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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"

36132 results found.

  1. GRB 250424A: Swift detection of a burst with an optical counterpart
  2. Swift GRB 250424A: Global MASTER-Net observations report
  3. Swift GRB 250424A: Global MASTER-Net OT detection
  4. EP250421a: Nickel optical upper limit
  5. EP250416a / GRB 250416C: Gemini GMOS-S likely host galaxy redshift z = 0.963
  6. EP250421a: Upper limits from Fermi-GBM Observations
  7. SVOM/sb25042207: GOTO optical upper limits
  8. GRB 250421A: AstroSat CZTI detection
  9. GRB250419A: VLA radio detection
  10. GRB 250419A: Mephisto Multi-band Optical Detection
  11. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  12. GRB 250419A: Optical Observations via Virtual Telescope Project
  13. GRB 250419A: Mondy Continued Optical Observations
  14. Fermi GRB 250421A: Global MASTER-Net observations report
  15. GRB 250421B: AstroSat CZTI detection of a bright long burst
  16. GRB 250421A: Fermi GBM Final Real-time Localization
  17. GRB 250419A: Liverpool Telescope observations
  18. GRB 250419A: LCO optical observation
  19. GRB 250419A: JinShan optical observations
  20. GRB 250419A: SVOM/VT optical continuous observations
  21. GRB 250419A: SVOM/C-GFT optical observations
  22. GRB 250419A: Swift/UVOT Follow up
  23. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  24. GRB 250419A: LCO optical afterglow multi-band observations
  25. GRB 250419A: Mondy and AbAO Optical Observations
  26. GRB 250419A: Liverpool Telescope observations
  27. GRB 250419A: AKO Optical Afterglow Detection
  28. GRB 250419A: MASTER optical afterglow observation
  29. GRB 250407A: rest-frame energetics from Konus-Wind observation
  30. GRB 250419A: Swift-XRT localisation
  31. GRB 250407A: GTC/OSIRIS+ spectroscopic redshift z = 1.36
  32. GRB 250419A: VLT/X-shooter spectroscopic redshift z = 0.845
  33. GRB 250419A: Swift-XRT refined Analysis
  34. GRB 250419A: GOTO optical counterpart detection
  35. GRB 250419A: KAIT optical afterglow observations
  36. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  37. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  38. GRB 250419A: SVOM detection of a soft burst
  39. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  40. Konus-Wind detection of GRB 250403A
  41. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  42. SVOM/sb25041603 is not a GRB
  43. Fermi Gamma-ray Burst Monitor trigger 766505186/250416588 (GRB 250416A) is not a GRB
  44. Fermi Gamma-ray Burst Monitor trigger 766511207/250416657 is not a GRB
  45. GRB 250416B: Fermi GBM Final Real-time Localization
  46. GRB 250416A: Fermi GBM Final Real-time Localization
  47. Fermi Gamma-ray Burst Monitor trigger 766474855/250416237 is not a GRB
  48. GRB 250413A: AstroSat CZTI detection
  49. EP250304a: ATCA radio observations
  50. GRB 250412A: AstroSat CZTI detection
  51. GRB 250411A: DDOTI Optical Observations
  52. Fermi GRB 250411A: Global MASTER-Net observations report
  53. GRB 250411A: Fermi GBM Final Real-time Localization
  54. GRB 250407A: Continued KAIT/Nickel optical observations
  55. GRB 250314A: e-MERLIN observations
  56. GRB 250407A: Mondy and AbAO Optical Observations
  57. GRB 250320B: cubesat Avion detection
  58. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  59. IPN triangulation of GRB 250407A
  60. GRB 250407A: LCO detection of a fading optical counterpart
  61. EP250407a: Swift-XRT observations
  62. Konus-Wind detection of GRB 250407A
  63. GRB 250407A: SVOM/GRM observation of a bright long burst
  64. GRB 250407A: EP-WXT afterglow detection
  65. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  66. GRB 250407A: KAIT Optical Afterglow Candidate
  67. GRB 250407A: Fermi GBM Detection
  68. GRB 250407A: Swift-XRT afterglow detection
  69. Fermi GRB 250407A: Global MASTER-Net observations report
  70. GRB 250407A: Swift ToO observations
  71. GRB 250407A: SRG/ART-XC afterglow detection
  72. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  73. Konus-Wind detection of GRB 250406B (short/hard)
  74. IPN triangulation of GRB 250406B (short/hard)
  75. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  76. GRB 250407A: Fermi GBM Final Real-time Localization
  77. GRB 250406A: AstroSat CZTI detection
  78. Fermi GRB 250406A: Global MASTER-Net observations report
  79. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  80. GRB 250406A: Fermi GBM Final Real-time Localization
  81. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  82. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  83. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  84. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  85. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  86. Konus-Wind detection of GRB 250404A / EP250404a
  87. GRB 250404A / EP250404a: Mondy optical observations
  88. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  89. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  90. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  91. GRB 250404A / EP250404a: NOT optical observations
  92. GRB 250331D: Swift-XRT afterglow detection
  93. GRB 250404B: AstroSat CZTI detection of a short burst
  94. GRB 250403A: AstroSat CZTI detection
  95. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  96. EP250404a: REM optical/NIR observations
  97. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  98. EP250404a: LCO optical counterpart detection
  99. Fermi GRB 250404A: Global MASTER-Net observations report
  100. GRB 250403A: Montarrenti Observatory optical detection

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