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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').

32047 results found.

  1. GRB 250314A: e-MERLIN observations
  2. GRB 250407A: Mondy and AbAO Optical Observations
  3. GRB 250320B: cubesat Avion detection
  4. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  5. IPN triangulation of GRB 250407A
  6. GRB 250407A: LCO detection of a fading optical counterpart
  7. EP250407a: Swift-XRT observations
  8. Konus-Wind detection of GRB 250407A
  9. GRB 250407A: SVOM/GRM observation of a bright long burst
  10. GRB 250407A: EP-WXT afterglow detection
  11. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  12. GRB 250407A: KAIT Optical Afterglow Candidate
  13. GRB 250407A: Fermi GBM Detection
  14. GRB 250407A: Swift-XRT afterglow detection
  15. Fermi GRB 250407A: Global MASTER-Net observations report
  16. GRB 250407A: Swift ToO observations
  17. GRB 250407A: SRG/ART-XC afterglow detection
  18. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  19. Konus-Wind detection of GRB 250406B (short/hard)
  20. IPN triangulation of GRB 250406B (short/hard)
  21. GRB 250407A: BALROG localization (Fermi Trigger 765733706 / GRB 250407659)
  22. GRB 250407A: Fermi GBM Final Real-time Localization
  23. GRB 250406A: AstroSat CZTI detection
  24. Fermi GRB 250406A: Global MASTER-Net observations report
  25. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  26. GRB 250406A: Fermi GBM Final Real-time Localization
  27. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  28. Fermi Gamma-ray Burst Monitor trigger 765619921/250406342 is not a GRB
  29. GRB 250404A / EP250404a: RC500 INASAN-Kislovodsk optical upper limit
  30. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  31. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  32. Konus-Wind detection of GRB 250404A / EP250404a
  33. GRB 250404A / EP250404a: Mondy optical observations
  34. GRB 250404A / EP250404a: GMG spectroscopic redshift at z ~ 2.627
  35. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  36. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  37. GRB 250404A / EP250404a: NOT optical observations
  38. GRB 250331D: Swift-XRT afterglow detection
  39. GRB 250404B: AstroSat CZTI detection of a short burst
  40. GRB 250403A: AstroSat CZTI detection
  41. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  42. EP250404a: REM optical/NIR observations
  43. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  44. EP250404a: LCO optical counterpart detection
  45. Fermi GRB 250404A: Global MASTER-Net observations report
  46. GRB 250403A: Montarrenti Observatory optical detection
  47. GRB 250404A: Fermi GBM Detection
  48. GRB 250403A: KAIT optical observations
  49. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  50. EP250404a: Xinglong-2.16m spectroscopic redshift
  51. GRB 250403A: Fermi GBM observations
  52. GRB 250327B: VIRT Optical Upper Limit
  53. GRB 250331C Swift-BAT refined analysis
  54. GRB 250331B Swift-BAT refined analysis
  55. GRB 250330A Swift-BAT refined analysis
  56. EP250404a: Nanshan/HMT optical counterpart detection
  57. EP250404a: Einstein Probe detection of an X-ray transient
  58. GRB 250404A: Fermi GBM Final Real-time Localization
  59. GRB 250402A: Mondy optical observations
  60. GRB 250403A: Swift/UVOT Detection
  61. GRB 250402A: Swift/UVOT Upper Limits
  62. GRB 250403A: SVOM/VT optical observation
  63. GRB 250403A: REM NIR afterglow detection
  64. GRB 250403A: LCO optical counterpart detection
  65. GRB 250403A: JinShan optical observations
  66. GRB 250402A: EP-FXT afterglow detection
  67. GRB 250403A: Optical counterpart detection by LCO.
  68. GRB 250403A: Swift-XRT observations
  69. GRB 250322A: 10 GHz VLA radio upper limits
  70. Fermi GRB 250403A: Global MASTER-Net observations report
  71. GRB 250403A: GOTO optical counterpart follow-up observations
  72. GRB 250402A: NUTTelA-TAO Early Optical Limits
  73. GRB 250403A: GMG Optical Observation
  74. GRB 250403A: 1.6m Mephisto multi-band optical detection
  75. GRB 250402A: Fermi GBM Observation
  76. GRB 250403A: SVOM/C-GFT optical observations
  77. GRB 250403A: GOTO detection of the optical afterglow
  78. GRB 250402A: Swift-XRT observations
  79. GRB 250403A : SVOM detection of a burst
  80. GRB 250403A: Fermi GBM Final Real-time Localization
  81. GRB 250225B: VLT host galaxy redshift z = 0.950
  82. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  83. GRB 250402A: VLT/FORS2 spectroscopic redshift z = 2.823
  84. GRB 250402A: REM optical/NIR upper limits
  85. GRB 250402A: LCO optical counterpart detection
  86. GRB 250402A: refined SVOM/MXT data analysis
  87. GRB 250402B: AstroSat CZTI detection of a short burst
  88. GRB 250402A: SVOM/VT optical counterpart
  89. GRB 250402A: SVOM detection of a burst
  90. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  91. GRB 250314A: ALMA detection
  92. GRB 250329B: Swift/UVOT Upper Limit
  93. GRB 250329A: Swift/UVOT Upper Limit
  94. GRB 250327B: Swift/UVOT Detection
  95. GRB 250327A: Swift/UVOT Upper Limits
  96. GRB 250331E: SVOM/GRM observation
  97. GRB 250327B: Kilonova-Catcher Observations
  98. GRB250331D: AbAO optical observations
  99. GRB 250331D: Fermi GBM observation
  100. GRB 250331C: Swift/UVOT Upper Limits

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