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"

28082 results found.

  1. EP 251220a: GOTO optical counterpart detection
  2. GRB 251221A: COLIBRÍ detection of the optical counterpart
  3. EP 251220a: COLIBRÍ detection of the optical counterpart
  4. GRB 251221A: Swift detection of a burst
  5. Swift GRB251221A: Global MASTER-Net observations report
  6. EP251220a: Global MASTER-Net observations report
  7. EP251220a: EP detection of a fast X-ray transient
  8. SVOM GRB251220.98: Global MASTER-Net observations report
  9. GRB 251219A: SVOM/GRM observation of a short burst
  10. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  11. Fermi-LAT Gamma-ray Observations of IceCube-251218A
  12. GRB 251220A: MAXI/GSC detection
  13. GRB 251215A: Swift-XRT afterglow detection
  14. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  15. IceCube-251218A: COLIBRÍ optical upper limits
  16. SVOM GRB251219.11: Global MASTER-Net observations report
  17. IceCube Alert 251218.85: Global MASTER-Net observations report
  18. GRB 251214B: VIRT Optical Upper Limit
  19. Fermi trigger No 787736968: Global MASTER-Net observations report
  20. Fermi GRB 251217A: Global MASTER-Net observations report
  21. GRB 251215A: Swift/UVOT Upper LImits
  22. GRB 251215A: Fermi GBM Observation
  23. Fermi GRB 251216A: Global MASTER-Net observations report
  24. GRB 251202A/EP251202a: Koshka optical upper limit
  25. GRB 251214B: Mondy optical upper limit
  26. GRB 251215A: COLIBRÍ optical upper limit
  27. EP251214b: KAIT optical upper limit
  28. GRB 251215A: Swift-XRT observations
  29. Fermi GRB 251215A: Global MASTER-Net observations report
  30. EP251214a: Optical upper limit with Kinder observations
  31. GRB 251214B: 1.6m Mephisto observations with newly installed mosaic cameras
  32. GRB 251215A: Glowbug gamma-ray detection
  33. GRB 251214B: UAFO optical upper limit
  34. GRB 251214B: VLT/X-shooter observations
  35. GRB 251214B: Swift-BAT refined analysis
  36. GRB 251202A: radio detection with the VLA
  37. EP251214b: Global MASTER-Net observations report
  38. EP251214b : Einstein Probe detection of a fast X-ray transient
  39. EP251214b : Einstein Probe detection of a fast X-ray transient
  40. GRB 251214B: AbAO optical observations
  41. GRB 251214B: LCO detection of the optical counterpart
  42. GRB 251214B: Fermi GBM Observation
  43. EP251214b (EP trigger 01709250023): LCO optical limits
  44. GRB 251203B: AbAO optical observations
  45. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  46. GRB 251214B: Swift-XRT refined Analysis
  47. GRB 251213A: SVOM/GRM observation
  48. EP251214a: KAIT optical upper limit
  49. GRB 251213A: AstroSat CZTI detection
  50. GRB 251214A: AstroSat CZTI detection
  51. GRB 251213A: GECAM-B detection
  52. GRB 251214B: Swift/UVOT Detection
  53. GRB 251214B: COLIBRÍ observations of the afterglow
  54. EP251214a: EP-FXT non-detection and upper limit
  55. GRB 251214B: 1.3m DFOT optical detection
  56. EP251214a: Global MASTER-Net observations report
  57. GRB 251214B: Enhanced Swift-XRT position
  58. GRB 251214B: Xinglong-2.16m optical observation
  59. GRB 251214B : MASTER optical afterglow detection
  60. Fermi trigger No 787396657: Global MASTER-Net observations report
  61. GRB 251214B: SVOM/C-GFT optical observations
  62. EP251214a: COLIBRÍ optical upper limit
  63. Swift GRB 251214B: Global MASTER-Net observations report
  64. EP251214.305: COLIBRÍ optical upper limit
  65. GRB 251214B: Swift detection of a burst with an optical counterpart
  66. EP251214a: EP-WXT detection of an X-ray transient possibly associated with GRB 251214A
  67. Fermi GRB 251214A: Global MASTER-Net observations report
  68. EP251212a: Global MASTER-Net observations report
  69. EP251212a: KAIT optical upper limit
  70. GRB 251211B: AstroSat CZTI detection
  71. GRB 251209A: NuSTAR detection of prompt emission
  72. EP251212a : COLIBRÍ optical upper limit
  73. EP251212a: Einstein Probe detection of an X-ray transient
  74. Fermi-LAT Gamma-ray Observations of IceCube-251210A
  75. IceCube-251210A: Upper limits from a search for additional neutrino events in IceCube
  76. Fermi GRB 251211B: Global MASTER-Net observations report
  77. IceCube-251210A: DDOTI Optical Upper Limit
  78. SVOM GRB251211.12: Global MASTER-Net observations report
  79. GRB 251209A: Fermi GBM observation
  80. GRB 251205A: 1.3m DFOT optical upper limit
  81. GRB 251209A: AstroSat CZTI detection
  82. IceCube Alert 251210.46: Global MASTER-Net observations report
  83. EP251124a: Mondy optical upper limit
  84. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  85. EP251130a: Mondy and AbAO optical observations
  86. GRB 251208A: AstroSat CZTI detection
  87. Fermi GBM Sub-Threshold Detection of GRB 251205A
  88. GRB 251208A: Glowbug gamma-ray detection
  89. GRB 251208B: COLIBRÍ optical upper limits
  90. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  91. Fermi GRB 251209A: Global MASTER-Net observations report
  92. Fermi GRB 251208C: Global MASTER-Net observations report
  93. GRB 251206A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  94. GRB 251208B: Swift-XRT afterglow detection
  95. GRB 251208D: LAST optical upper limit
  96. GRB 251208D: LCO analysis of the XRT sources
  97. GRB 251208B: Fermi GBM Observation
  98. GRB 251208B: GROWTH-India Telescope optical upper limits
  99. GRB 251205A: J-band detection with WINTER
  100. GRB 251208D: Swift-XRT 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