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"

37256 results found.

  1. GRB 250912A: Fermi GBM Final Real-time Localization
  2. EP250911a: Upper limit from Fermi-GBM Observations
  3. GRB 250911A: GECAM-B detection
  4. GRB 250911A: Swift-BAT refined analysis
  5. GRB 250910B: SVOM/GRM observation
  6. GRB 250911A: MASTER optical counterpart observations
  7. EP250911a: SAO RAS optical observations
  8. GRB 250911A: Swift-XRT refined Analysis
  9. GRB 250910C: Fermi GBM Final Localization Correction
  10. EP250911a: Optical detection with Kinder observations
  11. GRB 250911A: Swift/UVOT Detection
  12. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  13. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  14. GRB 250909B: Insight-HXMT detection
  15. GRB 250909B: SVOM/GRM observation
  16. GRB 250910A / EP250910a : VLT/HAWK-I NIR counterpart discovery
  17. Fermi GRB 250910B: Global MASTER-Net observations report
  18. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  19. GRB 250903A: SVOM/ECLAIRs refined analysis
  20. GRB 250911A: Enhanced Swift-XRT position
  21. GRB 250911A: Swift-XRT observations
  22. GRB 250911A: COLIBRÍ optical counterpart candidate
  23. GRB 250911A: Swift detection of a burst
  24. GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
  25. GRB 250910B: Fermi GBM Final Real-time Localization
  26. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  27. EP250910a/GRB 250910A: EP-WXT detection of a fast X-ray transient
  28. GRB 250909B: AstroSat CZTI detection of a long burst
  29. GRB 250910A: SVOM/VT optical upper limit
  30. GRB 250910A: LCO optical upper limit
  31. GRB 250909A: AstroSat CZTI detection
  32. GRB 250910A: SVOM/MXT possible afterglow detection
  33. GRB 250910A: SVOM detection of a faint burst
  34. GRB 250702B: Late time Chandra observations
  35. GRB 250907A: CALET Gamma-Ray Burst Monitor detection
  36. Fermi GRB 250909A: Global MASTER-Net observations report
  37. GRB 250909A: Fermi GBM Final Real-time Localization
  38. GRB 250907A: GECAM-B detection
  39. GRB 250905A: Swift-BAT refined analysis
  40. GRB 250903A: Swift-XRT afterglow detection
  41. GRB 250905A: Swift-XRT refined Analysis
  42. GRB 250904A: Swift-BAT refined analysis
  43. GRB 250905A: Swift/UVOT Upper Limits
  44. GRB 250901A - SVOM/ECLAIRs refined analysis
  45. GRB 250905B: Fermi GBM Final Localization
  46. GRB 250905A: Enhanced Swift-XRT position
  47. GRB 250904A: Swift/UVOT Detection
  48. GRB 250903A: Swift/UVOT detection
  49. GRB 250904A: Swift-XRT refined Analysis
  50. GRB 250905A: KAIT optical upper limit
  51. GRB 250905A: Swift detection of a burst
  52. Swift GRB 250904A: Global MASTER-Net observations report
  53. GRB 250904A: Enhanced Swift-XRT position
  54. GRB 250904A: TRT optical counterpart detection
  55. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  56. GRB 250902B: CALET Gamma-Ray Burst Monitor detection
  57. GRB 250904A: Prompt enhanced Swift-XRT position
  58. GRB 250904A: Swift detection of a burst
  59. GRB 250902A: CALET Gamma-Ray Burst Monitor detection
  60. GRB 250902A: VZLUSAT-2 detection
  61. GRB 250903A: Swift-XRT observations
  62. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  63. GRB 250830C: VZLUSAT-2 detection
  64. GRB 250903A: VLT X-shooter spectroscopic redshift z = 1.590
  65. GRB 250903A: EP-FXT counterpart detection
  66. GRB 250902A: GECAM-B detection
  67. GRB 250903A: LCO optical observation
  68. GRB 250903A: LCO optical afterglow detection
  69. GRB 250903A: SVOM/VT optical confirmation with VHF data
  70. EP250901a: Mondy, Assy and SAO RAS optical limits
  71. Subject GRB 250903A: SVOM/MXT afterglow detection
  72. GRB 250903A: TRT optical counterpart detection
  73. GRB 250902B: AstroSat CZTI detection
  74. GRB 250903A: SVOM detection of a burst
  75. EP 250827B: Detection of supernova counterpart by LCO.
  76. EP250827b / AT 2025wkm: TRT optical observations
  77. EP250827b: NOT spectroscopic observations and AT 2025wkm classification as a broad-lined type-Ic supernova
  78. GRB 250902B: SVOM/GRM observation
  79. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  80. Fermi GRB 250902B: Global MASTER-Net observations report
  81. GRB 250902A: Fermi GBM Detection
  82. GRB 250901A: Swift/UVOT Upper Limit
  83. GRB 250902B: Fermi GBM Final Real-time Localization
  84. GRB 250830B: Swift-XRT afterglow detection
  85. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  86. GRB 250902A: SVOM/GRM observation
  87. GRB 250901A: EP-FXT follow-up observation
  88. GRB 250901A: NOT optical observations
  89. GRB 250902A: Fermi GBM Final Real-time Localization
  90. GRB 250901A: SVOM/VT optical afterglow with VHF data
  91. GRB 250901A: Swift-XRT afterglow detection
  92. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  93. GRB 250901A: LCO optical upper limit
  94. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  95. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  96. GRB 250901A: SVOM detection of a burst
  97. GRB 250831B: SVOM/GRM observation
  98. GRB 250830C: Insight-HXMT detection
  99. EP250901a: Mephisto optical upper limits
  100. GRB 250830C: GECAM-B detection

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