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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"

32509 results found.

  1. GRB 260607A: Fermi GBM Final Real-time Localization (duplicate submission)
  2. GRB 260604C: GECAM-B observation
  3. GRB 260604C: 6 GHz VLA observations
  4. GRB 260604C: SAO RAS optical observations
  5. GRB 260604C: GRANDMA observations
  6. GRB 260604B: SVOM/GRM detection
  7. GRB260603A: SVOM/ECLAIRs refined analysis
  8. EP260603a: COLIBRÍ optical upper limit
  9. GRB 260604A: Glowbug gamma-ray detection
  10. GRB 260604C: LCO optical upper limit
  11. GRB 260604C: Liverpool Telescope optical detection
  12. EP260602d: EP-FXT follow-up observation
  13. EP260602c: EP-FXT follow-up observation
  14. GRB 260601B / EP260601a: AstroSat CZTI detection
  15. GRB 260527A/EP260527a: 6 GHz VLA observations
  16. GRB 260604C: GOTO detections of the optical afterglow
  17. GRB 260604C: Correction to GCN 44828
  18. GRB 260604C: Kilonova-Catcher optical afterglow detection
  19. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  20. GRB 260604C: Jinshan optical observations
  21. GRB 260604C: Fermi GBM Observation
  22. EP260602d: J-band upper limit with WINTER
  23. EP260602b: J-band upper limit with WINTER
  24. GRB 260604C: LAST detection of optical counterpart candidate
  25. Fermi GRB 260604C: Global MASTER-Net observations report
  26. Fermi GRB 260604C: Global MASTER-Net observations report
  27. GRB 260604C: SVOM detection of a long burst
  28. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  29. GRB 260603A: NOT optical observations
  30. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  31. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  32. EP260602a: EP-FXT follow-up observation
  33. EP260603a: Global MASTER-Net observations report
  34. EP260602d: Optical Upper limits with kinder observations
  35. EP260602b: Liverpool Telescope observations
  36. EP260602a: Liverpool Telescope optical upper limits
  37. EP260602b: Liverpool Telescope and LCO observations
  38. EP260602a: GTC and Liverpool Telescope optical observations
  39. Konus-Wind detection of GRB 260601B/EP260601a
  40. GRB 260603A: EP-FXT follow-up observation
  41. EP260601a/GRB 260601B: EP-FXT follow-up observation
  42. GRB 260601B / EP260601a: Mondy optical upper limit
  43. EP260602b: EP-FXT follow-up observation
  44. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  45. GRB 260603A: Kilonova-Catcher optical upper limit
  46. GRB 260603A: SVOM/VT optical observations
  47. EP260602a: NOT NIR J-band observations
  48. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  49. EP260602d: Einstein Probe detection of a fast X-ray transient
  50. EP260602a: SVOM/VT optical magnitudes correction
  51. GRB 260601A: SVOM/GRM observation of a short burst
  52. EP260602c: Einstein Probe detection of a fast X-ray transient
  53. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  54. EP260602a: COLIBRÍ optical observations
  55. GRB260601B/EP260601a: NOT near-infrared observations
  56. EP260602b: Einstein Probe detection of a fast X-ray transient
  57. GRB 260601B/EP260601a: Insight-HXMT detection
  58. Fermi GRB 260602B: Global MASTER-Net observations report
  59. Fermi GRB 260602B: Global MASTER-Net observations report
  60. EP260602a: SVOM/VT optical candidate
  61. GRB 260601A: GECAM-B observation of a short burst
  62. GRB 260601B/EP260601a: J-band upper limit with WINTER
  63. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  64. EP260530a/AT 2026nwl: KAIT optical observations
  65. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  66. EP260602a: Optical upper limits with Kinder observations
  67. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  68. GRB 260601B/EP260601a: SVOM/VT optical observations
  69. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  70. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  71. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  72. GRB 260601A: Glowbug gamma-ray detection of a short burst
  73. GRB 260531B: Glowbug gamma-ray detection
  74. GRB 260516D: VLA radio detection
  75. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  76. Fermi GRB 260601A: Global MASTER-Net observations report
  77. GRB 260531B: GECAM-B observation
  78. GRB 260518B: SVOM/ECLAIRs detection of a soft burst possibly associated with EP 260518a and AT 2026ndp
  79. AT 2026nuz: COLIBRÍ optical observations
  80. IPN triangulation of GRB 260527A / EP260527a
  81. EP260527a/GRB 260527A: further FTW optical and NIR observations
  82. GRB 260527A / EP260527a: VLA radio detection
  83. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  84. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  85. GRB 260529A: GOTO tentative optical afterglow candidate
  86. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  87. GRB 260527A/EP260527a: Insight-HXMT detection
  88. Fermi GRB 260529A: Global MASTER-Net observations report
  89. EP260526a: SVOM/VT optical upper limits
  90. GRB 260527A/EP260527a: Gemini GMOS-S Optical Observations
  91. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  92. EP260527a / GRB 260527A: NOT optical observations
  93. GRB 260527A/EP260527a: FTW optical and NIR observations
  94. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  95. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  96. EP260527a/GRB 260527A: EP-FXT follow-up observation
  97. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  98. GRB 260526A: GECAM-B observation
  99. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  100. EP260526a: EP-FXT follow-up observation

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