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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"

15252 results found.

  1. GRB 260903A: SVOM/ECLAIRs refined analysis
  2. GRB260903A: Liverpool Telescope optical observations
  3. GRB 260830A: GECAM-B detection of a burst
  4. GRB 260830A: Insight-HXMT/HE detection
  5. GRB 260903A: OHP/T193 optical afterglow detection
  6. GRB 260903A: NOT optical observations and afterglow fading
  7. NuSTAR Transient 260828: SOAR Optical Upper Limits
  8. GRB 260903A: Retraction of optical counterpart of GCN 45501
  9. GRB 260831A: GECAM-B observation
  10. GRB 260827A: Insight-HXMT/HE detection
  11. GRB 260903A: SVOM detection of a soft faint burst
  12. Konus-Wind detection of GRB 260829A
  13. GRB 260829A: SVOM/GRM observation
  14. GRB 260818A: ATCA detection of a candidate radio counterpart
  15. IceCube-260827A: No transient candidates from the Zwicky Transient Facility
  16. GRB 260831B / sb26083106: SVOM/GWAC-F60A/B confirmation of optical variation of nova V* GK Per
  17. SVOM trigger sb26083106 is not a GRB
  18. GRB 260829A: AstroSat CZTI detection
  19. GRB 260827A: SVOM/GRM observation
  20. NuSTAR 260828: a 1100s hard X-ray transient
  21. GRB 260831B: SVOM detection of a possible burst
  22. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  23. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  24. GRB 260829A: GECAM-B observation of a long burst
  25. GRB 260825A: SVOM/GRM observation of a long burst
  26. GRB 260825A: GECAM-B observation
  27. GRB 260829A: Fermi GBM Detection
  28. GRB 260825A: AstroSat CZTI detection
  29. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  30. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 260818B: VLT optical and nIR observations
  33. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 260818B: 6 GHz VLA observations
  35. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  36. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  37. GRB 260808B: SAO RAS observations of the optical rebrightening
  38. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  39. GRB 260809A: SVOM/ECLAIRs refined analysis
  40. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  41. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  42. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  43. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  44. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  45. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  46. GRB 260822A: GROWTH-India Telescope Upper Limits
  47. GRB 260822A: SVOM detection of a short burst
  48. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  49. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  50. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  51. GRB 260818B: SVOM/C-GFT optical upper limit
  52. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  53. GRB 260820A: Insight-HXMT/HE detection
  54. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 260818B: SVOM/GRM observation
  56. GRB 260818B: Insight-HXMT detection
  57. GRB 260818A: J-band observations with WINTER
  58. GRB 260818B: SVOM/ECLAIRs refined analysis
  59. GRB 260818A: SVOM/ECLAIRs refined analysis
  60. GRB 260810A: SVOM/GRM observation
  61. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  62. GRB 260818B: SVOM detection of a short burst
  63. GRB 260818A: LCO optical upper limits
  64. EP260812a: AbAO optical upper limit
  65. GRB 260810A: Insight-HXMT/HE detection
  66. GRB 260818A: SVOM possible detection of a long and faint GRB
  67. EP260806a: SVOM/ECLAIRs detection through targeted search
  68. EP260812b: GTC/OSIRIS+ tentative spectroscopic redshift z = 2.034
  69. EP260806a: WFST optical observations
  70. EP260812b: Optical upper limit with Kinder
  71. GRB 260805D: SVOM/GRM detection of a possible magnetar burst
  72. GRB 260808B: Liverpool Telescope further optical observations
  73. GRB 260808B: GTC/OSIRIS+ spectroscopic redshift z = 1.295
  74. EP260812a: NOT and Liverpool Telescope upper limits:
  75. EP260812b: COLIBRÍ optical observations
  76. GRB 260808A: SVOM/GRM observation
  77. GRB 260808B: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical rebrightening
  78. GRB 260810A: AstroSat CZTI detection of a long burst
  79. GRB 260317A: SVOM/ECLAIRs detection through offline targeted search and its possible association to magnetar 1E 1841-04.5
  80. GRB 260806A: CALET Gamma-Ray Burst Monitor detection
  81. GRB 260808A: GECAM-B observation
  82. GRB 260807A: SVOM/ECLAIRs refined analysis
  83. IceCube-260807A: Upper limits from a search for additional neutrino events in IceCube
  84. GRB260808B: MAO/AZT-22 optical observations
  85. GRB 250607A: SVOM/ECLAIRs detection through offline targeted search
  86. GRB 260808A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 260805C: CALET Gamma-Ray Burst Monitor detection
  88. GRB 260804A: CALET Gamma-Ray Burst Monitor detection
  89. GRB260809A/EPF_J234751.2+210212: EP-FXT follow-up observation
  90. GRB260809A: MAO/AZT-22 optical observations
  91. IceCube-260805A: Upper limits from a search for additional neutrino events in IceCube
  92. GRB 260808B: SVOM/ECLAIRs refined analysis
  93. GRB 260809A: SVOM detection of a faint burst
  94. GRB 260808B: Liverpool Telescope optical observations
  95. GRB 260808B: SVOM detection of a faint burst
  96. IceCube-260805A: One candidate from the Zwicky Transient Facility
  97. GRB 260807A: SVOM possible detection of a faint burst
  98. IceCube-260807A - IceCube observation of a high-energy neutrino candidate track-like event
  99. EP260806a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  100. EP260806a: SVOM/VT optical observation

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