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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"

2447 results found.

  1. GRB 260610A: Fermi GBM Final Real-time Localization
  2. EP260610a: COLIBRÍ optical upper limits
  3. EP260610a: Einstein Probe detection of a fast X-ray transient
  4. GRB 260609A: Fermi GBM Final Localization
  5. GRB 260608A: Fermi GRB Observation
  6. GRB 260604C: AstroSat CZTI detection
  7. GRB 260604C: SVOM/ECLAIRs refined analysis
  8. GRB 260608A: SVOM/ECLAIRs refined analysis
  9. GRB 260607B: GECAM-B observation
  10. GRB 260608C: Fermi GBM Final Real-time Localization
  11. GRB 260607A: AT2026ong (GOTO26fqf) is a type-Ia SN
  12. GRB 260607A / GOTO26fqf / AT2026ong: COLIBRÍ optical observations
  13. GRB 260608B: Fermi GBM Final Localization
  14. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) colour evolution and confirmation of the late rebrightening
  15. GRB 260604C: SVOM/C-GFT upper limit
  16. GRB 260607B: AstroSat CZTI detection
  17. GRB 260608A: SVOM detection of a burst
  18. GRB 260608A: Fermi GBM Final Real-time Localization
  19. EP260605a: EP-FXT follow-up observation
  20. GRB 260607A: TRT optical observations
  21. GRB 260607A: GOTO tentative optical counterpart candidate GOTO26fqf / AT2026ong
  22. GRB 260604A: SVOM/GRM detection
  23. GRB 260604C: Mondy optical observations: evidence of a possible brightening
  24. GRB 260607B: Fermi GBM Observation
  25. GRB 260607B: Fermi-LAT detection
  26. GRB 260607B: Fermi GBM Final Localization Correction
  27. GRB 260604C: Simeiz Zeiss-1000 optical observations of the afterglow
  28. GRB 260604C: OPD1.6m - GRANDMA observations - detection
  29. GRB 260607A: Fermi GBM Final Real-time Localization
  30. GRB 260604C: GECAM-B observation
  31. GRB 260604C: 6 GHz VLA observations
  32. GRB 260604B: SVOM/GRM detection
  33. GRB 260605A: Insight-HXMT/HE detection
  34. GRB260603A: SVOM/ECLAIRs refined analysis
  35. EP260605a: Einstein Probe detection of a fast X-ray transient
  36. EP260603a: COLIBRÍ optical upper limit
  37. GRB 260604A: Glowbug gamma-ray detection
  38. GRB 260604C: LCO optical upper limit
  39. GRB 260604C: Liverpool Telescope optical detection
  40. The EP-WXT trigger 01709267001 is likely a flaring star
  41. EP260602d: EP-FXT follow-up observation
  42. EP260602c: EP-FXT follow-up observation
  43. GRB 260601B / EP260601a: AstroSat CZTI detection
  44. GRB 260527A/EP260527a: 6 GHz VLA observations
  45. GRB 260604C: GOTO detections of the optical afterglow
  46. GRB 260604C: SVOM/COLIBRÍ (FM-GFT) optical observations
  47. The EP-WXT trigger 01709266798 is likely a flaring star
  48. GRB 260604C: Jinshan optical observations
  49. GRB 260604C: Fermi GBM Observation
  50. EP260602d: J-band upper limit with WINTER
  51. EP260602b: J-band upper limit with WINTER
  52. GRB 260604C: LAST detection of optical counterpart candidate
  53. GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
  54. Fermi GRB 260604C: Global MASTER-Net observations report
  55. Fermi GRB 260604C: Global MASTER-Net observations report
  56. SVOM GRB260604.85: Global MASTER-Net observations report
  57. GRB 260604C: SVOM detection of a long burst
  58. GRB 260604C: Fermi GBM Final Real-time Localization
  59. GRB 260515A: SVOM/VT optical detection at about 18 days post trigger
  60. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  61. GRB 260604B: Fermi GBM Final Real-time Localization
  62. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  63. EP260602a: EP-FXT follow-up observation
  64. EP260603a: Global MASTER-Net observations report
  65. EP260603a: Einstein Probe detection of a fast X-ray transient
  66. EP260602d: Optical Upper limits with kinder observations
  67. GRB 260604A: Fermi GBM Final Real-time Localization
  68. EP260602b: Liverpool Telescope observations
  69. EP260602a: Liverpool Telescope optical upper limits
  70. GRB 260603B: Fermi GBM Final Localization
  71. GRB 260603A: EP-FXT follow-up observation
  72. EP260601a/GRB 260601B: EP-FXT follow-up observation
  73. GRB 260601B / EP260601a: Mondy optical upper limit
  74. EP260602b: EP-FXT follow-up observation
  75. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  76. GRB 260603A: SVOM/VT optical observations
  77. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  78. EP260602d: Einstein Probe detection of a fast X-ray transient
  79. Fermi trigger No 802141998: Global MASTER-Net observations report
  80. GRB 260601A: SVOM/GRM observation of a short burst
  81. EP260602c: Einstein Probe detection of a fast X-ray transient
  82. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  83. EP260602a: COLIBRÍ optical observations
  84. GRB260601B/EP260601a: NOT near-infrared observations
  85. SVOM GRB260603.23: Global MASTER-Net observations report
  86. GRB 260603A: SVOM detection of a burst
  87. EP260602b: Einstein Probe detection of a fast X-ray transient
  88. GRB 260601B/EP260601a: Insight-HXMT detection
  89. Fermi GRB 260602B: Global MASTER-Net observations report
  90. Fermi GRB 260602B: Global MASTER-Net observations report
  91. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  92. EP260602a: SVOM/VT optical candidate
  93. GRB 260602B: Fermi GBM Final Localization
  94. GRB 260601A: GECAM-B observation of a short burst
  95. GRB 260601B/EP260601a: J-band upper limit with WINTER
  96. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  97. GRB 260602A: Fermi GBM Final Real-time Localization
  98. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  99. EP260602a: Optical upper limits with Kinder observations
  100. GRB 260601B / EP260601a: NuSTAR detection of prompt emission

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