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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"

42211 results found.

  1. GRB 260831B / sb26083106: SVOM/VT optical variability of V* GK Per
  2. NuSTAR Transient 260828: LCO Optical Upper Limits
  3. EP260901a: EP-WXT detection of a fast X-ray transient
  4. SVOM trigger sb26083106 is not a GRB
  5. GRB 260829A: AstroSat CZTI detection
  6. GRB 260831B: EP-FXT follow-up observation
  7. GRB 260830A: NuSTAR detection of prompt emission
  8. GRB 260831B: LCO optical upper limits
  9. EP260830a: Global MASTER-Net observations report
  10. EP260830a: EP-WXT detection of a fast X-ray transient
  11. GRB 260827A: SVOM/GRM observation
  12. NuSTAR 260828: a 1100s hard X-ray transient
  13. GRB 260831B: SVOM detection of a possible burst
  14. GRB 260827A: Glowbug gamma-ray detection
  15. EP260727a: ATCA 10 GHz detection
  16. GRB 260831A: Fermi GBM Final Real-time Localization
  17. Fermi-LAT Gamma-ray Observations of IceCube-260827A
  18. Fermi-LAT Gamma-ray Observations of IceCube-260825A
  19. GRB 260829A: GECAM-B observation of a long burst
  20. GRB 260825A: SVOM/GRM observation of a long burst
  21. GRB 260825A: GECAM-B observation
  22. GRB 260829A: Fermi GBM Detection
  23. GRB 260825A: AstroSat CZTI detection
  24. GRB 260829A: BALROG localization (Fermi Trigger 809676494 / GRB 260829256)
  25. GRB 260829A: Fermi GBM Final Real-time Localization
  26. IceCube-260827A: 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. IceCube-260825A: Upper limits from a search for additional neutrino events in IceCube
  29. GRB 260818B: Further EP-FXT observation
  30. GRB 260818B: VLT optical and nIR observations
  31. GRB 260818B: TNG NIR observations
  32. MAXI GRB260827.40: Global MASTER-Net observations report
  33. IceCube-260827A - IceCube observation of a high-energy neutrino candidate track-like event
  34. The EP-WXT trigger 01709291839 is likely the known LMXB 4U 1745-203
  35. GRB 260827A: Fermi GBM Final Real-time Localization
  36. GRB 260818B: 6 GHz VLA observations
  37. GRB 260818B: SVOM/VT optical upper limit and continuous observations
  38. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  39. GRB 260808B: SAO RAS observations of the optical rebrightening
  40. EP260822a: Global MASTER-Net observations report
  41. EP Alert 260820.31: Global MASTER-Net observations report
  42. IceCube-260825A: No transient candidates from the Zwicky Transient Facility
  43. GRB 260807A: EP-FXT follow-up observations
  44. GRB 260822A: SVOM/ECLAIRs refined analysis
  45. GRB 260809A: SVOM/ECLAIRs refined analysis
  46. GRB 260822A: SVOM/VT optical upper limits
  47. IceCube Alert 260825A: Global MASTER-Net observations report
  48. IceCube-Cascade 260824A: Upper limits from a search for additional neutrino events in IceCube
  49. GRB 260825A: Fermi GBM Final Real-time Localization
  50. IceCube-260825A - IceCube observation of a high-energy neutrino candidate track-like event
  51. GRB 260822A: PRIME near-infrared upper limits from multiple epochs
  52. GRB 260822A: EP/FXT follow-up observations
  53. GRB 260822A: the candidate optical afterglow is an unrelated type-Ia SN
  54. GRB 260818A: further EP-FXT observations and X-ray afterglow confirmation
  55. EP260822a: EP-FXT non-detection and upper limit
  56. GRB 260822A: Retraction of GOTO optical counterpart detection GCN 45431
  57. GRB 260822A: GOTO optical counterpart detection
  58. GRB 260822A: SVOM/VT optical detection of COLIBRÍ candidate
  59. GRB 260822A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  60. EP260822a: Einstein Probe detection of a fast X-ray transient
  61. GRB 260822A: LCO optical upper limits
  62. The EP-WXT trigger 01709287395 is likely a flaring star
  63. GRB260822B: Fermi GBM Final Localization
  64. GRB 260822A: GROWTH-India Telescope Upper Limits
  65. GRB 260822A: GOTO optical upper limit
  66. GRB 260822A: SVOM detection of a short burst
  67. Fermi-LAT Gamma-ray Observations of IceCube-260821A
  68. Fermi-LAT Gamma-ray Observations of IceCube-260807A
  69. IceCube-260821A: Upper limits from a search for additional neutrino events in IceCube
  70. GRB 260818B: VLA radio observations
  71. GRB 260818B: SVOM/C-GFT optical upper limit
  72. EP260731a: SVOM/ECLAIRs detection through offline targeted search
  73. IceCube Alert 260821A: Global MASTER-Net observations report
  74. The EP-WXT trigger 01709286204 is likely a flaring star
  75. GRB 260820A: Insight-HXMT/HE detection
  76. IceCube-260821A - IceCube observation of a high-energy neutrino candidate track-like event
  77. GRB 260818B: SVOM/GRM observation
  78. EP detected a brightening of LMXB 1ES 1735-26.9
  79. GRB260820A: Fermi GBM Final Real-Time Localization
  80. GRB 260818B: Insight-HXMT detection
  81. GRB 260818B: EP-FXT follow-up observation
  82. GRB 260818A: J-band observations with WINTER
  83. GRB 260818B: SVOM/ECLAIRs refined analysis
  84. GRB 260818A: SVOM/ECLAIRs refined analysis
  85. GRB 260818B: NOT optical upper limits
  86. GRB 260810A: SVOM/GRM observation
  87. GRB 260818B: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  88. GRB260818A: EP-FXT follow-up observation
  89. GRB 260818B: LCO optical upper limits
  90. GRB 260818B: SVOM detection of a short burst
  91. SVOM trigger sb26081806 is not a GRB
  92. EP260806a: SAO RAS multicolor optical observations
  93. GRB 260818A: LCO optical upper limits
  94. EP260812a: AbAO optical upper limit
  95. GRB 260818A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  96. GRB 260810A: Insight-HXMT/HE detection
  97. GRB 260818A: SVOM possible detection of a long and faint GRB
  98. EP260806a: SVOM/ECLAIRs detection through targeted search
  99. EP260806a: NUTTELA-TAO optical observations
  100. The EP-WXT trigger 01709281429 is likely a flaring star

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