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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').

19108 results found.

  1. GRB 250424A: PRIME near-infrared detection
  2. GRB 250424A: WINTER J-band detection
  3. GRB 250419A: Mondy Optical Observations
  4. GRB 250424A: Swift/UVOT Detection
  5. Konus-Wind detection of GRB 250424A
  6. GRB 250424A: Skynet Optical Observations
  7. GRB 250424A: Kilonova-Catcher optical afterglow detection
  8. GRB 250407A: GRBAlpha detection
  9. GRB 250404A / EP250404a: GRBAlpha detection
  10. GRB 250330B: GRBAlpha detection
  11. GRB 250419A: SVOM/ECLAIRs refined analysis
  12. GRB 250424A: Enhanced Swift-XRT position
  13. GRB 250424A: COLIBRÍ Detection of a Bright Optical Counterpart
  14. GRB 250424A: BlackGEM optical afterglow detection
  15. GRB 250424A: DDOTI Afterglow Detection
  16. GRB 250424A: REM optical/NIR afterglow detection
  17. GRB 250424A: Swift detection of a burst with an optical counterpart
  18. Swift GRB250424A: Global MASTER-Net OT detection
  19. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  20. EP250421a: Nickel optical upper limit
  21. SVOM/sb25042207: XRT observations
  22. SVOM/sb25042207: GOTO optical upper limits
  23. GRB 250421A: AstroSat CZTI detection
  24. SVOM/sb25042207: SVOM detection of an X-ray transient
  25. IceCube-250421A: DDOTI Detection of the LAST Candidate
  26. GRB 250419A: Mephisto Multi-band Optical Detection
  27. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  28. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  29. EP250421a: NOT optical observations
  30. GRB 250419A: Optical Observations via Virtual Telescope Project
  31. EP250421a: REM optical upper limit
  32. EP250421A: COLIBRÍ Optical Upper Limit
  33. GRB 250419A: Mondy Continued Optical Observations
  34. EP250421a: Einstein Probe detection of an X-ray transient
  35. EP250421a: Mephisto optical counterpart confirmation
  36. EP250421a: JinShan likely optical counterpart
  37. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  38. GRB 250419A: LCO optical observation
  39. GRB 250419A: JinShan optical observations
  40. GRB 250419A: SVOM/C-GFT optical observations
  41. GRB 250419A: Swift/UVOT Follow up
  42. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  43. GRB 250419A: LCO optical afterglow multi-band observations
  44. GRB 250419A: Mondy and AbAO Optical Observations
  45. GRB 250419A: AKO Optical Afterglow Detection
  46. GRB 250419A: KAIT optical afterglow observations
  47. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  48. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  49. GRB 250419A: SVOM detection of a soft burst
  50. EP20250416a: Swift/XRT counterpart detection
  51. IceCube-250416A: DDOTI Optical Observations
  52. EP250416a: Gemini South-GMOS optical counterpart
  53. SVOM/sb25041603 is not a GRB
  54. EP250416a: Einstein Probe detection of an X-ray transient
  55. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  56. SVOM/sb25041603: SVOM detection of an X-ray transient
  57. IceCube 250414.324: DDOTI Optical Observations
  58. EP250404a: Nanshan 0.43m Telescope optical observatios
  59. GRB 250411A: DDOTI Optical Observations
  60. GRB 250314A: e-MERLIN observations
  61. GRB 250407A: Mondy and AbAO Optical Observations
  62. EP250227a: Further NOT optical observations
  63. GRB 250320B: cubesat Avion detection
  64. IceCube-250406A: Swift-XRT observations
  65. EP250407a: Global MASTER-Net observations report
  66. GRB 250407A: LCO detection of a fading optical counterpart
  67. GRB 250407A: SVOM/GRM observation of a bright long burst
  68. GRB 250407A: EP-WXT afterglow detection
  69. EP250407a: EP-WXT detection of a fast X-ray transient
  70. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  71. GRB 250407A: KAIT Optical Afterglow Candidate
  72. IceCube-250406A: No candidates from the Zwicky Transient Facility
  73. GRB 250407A: Swift-XRT afterglow detection
  74. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  75. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  76. Konus-Wind detection of GRB 250406B (short/hard)
  77. IPN triangulation of GRB 250406B (short/hard)
  78. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  79. IceCube 250406.951: DDOTI Optical Observations
  80. GRB 250406A: AstroSat CZTI detection
  81. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  82. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  83. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  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. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  88. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  89. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  90. EP250402a: Optical upper limit with PD 1.3m observations
  91. GRB 250404A / EP250404a: NOT optical observations
  92. GRB 250331D: Swift-XRT afterglow detection
  93. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  94. EP250404a: REM optical/NIR observations
  95. EP250404a: Seimei/TriCCS optical counterpart detection
  96. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  97. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  98. EP250404a: LCO optical counterpart detection
  99. EP250404a: Xinglong decaying optical counterpart
  100. GRB 250403A: Montarrenti Observatory optical detection

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