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"

12172 results found.

  1. Fermi trigger No 772058337: Global MASTER-Net observations report
  2. Fermi Gamma-ray Burst Monitor trigger 772058337/250619860 is not a GRB
  3. GRB 250617B: Assy AZT-20 Optical Observations
  4. GRB 250615A/EP250615a: FTW optical and NIR observations
  5. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  6. GRB 250617B: COLIBRÍ optical observations
  7. GRB 250617B: Swift-XRT refined Analysis
  8. GRB 250617B: Swift detection of a burst with an optical counterpart
  9. EP#01709178975: Swift-XRT counterpart detection
  10. Konus-Wind detection of GRB 250615A / EP250615a
  11. GRB 250615A / EP250615a: AstroSat CZTI detection
  12. Konus-Wind detection of GRB 250612C (short/hard with extended emission)
  13. Fermi trigger No 771752663: Global MASTER-Net observations report
  14. sb25061218: Swift-XRT observations
  15. GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
  16. EP250612a / GRB 250612B: SVOM/VT optical candidate
  17. sb25061207: Swift-XRT observations
  18. GRB 250610B: Swift-XRT refined Analysis
  19. EP250612a: Einstein Probe detection of an X-ray transient
  20. GRB 250610B: MISTRAL/T193 and T120 OHP further observations
  21. sb25061207: SVOM detection of a X-ray transient
  22. Swift GRB250612.04: Global MASTER-Net observations report
  23. GRB 250610B: Swift-XRT counterpart detection
  24. GRB 250610B: SVOM/VT optical counterpart
  25. GRB 250610B: OHP/T120 optical counterpart candidate
  26. GRB 250610B: GOTO optical upper limit
  27. EP250610a: Global MASTER-Net observations report
  28. GRB 250610B: SVOM detection of a long burst
  29. EP250610a: Swift-XRT counterpart detection
  30. EP250610a: Einstein Probe detection of an X-ray transient
  31. Fermi trigger No 771072240: Global MASTER-Net observations report
  32. GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
  33. GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
  34. GRB 250605A: Swift-XRT refined Analysis
  35. Fermi GRB 250606A: Global MASTER-Net observations report
  36. Fermi trigger No 770867684: Global MASTER-Net observations report
  37. GRB 250605A: LT optical observations
  38. Konus-Wind detection of GRB 250601A
  39. Fermi Gamma-ray Burst Monitor trigger 770675211/250603852 is not a GRB
  40. Swift GRB250603.05: Global MASTER-Net observations report
  41. GRB 250602A: Fermi-LAT detection
  42. GRB 250530A: VLT/HAWK-I NIR counterpart fading
  43. Fermi GRB 250531A: Global MASTER-Net observations report
  44. EP#01709177494: Swift-XRT counterpart detection of known source
  45. GRB 250530C: Swift-XRT refined Analysis
  46. GRB 250530C: Swift detection of a burst
  47. GRB 250530A: Swift-XRT counterpart detection
  48. GRB 250527D: Swift/BAT-GUANO localization skymap of a burst
  49. EP J1350.0-8622: EP-FXT follow-up observation
  50. Fermi trigger No 770058372: Global MASTER-Net observations report
  51. GRB 250527B / MAXI J1450-527 : MAXI/GSC detection
  52. EP250526a: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 250314A: CIDER NB1008 upper limit
  54. EP J1350.0-8622: Einstein Probe detection of an X-ray transient candidate
  55. Fermi GRB 250523A: Global MASTER-Net observations report
  56. Fermi trigger No 769611916: Global MASTER-Net observations report
  57. EP-WXT trigger 01709176712: GOTO observations confirm stellar counterpart variability
  58. GRB 250520A: GRBAlpha detection
  59. EP#01709176612: Swift-XRT counterpart detection of flaring star
  60. Fermi trigger No 769533898: Global MASTER-Net observations report
  61. GRB 250521D: LAST tentative optical counterpart candidate
  62. GRB 250520A: CALET Gamma-Ray Burst Monitor detection
  63. Konus-Wind detection of GRB 250520A (short/hard)
  64. Konus-Wind detection of GRB 250516B
  65. GRB 250520A: Gemini-South optical observations
  66. GRB 250520A: REM optical/NIR early observations
  67. GRB 250520B: Fermi GBM Final Real-time Localization
  68. GRB 250520A: COLIBRÍ optical upper limit
  69. GRB 250520A: DDOTI Optical Upper Limit
  70. GRB 250520A: AstroSat CZTI detection of a short burst
  71. GRB 250520A: GOTO optical upper limit
  72. Swift GRB 250520A: Global MASTER-Net observations report
  73. GRB 250516A: Swift-BAT refined analysis
  74. GRB 250516A: COLIBRÍ optical upper limit
  75. Konus-Wind detection of GRB 250516A
  76. Fermi GRB 250516A: Global MASTER-Net observations report
  77. GRB 250515A/GOTO25cqo: SVOM/VT optical blue color
  78. GRB 250516A: Swift-XRT refined Analysis
  79. GRB 250516A: Swift detection of a burst
  80. GRB 250512B / EP250512a: SVOM/GRM analysis
  81. GRB 250515A: GOTO candidate optical counterpart
  82. GRB 250515A: Fermi GBM Final Localization
  83. Konus-Wind detection of GRB 250512B / EP250512a
  84. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Final Epochs)
  85. Konus-Wind detection of GRB 250506A
  86. GRB 250507B: AstroSat CZTI detection
  87. EP250512a/GRB 250512B refined analysis of the EP-WXT and EP-FXT observations
  88. EP250512a: Global MASTER-Net observations report
  89. GRB 250512B/EP250512a：SVOM/VT bright optical counterpart
  90. GRB 250512B: SVOM detection of a burst
  91. EP250512a: Einstein Probe detection of an X-ray transient
  92. EP250511a: Einstein Probe follow-up obsevation and refined analysis
  93. EP250511a: Global MASTER-Net observations report
  94. EP250511a: Einstein Probe detection of an X-ray transient
  95. Fermi GRB 250510C: Global MASTER-Net observations report
  96. GRB 250510B: Swift/BAT-GUANO localization skymap of a burst
  97. GRB 250510A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  98. GRB 250509A: Swift-XRT refined Analysis
  99. GRB 250510A: SVOM possible detection of a burst
  100. Fermi GRB 250509A: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov