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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"

45709 results found.

  1. GRB 260504B: SVOM detection of a short burst
  2. Fermi GRB 260504A: Global MASTER-Net observations report
  3. GRB 260504A: Fermi GBM Final Real-time Localization
  4. GRB 260503A: Fermi GBM Final Real-time Localization
  5. SVOM/GRM observation of a bright burst from SGR 1E1841-045
  6. GRB 260502A: GECAM-B observation of a short burst
  7. IPN triangulation of a bright burst from SGR 1E1841-045
  8. GRB 260502A: Fermi GBM Final Localization
  9. The EP-WXT trigger 01709261576 is likely a flaring star
  10. GRB 260429B / EP260429a: EP-FXT follow-up observation
  11. EP260502a: BOOTES-7 observations of a fading catalogued source close to the X-ray position
  12. GRB 260429B / EP260429a: AstroSat CZTI detection
  13. EP260502a: BOOTES-7: early optical upper limit
  14. EP260502a: Las Cumbres upper limit
  15. EP260502a: Einstein Probe detection of an X-ray transient
  16. GRB 260429A: SVOM/GRM observation of a short burst
  17. SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
  18. EP260429a: Global MASTER-Net observations report
  19. EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  20. GRB 260424B: AstroSat CZTI detection
  21. GRB 260429B / EP260429a: COLIBRÍ optical upper limit
  22. EP260429a: LCO optical upper limits
  23. EP260430a: LCO optical upper limits
  24. GRB 260430A / EP260430a: COLIBRÍ optical upper limit
  25. GRB 260429A: Fermi GBM Detection
  26. Fermi GRB 260429A: Global MASTER-Net observations report
  27. EP260430a: Global MASTER-Net observations report
  28. EP260430a: Einstein Probe detection of an X-ray transient
  29. EP260429a: EP-WXT detection of a fast X-ray transient
  30. GRB 260429A: Fermi GBM Final Real-time Localization
  31. GRB 260428A: SVOM/GRM observation of a possible short burst with extended emission
  32. GRB 260428A: GECAM-B detection of a possible long duration Type I burst
  33. IceCube-260425A: Upper limits from a search for additional neutrino events in IceCube
  34. GRB 260428A: AstroSat CZTI detection
  35. Fermi GRB 260428A: Global MASTER-Net observations report
  36. EP260416a: Mondy and Terskol optical upper limits
  37. GRB 260424B: Glowbug gamma-ray detection of a short burst
  38. GRB 260424B: COLIBRÍ optical upper limit
  39. Konus-Wind detection of GRB 260424B
  40. GRB 260428A: Fermi GBM Final Real-time Localization
  41. Fermi-LAT Gamma-ray Observations of IceCube-260425A
  42. GRB 260424C: Fermi GBM Final Localization
  43. EP260321a/SN 2026gzf: spectroscopy at Mondy observatory
  44. IPN triangulation of GRB 260424B (short)
  45. GRB 260424B: SVOM/GRM detection of a short burst
  46. IceCube-260425A - IceCube observation of a high-energy neutrino candidate track-like event
  47. GRB 260305A: likely detection by Fermi-LAT and the LAT gamma-ray position
  48. IceCube Alert 260425A: Global MASTER-Net observations report
  49. Fermi trigger No 798737427: Global MASTER-Net observations report
  50. GRB 260401A: cubesat Avion detection
  51. GRB 260424A: AstroSat CZTI detection of a long burst
  52. EP260321a: Upper limits from ATCA radio observations
  53. GRB 260421B: Kilonova-Catcher optical afterglow detection
  54. GRB 260421B: Insight-HXMT/HE detection
  55. The EP-WXT trigger 01709258652: Mondy optical observations
  56. GRB 250328A: VLT host galaxy discovery and redshift z = 1.250
  57. EP260416a: Mondy optical observations
  58. GRB 260421B: SVOM/ECLAIRs refined analysis
  59. GRB 260421B: 3.6m DOT optical observation
  60. EP260416a: ZTSh R band observations
  61. EP-WXT trigger 01709260362: FRAM-ORM optical observations confirm flaring star G 151-9
  62. IceCube-Cascade 260418A: Upper limits from a search for additional neutrino events in IceCube
  63. EP250512a / GRB 250512B: VLT/X-shooter host galaxy identification and redshift z = 1.773
  64. GRB 250530A: VLT/X-shooter host galaxy redshift z = 1.486
  65. GRB 260419A: AstroSat CZTI detection
  66. GRB 260421B: SVOM/GRM observation
  67. GRB260421B: J band upper limit by SYSU 80cm infrared telescope
  68. GRB 260421B: EP-FXT follow-up observation
  69. The EP-WXT trigger 01709260362 is likely a flaring star
  70. GOTO26djh/AT2026jpw: ATCA radio detection
  71. GRB 260421B: J-band upper limit with WINTER
  72. GRB 260421B: LCO optical counterpart detection
  73. GRB 260421B: Fermi GBM Observation
  74. Fermi Gamma-ray Burst Monitor trigger 798482368/260421694 is not a GRB
  75. GRB 260421A: AstroSat CZTI detection
  76. GOTO26djh/AT2026jpw: radio detection at 15GHz
  77. GRB 260412A: SVOM/ECLAIRs refined analysis
  78. GRB 260421B: SVOM/VT optical observations
  79. EP260416a: J band upper limit by SYSU 80cm infrared telescope
  80. GRB 260310A: Late-time Chandra X-ray Detection
  81. GRB 260418A: Insight-HXMT/HE detection
  82. EP260416a: 1.3m DFOT optical observation
  83. GRB 260415A: CALET Gamma-Ray Burst Monitor detection
  84. GRB 260415B: CALET Gamma-Ray Burst Monitor detection
  85. Fermi GRB 260421C: Global MASTER-Net observations report
  86. GRB 260421C: Fermi GBM Final Real-time Localization
  87. GRB 260421B: VLT/X-shooter spectroscopic redshift z = 2.115
  88. Fermi GRB 260421B: Global MASTER-Net observations report
  89. GRB 260421B: BOOTES-7 early optical afterglow detection
  90. GRB 260421B: LCO optical afterglow confirmation
  91. GRB 260421B: SVOM/COLIBRÍ (FM-GFT) optical detection of a candidate counterpart
  92. GRB 260421B: TRT optical counterpart detection
  93. GRB 260421B: SVOM detection of a long burst
  94. GRB 260421B: BALROG localization (Fermi Trigger 798437606 / GRB 260421176)
  95. GRB 260421B: Fermi GBM Final Real-time Localization
  96. Fermi GRB 260421A: Global MASTER-Net observations report
  97. GRB 260421A: Fermi GBM Final Real-time Localization
  98. EP260321a: VLA radio follow-up
  99. GRB 260412A: LCOGT Optical Upper Limits
  100. The EP-WXT trigger 01709260314 is likely a flaring star

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