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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"

45676 results found.

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

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