Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

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"

20362 results found.

  1. GRB 250419A: SVOM detection of a soft burst
  2. EP250416a: refined EP-WXT and EP-FXT analysis
  3. EP20250416a: Swift/XRT counterpart detection
  4. GRB 250403A: VLT/FORS2 spectroscopic redshift z = 1.847
  5. IceCube-250416A: DDOTI Optical Observations
  6. EP250416a: Gemini South-GMOS optical counterpart
  7. SVOM/sb25041603 is not a GRB
  8. EP250416a: Einstein Probe detection of an X-ray transient
  9. SVOM/sb25041603: SVOM/COLIBRÍ (FM-GFT) Upper Limit on the Optical Counterpart
  10. IceCube 250414.324: DDOTI Optical Observations
  11. GRB 250413A: AstroSat CZTI detection
  12. GRB 250412A: AstroSat CZTI detection
  13. EP250404a: Nanshan 0.43m Telescope optical observatios
  14. GRB 250411A: DDOTI Optical Observations
  15. GRB 250314A: e-MERLIN observations
  16. GRB 250407A: Mondy and AbAO Optical Observations
  17. EP250227a: Further NOT optical observations
  18. IceCube-250406A: Swift-XRT observations
  19. GRB 250407A: LCO detection of a fading optical counterpart
  20. Fermi-LAT gamma-ray observations of IceCube-250406A
  21. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube
  22. Konus-Wind detection of GRB 250407A
  23. GRB 250407A: SVOM/GRM observation of a bright long burst
  24. GRB 250407A: EP-WXT afterglow detection
  25. EP250407a: EP-WXT detection of a fast X-ray transient
  26. GRB 250407A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  27. GRB 250407A: KAIT Optical Afterglow Candidate
  28. IceCube-250406A: No candidates from the Zwicky Transient Facility
  29. GRB 250407A: Swift-XRT afterglow detection
  30. GRB 250407A: SRG/ART-XC afterglow detection
  31. IceCube 250406A: DDOTI Optical Observations of the Refined Position
  32. IPN triangulation of GRB 250406B (short/hard)
  33. IceCube 250406.951: COLIBRÍ/DDRAGO Optical Upper Limit
  34. IceCube 250406.951: DDOTI Optical Observations
  35. GRB 250406A: AstroSat CZTI detection
  36. EP250404a: Multi-band Optical Observations from UCAS-70 and XL-C14
  37. GRB 250404A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  38. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  39. GRB 250404A / EP250404a: SVOM/GWAC-F60 and F50 observations
  40. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  41. Konus-Wind detection of GRB 250404A / EP250404a
  42. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  43. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  44. GRB 250402A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  45. EP250402a: Optical upper limit with PD 1.3m observations
  46. GRB 250404A / EP250404a: NOT optical observations
  47. GRB 250331D: Swift-XRT afterglow detection
  48. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  49. EP250404a: REM optical/NIR observations
  50. EP250404a: Seimei/TriCCS optical counterpart detection
  51. EP250404A: COLIBRÍ/DDRAGO Optical Observations
  52. EP250404A / GRB250404A: Ondrejov D50 optical afterglow detection
  53. EP250404a: LCO optical counterpart detection
  54. EP250404a: Xinglong decaying optical counterpart
  55. GRB 250403A: Montarrenti Observatory optical detection
  56. GRB 250403A: KAIT optical observations
  57. EP250404a: AKO Optical Afterglow Detection
  58. EP250404a: LAST detection of optical counterpart
  59. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  60. GRB 250327B: VIRT Optical Upper Limit
  61. EP250404a: Mephisto multi-band optical detection
  62. EP250321A: J band upper limit by SYSU 80cm telescope
  63. EP250404a: BOOTES-4/JGT optical afterglow detection
  64. EP250404a: Nanshan/HMT optical counterpart detection
  65. EP250404a: Einstein Probe detection of an X-ray transient
  66. GRB 250404A: Fermi GBM Final Real-time Localization
  67. GRB 250403A: Swift/UVOT Detection
  68. GRB 250402A: Swift/UVOT Upper Limits
  69. EP250402a: Optical upper limit with Kinder observations
  70. GRB 250403A: REM NIR afterglow detection
  71. GRB 250403A: LCO optical counterpart detection
  72. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  73. GRB 250403A: JinShan optical observations
  74. GRB 250403A: Optical counterpart detection by LCO.
  75. GRB 250322A: 10 GHz VLA radio upper limits
  76. GRB 250402A: NUTTelA-TAO Early Optical Limits
  77. GRB 250403A: GMG Optical Observation
  78. GRB 250403A: 1.6m Mephisto multi-band optical detection
  79. GRB 250403A: SVOM/C-GFT optical observations
  80. GRB250402A: SVOM/COLIBRÍ (FM-GFT) Detection of the Optical Counterpart
  81. GRB 250402A: REM optical/NIR upper limits
  82. GRB 250402A: LCO optical counterpart detection
  83. EP250402a: Einstein Probe detection of a fast X-ray transient
  84. GRB 250402A: SVOM/VT optical counterpart
  85. GRB 250402A: SVOM detection of a burst
  86. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  87. GRB 250329B: Swift/UVOT Upper Limit
  88. GRB 250329A: Swift/UVOT Upper Limit
  89. GRB 250327B: Swift/UVOT Detection
  90. GRB 250327A: Swift/UVOT Upper Limits
  91. GRB 250331E: SVOM/GRM observation
  92. GRB 250327B: Kilonova-Catcher Observations
  93. GRB250331D: AbAO optical observations
  94. GRB 250331C: Swift/UVOT Upper Limits
  95. GRB 250331B: Swift/UVOT Upper Limits
  96. GRB 250328A: AbAO AS-32 Optical Observations
  97. GRB 250219A: NOT candidate host galaxy detection
  98. GRB 250331D: Swift-XRT observations
  99. GRB 250331B: Swift-XRT refined Analysis
  100. GRB 250331B: Swift-XRT refined Analysis

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov