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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"

36213 results found.

  1. GRB 250430A: Bassano Bresciano Observatory upper limit
  2. GRB 250430A : MITSuME Akeno optical upper limits
  3. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  4. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  5. GRB 250424A: CALET Gamma-Ray Burst Monitor detection
  6. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  7. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 250430A: AKO Optical Afterglow Detection
  9. GRB 250430A: Kanata optical upper limit
  10. EP 250427A: Optical counterpart detection by LCO.
  11. GRB 250430A: Swift detection of a burst with optical counterpart
  12. EP250427a / GRB 250427A: OHP/T193 continued photometric observations
  13. EP250428b: SAO RAS optical upper limit
  14. GRB 250427A: Swift/UVOT Detection
  15. EP250427a / GRB 250427A: OHP/T193 photometric observations
  16. EP250427a: EP-FXT follow-up observations
  17. EP250427a/GRB 250427A: FTW optical and NIR observations of the counterpart
  18. GRB250427A/EP250427a GIT optical afterglow detection:
  19. GRB 250427A: Swift-XRT refined Analysis
  20. EP250427a / GRB 250427A: LCO optical counterpart detection
  21. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  22. EP250427A/GRB250427A: Keck/LRIS redshift
  23. GRB 250424A: LCO optical observation
  24. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  25. GRB 250424A: Swift-BAT refined analysis
  26. GRB 250424A: SVOM/GRM observation of a long burst
  27. GRB 250424A: PRIME near-infrared detection
  28. GRB 250424A: WINTER J-band detection
  29. GRB 250424A: EIRSAT-1 GMOD Detection
  30. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  31. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 250424A: SVOM/VT optical observation
  33. GRB 250419A: Mondy Optical Observations
  34. GRB 250424A: Swift/UVOT Detection
  35. Konus-Wind detection of GRB 250424A
  36. GRB 250424A: Skynet Optical Observations
  37. GRB 250424A: Kilonova-Catcher optical afterglow detection
  38. GRB 250419a: Continued Liverpool Telescope observations
  39. GRB 250419A: Liverpool Telescope optical upper limit
  40. GRB 250407A: GRBAlpha detection
  41. GRB 250404A / EP250404a: GRBAlpha detection
  42. GRB 250330B: GRBAlpha detection
  43. GRB 250419A: SVOM/ECLAIRs refined analysis
  44. GRB 250424A: Swift-XRT refined Analysis
  45. GRB 250424A: Enhanced Swift-XRT position
  46. GRB 250424A: AstroSat CZTI detection of a bright long burst
  47. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  48. GRB 250424A: BlackGEM optical afterglow detection
  49. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  50. GRB 250424A: likely host galaxy
  51. GRB 250424A: DDOTI Afterglow Detection
  52. GRB 250424A: REM optical/NIR afterglow detection
  53. GRB 250424A: Swift detection of a burst with an optical counterpart
  54. Swift GRB 250424A: Global MASTER-Net observations report
  55. Swift GRB 250424A: Global MASTER-Net OT detection
  56. EP250421a: Nickel optical upper limit
  57. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  58. EP250421a: Upper limits from Fermi-GBM Observations
  59. SVOM/sb25042207: BOOTES-2 early optical upper limit
  60. SVOM/sb25042207: GOTO optical upper limits
  61. GRB 250421A: AstroSat CZTI detection
  62. GRB250419A: VLA radio detection
  63. GRB 250419A: Mephisto Multi-band Optical Detection
  64. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  65. GRB 250419A: Optical Observations via Virtual Telescope Project
  66. GRB 250419A: Mondy Continued Optical Observations
  67. Fermi GRB 250421A: Global MASTER-Net observations report
  68. GRB 250421B: AstroSat CZTI detection of a bright long burst
  69. GRB 250421A: Fermi GBM Final Real-time Localization
  70. GRB 250419A: Liverpool Telescope observations
  71. GRB 250419A: LCO optical observation
  72. GRB 250419A: JinShan optical observations
  73. GRB 250419A: SVOM/VT optical continuous observations
  74. GRB 250419A: SVOM/C-GFT optical observations
  75. GRB 250419A: Swift/UVOT Follow up
  76. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  77. GRB 250419A: LCO optical afterglow multi-band observations
  78. GRB 250419A: Mondy and AbAO Optical Observations
  79. GRB 250419A: Liverpool Telescope observations
  80. GRB 250419A: AKO Optical Afterglow Detection
  81. GRB 250419A: MASTER optical afterglow observation
  82. GRB 250407A: rest-frame energetics from Konus-Wind observation
  83. GRB 250419A: Swift-XRT localisation
  84. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  85. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  86. GRB 250419A: Swift-XRT refined Analysis
  87. GRB 250419A: GOTO optical counterpart detection
  88. GRB 250419A: KAIT optical afterglow observations
  89. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  90. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  91. GRB 250419A: SVOM detection of a soft burst
  92. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  93. Konus-Wind detection of GRB 250403A
  94. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  95. SVOM/sb25041603 is not a GRB
  96. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  97. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  98. GRB 250416B: Fermi GBM Final Real-time Localization
  99. GRB 250416A: Fermi GBM Final Real-time Localization
  100. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB

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