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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"

32531 results found.

  1. GRB 260604C: SVOM/ECLAIRs refined analysis
  2. GRB 260608A: SVOM/ECLAIRs refined analysis
  3. Konus-Wind detection of GRB 260607B
  4. GRB 260607B: GECAM-B observation
  5. GRB 260608C: Fermi GBM Final Real-time Localization (duplicate submission)
  6. GRB 260604C: further SAO RAS optical observations
  7. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  8. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  9. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  10. GRB 260604C: SVOM/C-GFT upper limit
  11. GRB 260607B: AstroSat CZTI detection
  12. GRB 260608A: SVOM detection of a burst
  13. GRB 260608A: Fermi GBM Final Real-time Localization (duplicate submission)
  14. EP260605a: EP-FXT follow-up observation
  15. GRB 260607A: TRT optical observations
  16. GRB 260604C: GRANDMA further observations
  17. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  18. GRB 260604A: SVOM/GRM detection
  19. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  20. GRB 260607B: Fermi GBM Observation
  21. GRB 260607B: Fermi-LAT detection
  22. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  23. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  24. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  25. GRB 260604C: GECAM-B observation
  26. GRB 260604C: 6 GHz VLA observations
  27. GRB 260604C: SAO RAS optical observations
  28. GRB 260604C: GRANDMA observations
  29. GRB 260604B: SVOM/GRM detection
  30. GRB260603A: SVOM/ECLAIRs refined analysis
  31. EP260603a: COLIBRÍ optical upper limit
  32. GRB 260604A: Glowbug gamma-ray detection
  33. GRB 260604C: LCO optical upper limit
  34. GRB 260604C: Liverpool Telescope optical detection
  35. EP260602d: EP-FXT follow-up observation
  36. EP260602c: EP-FXT follow-up observation
  37. GRB 260601B / EP260601a: AstroSat CZTI detection
  38. GRB 260527A/EP260527a: 6 GHz VLA observations
  39. GRB 260604C: GOTO detections of the optical afterglow
  40. GRB 260604C: Correction to GCN 44828
  41. GRB 260604C: Kilonova-Catcher optical afterglow detection
  42. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  43. GRB 260604C: Jinshan optical observations
  44. GRB 260604C: Fermi GBM Observation
  45. EP260602d: J-band upper limit with WINTER
  46. EP260602b: J-band upper limit with WINTER
  47. GRB 260604C: LAST detection of optical counterpart candidate
  48. Fermi GRB 260604C: Global MASTER-Net observations report
  49. Fermi GRB 260604C: Global MASTER-Net observations report
  50. GRB 260604C: SVOM detection of a long burst
  51. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  52. GRB 260603A: NOT optical observations
  53. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  54. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  55. EP260602a: EP-FXT follow-up observation
  56. EP260603a: Global MASTER-Net observations report
  57. EP260602d: Optical Upper limits with kinder observations
  58. EP260602b: Liverpool Telescope observations
  59. EP260602a: Liverpool Telescope optical upper limits
  60. EP260602b: Liverpool Telescope and LCO observations
  61. EP260602a: GTC and Liverpool Telescope optical observations
  62. Konus-Wind detection of GRB 260601B/EP260601a
  63. GRB 260603A: EP-FXT follow-up observation
  64. EP260601a/GRB 260601B: EP-FXT follow-up observation
  65. GRB 260601B / EP260601a: Mondy optical upper limit
  66. EP260602b: EP-FXT follow-up observation
  67. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  68. GRB 260603A: Kilonova-Catcher optical upper limit
  69. GRB 260603A: SVOM/VT optical observations
  70. EP260602a: NOT NIR J-band observations
  71. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  72. EP260602d: Einstein Probe detection of a fast X-ray transient
  73. EP260602a: SVOM/VT optical magnitudes correction
  74. GRB 260601A: SVOM/GRM observation of a short burst
  75. EP260602c: Einstein Probe detection of a fast X-ray transient
  76. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  77. EP260602a: COLIBRÍ optical observations
  78. GRB260601B/EP260601a: NOT near-infrared observations
  79. EP260602b: Einstein Probe detection of a fast X-ray transient
  80. GRB 260601B/EP260601a: Insight-HXMT detection
  81. Fermi GRB 260602B: Global MASTER-Net observations report
  82. Fermi GRB 260602B: Global MASTER-Net observations report
  83. EP260602a: SVOM/VT optical candidate
  84. GRB 260601A: GECAM-B observation of a short burst
  85. GRB 260601B/EP260601a: J-band upper limit with WINTER
  86. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  87. EP260530a/AT 2026nwl: KAIT optical observations
  88. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  89. EP260602a: Optical upper limits with Kinder observations
  90. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  91. GRB 260601B/EP260601a: SVOM/VT optical observations
  92. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  93. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  94. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  95. GRB 260601A: Glowbug gamma-ray detection of a short burst
  96. GRB 260531B: Glowbug gamma-ray detection
  97. GRB 260516D: VLA radio detection
  98. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  99. Fermi GRB 260601A: Global MASTER-Net observations report
  100. GRB 260531B: GECAM-B observation

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