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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

38573 results found.

  1. GRB 260611B: Fermi GBM Final Real-time Localization
  2. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  3. EP260610b: GTC likely spectroscopic redshift z = 1.10
  4. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  5. The EP-WXT trigger 01709269176 is likely a flaring star
  6. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  7. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  8. GRB 260610B / AT2026owq: Early ATLAS observations
  9. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  10. GRB 260611A: Fermi GBM Final Real-time Localization
  11. EP260610b: COLIBRÍ optical observations
  12. GRB 260610B: DDOTI optical observations
  13. EP260610b: MAO/AZT-22 optical observations
  14. GRB 260610B: GOTO optical counterpart candidate
  15. EP260610b: NOT optical observation
  16. GRB 260610B: Fermi GBM Final Localization
  17. EP260610b: SVOM/VT optical confirmation with blue color
  18. IceCube-260610A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 260515A: SOAR optical observations
  20. EP260610b: Gemini North optical counterpart candidate
  21. EP260610a: SVOM/VT optical upper limits
  22. EP260610b: Einstein Probe detection of an X-ray transient
  23. Konus-Wind detection of GRB 260601A
  24. IPN triangulation of GRB 260601A (short/hard)
  25. GRB 260610A: Fermi GBM Final Real-time Localization
  26. EP260610a: COLIBRÍ optical upper limits
  27. EP260610a: Einstein Probe detection of a fast X-ray transient
  28. GRB 260609A: Fermi GBM Final Localization
  29. Konus-Wind detection of GRB 260604C
  30. GRB 260608A: Fermi GRB Observation
  31. GRB 260604C: AstroSat CZTI detection
  32. IPN triangulation of GRB 260601B / EP260601a
  33. GRB 260604C: SVOM/ECLAIRs refined analysis
  34. GRB 260608A: SVOM/ECLAIRs refined analysis
  35. Konus-Wind detection of GRB 260607B
  36. GRB 260607B: GECAM-B observation
  37. GRB 260608C: Fermi GBM Final Real-time Localization
  38. GRB 260604C: further SAO RAS optical observations
  39. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  40. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  41. GRB 260608B: Fermi GBM Final Localization
  42. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  43. GRB 260604C: SVOM/C-GFT upper limit
  44. GRB 260607B: AstroSat CZTI detection
  45. GRB 260608A: SVOM detection of a burst
  46. GRB 260608A: Fermi GBM Final Real-time Localization
  47. EP260605a: EP-FXT follow-up observation
  48. GRB 260604C: GRANDMA further observations
  49. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  50. GRB 260604A: SVOM/GRM detection
  51. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  52. GRB 260607B: Fermi GBM Observation
  53. GRB 260607B: Fermi-LAT detection
  54. GRB 260607B: Fermi GBM Final Localization Correction
  55. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  56. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  57. GRB 260607A: Fermi GBM Final Real-time Localization
  58. GRB 260604C: GECAM-B observation
  59. GRB 260604C: 6 GHz VLA observations
  60. GRB 260604C: SAO RAS optical observations
  61. GRB 260604C: GRANDMA observations
  62. GRB 260604B: SVOM/GRM detection
  63. GRB 260605A: Insight-HXMT/HE detection
  64. GRB260603A: SVOM/ECLAIRs refined analysis
  65. EP260605a: Einstein Probe detection of a fast X-ray transient
  66. EP260603a: COLIBRÍ optical upper limit
  67. GRB 260604A: Glowbug gamma-ray detection
  68. GRB 260604C: LCO optical upper limit
  69. GRB 260604C: Liverpool Telescope optical detection
  70. The EP-WXT trigger 01709267001 is likely a flaring star
  71. EP260602d: EP-FXT follow-up observation
  72. EP260602c: EP-FXT follow-up observation
  73. GRB 260601B / EP260601a: AstroSat CZTI detection
  74. GRB 260527A/EP260527a: 6 GHz VLA observations
  75. GRB 260604C: GOTO detections of the optical afterglow
  76. GRB 260604C: Correction to GCN 44828
  77. GRB 260604C: Kilonova-Catcher optical afterglow detection
  78. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  79. The EP-WXT trigger 01709266798 is likely a flaring star
  80. GRB 260604C: Jinshan optical observations
  81. GRB 260604C: Fermi GBM Observation
  82. GRB 260604C: LAST detection of optical counterpart candidate
  83. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  84. SVOM GRB260604.85: Global MASTER-Net observations report
  85. GRB 260604C: SVOM detection of a long burst
  86. GRB 260604C: Fermi GBM Final Real-time Localization
  87. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  88. GRB 260603A: NOT optical observations
  89. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  90. GRB 260604B: Fermi GBM Final Real-time Localization
  91. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  92. EP260602a: EP-FXT follow-up observation
  93. EP260603a: Einstein Probe detection of a fast X-ray transient
  94. EP260602d: Optical Upper limits with kinder observations
  95. GRB 260604A: Fermi GBM Final Real-time Localization
  96. EP260602b: Liverpool Telescope observations
  97. EP260602a: Liverpool Telescope optical upper limits
  98. EP260602b: Liverpool Telescope and LCO observations
  99. GRB 260603B: Fermi GBM Final Localization
  100. EP260602a: GTC and Liverpool Telescope optical observations

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