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"

36143 results found.

  1. GRB 251221A: Fermi GBM Final Real-time Localization
  2. GRB 251220B: Fermi GBM Final Real-time Localization
  3. GRB 251219A: SVOM/GRM observation of a short burst
  4. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  5. GRB 251220A: MAXI/GSC detection
  6. GRB 251215A: Swift-XRT afterglow detection
  7. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  8. GRB 251214B: VIRT Optical Upper Limit
  9. Fermi GRB 251217A: Global MASTER-Net observations report
  10. GRB 251217A: Fermi GBM Final Real-time Localization
  11. GRB 251215A: Swift/UVOT Upper LImits
  12. GRB 251215A: Fermi GBM Observation
  13. Fermi GRB 251216A: Global MASTER-Net observations report
  14. GRB 251202A/EP251202a: Koshka optical upper limit
  15. GRB 251214B: Mondy optical upper limit
  16. GRB 251215A: COLIBRÍ optical upper limit
  17. GRB 251216A: Fermi GBM Final Real-time Localization
  18. EP251214b: KAIT optical upper limit
  19. GRB 251215A: Swift-XRT observations
  20. Fermi GRB 251215A: Global MASTER-Net observations report
  21. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  22. GRB 251215A: Glowbug gamma-ray detection
  23. GRB 251214B: UAFO optical upper limit
  24. GRB 251214B: VLT/X-shooter observations
  25. GRB 251213A: GRID-10B observation
  26. GRB 251214B: Swift-BAT refined analysis
  27. GRB 251202A: radio detection with the VLA
  28. GRB 251214B: AbAO optical observations
  29. GRB 251214B: LCO detection of the optical counterpart
  30. GRB 251209A: GECAM-B observation of a long burst
  31. GRB 251214D: GECAM-B observation of a long burst
  32. GRB 251214B: Fermi GBM Observation
  33. GRB 251209A: Insight-HXMT/HE detection
  34. GRB 251215A: Swift ToO observations
  35. GRID detection of GRB 251213A
  36. GRB 251203B: AbAO optical observations
  37. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  38. GRB 251214B: GECAM-B observation of a long burst
  39. GRB 251214B: Swift-XRT refined Analysis
  40. GRB 251213A: SVOM/GRM observation
  41. EP251214a: KAIT optical upper limit
  42. GRB 251214D: AstroSat CZTI detection of a long burst
  43. GRB 251213A: AstroSat CZTI detection
  44. GRB 251214A: AstroSat CZTI detection
  45. GRB 251213A: GECAM-B detection
  46. GRB 251214B: Swift/UVOT Detection
  47. GRB 251215A: Fermi GBM Final Real-time Localization
  48. GRB 251214B: COLIBRÍ observations of the afterglow
  49. GRB 251214A: GECAM-B observation of a likely long burst
  50. GRB 251214B: 1.3m DFOT optical detection
  51. GRB 251214B: Enhanced Swift-XRT position
  52. GRB 251214B: Xinglong-2.16m optical observation
  53. GRB 251214C: Fermi GBM Final Localization
  54. GRB 251214B : MASTER optical afterglow detection
  55. GRB 251214B: SVOM/C-GFT optical observations
  56. EP251214a: COLIBRÍ optical upper limit
  57. Swift GRB 251214B: Global MASTER-Net observations report
  58. GRB 251214B: Swift detection of a burst with an optical counterpart
  59. GRB 251214B: Fermi GBM Final Real-time Localization
  60. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  61. Fermi GRB 251214A: Global MASTER-Net observations report
  62. GRB 251214A: Fermi GBM Final Real-time Localization
  63. EP251212a: KAIT optical upper limit
  64. EP251212a / GRB 251212A: AstroSat CZTI detection
  65. GRB 251211B: AstroSat CZTI detection
  66. GRB 251209A: NuSTAR detection of prompt emission
  67. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  68. Fermi GRB 251211B: Global MASTER-Net observations report
  69. GRB 251211B: Fermi GBM Final Real-time Localization
  70. GRB 251211A: Fermi GBM Final Real-time Localization
  71. GRB 251209A: Fermi GBM observation
  72. GRB 251205A: 1.3m DFOT optical upper limit
  73. GRB 251209A: AstroSat CZTI detection
  74. EP251124a: Mondy optical upper limit
  75. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  76. EP251130a: Mondy and AbAO optical observations
  77. GRB 251208A: AstroSat CZTI detection
  78. Fermi GBM Sub-Threshold Detection of GRB 251205A
  79. GRB 251208A: Glowbug gamma-ray detection
  80. GRB 251208B: COLIBRÍ optical upper limits
  81. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  82. GRB 251208C: GECAM-B observation of a short burst
  83. GRB 251208A: GECAM-B observation of a short burst
  84. Fermi GRB 251209A: Global MASTER-Net observations report
  85. Fermi GRB 251208C: Global MASTER-Net observations report
  86. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. GRB 251208B: Swift-XRT afterglow detection
  88. GRB 251208D: LAST optical upper limit
  89. GRB 251209A: Fermi GBM Final Real-time Localization
  90. GRB 251208D: LCO analysis of the XRT sources
  91. GRB 251208B: Fermi GBM Observation
  92. GRB 251208B: GROWTH-India Telescope optical upper limits
  93. GRB 251205A: J-band detection with WINTER
  94. GRB 251208D: Swift-XRT observations
  95. GRB 251208A: SVOM/GRM observation of a short burst
  96. GRB 251208C: SVOM/GRM observation of a short burst
  97. GRB 251129A: e-MERLIN C-band observations
  98. GRB 251205A: Liverpool Telescope further optical follow-up observations
  99. GRB 251208D: LCO optical upper limits
  100. GRB 251208B: Swift ToO observations

Advanced

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