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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"

35927 results found.

  1. GRB 260710A: Fermi GBM Final Real-time Localization
  2. GRB 260708A: Glowbug gamma-ray detection
  3. GRB 260704A: SVOM/ECLAIRs refined analysis
  4. GRB 260706A : GRANDMA Upper limits
  5. GRB 260708A: Kilonova-Catcher optical afterglow detection
  6. GRB 260708A: GECAM-B observation of a burst
  7. GRB 260708A: Fermi-GBM observation
  8. Fermi LAT GRB 260708A: MASTER OT J150237.02-435307.7 optical counterpart detection
  9. GRB 260709A: Fermi GBM Final Real-time Localization
  10. GRB 260708A: Fermi-LAT detection
  11. GRB 260705B: SVOM/GRM observation
  12. GRB 260708A: Fermi-GBM detection
  13. GRB 260706A: Further EP-FXT follow-up observation
  14. GRB 260706A: SVOM/VT optical upper limits
  15. Fermi GBM trigger 805087514/260707142 (GRB 260707A) is not a GRB
  16. GRB 260705A: Candidate Optical Counterpart from SOAR and Gemini-South and Possible Association with GRB 260705B
  17. GRB 260705C: Glowbug gamma-ray detection of a short burst
  18. GRB 260706A: SVOM/ECLAIRs refined analysis
  19. GRB 260704A: SVOM/COLIBRÍ (FM-GFT) possible optical counterpart candidate
  20. GRB 260706A: SVOM/GRM observation
  21. GRB 260706A: REM optical/NIR observations
  22. GRB 260706A: LCO optical upper limit
  23. GRB 260706A: EP-FXT follow-up observation
  24. GRB 260707A: Fermi GBM Final Real-time Localization
  25. GRB 260706A: Fermi GBM Observation
  26. IPN triangulation of GRB 260627A
  27. GRB 260705A: SVOM/ECLAIRs refined analysis
  28. GRB 260706A: SVOM detection of a burst
  29. GRB 260706A: Fermi GBM Final Real-time Localization
  30. The EP-WXT trigger 01709274014: KAIT confirmation of a stellar flare
  31. GRB 260705A: LCO optical upper limits
  32. GRB 260704A: NOT optical upper limits
  33. GRB 260705C: Fermi GBM Final Localization
  34. GRB 260705B: Fermi GBM Final Real-time Localization
  35. Fermi GBM Sub-Threshold Detection of GRB 260705A
  36. GRB 260705A: SVOM detection of a burst
  37. GRB 260704A: EP-FXT follow-up observation
  38. GRB 260629A: SVOM/GRM observation of a short burst
  39. GRB 260629A: GECAM-A observation of a short burst
  40. GRB 260629A: AstroSat CZTI detection
  41. GRB 260704A: SVOM detection of a possible GRB
  42. GRB 260703B: Fermi GBM Final Localization
  43. Fermi GRB 260703A: Global MASTER-Net observations report
  44. GRB 260703A: Fermi GBM Final Localization
  45. GRB 260610B: VLA detection
  46. GRB 260623A: Glowbug gamma-ray detection
  47. GRB 260614B: ATCA Radio Upper Limits
  48. GRB 260610B / AT2026owq: SAO RAS, CrAO and INASAN further optical observations and light curve
  49. GRB 260701A: Fermi GBM Final Real-time Localization
  50. Fermi GBM trigger 804552016/260630945 is not a GRB
  51. GRB 260629A: Fermi GBM Final Real-time Localization
  52. Fermi GRB 260628A: Global MASTER-Net observations report
  53. GRB 260628A: Fermi GBM Final Real-time Localization
  54. Konus-Wind detection of GRB 260623B / EP260623a
  55. GRB 260618A: Fermi GBM Observation
  56. MASS-Cube (GRID 2.0) detection of GRB 260616B
  57. GRB 260619A: SVOM/ECLAIRs refined analysis
  58. Fermi GBM trigger 804010507/260624677 is not a GRB
  59. Konus-Wind detection of GRB 260618B
  60. GRB 260624A: Fermi GBM Final Real-time Localization (Duplicate Submission)
  61. GRB 260624A: Fermi GBM Final Real-time Localization
  62. GRB 260617A: Glowbug gamma-ray detection of a short burst
  63. IPN triangulation of GRB 260605A
  64. GRB 260623A: Fermi GBM Final Real-time Localization
  65. GRB 260616B/EP260616a: Insight-HXMT/HE detection
  66. GRB 260614B: EP-FXT follow-up observation
  67. GRB 260618C: SVOM/ECLAIRs detection of a possible burst through on-ground search
  68. GRB 260619A: NOT optical observations
  69. GRB 260618B: LCO optical observations
  70. EP260618a: JinShan optical observations
  71. GRB 260616B/EP260616a: SVOM/GRM detection of a burst
  72. GRB 260618B: Fermi GBM Observation
  73. GRB 260619A: TRT optical counterpart confirmation
  74. GRB 260610B: Further GRANDMA Optical Observations and re-brightening detection
  75. GRB 260604B: 239Alferov CubeSat detection
  76. GRB 260604A: 239Alferov CubeSat detection
  77. GRB 260610B: VLT/FORS2 spectroscopic observation suggests the non-thermal nature of the optical rebrightening
  78. GRB 260619A: SVOM/VT optical counterpart confirmation
  79. GRB 260618B: SVOM/VT optical candidate
  80. GRB 260618B: SVOM/VT optical candidate (duplicate Submission of 45001)
  81. GRB 260619A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  82. Konus-Wind detection of GRB 260617A
  83. GRB 260616B: AstroSat CZTI detection
  84. GRB 260616A: AstroSat CZTI detection
  85. GRB 260616A: SVOM/GRM observation
  86. GRB 260610B/AT2026owq: 1.3m DFOT optical rebrightening detection
  87. GRB 260619A: Kilonova-Catcher optical upper limit
  88. EP260618a: EP-FXT follow-up observation
  89. EP260618a: LCO optical counterpart confirmation
  90. GRB 260617A: CALET Gamma-Ray Burst Monitor detection
  91. EP260618a: COLIBRÍ optical counterpart candidate
  92. GRB 260616A: NuSTAR detection of prompt emission
  93. GRB 260614B: NuSTAR detection of prompt emission
  94. GRB 260619A: SVOM possible detection of a faint burst
  95. GRB 260618B: Fermi-LAT detection
  96. IPN triangulation of GRB 260617A (short)
  97. GRB 260610B/AT 2026owq: FTW optical and NIR observations
  98. GRB 260616A: Insight-HXMT detection
  99. GRB 260618B: Fermi GBM Final Real-time Localization
  100. EP260618a: EP-WXT detection of an X-ray transient

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