Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

27918 results found.

  1. GRB 250806A: SVOM/MXT refined analysis
  2. GRB 250806A: SVOM/ECLAIRs refined analysis
  3. GRB 250804B: Insight-HXMT detection
  4. GRB 250807A: SVOM/GRM observation
  5. Swift GRB250807.45: Global MASTER-Net observations report
  6. GRB 250807A: AstroSat CZTI detection of bright long burst
  7. GRB 250807B: Swift-XRT refined Analysis
  8. GRB 250807B: NTT optical observations
  9. EP250807a: EP-WXT detection of a fast X-ray transient
  10. GRB 250807A: SVOM/VT optical observation
  11. GRB 250807B: Enhanced Swift-XRT position
  12. Swift GRB250807.65: Global MASTER-Net observations report
  13. GRB 250807A: Enhanced Swift-XRT position
  14. GRB 250807B: Swift detection of a burst with an optical counterpart.
  15. GRB 250805A: Kilonova-Catcher optical upper limits
  16. GRB 250805A: Swift/UVOT Upper Limits
  17. GRB 250806A: Swift/UVOT U-band detection
  18. GRB 250807A: Swift detection of a burst with an optical counterpart
  19. GRB 250806A: EP-FXT observation
  20. EP#01709198415/EP250806a: Swift-XRT observations
  21. EP250802a: EP-FXT follow-up observation
  22. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  23. GRB 250805A: Swift-BAT refined analysis
  24. GRB 250806A: KAIT optical upper limit
  25. GRB 250806A: SVOM/VT refined analysis
  26. GRB 250806A: Swift-XRT counterpart detection
  27. EP250806a: Einstein Probe detection of an X-ray transient
  28. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 250806A: SVOM detection of a soft burst
  30. GRB 250805A: SVOM/VT optical counterpart
  31. GRB 250805A: ESO/VLT observations
  32. GRB 250805A: Swift-XRT refined Analysis
  33. GRB 250804B: Swift-XRT observations
  34. GRB 250805A: Enhanced Swift-XRT position
  35. GRB 250804C: AstroSat CZTI detection of a long burst
  36. GRB 250805A: TRT optical upper limits
  37. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  38. GRB 250805A: Swift-XRT observations
  39. GRB 250805A: Swift detection of a burst
  40. Swift GRB250805.26: Global MASTER-Net observations report
  41. GRB 250804B: Tiled Swift observations
  42. GRB 250804A: Fermi GBM Final Localization
  43. EP250802a: additional Liverpool Telescope upper limits
  44. EP250802a: Einstein Probe detection of an X-ray transient
  45. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  46. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  47. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  48. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  49. EP250730a: Einstein Probe detection of an X-ray transient
  50. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT follow up of AT 2025smm
  51. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  52. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  55. GRB 250725A: AstroSat CZTI detection
  56. GRB 250727A: EP-FXT follow-up observation
  57. GRB 250725A: PRIME near-infrared observations
  58. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  59. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  60. GRB: Clarification on Gamma-Ray Burst Naming Convention
  61. GRB 250728A: Swift-XRT observations
  62. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  63. GRB 250728A: COLIBRÍ optical upper limit
  64. GRB 250728A: Fermi GBM Observation
  65. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  66. GRB 250728A: Swift ToO observations
  67. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  68. GRB 250727A: AST3-2 Upper limit
  69. GRB 250727A: EP-FXT counterpart detection
  70. GRB250727A: SVOM/VT optical upper limit
  71. GRB 250727A: Swift-XRT observations
  72. GRB 250727A: SVOM detection of a burst
  73. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  74. GRB 250725A: Swift-XRT refined Analysis
  75. GRB 250725A: Fermi GBM Observation
  76. GRB 250725A: Swift-BAT refined analysis
  77. Konus-Wind detection of GRB 250725A
  78. GRB 250725A: SVOM/GRM observation
  79. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  80. GRB 250725A: Swift/UVOT Upper Limits
  81. GRB 250725A: Fermi-LAT detection
  82. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  83. GRB 250725A: BOOTES-7 early optical detection
  84. GRB 250725A: SVOM/VT optical candidate
  85. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  86. GRB 250725A: Enhanced Swift-XRT position
  87. GRB 250725A: Swift detection of a burst
  88. Swift GRB 250725A: Global MASTER-Net OT detection
  89. GRB 250725A: Fermi GBM Final Real-time Localization
  90. Swift GRB 250725A: Global MASTER-Net observations report
  91. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  92. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  93. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  94. GRB 250723B: Fermi GBM Final Real-time Localization
  95. GRB 250723A: Fermi GBM Final Real-time Localization
  96. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  97. Swift-BAT trigger 1334535 is not a GRB
  98. GRB 250721A: Swift-XRT observations
  99. GRB 250722A: Fermi GBM Final Real-time Localization
  100. GRB 250717B: SVOM/GRM observation

Advanced

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