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"

24376 results found.

  1. Swift GRB 251007A: Global MASTER-Net observations report
  2. GRB 251007B: SVOM detection of a faint burst
  3. GRB 251007B: Swift detection of a burst
  4. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  5. GRB 251005B: Glowbug gamma-ray detection
  6. EP251003a: LCO and VST fading optical counterpart
  7. GRB 251006B/EP251006a: SVOM/VT optical candidate
  8. GRB 251006B/EP251006a: EP-FXT follow-up observation
  9. GRB 251006B: SVOM/GRM observation
  10. GRB 251006B/EP251006a: EP-WXT detection
  11. GRB 251005C: SVOM/VT optical fading
  12. GRB 251005C: SVOM/GRM observation of a likely short GRB
  13. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  14. Fermi GRB 251006B: Global MASTER-Net observations report
  15. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  16. GRB 251006B: Fermi GBM Final Real-time Localization
  17. Fermi GRB 251006A: Global MASTER-Net observations report
  18. GRB 251006A: Fermi GBM Final Real-time Localization
  19. GRB 251005C: SVOM/VT optical candidate
  20. GRB 250902A: MSU cubesats detection
  21. GRB 251005C: Fermi GBM Observation
  22. Swift GRB 251005A: Global MASTER-Net observations report
  23. Fermi trigger No 781367244: Global MASTER-Net observations report
  24. GRB 251005B: Fermi GBM Final Real-time Localization
  25. GRB 251005A: Fermi GBM Final Localization
  26. Fermi GBM Sub-Threshold Detection of GRB 250910A
  27. GRB 251003A: Swift-BAT refined analysis
  28. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  29. GRB 251003A: Swift-XRT refined Analysis
  30. GRB 251002A: Fermi GBM Observation
  31. LIGO/Virgo/KAGRA S251003at: Retraction of GW compact binary merger candidate
  32. GRB 251001C: SVOM/GRM observation
  33. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  34. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  35. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  36. GRB 251002A: EP-FXT counterpart detection
  37. GRB 251003A: LCOGT Optical Detection
  38. GRB 251003A: Fermi GBM Final Real-time Localization
  39. Swift GRB251003A: Global MASTER-Net observations report
  40. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  41. GRB 251002A: BOOTES-6 early optical detection
  42. GRB 251002A: LCO optical observation
  43. GRB 251002A: SVOM/VT optical observation
  44. GRB 251002A: SVOM detection of a burst
  45. Fermi GRB 251002A: Global MASTER-Net observations report
  46. GRB 251001B: Swift-BAT refined analysis
  47. GRB 251001A: SVOM/GRM observation
  48. GRB 251001B: SVOM/VT optical observation
  49. GRB 251001C: Glowbug gamma-ray detection
  50. Swift GRB 251001B: Global MASTER-Net observations report
  51. GRB 251001B: Fermi GBM Observation
  52. GRB 250930A: Fermi GBM Final Localization
  53. GRB 251001B: LCOGT Optical Observations
  54. GRB 250930A: SVOM/GRM observation
  55. GRB 251001B: GOTO optical counterpart detection
  56. GRB 251001B: Swift detection of a burst
  57. GRB 251001B: Fermi GBM Final Real-time Localization
  58. GRB 251001A: Fermi GBM Detection
  59. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  60. GRB 251001A: BALROG localization (Fermi Trigger 780979261 / GRB 251001112)
  61. GRB 251001A: Fermi GBM Final Real-time Localization
  62. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  63. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  64. Fermi GRB 250929A: Global MASTER-Net observations report
  65. GRB 250929A: Fermi GBM Final Real-time Localization
  66. GRB 250926A: CALET Gamma-Ray Burst Monitor detection
  67. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  68. GRB 250916A: SVOM/VT optical observation
  69. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  70. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  71. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  72. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  73. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  74. GRB 250924A: SVOM/GRM observation
  75. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  77. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 250926B: Fermi GBM Final Localization
  79. Fermi trigger No 780609036: Global MASTER-Net observations report
  80. IceCube Alert 250926.52: Global MASTER-Net observations report
  81. GRB 250925A: Swift-BAT refined analysis
  82. IceCube-250926A - IceCube observation of a high-energy neutrino candidate track-like event
  83. GRB 250925A: SVOM/GWAC-F60A upper limit
  84. GRB 250925A/EP250925a: EP-WXT detection
  85. GRB 250925A : MITSuME Akeno optical upper limits
  86. Fermi GRB 250926A: Global MASTER-Net observations report
  87. GRB 250926A: Fermi GBM Final Real-time Localization
  88. GRB 250925A: Optical Observations via Virtual Telescope Project, Italy
  89. GRB 250925A: Leavitt Observatory optical upper limit
  90. GRB 250924A: Swift-BAT refined analysis
  91. GRB 250925A: GROWTH-India Telescope Upper Limits
  92. GRB 250925A: Swift detection of a burst
  93. Swift GRB 250925A: Global MASTER-Net observations report
  94. GRB 250922A: SVOM/GRM observation
  95. GRB 250924A: 1.6m Mephisto optical upper limits
  96. GRB 250924A: SVOM/VT optical observation
  97. GRB 250924A: GROWTH-India Telescope Upper Limits
  98. GRB 250922B: SVOM/GRM observation
  99. GRB 250924B: Fermi GBM Final Localization
  100. Swift GRB 250924A: Global MASTER-Net observations report

Advanced

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