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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').
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"

21795 results found.

  1. GRB 250424A: BlackGEM optical afterglow detection
  2. GRB 250424A: DDOTI Afterglow Detection
  3. GRB 250424A: REM optical/NIR afterglow detection
  4. GRB 250424A: Swift detection of a burst with an optical counterpart
  5. Swift GRB 250424A: Global MASTER-Net OT detection
  6. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  7. EP250421a: Nickel optical upper limit
  8. SVOM/sb25042207: XRT observations
  9. SVOM/sb25042207: GOTO optical upper limits
  10. GRB 250421A: AstroSat CZTI detection
  11. SVOM/sb25042207: SVOM detection of an X-ray transient
  12. IceCube-250421A: DDOTI Detection of the LAST Candidate
  13. GRB 250419A: Mephisto Multi-band Optical Detection
  14. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  15. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  16. EP250421a: NOT optical observations
  17. GRB 250419A: Optical Observations via Virtual Telescope Project
  18. EP250421a: REM optical upper limit
  19. EP250421A: COLIBRÍ Optical Upper Limit
  20. GRB 250419A: Mondy Continued Optical Observations
  21. EP250421a: Einstein Probe detection of an X-ray transient
  22. EP250421a: Mephisto optical counterpart confirmation
  23. EP250421a: JinShan likely optical counterpart
  24. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  25. GRB 250419A: LCO optical observation
  26. GRB 250419A: JinShan optical observations
  27. GRB 250419A: SVOM/C-GFT optical observations
  28. GRB 250419A: Swift/UVOT Follow up
  29. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  30. GRB 250419A: LCO optical afterglow multi-band observations
  31. GRB 250419A: Mondy and AbAO Optical Observations
  32. GRB 250419A: AKO Optical Afterglow Detection
  33. GRB 250419A: KAIT optical afterglow observations
  34. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  35. GRB 250419A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  36. GRB 250419A: SVOM detection of a soft burst
  37. EP20250416a: Swift/XRT counterpart detection
  38. IceCube-250416A: DDOTI Optical Observations
  39. EP250416a: Gemini South-GMOS optical counterpart
  40. SVOM/sb25041603 is not a GRB
  41. EP250416a: Einstein Probe detection of an X-ray transient
  42. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  43. SVOM/sb25041603: SVOM detection of an X-ray transient
  44. IceCube 250414.324: DDOTI Optical Observations
  45. EP250404a: Nanshan 0.43m Telescope optical observatios
  46. GRB 250411A: DDOTI Optical Observations
  47. GRB 250314A: e-MERLIN observations
  48. GRB 250407A: Mondy and AbAO Optical Observations
  49. EP250227a: Further NOT optical observations
  50. GRB 250320B: cubesat Avion detection
  51. IceCube-250406A: Swift-XRT observations
  52. EP250407a: Global MASTER-Net observations report
  53. GRB 250407A: LCO detection of a fading optical counterpart
  54. GRB 250407A: SVOM/GRM observation of a bright long burst
  55. GRB 250407A: EP-WXT afterglow detection
  56. EP250407a: EP-WXT detection of a fast X-ray transient
  57. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  58. GRB 250407A: KAIT Optical Afterglow Candidate
  59. IceCube-250406A: No candidates from the Zwicky Transient Facility
  60. GRB 250407A: Swift-XRT afterglow detection
  61. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  62. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  63. Konus-Wind detection of GRB 250406B (short/hard)
  64. IPN triangulation of GRB 250406B (short/hard)
  65. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  66. IceCube 250406.951: DDOTI Optical Observations
  67. GRB 250406A: AstroSat CZTI detection
  68. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  69. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  70. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  71. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  72. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  73. Konus-Wind detection of GRB 250404A / EP250404a
  74. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  75. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  76. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  77. EP250402a: Optical upper limit with PD 1.3m observations
  78. GRB 250404A / EP250404a: NOT optical observations
  79. GRB 250331D: Swift-XRT afterglow detection
  80. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  81. EP250404a: REM optical/NIR observations
  82. EP250404a: Seimei/TriCCS optical counterpart detection
  83. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  84. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  85. EP250404a: LCO optical counterpart detection
  86. EP250404a: Xinglong decaying optical counterpart
  87. GRB 250403A: Montarrenti Observatory optical detection
  88. GRB 250403A: KAIT optical observations
  89. EP250404a: AKO Optical Afterglow Detection
  90. EP250404a: LAST detection of optical counterpart
  91. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  92. GRB 250327B: VIRT Optical Upper Limit
  93. EP250404a: Mephisto multi-band optical detection
  94. EP250321A: J band upper limit by SYSU 80cm telescope
  95. EP250404a: Nanshan/HMT optical counterpart detection
  96. EP250404a: Einstein Probe detection of an X-ray transient
  97. GRB 250403A: Swift/UVOT Detection
  98. GRB 250402A: Swift/UVOT Upper Limits
  99. EP250402a: Optical upper limit with Kinder observations
  100. GRB 250403A: REM NIR afterglow detection

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