Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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 251203B: AbAO optical observations
  2. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  3. GRB 251214B: GECAM-B observation of a long burst
  4. GRB 251214B: Swift-XRT refined Analysis
  5. GRB 251213A: SVOM/GRM observation
  6. EP251214a: KAIT optical upper limit
  7. GRB 251214D: AstroSat CZTI detection of a long burst
  8. GRB 251213A: AstroSat CZTI detection
  9. GRB 251214A: AstroSat CZTI detection
  10. GRB 251213A: GECAM-B detection
  11. GRB 251214B: Swift/UVOT Detection
  12. GRB 251215A: Fermi GBM Final Real-time Localization
  13. GRB 251214B: COLIBRÍ observations of the afterglow
  14. EP251214a: EP-FXT non-detection and upper limit
  15. GRB 251214A: GECAM-B observation of a likely long burst
  16. GRB 251214B: 1.3m DFOT optical detection
  17. EP251214a: Global MASTER-Net observations report
  18. GRB 251214B: Enhanced Swift-XRT position
  19. GRB 251214B: Xinglong-2.16m optical observation
  20. GRB 251214C: Fermi GBM Final Localization
  21. GRB 251214B : MASTER optical afterglow detection
  22. Fermi trigger No 787396657: Global MASTER-Net observations report
  23. GRB 251214B: SVOM/C-GFT optical observations
  24. EP251214a: COLIBRÍ optical upper limit
  25. Swift GRB 251214B: Global MASTER-Net observations report
  26. EP251214.305: COLIBRÍ optical upper limit
  27. GRB 251214B: Swift detection of a burst with an optical counterpart
  28. GRB 251214B: Fermi GBM Final Real-time Localization
  29. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  30. Fermi GRB 251214A: Global MASTER-Net observations report
  31. GRB 251214A: Fermi GBM Final Real-time Localization
  32. EP251212a: Global MASTER-Net observations report
  33. EP251212a: KAIT optical upper limit
  34. EP251212a / GRB 251212A: AstroSat CZTI detection
  35. EP251212a: EP-FXT follow-up observation
  36. GRB 251211B: AstroSat CZTI detection
  37. IceCube-251210A: No Candidate Transients from the Zwicky Transient Facility
  38. GRB 251209A: NuSTAR detection of prompt emission
  39. EP251212a : COLIBRÍ optical upper limit
  40. EP251212a: Einstein Probe detection of an X-ray transient
  41. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  42. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  43. Fermi GRB 251211B: Global MASTER-Net observations report
  44. GRB 251211B: Fermi GBM Final Real-time Localization
  45. IceCube-251210A: DDOTI Optical Upper Limit
  46. SVOM GRB251211.12: Global MASTER-Net observations report
  47. GRB 251211A: Fermi GBM Final Real-time Localization
  48. GRB 251209A: Fermi GBM observation
  49. GRB 251205A: 1.3m DFOT optical upper limit
  50. GRB 251209A: AstroSat CZTI detection
  51. IceCube Alert 251210.46: Global MASTER-Net observations report
  52. IceCube-251210A - IceCube observation of a high-energy neutrino candidate track-like event
  53. EP251124a: Mondy optical upper limit
  54. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  55. EP251130a: Mondy and AbAO optical observations
  56. GRB 251208A: AstroSat CZTI detection
  57. Fermi GBM Sub-Threshold Detection of GRB 251205A
  58. GRB 251208A: Glowbug gamma-ray detection
  59. GRB 251208B: COLIBRÍ optical upper limits
  60. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  61. GRB 251208C: GECAM-B observation of a short burst
  62. GRB 251208A: GECAM-B observation of a short burst
  63. Fermi GRB 251209A: Global MASTER-Net observations report
  64. Fermi GRB 251208C: Global MASTER-Net observations report
  65. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  66. GRB 251208B: Swift-XRT afterglow detection
  67. GRB 251208D: LAST optical upper limit
  68. GRB 251209A: Fermi GBM Final Real-time Localization
  69. GRB 251208D: LCO analysis of the XRT sources
  70. GRB 251208B: Fermi GBM Observation
  71. GRB 251208B: GROWTH-India Telescope optical upper limits
  72. GRB 251205A: J-band detection with WINTER
  73. GRB 251208D: Swift-XRT observations
  74. GRB 251208A: SVOM/GRM observation of a short burst
  75. GRB 251208C: SVOM/GRM observation of a short burst
  76. GRB 251129A: e-MERLIN C-band observations
  77. LAT GRB251208.43: Global MASTER-Net observations report
  78. GRB 251205A: Liverpool Telescope further optical follow-up observations
  79. GRB 251208D: LCO optical upper limits
  80. SVOM GRB251208D: Global MASTER-Net observations report
  81. GRB 251208B: Swift ToO observations
  82. GRB 251208B: Fermi-LAT detection
  83. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  84. GRB 251208D: SVOM possible detection of a faint burst
  85. GRB 251206A: SVOM detection of a burst through offline search
  86. GRB 251208C: Fermi GBM Final Real-time Localization
  87. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  88. GRB 251208B: Fermi GBM Final Real-time Localization
  89. GRB 251208A: Fermi GBM Final Real-time Localization
  90. GRB 251205A: FTW optical and NIR observations
  91. EP-WXT trigger 01709249380: KAIT confirmation of a stellar flare
  92. GRB 251205A: Liverpool Telescope further optical follow-up observations
  93. SVOM GRB251206.86: Global MASTER-Net observations report
  94. EP-WXT trigger 01709249380: confirmation of a stellar flare by BOOTES-5
  95. The EP-WXT trigger 01709249380 is likely a flaring star
  96. GRB 251205A: ZTF and ATLAS optical afterglow detections
  97. GRB 251205A: GROWTH-India Telescope optical observations
  98. GRB 251205A: Swift-BAT refined analysis
  99. GRB 251205A: Swift-XRT refined Analysis
  100. GRB 251205A: Swift/UVOT Detection

Advanced

Download all Circulars as a .tar.gz archive:
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