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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"

41875 results found.

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

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