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"

19578 results found.

  1. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  2. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  3. Swift GRB 251230A: Global MASTER-Net observations report
  4. GRB 251230A: Swift detection of a burst with a bright optical counterpart
  5. GRB 251222A/EP251222b: Optical detection with Kinder observations
  6. GRB 251221A: Swift-BAT refined analysis
  7. GRB 251205A: Kilonova-Catcher optical afterglow detection
  8. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  9. GRB 251222A: Fermi GBM Observation
  10. GRB 251222A: Swift-XRT afterglow detection
  11. GRB 251222A / EP251222b: LCO detection of the optical counterpart
  12. GRB251221A: 7DT optical upper limits
  13. IPN triangulation of GRB 251220B (short)
  14. GRB 251222A: Swift ToO observations
  15. GRB 251221A: PRIME near-infrared observation
  16. GRB 251221A: UAFO and Mondy optical upper limit
  17. GRB 251221A: Swift-XRT refined Analysis
  18. GRB 251221A: Swift/UVOT Upper Limits
  19. GRB 251221A: Enhanced Swift-XRT position
  20. GRB 251221A: Fermi GBM Observation
  21. GRB 251221A: COLIBRÍ detection of the optical counterpart
  22. GRB 251221A: Swift detection of a burst
  23. Swift GRB251221A: Global MASTER-Net observations report
  24. GRB 251215A: Swift-XRT afterglow detection
  25. GRB 251214B: VIRT Optical Upper Limit
  26. GRB 251215A: Swift/UVOT Upper LImits
  27. GRB 251215A: Fermi GBM Observation
  28. GRB 251214B: Mondy optical upper limit
  29. GRB 251215A: COLIBRÍ optical upper limit
  30. GRB 251215A: Swift-XRT 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. GRB 251214B: AbAO optical observations
  38. GRB 251214B: LCO detection of the optical counterpart
  39. GRB 251214B: Fermi GBM Observation
  40. GRB 251215A: Swift ToO observations
  41. EP251214b (EP trigger 01709250023): LCO optical limits
  42. GRB 251215A: Swift/BAT-GUANO arcminute localization of a burst
  43. GRB 251214B: Swift-XRT refined Analysis
  44. GRB 251214B: Swift/UVOT Detection
  45. GRB 251214B: COLIBRÍ observations of the afterglow
  46. GRB 251214B: 1.3m DFOT optical detection
  47. GRB 251214B: Enhanced Swift-XRT position
  48. GRB 251214B: Xinglong-2.16m optical observation
  49. GRB 251214B : MASTER optical afterglow detection
  50. GRB 251214B: SVOM/C-GFT optical observations
  51. Swift GRB 251214B: Global MASTER-Net observations report
  52. GRB 251214B: Swift detection of a burst with an optical counterpart
  53. GRB 251205A: 1.3m DFOT optical upper limit
  54. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  55. EP251130a: Mondy and AbAO optical observations
  56. Fermi GBM Sub-Threshold Detection of GRB 251205A
  57. GRB 251208B: COLIBRÍ optical upper limits
  58. EP251118a / GRB 251118C: VLT/MUSE redshift confirmation
  59. GRB 251208B: Swift-XRT afterglow detection
  60. GRB 251208D: LCO analysis of the XRT sources
  61. GRB 251208B: Fermi GBM Observation
  62. GRB 251208B: GROWTH-India Telescope optical upper limits
  63. GRB 251208D: Swift-XRT observations
  64. GRB 251208B: Swift ToO observations
  65. GRB 251208B: Fermi-LAT detection
  66. GRB 251208B: Swift/BAT-GUANO arcminute localization of a burst
  67. GRB 251205A : MITSuME Akeno optical afterglow candidate detection
  68. GRB 251205A: ZTF and ATLAS optical afterglow detections
  69. GRB 251205A: GROWTH-India Telescope optical observations
  70. GRB 251205A: Swift-BAT refined analysis
  71. GRB 251205A: Swift-XRT refined Analysis
  72. GRB 251205A: Swift/UVOT Detection
  73. GRB 251203C: Swift/UVOT Upper Limit
  74. GRB 251205A: COLIBRÍ optical observations
  75. GRB 251205A: Enhanced Swift-XRT position
  76. Swift GRB 251205A : MASTER OT detection with host galaxy
  77. GRB 251205A: Swift detection of a burst with an optical afterglow
  78. Swift GRB251205A: Global MASTER-Net observations report
  79. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  80. GRB 251202A: SVOM/GRM observation
  81. GRB 251201B: SALT spectroscopic redshift z = 1.599
  82. GRB 251129B: Glowbug gamma-ray detection of a short burst
  83. GRB 251203B: Swift-XRT observations
  84. GRB 251203B: LCO optical upper limits
  85. EP251130a: MAO/AZT-22 optical observations
  86. GRB 251202A / EP251202a: SVOM/VT optical observation
  87. GRB 251201B: Fermi GBM Observation
  88. EP251130a: ULL-ASTRO-MASTER late detection of the optical afterglow with LCO 1-m telescope at Teide Observatory
  89. IPN triangulation of GRB 251129B (short/hard)
  90. GRB251129A/EP251129a: Swift UVOT detection
  91. GRB 251202A: Fermi GBM Observation
  92. GRB 251202A: Swift/UVOT Detection
  93. GRB 251201B: Kilonova-Catcher optical afterglow detection
  94. GRB 251201B: Swift/UVOT Detection
  95. GRB 251126A: SAO RAS optical marginal detection
  96. GRB 251202A: Swift-XRT afterglow detection
  97. GRB 251126A: SVOM/VT optical observation
  98. EP251130a: SVOM/VT optical observation
  99. GRB 251201B: Swift-XRT refined Analysis
  100. GRB 251201B: SVOM/VT optical fading

Advanced

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