Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

27814 results found.

  1. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  2. GRB 250909B: Insight-HXMT detection
  3. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  4. EP250911a: LCO optical counterpart discovery
  5. EP250911a: Einstein Probe detection of an X-ray transient
  6. GRB 250911A: Enhanced Swift-XRT position
  7. GRB 250911A: Swift-XRT observations
  8. GRB 250911A: COLIBRÍ optical counterpart candidate
  9. GRB 250911A: Swift detection of a burst
  10. GRB 250910B: Fermi GBM Final Real-time Localization
  11. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  12. GRB 250909B: AstroSat CZTI detection of a long burst
  13. GRB 250909A: AstroSat CZTI detection
  14. GRB 250910A: SVOM/MXT possible afterglow detection
  15. GRB 250910A: SVOM detection of a faint burst
  16. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  17. GRB 250702B: Late time Chandra observations
  18. EP250908b/EP#01709240653: Swift/UVOT Detection
  19. EP#01709240653: Swift-XRT observations
  20. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  21. EP250908c: Einstein Probe detection of an X-ray transient
  22. GRB 250909A: Fermi GBM Final Real-time Localization
  23. EP250908b: EP-WXT detection of a fast X-ray transient and EP-FXT observation
  24. GRB 250907A: GECAM-B detection
  25. GRB 250905A: Swift-BAT refined analysis
  26. GRB 250903A: Swift-XRT afterglow detection
  27. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  28. EP250905b: EP-FXT follow-up observation
  29. EP250905a: Liverpool Telescope observations
  30. EP250905b: EP-WXT detection of a fast X-ray transient
  31. GRB 250905A: Swift-XRT refined Analysis
  32. EP250905a: JinShan likely optical counterpart detection
  33. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 250904A: Swift-BAT refined analysis
  35. GRB 250905A: Swift/UVOT Upper Limits
  36. EP250905a: Einstein Probe detection of an X-ray transient
  37. GRB 250905B: Fermi GBM Final Localization
  38. GRB 250905A: Enhanced Swift-XRT position
  39. GRB 250904A: Swift/UVOT Detection
  40. GRB 250903A: Swift/UVOT detection
  41. GRB 250904A: Swift-XRT refined Analysis
  42. EP detected a brightening of LMXB 1ES 1735-26.9
  43. GRB 250905A: KAIT optical upper limit
  44. GRB 250905A: Swift detection of a burst
  45. Swift GRB250905.09: Global MASTER-Net observations report
  46. Swift GRB 250904A: Global MASTER-Net observations report
  47. GRB 250904A: Enhanced Swift-XRT position
  48. GRB 250904A: TRT optical counterpart detection
  49. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  50. GRB 250904A: Prompt enhanced Swift-XRT position
  51. GRB 250904A: Swift detection of a burst
  52. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  53. GRB 250902A: VZLUSAT-2 detection
  54. GRB 250903A: Swift-XRT observations
  55. EP250903a: Swift-XRT observations
  56. EP#01709201209: Swift-XRT observations
  57. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  58. EP-WXT trigger 01709201209: Liverpool Telescope upper limits
  59. GRB 250830C: VZLUSAT-2 detection
  60. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  61. GRB 250903A: EP-FXT counterpart detection
  62. GRB 250902A: GECAM-B detection
  63. GRB 250903A: LCO optical afterglow detection
  64. EP250901a: Mondy, Assy and SAO RAS optical limits
  65. Subject GRB 250903A: SVOM/MXT afterglow detection
  66. GRB 250903A: TRT optical counterpart detection
  67. GRB 250902B: AstroSat CZTI detection
  68. GRB 250903A: SVOM detection of a burst
  69. EP250903a: Einstein Probe detection of an X-ray transient
  70. EP 250827B: Detection of supernova counterpart by LCO.
  71. EP250827b: continued Liverpool Telescope observations
  72. EP250827b: SVOM/VT observation of AT 2025wkm
  73. GRB 250902A: Fermi GBM Detection
  74. GRB 250901A: Swift/UVOT Upper Limit
  75. GRB 250902B: Fermi GBM Final Real-time Localization
  76. GRB 250830B: Swift-XRT afterglow detection
  77. EP250827b: Liverpool Telescope observations
  78. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  79. EP250901a: refined analysis of the EP-WXT and EP-FXT observations
  80. GRB 250901A: EP-FXT follow-up observation
  81. GRB 250902A: Fermi GBM Final Real-time Localization
  82. GRB 250901A: SVOM/VT optical afterglow with VHF data
  83. GRB 250901A: Swift-XRT afterglow detection
  84. EP250901a: Swift-XRT observations
  85. GRB 250901A: LCO optical upper limit
  86. EP250827b: Swift observations of AT 2025wkm
  87. EP250831a: NOT optical observations and tentative afterglow candidate
  88. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  89. GRB 250901A: SVOM detection of a burst
  90. GRB 250830C: Insight-HXMT detection
  91. GRB 250830C: GECAM-B detection
  92. GRB 250830C: AstroSat CZTI detection of a long burst
  93. EP250901a: Einstein Probe detection of an X-ray transient
  94. EP250831a: EP-FXT follow-up observation
  95. EP250831a: Swift-XRT observations
  96. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  97. EP250831a: EP-WXT detection of a fast X-ray transient
  98. GRB 250831A: Swift-XRT counterpart detection
  99. GRB 250831A: SVOM detection of a soft burst
  100. GRB 250830B: 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