Skip to main content
End of Swift Science Operations, CHIME Notices Unavailable During Upgrade. 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"

37750 results found.

  1. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  2. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  3. GRB 250909B: AstroSat CZTI detection of a long burst
  4. GRB 250910A: SVOM/VT optical upper limit
  5. GRB 250910A: LCO optical upper limit
  6. GRB 250909A: AstroSat CZTI detection
  7. GRB 250910A: SVOM/MXT possible afterglow detection
  8. GRB 250910A: SVOM detection of a faint burst
  9. GRB 250702B: Late time Chandra observations
  10. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  11. Fermi GRB 250909A: Global MASTER-Net observations report
  12. GRB 250909A: Fermi GBM Final Real-time Localization
  13. GRB 250907A: GECAM-B detection
  14. GRB 250905A: Swift-BAT refined analysis
  15. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  16. GRB 250903A: Swift-XRT afterglow detection
  17. GRB 250905A: Swift-XRT refined Analysis
  18. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  19. GRB 250904A: Swift-BAT refined analysis
  20. GRB 250905A: Swift/UVOT Upper Limits
  21. GRB 250901A - SVOM/ECLAIRs refined analysis
  22. GRB 250905B: Fermi GBM Final Localization
  23. GRB 250905A: Enhanced Swift-XRT position
  24. GRB 250904A: Swift/UVOT Detection
  25. GRB 250903A: Swift/UVOT detection
  26. GRB 250904A: Swift-XRT refined Analysis
  27. GRB 250905A: KAIT optical upper limit
  28. GRB 250905A: Swift detection of a burst
  29. Swift GRB 250904A: Global MASTER-Net observations report
  30. GRB 250904A: Enhanced Swift-XRT position
  31. GRB 250904A: TRT optical counterpart detection
  32. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  33. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  34. GRB 250904A: Prompt enhanced Swift-XRT position
  35. GRB 250904A: Swift detection of a burst
  36. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  37. GRB 250902A: VZLUSAT-2 detection
  38. GRB 250903A: Swift-XRT observations
  39. GRB 250830C: VZLUSAT-2 detection
  40. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  41. GRB 250903A: EP-FXT counterpart detection
  42. GRB 250902A: GECAM-B detection
  43. GRB 250903A: LCO optical observation
  44. GRB 250903A: LCO optical afterglow detection
  45. GRB 250903A: SVOM/VT optical confirmation with VHF data
  46. EP250901a: Mondy, Assy and SAO RAS optical limits
  47. Subject GRB 250903A: SVOM/MXT afterglow detection
  48. GRB 250903A: TRT optical counterpart detection
  49. GRB 250902B: AstroSat CZTI detection
  50. GRB 250903A: SVOM detection of a burst
  51. EP 250827B: Detection of supernova counterpart by LCO.
  52. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  53. GRB 250902B: SVOM/GRM observation
  54. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  55. Fermi GRB 250902B: Global MASTER-Net observations report
  56. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  57. GRB 250902A: Fermi GBM Detection
  58. GRB 250901A: Swift/UVOT Upper Limit
  59. GRB 250902B: Fermi GBM Final Real-time Localization
  60. GRB 250830B: Swift-XRT afterglow detection
  61. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  62. GRB 250902A: SVOM/GRM observation
  63. GRB 250901A: EP-FXT follow-up observation
  64. GRB 250901A: NOT optical observations
  65. GRB 250902A: Fermi GBM Final Real-time Localization
  66. GRB 250901A: SVOM/VT optical afterglow with VHF data
  67. GRB 250901A: Swift-XRT afterglow detection
  68. GRB 250901A: LCO optical upper limit
  69. GRB 250901A: SVOM detection of a burst
  70. GRB 250831B: SVOM/GRM observation
  71. GRB 250830C: Insight-HXMT detection
  72. GRB 250830C: GECAM-B detection
  73. GRB 250830C: AstroSat CZTI detection of a long burst
  74. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  75. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  76. GRB 250831A: Swift-XRT counterpart detection
  77. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  78. GRB 250831A: SVOM/VT upper limit with VHF data
  79. GRB 250831A: SVOM detection of a soft burst
  80. GRB 250830B: Swift-XRT observations
  81. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  82. GRB 250830B: Swift ToO observations
  83. GRB 250830B: MAXI/GSC detection
  84. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  85. GRB 250828B: Swift-BAT refined analysis
  86. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  87. GRB 250808B: SVOM detection of a burst through offline search
  88. Swift GRB 250828B: Global MASTER-Net observations report
  89. EP-WXT trigger 01709200800 : KAIT optical observations
  90. EP250828a: KAIT optical upper limit
  91. GRB 250828B: Swift detection of a burst
  92. GRB 250828A: Fermi GBM Final Localization
  93. GRID detection of GRB 250824A
  94. Fermi GRB 250827A: Global MASTER-Net observations report
  95. EP250827a: GOTO observation of the optical afterglow
  96. GRB 250826A: SVOM/GRM observation
  97. GRB 250827A: Fermi GBM Final Real-time Localization
  98. EP250827A: An optical rebrightening was detected by LCO.
  99. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  100. Fermi GRB 250826A: Global MASTER-Net observations report

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Questions or comments?
Contact GCN directly.
Have you found a bug in GCN?
Open an issue.
Want to contribute code to GCN?
Get involved on GitHub.

gcn.nasa.gov

A service of the Astrophysics Science Division at NASA Goddard Space Flight Center

Looking for U.S. government information and services? Visit USA.gov