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"

15398 results found.

  1. GRB 250919A: Fermi-LAT detection
  2. GRB 250919A: SVOM/GRM observation of a very bright GRB
  3. GRB 250916A: Fermi GBM Observation
  4. GRB 250917B: VLT/HAWK-I near-infrared observations
  5. GRB 250912A: SVOM/ECLAIRs refined analysis
  6. GRB 250916A : GIT optical observations
  7. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  8. GRB 250916A: Glowbug gamma-ray detection
  9. GRB 250916A: Swift ToO observations
  10. GRB 250917B: Fermi GBM Observation
  11. GRB 250916A: AstroSat CZTI detection of a bright long burst
  12. GRB 250910A: SVOM/ECLAIRs refined analysis
  13. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  14. SVOM/sb25091517: Confirmation of a stellar flare by SVOM/VT
  15. SVOM/sb25091517: FRAM-ORM stellar flare - transient observation
  16. SVOM/sb25091517: SVOM detection of an X-ray transient
  17. GRB 250912A: SVOM/COLIBRÍ (FM-GFT) optical observations
  18. GRB 250912A: Swift-XRT observations
  19. GRB250912A: VLT/HAWK-I follow-up observations
  20. GRB 250912A: Fermi GBM Observation
  21. GRB 250911A: Insight-HXMT detection
  22. GRB 250912A: SVOM/GRM analysis suggests a possible short GRB with extended emission
  23. GRB 250912A: SVOM detection of a burst
  24. IceCube-Cascade 250911A: Upper limits from a search for additional neutrino events in IceCube
  25. EP250911a: Upper limit from Fermi-GBM Observations
  26. GRB 250911A: GECAM-B detection
  27. GRB 250910B: SVOM/GRM observation
  28. GRB 250911A: MASTER optical counterpart observations
  29. EP250911a: Swift-XRT observations
  30. GRB 250910A / EP250910a: Swift-XRT afterglow detection
  31. GRB 250910A / EP250910a: SVOM/VT afterglow confirmation
  32. GRB 250909B: Insight-HXMT detection
  33. GRB 250909B: SVOM/GRM observation
  34. EP250911a: COLIBRÍ optical observations
  35. GRB 250404A / EP250404a: spectroscopic redshift at z = 1.88 (correction to GCN 40084)
  36. GRB 250903A: SVOM/ECLAIRs refined analysis
  37. GRB 250910A / EP250910a: VLT/HAWK-I near-infrared observations
  38. GRB 250909B: AstroSat CZTI detection of a long burst
  39. EP250908C: GROND observation of the fading optical counterpart
  40. GRB 250909A: AstroSat CZTI detection
  41. GRB 250910A: SVOM detection of a faint burst
  42. EP250908b/EP#01709240653: Swift/UVOT Detection
  43. EP250908c: VLT/FORS2 optical counterpart identification
  44. GRB 250907A: GECAM-B detection
  45. Fermi-LAT Gamma-ray Observations of IceCube-250905A
  46. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  47. SVOM/sb25090605: detection of an X-ray transient from the LMXB 4U 0513-40
  48. EP250905a: Liverpool Telescope i-band upper limits
  49. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  50. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  51. EP250905a: FTW one optical and multiple NIR counterpart candidates
  52. IceCube-250905A - IceCube observation of a high-energy neutrino candidate track-like event
  53. GRB 250901A - SVOM/ECLAIRs refined analysis
  54. GRB250904A: Liverpool Telescope upper limits
  55. GRB 250903A: Swift/UVOT detection
  56. IceCube-Cascade 250903A: Upper limits from a search for additional neutrino events in IceCube
  57. EP250827a and EP250827b: Upper limit from Fermi-GBM Observations
  58. EP250827b: Gemini Spectroscopic Confirmation of AT2025wkm as a Ic-BL Supernova
  59. GRB 250902A: VZLUSAT-2 detection
  60. EP#01709201209: Swift-XRT observations
  61. EP250903a: retraction of the LCO candidate, and discovery of the likely counterpart
  62. GRB 250830C: VZLUSAT-2 detection
  63. GRB 250903A: EP-FXT counterpart detection
  64. GRB 250902A: GECAM-B detection
  65. GRB 250903A: LCO optical afterglow detection
  66. GRB 250903A: SVOM/VT optical confirmation with VHF data
  67. EP250903a: SVOM/VT optical confirmation
  68. Subject GRB 250903A: SVOM/MXT afterglow detection
  69. GRB 250902B: AstroSat CZTI detection
  70. GRB 250903A: SVOM detection of a burst
  71. EP 250827B: Detection of supernova counterpart by LCO.
  72. GRB 250902B: SVOM/GRM observation
  73. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  74. GRB 250831A (SVOM trigger sb25083102): KAIT confirmation of stellar flare
  75. Fermi-LAT Gamma-ray Observations of IceCube-250831A
  76. GRB 250902A: Fermi GBM Detection
  77. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 250830B: Swift-XRT afterglow detection
  79. GRB 250831A (SVOM trigger sb25083102): confirmation of a stellar flare by SVOM/VT
  80. GRB 250902A: SVOM/GRM observation
  81. EP250828a: Early near-infrared follow-up with MIRAGE on the MDM 1.3m telescope
  82. GRB 250901A: EP-FXT follow-up observation
  83. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  84. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  85. EP250827b: Swift observations of AT 2025wkm
  86. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  87. EP250827b: Gemini Spectroscopy of AT 2025wkm
  88. EP250827b: FTW Observations of AT 2025wkm
  89. GRB 250901A: SVOM detection of a burst
  90. GRB 250831B: SVOM/GRM observation
  91. GRB 250830C: Insight-HXMT detection
  92. EP250901a: Mephisto optical upper limits
  93. GRB 250830C: GECAM-B detection
  94. GRB 250830C: AstroSat CZTI detection of a long burst
  95. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  96. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  97. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  98. GRB 250831A: Swift-XRT counterpart detection
  99. GRB 250831A: SVOM detection of a soft burst
  100. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations

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