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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"

28117 results found.

  1. GRB 250424A: Swift detection of a burst with an optical counterpart
  2. Swift GRB 250424A: Global MASTER-Net OT detection
  3. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  4. EP250421a: Nickel optical upper limit
  5. EP250421a: Upper limits from Fermi-GBM Observations
  6. SVOM/sb25042207: SVOM detection of an X-ray transient
  7. IceCube-250421A: DDOTI Detection of the LAST Candidate
  8. GRB 250419A: Mephisto Multi-band Optical Detection
  9. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  10. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  11. EP250421a: NOT optical observations
  12. GRB 250419A: Optical Observations via Virtual Telescope Project
  13. EP250421a: REM optical upper limit
  14. EP250421A: COLIBRÍ Optical Upper Limit
  15. GRB 250419A: Mondy Continued Optical Observations
  16. GRB 250421B: AstroSat CZTI detection of a bright long burst
  17. EP250421a: Einstein Probe detection of an X-ray transient
  18. EP250421a: Mephisto optical counterpart confirmation
  19. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  20. EP250421a: JinShan likely optical counterpart
  21. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  22. GRB 250419A: LCO optical observation
  23. GRB 250419A: JinShan optical observations
  24. GRB 250419A: SVOM/C-GFT optical observations
  25. GRB 250419A: Swift/UVOT Follow up
  26. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  27. GRB 250419A: LCO optical afterglow multi-band observations
  28. GRB 250419A: Mondy and AbAO Optical Observations
  29. GRB 250419A: AKO Optical Afterglow Detection
  30. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  31. GRB 250419A: Swift-XRT refined Analysis
  32. GRB 250419A: KAIT optical afterglow observations
  33. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  34. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  35. GRB 250419A: SVOM detection of a soft burst
  36. EP250416a: Swift/XRT counterpart fading
  37. EP20250416a: Swift/XRT counterpart detection
  38. IceCube-250416A: DDOTI Optical Observations
  39. EP250416a: Gemini South-GMOS optical counterpart
  40. SVOM/sb25041603 is not a GRB
  41. EP250416a: GSP optical upper limit
  42. EP250416a: Einstein Probe detection of an X-ray transient
  43. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  44. SVOM/sb25041603: SVOM detection of an X-ray transient
  45. IceCube 250414.324: DDOTI Optical Observations
  46. GRB 250413A: AstroSat CZTI detection
  47. EP250304a: ATCA radio observations
  48. EP250404a: Nanshan 0.43m Telescope optical observatios
  49. GRB 250411A: DDOTI Optical Observations
  50. Fermi GRB 250411A: Global MASTER-Net observations report
  51. GRB 250407A: Continued KAIT/Nickel optical observations
  52. GRB 250314A: e-MERLIN observations
  53. GRB 250407A: Mondy and AbAO Optical Observations
  54. EP250227a: Further NOT optical observations
  55. GRB 250320B: cubesat Avion detection
  56. IceCube-250406A: Swift-XRT observations
  57. GRB 250407A: LCO detection of a fading optical counterpart
  58. Fermi-LAT gamma-ray observations of IceCube-250406A
  59. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 250407A: SVOM/GRM observation of a bright long burst
  61. GRB 250407A: EP-WXT afterglow detection
  62. EP250407a: EP-WXT detection of a fast X-ray transient
  63. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  64. GRB 250407A: KAIT Optical Afterglow Candidate
  65. IceCube-250406A: No candidates from the Zwicky Transient Facility
  66. GRB 250407A: Fermi GBM Detection
  67. GRB 250407A: Swift-XRT afterglow detection
  68. GRB 250407A: SRG/ART-XC afterglow detection
  69. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  70. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  71. IPN triangulation of GRB 250406B (short/hard)
  72. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  73. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  74. IceCube 250406.951: DDOTI Optical Observations
  75. GRB 250406A: AstroSat CZTI detection
  76. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  77. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  78. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  79. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  80. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  81. Konus-Wind detection of GRB 250404A / EP250404a
  82. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  84. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  85. EP250402a: Optical upper limit with PD 1.3m observations
  86. GRB 250404A / EP250404a: NOT optical observations
  87. GRB 250331D: Swift-XRT afterglow detection
  88. GRB 250404B: AstroSat CZTI detection of a short burst
  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. EP250404a: Xinglong decaying optical counterpart
  96. GRB 250403A: Montarrenti Observatory optical detection
  97. GRB 250404A: Fermi GBM Detection
  98. GRB 250403A: KAIT optical observations
  99. EP250404a: AKO Optical Afterglow Detection
  100. EP250404a: LAST detection of optical counterpart

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