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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"

39063 results found.

  1. GRB 260727A: SVOM/GRM observation
  2. GRB 260726A: Fermi GBM Observation
  3. Konus-Wind detection of GRB 260727A
  4. GRB 260726A: Liverpool Telescope optical observations
  5. GRB 260727A: Liverpool Telescope optical upper limits
  6. GRB 260728A: Fermi GBM Final Localization
  7. GRB 260727A: EP/FXT follow-up observations
  8. GRB 260727A: Glowbug gamma-ray detection
  9. GRB 260726A: J-band upper limit with WINTER
  10. GRB 260727A: J-band upper limit with WINTER
  11. GRB 260726A: SVOM/VT optical candidate
  12. GRB 260726A: SVOM ECLAIRs improved position and MXT possible detection of a counterpart
  13. GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
  14. GRB 260727A: GOTO early optical upper limit
  15. GRB 260727A: AstroSat CZTI detection
  16. GRB 260727A: Kilonova-Catcher optical upper limit
  17. GRB 260727A: LCO optical upper limits
  18. GRB 260727B: Fermi GBM Final Real-time Localization
  19. Fermi GRB 260726A: Global MASTER-Net observations report
  20. GRB 260727A: SVOM detection of a bright long burst
  21. GRB 260726A: SVOM detection of a burst
  22. GRB 260726A: Fermi GBM Final Real-time Localization
  23. GRB 260616A: cubesat Avion detection
  24. GRB 260602B: cubesat Avion detection
  25. GRB 260601A: cubesat Avion detection
  26. IPN triangulation of GRB 260706B
  27. GRB 260718A: SVOM/ECLAIRs refined analysis
  28. Fermi Gamma-ray Burst Monitor trigger 806592752 / 260724564 is not a GRB
  29. EP260723a: COLIBRÍ optical observations
  30. GRB 260723A: Fermi GBM Final Localization
  31. IceCube Alert 260722A: Global MASTER-Net observations report
  32. Konus-Wind detection of GRB 260721A
  33. GRB 260722A: Fermi GBM Final Real-time Localization
  34. IceCube-260722A - IceCube observation of a high-energy neutrino candidate track-like event
  35. Fermi GBM trigger 806384210/260722151 is not a GRB
  36. GRB 260721A: NuSTAR detection of prompt emission
  37. Konus-Wind detection of GRB 260714B
  38. SVOM trigger sb26071506: SVOM/VT confirmation of a stellar flare
  39. GRB 260705A: Retraction of optical counterpart
  40. GRB 260714B: Insight-HXMT/HE detection
  41. GRB 260718A: EP-FXT follow-up observation
  42. Fermi trigger No 806104130: Global MASTER-Net observations report
  43. Fermi GRB 260718A: Global MASTER-Net observations report
  44. GRB 260718A: LCO optical upper limits
  45. GRB 260711A: SVOM/GRM observation
  46. GRB 260710A: SVOM/GRM observation
  47. GRB 260718A: Fermi GBM Observation
  48. GRB 260718A : GRANDMA and KNC upper limits
  49. GRB 260718A: SVOM/VT optical upper limits
  50. GRB 260718A: SVOM/VT optical upper limits from VHF data
  51. GRB 260718A: SVOM detection of a burst
  52. GRB 260714B: SVOM/GRM observation
  53. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  54. GRB 260714B: GECAM-B observation of a burst
  55. GRB 260618B: EP-FXT follow-up observation upper limit
  56. GRB 260714B: COLIBRÍ optical counterpart candidate
  57. SVOM sb26071506: Global MASTER-Net observations report
  58. sb26071506: SVOM detection of a X-ray transient
  59. GRB 260715A: Fermi GBM Final Real-time Localization
  60. GRB 260710A: AstroSat CZTI detection
  61. GRB 260709A: AstroSat CZTI detection
  62. GRB 260714B: AstroSat CZTI detection
  63. GRB 260714B: Fermi-LAT detection
  64. GRB 260714B: Fermi GBM Detection
  65. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  66. GRB 260714B: Fermi GBM Final Real-time Localization
  67. GRB 260706A: ATCA detection of possible radio counterpart
  68. GRB 260705A: ATCA radio observations
  69. GRB 260714A: Fermi GBM Final Real-time Localization
  70. GRB 260619A: SVOM/VT continuous optical observations
  71. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  72. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  73. EP260623a: KAIT optical observations
  74. GRB 260708A: GRANDMA Optical Observations
  75. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  76. GRB 260710A: Insight-HXMT/HE detection
  77. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  78. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 260708A: LCO optical observations
  80. GRB 260710A: Fermi GBM Detection
  81. GRB 260709A: SVOM/GRM detection
  82. GRB 260709A: GECAM-B observation
  83. GRB 260705C: AstroSat CZTI detection
  84. GRB 260710A: Fermi GBM Final Real-time Localization
  85. GRB 260708A: Glowbug gamma-ray detection
  86. GRB 260704A: SVOM/ECLAIRs refined analysis
  87. GRB 260706A : GRANDMA Upper limits
  88. GRB 260708A: Kilonova-Catcher optical afterglow detection
  89. GRB 260708A: GECAM-B observation of a burst
  90. GRB 260708A: Fermi-GBM observation
  91. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  92. IceCube Alert 260709A: Global MASTER-Net observations report
  93. GRB 260709A: Fermi GBM Final Real-time Localization
  94. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  95. LAT GRB260708.42: Global MASTER-Net observations report
  96. GRB 260708A: Fermi-LAT detection
  97. GRB 260705B: SVOM/GRM observation
  98. GRB 260708A: Fermi-GBM detection
  99. GRB 260706A: Further EP-FXT follow-up observation
  100. GRB 260706A: SVOM/VT optical upper limits

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