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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"

32496 results found.

  1. GRB 260818A: ATCA detection of a candidate radio counterpart
  2. EP260830a: EP-FXT follow-up observation
  3. EP260901a: Global MASTER-Net observations report
  4. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  5. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  6. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  7. NuSTAR Transient 260828: LCO Optical Upper Limits
  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. EP260830a: Global MASTER-Net observations report
  14. GRB 260827A: SVOM/GRM observation
  15. IPN triangulation of GRB 260829A
  16. GRB 260827A: Glowbug gamma-ray detection
  17. EP260727a: ATCA 10 GHz detection
  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. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  26. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  27. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  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 260818B: 6 GHz VLA observations
  33. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  34. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  35. GRB 260808B: SAO RAS observations of the optical rebrightening
  36. EP260822a: Global MASTER-Net observations report
  37. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  38. GRB 260807A: EP-FXT follow-up observations
  39. GRB 260822A: SVOM/ECLAIRs refined analysis
  40. GRB 260809A: SVOM/ECLAIRs refined analysis
  41. GRB 260822A: SVOM/VT optical upper limits
  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. EP260822a: EP-FXT non-detection and upper limit
  48. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  49. GRB 260822A: GOTO optical counterpart detection
  50. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  51. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  52. GRB 260822A: LCO optical upper limits
  53. GRB 260822A: GROWTH-India Telescope Upper Limits
  54. GRB 260822A: GOTO optical upper limit
  55. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  56. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  57. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 260818B: VLA radio observations
  59. GRB 260818B: SVOM/C-GFT optical upper limit
  60. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  61. GRB 260820A: Insight-HXMT/HE detection
  62. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  63. GRB 260818B: SVOM/GRM observation
  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. EP260806a: SAO RAS multicolor optical observations
  75. GRB 260818A: LCO optical upper limits
  76. EP260812a: AbAO optical upper limit
  77. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 260810A: Insight-HXMT/HE detection
  79. EP260806a: SVOM/ECLAIRs detection through targeted search
  80. EP260806a: NUTTELA-TAO optical observations
  81. EP260812a: AZT-22 optical upper limit
  82. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  83. EP260806a: WFST optical observations
  84. EP260812b: Optical upper limit with Kinder
  85. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  86. GRB 260808B: Liverpool Telescope further optical observations
  87. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  88. EP260812a: NOT and Liverpool Telescope upper limits:
  89. EP260812b: Liverpool Telescope observations
  90. EP260812b: GOTO detection of the optical counterpart
  91. EP260812a: refined analysis of the EP-WXT and autonomous EP-FXT observation
  92. EP260812a: SVOM/C-GFT optical upper limit
  93. EP260812b: COLIBRÍ optical observations
  94. EP260812b: SVOM/VT optical observation
  95. GRB 260808A: SVOM/GRM observation
  96. EP260812b: Einstein Probe detection of an X-ray transient
  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 260809A: SAO RAS optical observations

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