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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"

37412 results found.

  1. GRB 260714B: Insight-HXMT/HE detection
  2. GRB 260718A: EP-FXT follow-up observation
  3. Fermi trigger No 806104130: Global MASTER-Net observations report
  4. Fermi GRB 260718A: Global MASTER-Net observations report
  5. GRB 260718A: LCO optical upper limits
  6. GRB 260711A: SVOM/GRM observation
  7. GRB 260710A: SVOM/GRM observation
  8. GRB 260718A: Fermi GBM Observation
  9. GRB 260718A : GRANDMA and KNC upper limits
  10. GRB 260718A: SVOM/VT optical upper limits
  11. GRB 260718A: SVOM/VT optical upper limits from VHF data
  12. GRB 260718A: SVOM detection of a burst
  13. GRB 260714B: SVOM/GRM observation
  14. GRB 260310A / AT2026fgk: Late-time Chandra Detection
  15. GRB 260714B: GECAM-B observation of a burst
  16. GRB 260618B: EP-FXT follow-up observation upper limit
  17. GRB 260714B: COLIBRÍ optical counterpart candidate
  18. GRB 260715A: Fermi GBM Final Real-time Localization
  19. GRB 260710A: AstroSat CZTI detection
  20. GRB 260709A: AstroSat CZTI detection
  21. GRB 260714B: AstroSat CZTI detection
  22. GRB 260714B: Fermi-LAT detection
  23. GRB 260714B: Fermi GBM Detection
  24. GRB 260714B: BALROG localization (Fermi Trigger 805746211 / GRB 260714766)
  25. GRB 260714B: Fermi GBM Final Real-time Localization
  26. GRB 260706A: ATCA detection of possible radio counterpart
  27. GRB 260705A: ATCA radio observations
  28. GRB 260714A: Fermi GBM Final Real-time Localization
  29. GRB 260619A: SVOM/VT continuous optical observations
  30. GRB 260618B: SVOM/VT optical observations indicate shallow decay and reddening
  31. GRB 260708A: slowly decaying X-ray emission observed by EP/FXT
  32. EP260623a: KAIT optical observations
  33. GRB 260708A: GRANDMA Optical Observations
  34. Fermi-LAT Gamma-ray Observations of IceCube-260712A
  35. Fermi-LAT Gamma-ray Observations of IceCube-260708A
  36. GRB 260710A: Insight-HXMT/HE detection
  37. Fermi-LAT Gamma-ray Observations of IceCube-260704A
  38. IceCube-260712A - IceCube observation of a high-energy neutrino candidate track-like event
  39. GRB 260708A: LCO optical observations
  40. GRB 260710A: Fermi GBM Detection
  41. GRB 260709A: SVOM/GRM detection
  42. GRB 260709A: GECAM-B observation
  43. GRB 260705C: AstroSat CZTI detection
  44. GRB 260710A: Fermi GBM Final Real-time Localization
  45. GRB 260708A: Glowbug gamma-ray detection
  46. GRB 260704A: SVOM/ECLAIRs refined analysis
  47. GRB 260706A : GRANDMA Upper limits
  48. GRB 260708A: Kilonova-Catcher optical afterglow detection
  49. GRB 260708A: GECAM-B observation of a burst
  50. GRB 260708A: Fermi-GBM observation
  51. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  52. GRB 260709A: Fermi GBM Final Real-time Localization
  53. IceCube-260708A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 260708A: Fermi-LAT detection
  55. GRB 260705B: SVOM/GRM observation
  56. GRB 260708A: Fermi-GBM detection
  57. GRB 260706A: Further EP-FXT follow-up observation
  58. GRB 260706A: SVOM/VT optical upper limits
  59. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  60. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  61. GRB 260705C: Glowbug gamma-ray detection of a short burst
  62. GRB 260706A: SVOM/ECLAIRs refined analysis
  63. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  64. GRB 260706A: SVOM/GRM observation
  65. GRB 260706A: REM optical/NIR observations
  66. GRB 260706A: LCO optical upper limit
  67. GRB 260706A: EP-FXT follow-up observation
  68. GRB 260707A: Fermi GBM Final Real-time Localization
  69. GRB 260706A: Fermi GBM Observation
  70. IPN triangulation of GRB 260627A
  71. GRB 260705A: SVOM/ECLAIRs refined analysis
  72. GRB 260706A: SVOM detection of a burst
  73. GRB 260706A: Fermi GBM Final Real-time Localization
  74. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  75. GRB 260705A: LCO optical upper limits
  76. GRB 260704A: NOT optical upper limits
  77. GRB 260705C: Fermi GBM Final Localization
  78. GRB 260705B: Fermi GBM Final Real-time Localization
  79. Fermi GBM Sub-Threshold Detection of GRB 260705A
  80. GRB 260705A: SVOM detection of a burst
  81. GRB 260704A: EP-FXT follow-up observation
  82. GRB 260629A: SVOM/GRM observation of a short burst
  83. GRB 260629A: GECAM-A observation of a short burst
  84. IceCube-260704A - IceCube observation of a high-energy neutrino candidate track-like event
  85. GRB 260629A: AstroSat CZTI detection
  86. GRB 260704A: SVOM detection of a possible GRB
  87. GRB 260703B: Fermi GBM Final Localization
  88. Fermi trigger No 804738310: Global MASTER-Net observations report
  89. Fermi GRB 260703A: Global MASTER-Net observations report
  90. GRB 260703A: Fermi GBM Final Localization
  91. GRB 260610B: VLA detection
  92. GRB 260623A: Glowbug gamma-ray detection
  93. GRB 260614B: ATCA Radio Upper Limits
  94. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  95. Fermi trigger No 804552016: Global MASTER-Net observations report
  96. GRB 260701A: Fermi GBM Final Real-time Localization
  97. Fermi GBM trigger 804552016/260630945 is not a GRB
  98. Fermi-LAT Gamma-ray Observations of IceCube-260622A
  99. GRB 260629A: Fermi GBM Final Real-time Localization
  100. Fermi GRB 260628A: Global MASTER-Net observations report

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