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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"

36329 results found.

  1. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  2. GRB 250419A: Swift-XRT refined Analysis
  3. GRB 250419A: GOTO optical counterpart detection
  4. GRB 250419A: KAIT optical afterglow observations
  5. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  6. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  7. GRB 250419A: SVOM detection of a soft burst
  8. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  9. Konus-Wind detection of GRB 250403A
  10. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  11. SVOM/sb25041603 is not a GRB
  12. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  13. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  14. GRB 250416B: Fermi GBM Final Real-time Localization
  15. GRB 250416A: Fermi GBM Final Real-time Localization
  16. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  17. GRB 250413A: AstroSat CZTI detection
  18. EP250304a: ATCA radio observations
  19. GRB 250412A: AstroSat CZTI detection
  20. GRB 250411A: DDOTI Optical Observations
  21. Fermi GRB 250411A: Global MASTER-Net observations report
  22. GRB 250411A: Fermi GBM Final Real-time Localization
  23. GRB 250407A: Continued KAIT/Nickel optical observations
  24. GRB 250314A: e-MERLIN observations
  25. GRB 250407A: Mondy and AbAO Optical Observations
  26. GRB 250320B: cubesat Avion detection
  27. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  28. IPN triangulation of GRB 250407A
  29. GRB 250407A: LCO detection of a fading optical counterpart
  30. EP250407a: Swift-XRT observations
  31. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  32. Konus-Wind detection of GRB 250407A
  33. GRB 250407A: SVOM/GRM observation of a bright long burst
  34. GRB 250407A: EP-WXT afterglow detection
  35. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  36. GRB 250407A: KAIT Optical Afterglow Candidate
  37. GRB 250407A: Fermi GBM Detection
  38. GRB 250407A: Swift-XRT afterglow detection
  39. Fermi GRB 250407A: Global MASTER-Net observations report
  40. GRB 250407A: Swift ToO observations
  41. GRB 250407A: SRG/ART-XC afterglow detection
  42. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  43. Konus-Wind detection of GRB 250406B (short/hard)
  44. IPN triangulation of GRB 250406B (short/hard)
  45. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  46. GRB 250407A: Fermi GBM Final Real-time Localization
  47. GRB 250406A: AstroSat CZTI detection
  48. Fermi GRB 250406A: Global MASTER-Net observations report
  49. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  50. GRB 250406A: Fermi GBM Final Real-time Localization
  51. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  52. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  53. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  54. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  55. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  56. Konus-Wind detection of GRB 250404A / EP250404a
  57. GRB 250404A / EP250404a: Mondy optical observations
  58. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  59. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  60. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  61. GRB 250404A / EP250404a: NOT optical observations
  62. GRB 250331D: Swift-XRT afterglow detection
  63. GRB 250404B: AstroSat CZTI detection of a short burst
  64. GRB 250403A: AstroSat CZTI detection
  65. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  66. EP250404a: REM optical/NIR observations
  67. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  68. EP250404a: LCO optical counterpart detection
  69. Fermi GRB 250404A: Global MASTER-Net observations report
  70. GRB 250403A: Montarrenti Observatory optical detection
  71. GRB 250404A: Fermi GBM Detection
  72. GRB 250403A: KAIT optical observations
  73. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  74. EP250404a: Xinglong-2.16m spectroscopic redshift
  75. GRB 250403A: Fermi GBM observations
  76. GRB 250327B: VIRT Optical Upper Limit
  77. GRB 250331C Swift-BAT refined analysis
  78. GRB 250331B Swift-BAT refined analysis
  79. GRB 250330A Swift-BAT refined analysis
  80. EP250404a: BOOTES-4/JGT optical afterglow detection
  81. EP250404a: Nanshan/HMT optical counterpart detection
  82. EP250404a: Einstein Probe detection of an X-ray transient
  83. GRB 250404A: Fermi GBM Final Real-time Localization
  84. GRB 250402A: Mondy optical observations
  85. GRB 250403A: Swift/UVOT Detection
  86. GRB 250402A: Swift/UVOT Upper Limits
  87. GRB 250403A: SVOM/VT optical observation
  88. GRB 250403A: REM NIR afterglow detection
  89. GRB 250403A: LCO optical counterpart detection
  90. GRB 250403A: JinShan optical observations
  91. GRB 250402A: EP-FXT afterglow detection
  92. GRB 250403A: Optical counterpart detection by LCO.
  93. GRB 250403A: Swift-XRT observations
  94. GRB 250322A: 10 GHz VLA radio upper limits
  95. Fermi GRB 250403A: Global MASTER-Net observations report
  96. GRB 250403A: GOTO optical counterpart follow-up observations
  97. GRB 250402A: NUTTelA-TAO Early Optical Limits
  98. GRB 250403A: GMG Optical Observation
  99. GRB 250403A: 1.6m Mephisto multi-band optical detection
  100. GRB 250402A: Fermi GBM Observation

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