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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"

45742 results found.

  1. Konus-Wind detection of GRB 250403A
  2. EP20250416a: Swift/XRT counterpart detection
  3. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  4. IceCube-250416A: DDOTI Optical Observations
  5. EP250416a: Gemini South-GMOS optical counterpart
  6. EP250225a: SVOM/VT optical brightening
  7. SVOM/sb25041603 is not a GRB
  8. EP250416a: GSP optical upper limit
  9. EP250416a: Global MASTER-Net observations report
  10. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  11. EP250416a: Einstein Probe detection of an X-ray transient
  12. IceCube-250416A - IceCube observation of a high-energy neutrino candidate track-like event
  13. IceCube-250416A: Global MASTER-Net observations report
  14. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  15. GRB 250416B: Fermi GBM Final Real-time Localization
  16. GRB 250416A: Fermi GBM Final Real-time Localization
  17. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  18. SVOM/sb25041603: SVOM detection of an X-ray transient
  19. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  20. IceCube 250414.324: DDOTI Optical Observations
  21. GRB 250413A: AstroSat CZTI detection
  22. EP250304a: ATCA radio observations
  23. GRB 250412A: AstroSat CZTI detection
  24. EP250404a: Nanshan 0.43m Telescope optical observatios
  25. Fermi trigger No 766148493: Global MASTER-Net observations report
  26. Fermi trigger No 766173972: Global MASTER-Net observations report
  27. GRB 250411A: DDOTI Optical Observations
  28. Fermi GRB 250411A: Global MASTER-Net observations report
  29. GRB 250411A: Fermi GBM Final Real-time Localization
  30. GRB 250407A: Continued KAIT/Nickel optical observations
  31. GRB 250314A: e-MERLIN observations
  32. GRB 250407A: Mondy and AbAO Optical Observations
  33. EP250227a: Further NOT optical observations
  34. GRB 250320B: cubesat Avion detection
  35. IceCube-250406A: Swift-XRT observations
  36. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  37. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-250409A
  38. IPN triangulation of GRB 250407A
  39. EP250407a: Global MASTER-Net observations report
  40. GRB 250407A: LCO detection of a fading optical counterpart
  41. Fermi-LAT gamma-ray observations of IceCube-250406A
  42. EP250407a: Swift-XRT observations
  43. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  44. Konus-Wind detection of GRB 250407A
  45. GRB 250407A: SVOM/GRM observation of a bright long burst
  46. GRB 250407A: EP-WXT afterglow detection
  47. EP250407a: EP-WXT detection of a fast X-ray transient
  48. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  49. GRB 250407A: KAIT Optical Afterglow Candidate
  50. IceCube-250406A: No candidates from the Zwicky Transient Facility
  51. GRB 250407A: Fermi GBM Detection
  52. GRB 250407A: Swift-XRT afterglow detection
  53. Fermi GRB 250407A: Global MASTER-Net observations report
  54. GRB 250407A: Swift ToO observations
  55. GRB 250407A: SRG/ART-XC afterglow detection
  56. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  57. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  58. Konus-Wind detection of GRB 250406B (short/hard)
  59. IPN triangulation of GRB 250406B (short/hard)
  60. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  61. GRB 250407A: Fermi GBM Final Real-time Localization
  62. IceCube-250406A - IceCube observation of a high-energy neutrino candidate track-like event
  63. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  64. IceCube 250406.951: DDOTI Optical Observations
  65. GRB 250406A: AstroSat CZTI detection
  66. IceCube Alert 250406.95: Global MASTER-Net observations report
  67. Fermi trigger No 765663719: Global MASTER-Net observations report
  68. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  69. Fermi GRB 250406A: Global MASTER-Net observations report
  70. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  71. GRB 250406A: Fermi GBM Final Real-time Localization
  72. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  73. Fermi trigger No 765619921: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  75. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  76. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  77. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  78. Konus-Wind detection of GRB 250404A / EP250404a
  79. GRB 250404A / EP250404a: Mondy optical observations
  80. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  81. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  82. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  83. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  84. EP250402a: Optical upper limit with PD 1.3m observations
  85. GRB 250404A / EP250404a: NOT optical observations
  86. GRB 250331D: Swift-XRT afterglow detection
  87. GRB 250404B: AstroSat CZTI detection of a short burst
  88. GRB 250403A: AstroSat CZTI detection
  89. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  90. EP250404a: REM optical/NIR observations
  91. EP250404a: Seimei/TriCCS optical counterpart detection
  92. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  93. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  94. EP250404a: LCO optical counterpart detection
  95. Fermi GRB 250404A: Global MASTER-Net observations report
  96. EP250404a: Xinglong decaying optical counterpart
  97. GRB 250403A: Montarrenti Observatory optical detection
  98. GRB 250404A: Fermi GBM Detection
  99. EP250404a: Global MASTER-Net observations report
  100. GRB 250403A: KAIT optical observations

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