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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"

37264 results found.

  1. GRB 250407A: Swift-XRT afterglow detection
  2. Fermi GRB 250407A: Global MASTER-Net observations report
  3. GRB 250407A: Swift ToO observations
  4. GRB 250407A: SRG/ART-XC afterglow detection
  5. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  6. Konus-Wind detection of GRB 250406B (short/hard)
  7. IPN triangulation of GRB 250406B (short/hard)
  8. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  9. GRB 250407A: Fermi GBM Final Real-time Localization
  10. GRB 250406A: AstroSat CZTI detection
  11. Fermi GRB 250406A: Global MASTER-Net observations report
  12. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  13. GRB 250406A: Fermi GBM Final Real-time Localization
  14. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  15. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  16. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  17. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  18. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  19. Konus-Wind detection of GRB 250404A / EP250404a
  20. GRB 250404A / EP250404a: Mondy optical observations
  21. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  22. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  23. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  24. GRB 250404A / EP250404a: NOT optical observations
  25. GRB 250331D: Swift-XRT afterglow detection
  26. GRB 250404B: AstroSat CZTI detection of a short burst
  27. GRB 250403A: AstroSat CZTI detection
  28. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  29. EP250404a: REM optical/NIR observations
  30. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  31. EP250404a: LCO optical counterpart detection
  32. Fermi GRB 250404A: Global MASTER-Net observations report
  33. GRB 250403A: Montarrenti Observatory optical detection
  34. GRB 250404A: Fermi GBM Detection
  35. GRB 250403A: KAIT optical observations
  36. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  37. EP250404a: Xinglong-2.16m spectroscopic redshift
  38. GRB 250403A: Fermi GBM observations
  39. GRB 250327B: VIRT Optical Upper Limit
  40. EP250404a: Mephisto multi-band optical detection
  41. GRB 250331C Swift-BAT refined analysis
  42. GRB 250331B Swift-BAT refined analysis
  43. GRB 250330A Swift-BAT refined analysis
  44. EP250404a: Nanshan/HMT optical counterpart detection
  45. EP250404a: Einstein Probe detection of an X-ray transient
  46. GRB 250404A: Fermi GBM Final Real-time Localization
  47. GRB 250402A: Mondy optical observations
  48. GRB 250403A: Swift/UVOT Detection
  49. GRB 250402A: Swift/UVOT Upper Limits
  50. EP250402a: Optical upper limit with Kinder observations
  51. GRB 250403A: SVOM/VT optical observation
  52. GRB 250403A: REM NIR afterglow detection
  53. GRB 250403A: LCO optical counterpart detection
  54. GRB 250403A: JinShan optical observations
  55. GRB 250402A: EP-FXT afterglow detection
  56. GRB 250403A: Optical counterpart detection by LCO.
  57. EP250402a: EP-FXT follow-up observations
  58. GRB 250403A: Swift-XRT observations
  59. GRB 250322A: 10 GHz VLA radio upper limits
  60. Fermi GRB 250403A: Global MASTER-Net observations report
  61. GRB 250403A: GOTO optical counterpart follow-up observations
  62. GRB 250402A: NUTTelA-TAO Early Optical Limits
  63. GRB 250403A: GMG Optical Observation
  64. GRB 250403A: 1.6m Mephisto multi-band optical detection
  65. GRB 250402A: Fermi GBM Observation
  66. GRB 250403A: SVOM/C-GFT optical observations
  67. GRB 250403A: GOTO detection of the optical afterglow
  68. GRB 250402A: Swift-XRT observations
  69. GRB 250403A : SVOM detection of a burst
  70. GRB 250403A: Fermi GBM Final Real-time Localization
  71. GRB 250225B: VLT host galaxy redshift z = 0.950
  72. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  73. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  74. GRB 250402A: REM optical/NIR upper limits
  75. GRB 250402A: LCO optical counterpart detection
  76. GRB 250402A: refined SVOM/MXT data analysis
  77. GRB 250402B: AstroSat CZTI detection of a short burst
  78. GRB 250402A: SVOM/VT optical counterpart
  79. GRB 250402A: SVOM detection of a burst
  80. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  81. GRB 250314A: ALMA detection
  82. GRB 250329B: Swift/UVOT Upper Limit
  83. GRB 250329A: Swift/UVOT Upper Limit
  84. GRB 250327B: Swift/UVOT Detection
  85. GRB 250327A: Swift/UVOT Upper Limits
  86. GRB 250331E: SVOM/GRM observation
  87. GRB 250327B: Kilonova-Catcher Observations
  88. GRB250331D: AbAO optical observations
  89. GRB 250331D: Fermi GBM observation
  90. GRB 250331C: Swift/UVOT Upper Limits
  91. GRB 250331B: Swift/UVOT Upper Limits
  92. GRB 250328A: AbAO AS-32 Optical Observations
  93. GRB 250219A: NOT candidate host galaxy detection
  94. GRB 250322B: GRBAlpha detection
  95. GRB 250331D: Swift-XRT observations
  96. GRB 250331C: Swift-XRT refined Analysis
  97. GRB 250331B: Swift-XRT refined Analysis
  98. GRB 250331B: Swift-XRT refined Analysis
  99. GRB 250322B possible detection by the AstroSat Satellite
  100. GRB 250330B: SVOM/GRM observation of a short burst

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