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"
  1. GRB 240529A: Insight-HXMT/HE detection
  2. GRB 240529A: optical photometry from Konkoly
  3. GRB 240529A: GROWTH-India optical follow-up
  4. GRB 240529A: T193/MISTRAL observations
  5. GRB 240529A: Redshift from GTC/OSIRIS+
  6. GRB 240529A: AKO Optical Afterglow Detection
  7. LIGO/Virgo/KAGRA S240530a: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S240527fv: Upper limits from Swift/BAT-GUANO
  9. LIGO/Virgo/KAGRA S240525p: Upper limits from Swift/BAT-GUANO
  10. GRB 240529A: J-band detections with WINTER
  11. GRB 240529A: Skynet Optical Observations
  12. LXT 240528A: LEIA detection of a fast X-ray transient
  13. GRB 240529A: Swift-BAT refined analysis
  14. LIGO/Virgo S240527fv: GRANDMA/FRAM-Auger Optical Observations
  15. GRB 240529A: Swift-XRT refined Analysis
  16. GRB240529A: BOOTES-6/DPRT optical detection
  17. GRB 240529A: Swift/UVOT Detection
  18. GRB 240529A: NOT optical observations
  19. GRB 240529A: AstroSat CZTI detection
  20. GRB 240529A: GOTO optical afterglow detection
  21. GRB 240527B: Swift-XRT afterglow detection
  22. GRB 240529A: Enhanced Swift-XRT position
  23. GRB 240529A: Swift detection of a burst with an optical counterpart
  24. Swift GRB240529.12: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S240527fv: Updated Sky localization
  26. GRB 240527B: Fermi GBM Observation
  27. Fermi GRB 240527A: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S240527fv: Identification of a GW compact binary merger candidate
  29. GRB 240527B: Fermi-LAT detection
  30. LAT GRB240527.59: Global MASTER-Net observations report
  31. LIGO/Virgo/KAGRA S240527en: Identification of a GW compact binary merger candidate
  32. Fermi GRB 240527B: Global MASTER-Net observations report
  33. GRB 240527B: Fermi GBM Final Localization
  34. GRB 240527B: BALROG localization (Fermi Trigger 738511436 / GRB 240527586)
  35. GRB 240527A: Fermi GBM Final Real-time Localization
  36. GRB 240523A: Swift-BAT refined analysis
  37. Fermi trigger No 738348224: Global MASTER-Net observations report
  38. Fermi trigger No 738330463: Global MASTER-Net observations report
  39. LIGO/Virgo/KAGRA S240525p: Updated Sky localization
  40. LIGO/Virgo/KAGRA S240525p: Identification of a GW compact binary merger candidate
  41. GRB 240523A: Swift-XRT refined Analysis
  42. GRB 240523A: Enhanced Swift-XRT position
  43. GRB 240523A: Swift detection of a burst
  44. GRB 240521B: Fermi GBM Observation
  45. Fermi GBM Sub-Threshold Detection of GRB 240516B
  46. GRB 240513A: Swift-XRT afterglow detection
  47. GRB 240521B: Swift/BAT-GUANO arcminute localization of a long burst
  48. Fermi trigger No 737996942: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S240520cv: Updated Sky localization and EM Bright Classification
  50. EP240518a: GSP optical upper limit
  51. GRB 240521A: GECAM-B detection of a long burst
  52. GRB 240516B: AstroSat CZTI detection
  53. LIGO/Virgo/KAGRA S240515m: Upper limits from Swift/BAT-GUANO
  54. LIGO/Virgo/KAGRA S240514x: Upper limits from Swift/BAT-GUANO
  55. LIGO/Virgo/KAGRA S240513ei: Upper limits from Swift/BAT-GUANO
  56. LIGO/Virgo/KAGRA S240520cv: Identification of a GW compact binary merger candidate
  57. IceCube-Cascade 240518A: Upper limits from a search for additional neutrino events in IceCube
  58. GRB 240514B: VZLUSAT-2 detection
  59. GRB 240504A: VZLUSAT-2 detection
  60. GRB 240502A: VZLUSAT-2 detection
  61. GRB 240519A: GRBAlpha detection
  62. GRB 240516A: Swift/UVOT Upper Limits
  63. GRB 240519A: AstroSat CZTI detection
  64. Fermi trigger No 737788024: Global MASTER-Net observations report
  65. EP240518a: possibly identified with a flare star by EP-FXT
  66. GRB 240519A: BALROG localization (Fermi Trigger 737788024 / GRB 240519213)
  67. EP240518a: EP-WXT detection of a new X-ray transient
  68. LIGO/Virgo/KAGRA S240514c: Updated Sky localization
  69. GRB 240516A: Swift-BAT refined analysis
  70. Fermi GRB 240517A: Global MASTER-Net observations report
  71. GRB 240516A ATCA radio observations
  72. IPN triangulation of GRB 240514B (short)
  73. GRB 240513A: Swift ToO observations
  74. GRB 240517A: Fermi GBM Final Real-time Localization
  75. Konus-Wind detection of GRB 240513A
  76. GRB 240516A: AstroSat CZTI detection
  77. GRB 240516A: Swift-XRT refined Analysis
  78. GRB 240514E: A possible candidate BD-21 1074
  79. Fermi trigger No 737559855: Global MASTER-Net observations report
  80. GRB 240516A: Fermi GBM Observation
  81. GRB 240511A: Observations from GTC/OSIRIS+
  82. GRB 240502C: Zeiss-1000 at Koshka observations of GOTO24bao optical counterpart candidate
  83. GRB 240516A: GOTO optical upper limit
  84. LIGO/Virgo/KAGRA S240422ed: GRID non-detection and upper limits
  85. Fermi trigger No 737523389: Global MASTER-Net observations report
  86. GRB 240516A: Swift detection of a burst
  87. Swift GRB240516.15: Global MASTER-Net observations report
  88. GRB 240514B: AT2024ixa/GOTO24bph is not consistent with the Fermi localisation
  89. Fermi trigger No 737476171: Global MASTER-Net observations report
  90. GRB 240511A: radio detection of afterglow candidate
  91. GRB 240514B: GOTO candidate optical counterpart
  92. MAXI GRB240514.78: Global MASTER-Net observations report
  93. Fermi Gamma-ray Burst Monitor list of triggers that are not a GRB
  94. GRB 240514E: MAXI/GSC detection of a probable afterglow
  95. GRB 240514B: GRBAlpha detection
  96. LIGO/Virgo/KAGRA S240514x: Updated Sky localization
  97. LIGO/Virgo/KAGRA S240515m: Identification of a GW compact binary merger candidate
  98. GRB 240514B: Fermi GBM Detection
  99. LIGO/Virgo/KAGRA S240422ed: Las Cumbres Observatory Follow-up Observations of the Localization Region
  100. GRB 240513A: Fermi GBM observation

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