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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"

42604 results found.

  1. SVOM GRB260903A: Global MASTER-Net observations report
  2. GRB 260903A: LCO optical observations
  3. GRB 260903A: SVOM/VT optical candidate
  4. GRB 260831A: GECAM-B observation
  5. GRB 260903A: LCO optical counterpart detection
  6. GRB 260827A: Insight-HXMT/HE detection
  7. GRB 260903A: SVOM detection of a soft faint burst
  8. EP260901a: SVOM/VT optical upper limits
  9. EP260901a: EP-FXT follow-up observation
  10. Konus-Wind detection of GRB 260829A
  11. GRB 260829A: SVOM/GRM observation
  12. GRB 260818A: ATCA detection of a candidate radio counterpart
  13. EP260830a: EP-FXT follow-up observation
  14. EP260901a: Global MASTER-Net observations report
  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. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  18. NuSTAR Transient 260828: LCO Optical Upper Limits
  19. EP260901a: EP-WXT detection of a fast X-ray transient
  20. GRB 260829A: AstroSat CZTI detection
  21. GRB 260831B: EP-FXT follow-up observation
  22. GRB 260830A: NuSTAR detection of prompt emission
  23. GRB 260831B: LCO optical upper limits
  24. EP260830a: Global MASTER-Net observations report
  25. EP260830a: EP-WXT detection of a fast X-ray transient
  26. GRB 260827A: SVOM/GRM observation
  27. NuSTAR 260828: a 1100s hard X-ray transient
  28. GRB 260831B: SVOM detection of a possible burst
  29. IPN triangulation of GRB 260829A
  30. GRB 260827A: Glowbug gamma-ray detection
  31. EP260727a: ATCA 10 GHz detection
  32. GRB 260831A: Fermi GBM Final Real-time Localization
  33. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  34. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  35. GRB 260829A: GECAM-B observation of a long burst
  36. GRB 260825A: SVOM/GRM observation of a long burst
  37. GRB 260825A: GECAM-B observation
  38. GRB 260829A: Fermi GBM Detection
  39. GRB 260825A: AstroSat CZTI detection
  40. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  41. GRB 260829A: Fermi GBM Final Real-time Localization
  42. IceCube-260827A: Upper limits from a search for additional neutrino events in IceCube
  43. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  44. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 260818B: Further EP-FXT observation
  46. GRB 260818B: VLT optical and nIR observations
  47. GRB 260818B: TNG NIR observations
  48. MAXI GRB260827.40: Global MASTER-Net observations report
  49. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  50. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  51. GRB 260827A: Fermi GBM Final Real-time Localization
  52. GRB 260818B: 6 GHz VLA observations
  53. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  54. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  55. GRB 260808B: SAO RAS observations of the optical rebrightening
  56. EP260822a: Global MASTER-Net observations report
  57. EP Alert 260820.31: Global MASTER-Net observations report
  58. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  59. GRB 260807A: EP-FXT follow-up observations
  60. GRB 260822A: SVOM/ECLAIRs refined analysis
  61. GRB 260809A: SVOM/ECLAIRs refined analysis
  62. GRB 260822A: SVOM/VT optical upper limits
  63. IceCube Alert 260825A: Global MASTER-Net observations report
  64. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  65. GRB 260825A: Fermi GBM Final Real-time Localization
  66. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  67. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  68. GRB 260822A: EP/FXT follow-up observations
  69. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  70. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  71. EP260822a: EP-FXT non-detection and upper limit
  72. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  73. GRB 260822A: GOTO optical counterpart detection
  74. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  75. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  76. EP260822a: Einstein Probe detection of a fast X-ray transient
  77. GRB 260822A: LCO optical upper limits
  78. The EP-WXT trigger 01709287395 is likely a flaring star
  79. GRB260822B: Fermi GBM Final Localization
  80. GRB 260822A: GROWTH-India Telescope Upper Limits
  81. GRB 260822A: GOTO optical upper limit
  82. GRB 260822A: SVOM detection of a short burst
  83. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  84. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  85. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 260818B: VLA radio observations
  87. GRB 260818B: SVOM/C-GFT optical upper limit
  88. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  89. IceCube Alert 260821A: Global MASTER-Net observations report
  90. The EP-WXT trigger 01709286204 is likely a flaring star
  91. GRB 260820A: Insight-HXMT/HE detection
  92. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  93. GRB 260818B: SVOM/GRM observation
  94. EP detected a brightening of LMXB 1ES 1735-26.9
  95. GRB260820A: Fermi GBM Final Real-Time Localization
  96. GRB 260818B: Insight-HXMT detection
  97. GRB 260818B: EP-FXT follow-up observation
  98. GRB 260818A: J-band observations with WINTER
  99. GRB 260818B: SVOM/ECLAIRs refined analysis
  100. GRB 260818A: SVOM/ECLAIRs refined analysis

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