probe detection of a fast X-ray transient
  36. GRB 260822A: LCO optical upper limits
  37. The EP-WXT trigger 01709287395 is likely a flaring star
  38. GRB260822B: Fermi GBM Final Localization
  39. GRB 260822A: GROWTH-India Telescope Upper Limits
  40. GRB 260822A: GOTO optical upper limit
  41. GRB 260822A: SVOM detection of a short burst
  42. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  43. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  44. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 260818B: VLA radio observations
  46. GRB 260818B: SVOM/C-GFT optical upper limit
  47. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  48. IceCube Alert 260821A: Global MASTER-Net observations report
  49. The EP-WXT trigger 01709286204 is likely a flaring star
  50. GRB 260820A: Insight-HXMT/HE detection
  51. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 260818B: SVOM/GRM observation
  53. EP detected a brightening of LMXB 1ES 1735-26.9
  54. GRB260820A: Fermi GBM Final Real-Time Localization
  55. GRB 260818B: Insight-HXMT detection
  56. GRB 260818B: EP-FXT follow-up observation
  57. GRB 260818A: J-band observations with WINTER
  58. GRB 260818B: SVOM/ECLAIRs refined analysis
  59. GRB 260818A: SVOM/ECLAIRs refined analysis
  60. GRB 260818B: NOT optical upper limits
  61. GRB 260810A: SVOM/GRM observation
  62. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  63. GRB260818A: EP-FXT follow-up observation
  64. GRB 260818B: LCO optical upper limits
  65. GRB 260818B: SVOM detection of a short burst
  66. SVOM trigger sb26081806 is not a GRB
  67. EP260806a: SAO RAS multicolor optical observations
  68. GRB 260818A: LCO optical upper limits
  69. EP260812a: AbAO optical upper limit
  70. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  71. GRB 260810A: Insight-HXMT/HE detection
  72. GRB 260818A: SVOM possible detection of a long and faint GRB
  73. EP260806a: SVOM/ECLAIRs detection through targeted search
  74. EP260806a: NUTTELA-TAO optical observations
  75. The EP-WXT trigger 01709281429 is likely a flaring star
  76. EP260812a: AZT-22 optical upper limit
  77. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  78. EP260806a: WFST optical observations
  79. The EP-WXT trigger 01709280562 is likely a flaring star
  80. EP260812b: Optical upper limit with Kinder
  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. EP260812b: Liverpool Telescope observations
  89. EP260812b: GOTO detection of the optical counterpart
  90. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  91. EP260812a: SVOM/C-GFT optical upper limit
  92. EP260812b: COLIBRÍ optical observations
  93. EP260812b: SVOM/VT optical observation
  94. GRB 260808A: SVOM/GRM observation
  95. EP260812b: Einstein Probe detection of an X-ray transient
  96. EP trigger #01709278129 (EP260812b?): NOT optical counterpart
  97. Fermi GBM Sub-Threshold Detection of GRB 260809A
  98. GRB 260810A: Glowbug gamma-ray detection
  99. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  100. GRB 260810A: AstroSat CZTI detection of a long burst

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