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"

24375 results found.

  1. EP250427a / GRB 250427A: OHP/T193 photometric observations: third visit
  2. GRB 250430A: Leavitt Observatory optical upper limit
  3. GRB 250430A : MITSuME Akeno optical upper limits
  4. GRB 250430A / EP250430a: VLT/X-shooter spectroscopic redshift z = 0.767
  5. EP250430a/GRB 250430A: Einstein Probe WXT detection of the X-ray prompt emission
  6. IceCube-250429A: Upper limits from a search for additional neutrino events in IceCube
  7. IceCube-250426A: Upper limits from a search for additional neutrino events in IceCube
  8. Swift GRB250430.73: Global MASTER-Net observations report
  9. EP250428b: FTW optical and NIR observations
  10. SVOM/sb25043004: SVOM detection of a X-ray transient
  11. Fermi trigger No 767623859: Global MASTER-Net observations report
  12. EP250428b: refined analysis of the EP-FXT follow-up observation
  13. EP250428b: SVOM/VT upper limit
  14. IceCube-250429A - IceCube observation of a high-energy neutrino candidate track-like event
  15. EP250428b: Global MASTER-Net observations report
  16. Fermi-LAT Gamma-ray Observations of IceCube-250426A
  17. EP250427a: EP-FXT follow-up observations
  18. EP250427a: LT optical counterpart detection
  19. EP250427a / GRB 250427A: LCO optical counterpart detection
  20. EP250427a / GRB 250427A: VLT/X-shooter redshift confirmation z = 1.520
  21. EP250427A/GRB250427A: Keck/LRIS redshift
  22. EP250427a: REM optical/NIR afterglow detection
  23. GRB 250427A/ EP250427a: Fermi-GBM Sub-Threshold Detection
  24. EP250427a: Global MASTER-Net observations report
  25. EP250427a: Einstein Probe detection of a fast X-ray transient
  26. IceCube Alert 250426.74: Global MASTER-Net observations report
  27. GRB 250424A: Swift-BAT refined analysis
  28. IceCube-250426A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 250424A: SVOM/GRM observation of a long burst
  30. GRB 250424A: EIRSAT-1 GMOD Detection
  31. IceCube-250416A: Upper limits from a search for additional neutrino events in IceCube
  32. IceCube-250421A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250424A: SVOM/VT optical observation
  34. Konus-Wind detection of GRB 250424A
  35. Fermi-LAT gamma-ray observations of IceCube-250421A
  36. GRB 250419A: Liverpool Telescope optical upper limit
  37. GRB 250407A: GRBAlpha detection
  38. GRB 250404A / EP250404a: GRBAlpha detection
  39. GRB 250330B: GRBAlpha detection
  40. GRB 250419A: SVOM/ECLAIRs refined analysis
  41. GRB 250424A: BlackGEM optical afterglow detection
  42. GRB 250424A: VLT/X-shooter spectroscopic redshift z = 0.310
  43. GRB 250424A: REM optical/NIR afterglow detection
  44. Swift GRB 250424A: Global MASTER-Net observations report
  45. Swift GRB 250424A: Global MASTER-Net OT detection
  46. LIGO/Virgo/KAGRA S250328ae: Subaru/PFS Spectroscopic Follow up and Candidates
  47. EP250421a: Nickel optical upper limit
  48. EP250421a: Upper limits from Fermi-GBM Observations
  49. SVOM/sb25042207: BOOTES-2 early optical upper limit
  50. SVOM/sb25042207: GOTO optical upper limits
  51. SVOM/sb25042207: SVOM detection of an X-ray transient
  52. GRB 250419A: Mephisto Multi-band Optical Detection
  53. GRB 250419A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations.
  54. IC-250421A: LAST optical observations of the IceCube neutrino candidate
  55. GRB 250419A: Optical Observations via Virtual Telescope Project
  56. EP250421a: REM optical upper limit
  57. Fermi GRB 250421A: Global MASTER-Net observations report
  58. EP250421a: Global MASTER-Net observations report
  59. EP250421a: Mephisto optical counterpart confirmation
  60. IceCube Alert 250421.71: Global MASTER-Net observations report
  61. IceCube-250421A - IceCube observation of a high-energy neutrino candidate track-like event
  62. IceCube-Cascade 250414A: Upper limits from a search for additional neutrino events in IceCube
  63. The EP-WXT trigger 01709135179: Kinder optical counterpart candidate
  64. GRB 250421A: Fermi GBM Final Real-time Localization
  65. GRB 250419A: SVOM/VT optical continuous observations
  66. GRB 250416C / EP250416a: SVOM/GRM observation of a burst
  67. GRB 250419A: LCO optical afterglow multi-band observations
  68. GRB 250419A: MASTER optical afterglow observation
  69. Fermi-LAT Gamma-ray Observations of IceCube-250416A
  70. GRB 250407A: rest-frame energetics from Konus-Wind observation
  71. GRB 250419A: GOTO optical counterpart detection
  72. GRB 250419A: SVOM/VT optical bright counterpart confirmation
  73. GRB 250419A: SVOM detection of a soft burst
  74. Konus-Wind detection of GRB 250416C (a counterpart of EP250416a)
  75. EP250416a: refined EP-WXT and EP-FXT analysis
  76. Konus-Wind detection of GRB 250403A
  77. EP250416a: Gemini South-GMOS optical counterpart
  78. EP250225a: SVOM/VT optical brightening
  79. SVOM/sb25041603 is not a GRB
  80. EP250416a: Global MASTER-Net observations report
  81. IceCube-250416A - IceCube observation of a high-energy neutrino candidate track-like event
  82. IceCube-250416A: Global MASTER-Net observations report
  83. GRB 250416B: Fermi GBM Final Real-time Localization
  84. GRB 250416A: Fermi GBM Final Real-time Localization
  85. SVOM/sb25041603: SVOM detection of an X-ray transient
  86. GRB 250413A: AstroSat CZTI detection
  87. EP250404a: Nanshan 0.43m Telescope optical observatios
  88. Fermi trigger No 766148493: Global MASTER-Net observations report
  89. Fermi trigger No 766173972: Global MASTER-Net observations report
  90. Fermi GRB 250411A: Global MASTER-Net observations report
  91. GRB 250411A: Fermi GBM Final Real-time Localization
  92. EP250227a: Further NOT optical observations
  93. GRB 250320B: cubesat Avion detection
  94. IPN triangulation of GRB 250321D (consistent with the fast X-ray transient EP250321a)
  95. AMON Coincidence Alert from the sub-threshold IceCube-HAWC search NuEm-250409A
  96. IPN triangulation of GRB 250407A
  97. EP250407a: Global MASTER-Net observations report
  98. GRB 250407A: LCO detection of a fading optical counterpart
  99. Fermi-LAT gamma-ray observations of IceCube-250406A
  100. IceCube-250406A: Upper limits from a search for additional neutrino events in IceCube

Advanced

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