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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"

45577 results found.

  1. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  2. Konus-Wind detection of GRB 250406B (short/hard)
  3. IPN triangulation of GRB 250406B (short/hard)
  4. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  5. GRB 250407A: Fermi GBM Final Real-time Localization
  6. IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
  7. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  8. IceCube 250406.951: DDOTI Optical Observations
  9. GRB 250406A: AstroSat CZTI detection
  10. IceCube Alert 250406.95: Global MASTER-Net observations report
  11. Fermi trigger No 765663719: Global MASTER-Net observations report
  12. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  13. Fermi GRB 250406A: Global MASTER-Net observations report
  14. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  15. GRB 250406A: Fermi GBM Final Real-time Localization
  16. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  17. Fermi trigger No 765619921: Global MASTER-Net observations report
  18. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  19. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  20. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  21. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  22. Konus-Wind detection of GRB 250404A / EP250404a
  23. GRB 250404A / EP250404a: Mondy optical observations
  24. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  25. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  26. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  27. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  28. EP250402a: Optical upper limit with PD 1.3m observations
  29. GRB 250404A / EP250404a: NOT optical observations
  30. GRB 250331D: Swift-XRT afterglow detection
  31. GRB 250404B: AstroSat CZTI detection of a short burst
  32. GRB 250403A: AstroSat CZTI detection
  33. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  34. EP250404a: REM optical/NIR observations
  35. EP250404a: Seimei/TriCCS optical counterpart detection
  36. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  37. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  38. EP250404a: LCO optical counterpart detection
  39. Fermi GRB 250404A: Global MASTER-Net observations report
  40. EP250404a: Xinglong decaying optical counterpart
  41. GRB 250403A: Montarrenti Observatory optical detection
  42. GRB 250404A: Fermi GBM Detection
  43. EP250404a: Global MASTER-Net observations report
  44. GRB 250403A: KAIT optical observations
  45. EP250404a: AKO Optical Afterglow Detection
  46. EP250404a: LAST detection of optical counterpart
  47. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  48. EP250404a: Xinglong-2.16m spectroscopic redshift
  49. GRB 250403A: Fermi GBM observations
  50. GRB 250327B: VIRT Optical Upper Limit
  51. EP250404a: Mephisto multi-band optical detection
  52. GRB 250331C Swift-BAT refined analysis
  53. GRB 250331B Swift-BAT refined analysis
  54. GRB 250330A Swift-BAT refined analysis
  55. EP250321A: J band upper limit by SYSU 80cm telescope
  56. EP250404a: BOOTES-4/JGT optical afterglow detection
  57. EP250404a: Nanshan/HMT optical counterpart detection
  58. EP250404a: Einstein Probe detection of an X-ray transient
  59. GRB 250404A: Fermi GBM Final Real-time Localization
  60. GRB 250402A: Mondy optical observations
  61. GRB 250403A: Swift/UVOT Detection
  62. GRB 250402A: Swift/UVOT Upper Limits
  63. EP250402a: Optical upper limit with Kinder observations
  64. GRB 250403A: SVOM/VT optical observation
  65. GRB 250403A: REM NIR afterglow detection
  66. GRB 250403A: LCO optical counterpart detection
  67. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  68. GRB 250403A: JinShan optical observations
  69. GRB 250402A: EP-FXT afterglow detection
  70. GRB 250403A: Optical counterpart detection by LCO.
  71. EP250402a: EP-FXT follow-up observations
  72. GRB 250403A: Swift-XRT observations
  73. GRB 250322A: 10 GHz VLA radio upper limits
  74. Fermi GRB 250403A: Global MASTER-Net observations report
  75. GRB 250403A: GOTO optical counterpart follow-up observations
  76. GRB 250402A: NUTTelA-TAO Early Optical Limits
  77. GRB 250403A: GMG Optical Observation
  78. GRB 250403A: 1.6m Mephisto multi-band optical detection
  79. GRB 250402A: Fermi GBM Observation
  80. GRB 250403A: SVOM/C-GFT optical observations
  81. GRB 250403A: GOTO detection of the optical afterglow
  82. GRB 250402A: Swift-XRT observations
  83. GRB 250403A : SVOM detection of a burst
  84. GRB 250403A: Fermi GBM Final Real-time Localization
  85. GRB 250225B: VLT host galaxy redshift z = 0.950
  86. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  87. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  88. GRB 250402A: REM optical/NIR upper limits
  89. GRB 250402A: LCO optical counterpart detection
  90. GRB 250402A: refined SVOM/MXT data analysis
  91. The EP-WXT trigger 01709133862 is a flaring star
  92. EP250402a: Einstein Probe detection of a fast X-ray transient
  93. GRB 250402B: AstroSat CZTI detection of a short burst
  94. GRB 250402A: SVOM/VT optical counterpart
  95. GRB 250402A: SVOM detection of a burst
  96. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  97. GRB 250314A: ALMA detection
  98. GRB 250329B: Swift/UVOT Upper Limit
  99. GRB 250329A: Swift/UVOT Upper Limit
  100. GRB 250327B: Swift/UVOT Detection

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