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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 260504B: GECAM-B detection
  2. Fermi-LAT Gamma-ray Observations of IceCube-260504A
  3. GRB 260504C: SVOM/GRM observation of short GRB
  4. GRB 260430B: AstroSat CZTI detection of a long burst
  5. GRB 260504B: SVOM/MXT refined analysis and potential detection
  6. GRB 260504B: EP-FXT upper limit
  7. GRB 260502A: SVOM/GRM observation of a short GRB
  8. GRB 260503A: SVOM/GRM observation of a GRB
  9. GRB 260310A / AT2026fgk: photometric monitoring and tentative maximum of a possible SN
  10. GRB 260504B: REM optical/NIR observations
  11. GRB 260504B: AST3-2 i-band upper limit
  12. GRB 260504B: LCO z-band upper limit
  13. SVOM GRB 260504B: MASTER-OAFA optical observations
  14. GRB 260504B: SVOM detection of a short burst
  15. Fermi GRB 260504A: Global MASTER-Net observations report
  16. GRB 260504A: Fermi GBM Final Real-time Localization
  17. GRB 260503A: Fermi GBM Final Real-time Localization
  18. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  19. GRB 260502A: GECAM-B observation of a short burst
  20. GRB 260502A: Fermi GBM Final Localization
  21. The EP-WXT trigger 01709261576 is likely a flaring star
  22. GRB 260429B / EP260429a: EP-FXT follow-up observation
  23. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  24. GRB 260429B / EP260429a: AstroSat CZTI detection
  25. EP260502a: BOOTES-7: early optical upper limit
  26. EP260502a: Einstein Probe detection of an X-ray transient
  27. GRB 260429A: SVOM/GRM observation of a short burst
  28. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  29. EP260429a: Global MASTER-Net observations report
  30. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  31. GRB 260424B: AstroSat CZTI detection
  32. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  33. EP260429a: LCO optical upper limits
  34. EP260430a: LCO optical upper limits
  35. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  36. GRB 260429A: Fermi GBM Detection
  37. Fermi GRB 260429A: Global MASTER-Net observations report
  38. EP260430a: Global MASTER-Net observations report
  39. EP260430a: Einstein Probe detection of an X-ray transient
  40. EP260429a: EP-WXT detection of a fast X-ray transient
  41. GRB 260429A: Fermi GBM Final Real-time Localization
  42. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  43. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  44. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  45. GRB 260428A: AstroSat CZTI detection
  46. Fermi GRB 260428A: Global MASTER-Net observations report
  47. EP260416a: Mondy and Terskol optical upper limits
  48. GRB 260424B: Glowbug gamma-ray detection of a short burst
  49. GRB 260424B: COLIBRÍ optical upper limit
  50. GRB 260428A: Fermi GBM Final Real-time Localization
  51. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  52. GRB 260424C: Fermi GBM Final Localization
  53. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  54. GRB 260424B: SVOM/GRM detection of a short burst
  55. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  56. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  57. IceCube Alert 260425A: Global MASTER-Net observations report
  58. Fermi trigger No 798737427: Global MASTER-Net observations report
  59. GRB 260401A: cubesat Avion detection
  60. GRB 260424A: AstroSat CZTI detection of a long burst
  61. EP260321a: Upper limits from ATCA radio observations
  62. GRB 260421B: Insight-HXMT/HE detection
  63. The EP-WXT trigger 01709258652: Mondy optical observations
  64. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  65. EP260416a: Mondy optical observations
  66. GRB 260421B: SVOM/ECLAIRs refined analysis
  67. GRB 260421B: 3.6m DOT optical observation
  68. EP260416a: ZTSh R band observations
  69. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  70. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  71. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  72. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  73. GRB 260419A: AstroSat CZTI detection
  74. GRB 260421B: SVOM/GRM observation
  75. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  76. GRB 260421B: EP-FXT follow-up observation
  77. The EP-WXT trigger 01709260362 is likely a flaring star
  78. GOTO26djh/AT2026jpw: ATCA radio detection
  79. GRB 260421B: J-band upper limit with WINTER
  80. GRB 260421B: LCO optical counterpart detection
  81. GRB 260421B: Fermi GBM Observation
  82. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  83. GRB 260421A: AstroSat CZTI detection
  84. GOTO26djh/AT2026jpw: radio detection at 15GHz
  85. GRB 260412A: SVOM/ECLAIRs refined analysis
  86. GRB 260421B: SVOM/VT optical observations
  87. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  88. GRB 260310A: Late-time Chandra X-ray Detection
  89. GRB 260418A: Insight-HXMT/HE detection
  90. EP260416a: 1.3m DFOT optical observation
  91. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  92. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  93. Fermi GRB 260421C: Global MASTER-Net observations report
  94. GRB 260421C: Fermi GBM Final Real-time Localization
  95. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  96. Fermi GRB 260421B: Global MASTER-Net observations report
  97. GRB 260421B: LCO optical afterglow confirmation
  98. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  99. GRB 260421B: SVOM detection of a long burst
  100. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)

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