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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"

2482 results found.

  1. GRB 260610B: Fermi GBM Observation
  2. GRB 260610B / AT2026owq: GRANDMA optical observations
  3. GRB 260610B / AT2026owq: further SAO RAS optical observations
  4. EP260605a: COLIBRÍ optical upper limits
  5. GRB 260610b: Liverpool Telescope optical observations
  6. EP260610b: Liverpool Telescope optical upper limits
  7. IceCube-260610A: No candidates from the Zwicky Transient Facility
  8. IceCube-260610A: EP-FXT follow-up observation
  9. GRB 260611B: CALET Gamma-Ray Burst Monitor detection
  10. The EP-WXT trigger 01709269176: SVOM/C-GFT confirmation of a stellar flare
  11. GRB 260610B / AT2026owq: SVOM/VT optical observations
  12. GRB 260610B / AT2026owq: OASDG optical observations
  13. GRB 260610B: IAC-80 Optical observations
  14. GRB 260610B / AT2026owq: SAO RAS optical observations
  15. GRB 260611B: Fermi GBM Final Real-time Localization
  16. EP260601a: VLT/X-shooter spectroscopic host galaxy redshift z = 1.068
  17. EP260610b: GTC likely spectroscopic redshift z = 1.10
  18. GRB 260610B: optical counterpart shows spectroscopic redshift of z=0.473
  19. The EP-WXT trigger 01709269176 is likely a flaring star
  20. EP260610b: refined analysis of the EP-WXT and follow-up EP-FXT observations
  21. GRB 260610B / AT 2026owq: COLIBRÍ optical observations
  22. GRB 260610B: TRT optical observation
  23. EP260610a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  24. GRB 260611A: Fermi GBM Final Real-time Localization
  25. EP260610b: COLIBRÍ optical observations
  26. GRB 260610B: DDOTI optical observations
  27. EP260610b: MAO/AZT-22 optical observations
  28. GRB 260610B: GOTO optical counterpart candidate
  29. EP260610b: NOT optical observation
  30. GRB 260610B: Fermi GBM Final Localization
  31. EP260610b: SVOM/VT optical confirmation with blue color
  32. GRB 260515A: SOAR optical observations
  33. EP260610b: Gemini North optical counterpart candidate
  34. EP260610a: SVOM/VT optical upper limits
  35. EP260610b: Einstein Probe detection of an X-ray transient
  36. GRB 260610A: Fermi GBM Final Real-time Localization
  37. EP260610a: COLIBRÍ optical upper limits
  38. EP260610a: Einstein Probe detection of a fast X-ray transient
  39. GRB 260609A: Fermi GBM Final Localization
  40. GRB 260608A: Fermi GRB Observation
  41. GRB 260604C: AstroSat CZTI detection
  42. GRB 260604C: SVOM/ECLAIRs refined analysis
  43. GRB 260608A: SVOM/ECLAIRs refined analysis
  44. GRB 260607B: GECAM-B observation
  45. GRB 260608C: Fermi GBM Final Real-time Localization
  46. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  47. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  48. GRB 260608B: Fermi GBM Final Localization
  49. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  50. GRB 260604C: SVOM/C-GFT upper limit
  51. GRB 260607B: AstroSat CZTI detection
  52. GRB 260608A: SVOM detection of a burst
  53. GRB 260608A: Fermi GBM Final Real-time Localization
  54. EP260605a: EP-FXT follow-up observation
  55. GRB 260607A: TRT optical observations
  56. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  57. GRB 260604A: SVOM/GRM detection
  58. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  59. GRB 260607B: Fermi GBM Observation
  60. GRB 260607B: Fermi-LAT detection
  61. GRB 260607B: Fermi GBM Final Localization Correction
  62. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  63. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  64. GRB 260607A: Fermi GBM Final Real-time Localization
  65. GRB 260604C: GECAM-B observation
  66. GRB 260604C: 6 GHz VLA observations
  67. GRB 260604B: SVOM/GRM detection
  68. GRB 260605A: Insight-HXMT/HE detection
  69. GRB260603A: SVOM/ECLAIRs refined analysis
  70. EP260605a: Einstein Probe detection of a fast X-ray transient
  71. EP260603a: COLIBRÍ optical upper limit
  72. GRB 260604A: Glowbug gamma-ray detection
  73. GRB 260604C: LCO optical upper limit
  74. GRB 260604C: Liverpool Telescope optical detection
  75. The EP-WXT trigger 01709267001 is likely a flaring star
  76. EP260602d: EP-FXT follow-up observation
  77. EP260602c: EP-FXT follow-up observation
  78. GRB 260601B / EP260601a: AstroSat CZTI detection
  79. GRB 260527A/EP260527a: 6 GHz VLA observations
  80. GRB 260604C: GOTO detections of the optical afterglow
  81. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  82. The EP-WXT trigger 01709266798 is likely a flaring star
  83. GRB 260604C: Jinshan optical observations
  84. GRB 260604C: Fermi GBM Observation
  85. EP260602d: J-band upper limit with WINTER
  86. EP260602b: J-band upper limit with WINTER
  87. GRB 260604C: LAST detection of optical counterpart candidate
  88. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  89. Fermi GRB 260604C: Global MASTER-Net observations report
  90. Fermi GRB 260604C: Global MASTER-Net observations report
  91. SVOM GRB260604.85: Global MASTER-Net observations report
  92. GRB 260604C: SVOM detection of a long burst
  93. GRB 260604C: Fermi GBM Final Real-time Localization
  94. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  95. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  96. GRB 260604B: Fermi GBM Final Real-time Localization
  97. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  98. EP260602a: EP-FXT follow-up observation
  99. EP260603a: Global MASTER-Net observations report
  100. EP260603a: Einstein Probe detection of a fast X-ray transient

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