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"

25666 results found.

  1. GRB 251201B: SALT spectroscopic redshift z = 1.599
  2. GRB 251203C: J-band observations with WINTER
  3. GRB 251129B: Glowbug gamma-ray detection of a short burst
  4. Fermi Gamma-ray Burst Monitor trigger 786496343/251203967 is not a GRB
  5. GRB 251203C: LCO optical afterglow confirmation
  6. GRB 251203C: SVOM/VT optical counterpart
  7. GRB 251203C: EP-FXT follow-up observation
  8. GRB 251203B: Swift-XRT observations
  9. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  10. GRB 251203B : SVOM trigger sb25120304 is not a GRB
  11. GRB 251203C: LCO optical upper limits
  12. GRB 251203B: LCO optical upper limits
  13. GRB 251203B: SVOM/VT optical observation
  14. GRB 251202A / EP251202a: Liverpool Telescope optical follow-up observations
  15. GRB 251203C: SVOM detection of a burst
  16. SVOM GRB251203.77: Global MASTER-Net observations report
  17. SVOM GRB251203B: Global MASTER-Net observations report
  18. GRB 251203B: SVOM detection of a burst
  19. GRB 251203A: Fermi GBM Final Real-time Localization
  20. GRB 251202A / EP251202a: SVOM/VT optical observation
  21. GRB 251201B: Fermi GBM Observation
  22. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  23. Fermi GRB 251202B: Global MASTER-Net observations report
  24. GRB 251202B: Fermi GBM Final Real-time Localization
  25. IPN triangulation of GRB 251129B (short/hard)
  26. GRB251129A/EP251129a: Swift UVOT detection
  27. GRB 251202A: Fermi GBM Observation
  28. GRB 251202A: Swift/UVOT Detection
  29. GRB 251201B: Kilonova-Catcher optical afterglow detection
  30. GRB 251201B: Swift/UVOT Detection
  31. GRB 251130B: Glowbug gamma-ray detection
  32. EP251130a: continued NOT optical observations indicate steep fading phase
  33. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  34. GRB 251202A: GOTO optical afterglow detection
  35. GRB 251126A: SVOM/VT optical observation
  36. EP251130a: SVOM/VT optical observation
  37. EP251202a / GRB 251202A: NOT spectroscopic redshift z = 2.785
  38. Fermi GRB 251202A: Global MASTER-Net observations report
  39. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  40. GRB 251201B: Swift-XRT refined Analysis
  41. EP251202a/trigger 01709249064: Las Cumbres discovery of the optical counterpart
  42. GRB 251202A: Fermi GBM Final Real-time Localization
  43. GRB 251201A: SVOM/GRM observation of a burst
  44. GRB 251201B: SVOM/VT optical fading
  45. Swift GRB 251201B : MASTER optical counterpart detection
  46. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  47. Swift GRB 251201B: Global MASTER-Net observations report
  48. GRB 251201B: Swift detection of a burst with an optical counterpart
  49. GRB 251201B: Fermi GBM Final Real-time Localization
  50. EP251130a: Optical detections with Kinder observations
  51. SVOM GRB251201.19: Global MASTER-Net observations report
  52. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  53. EP251130A: Optical observation from 1.3m DFOT
  54. Fermi GRB 251130B: Global MASTER-Net observations report
  55. IceCube Alert 251130.75: Global MASTER-Net observations report
  56. EP251130a: Swift-XRT counterpart detection
  57. GRB 251130B: Fermi GBM Final Localization Correction
  58. EP251130a: Global MASTER-Net observations report
  59. GRB 251130B: Fermi GBM Final Real-time Localization
  60. EP251130a: COLIBRÍ optical counterpart candidate
  61. GRB 251130A: Fermi GBM Final Real-time Localization
  62. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  63. GRB 251128A: AstroSat CZTI detection
  64. SVOM GRB 251129A : MASTER optical counterpart detection
  65. The EP-WXT trigger 01709248941 is triggered by the known source Perseus Cluster
  66. Swift trigger 1418333 is not an astrophysical source
  67. GRB 251129A / EP251129a: SVOM/VT optical fading
  68. EP251129a: Global MASTER-Net observations report
  69. GRB 251129A: SVOM/VT optical counterpart confirmation with VHF data
  70. GRB 251128A: Fermi GBM Observation
  71. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  72. GRB 251129A: SVOM detection of a burst
  73. SVOM GRB251129A: Global MASTER-Net observations report
  74. GRB 251129A: SVOM detection of a burst
  75. GRB 251126A: Swift-BAT refined analysis
  76. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  77. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  78. Fermi GRB 251128A: Global MASTER-Net observations report
  79. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  80. GRB 251126A NUTTelA-TAO Early Measurements
  81. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  82. GRB251126A: MAO/AZT-22 optical observations
  83. GRB 251128A: Fermi GBM Final Real-time Localization
  84. GRB251126A: Continued optical observation from 1.3m DFOT
  85. GRB 251126A: Swift/UVOT Detection
  86. GRB 251126A: Mondy and SAO RAS optical observations
  87. GRB 251126A: Swift-XRT refined Analysis
  88. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  89. GRB 251126A: NOT optical observations
  90. GRB 251126A: 1.3m DFOT optical afterglow detection
  91. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  92. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  93. Fermi GRB 251127A: Global MASTER-Net observations report
  94. GRB 251127A: Fermi GBM Final Real-time Localization
  95. GRB 251126A: Asiago i-band detection
  96. GRB 251126A: Nanshan/HMT optical afterglow detection
  97. Swift GRB 251126A: Global MASTER-Net observations report
  98. GRB 251121A: Fermi GBM Observation
  99. GRB 251126A: GIT discovery of the likely optical afterglow
  100. GRB 251126A: Swift detection of a burst

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