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"

32760 results found.

  1. EP260105b / GRB 260105C : Fermi-GBM Sub-Threshold Detection
  2. GRB 260104A: Swift-BAT refined analysis
  3. GRB 260101A: Swift-BAT refined analysis
  4. Swift GRB 251230A: Global MASTER-Net OT detection
  5. Fermi GRB 260107A: Global MASTER-Net observations report
  6. GRB 260102A: AbAO optical observations
  7. EP260105b/EP-WXT trigger 01709251028: Einstein Probe detection of an X-ray transient
  8. Fermi GRB 260105A: Global MASTER-Net observations report
  9. EP260105a: FTW optical observations
  10. EP260104a: FTW optical observations
  11. GRB 260105A: SVOM/GRM observation
  12. GRB 260105B: SVOM/GRM observation
  13. FRB 20251229A: COLIBRÍ optical upper limits
  14. Fermi GRB 260105B: Global MASTER-Net observations report
  15. EP260105a: SVOM/VT optical upperlimit
  16. EP260105a: refined analysis of the EP-WXT and EP-FXT observations
  17. EP260105a: LCO Optical Upper limit
  18. EP260104a: Global MASTER-Net observations report
  19. GRB 260101A: COLIBRÍ optical upper limits
  20. EP260105a: Global MASTER-Net observations report
  21. GRB 260103A: Insight-HXMT/HE detection
  22. GRB 260104A: COLIBRÍ optical upper limits
  23. Fermi GRB 260104B: Global MASTER-Net observations report
  24. Swift GRB 260104A: Global MASTER-Net observations report
  25. GRB 251230A/EP-WXT trigger 01709250693: Mephisto optical upper limits
  26. GRB 260101A: Swift/UVOT Detection
  27. GRB 260103A: GECAM-B observation of a burst
  28. Fermi-LAT Gamma-ray Observations of IceCube-251225A
  29. GRB 260101A: COLIBRÍ optical observations
  30. Fermi GBM Sub-Threshold Detection of GRB 260102A
  31. GRB 260102A: EP-FXT follow-up observation
  32. EP260101a: Global MASTER-Net observations report
  33. GRB 260102A: LCO optical upper limits
  34. GRB 260102A: Swift-XRT observations
  35. GRB 260102A: SVOM/COLIBRÍ (FM-GFT) optical observations
  36. GRB 251230A / EP251230a: GECAM-B detection
  37. GRB 260102A: SVOM/VT optical counterpart
  38. GRB 251230A / EP251230a: Insight-HXMT/HE detection
  39. GRB 260102A: Swift ToO observations
  40. GRB 260101A: Fermi GBM Observation
  41. EP260101a: refined analysis of the EP-WXT and EP-FXT observations
  42. GRB 260101A: GECAM-B detection
  43. GRB 260101A: NOT spectroscopic observations
  44. GRB 260101A: SVOM/GRM observation
  45. Swift GRB 260101A: Global MASTER-Net observations report
  46. GRB 260101A: OSIRIS+ redshift z = 2.623 for the new year burst
  47. GRB 260101A: LCO detection of the optical counterpart
  48. GRB 251230A / EP251230a: SVOM/VT optical continued observations and upper limit
  49. GRB 251230A: GRANDMA/TAROT Early Detection
  50. GRB 251230A / EP251230a: further NOT optical observations revealing shallower decay or possible rebrightening
  51. GRB 251230A/EP251230a: Optical upper limit with Kinder observations
  52. EP251229a: Optical upper limit with Kinder observations
  53. GRB 251230A: 1.3m DFOT optical upper limit
  54. GRB 251222A: Mondy Optical Observations
  55. EP251230a / GRB 251230A: refined analysis of the EP-WXT and EP-FXT observations
  56. GRB 251230A: Swift/UVOT detection
  57. GRB251230A: 7DT optical upper limits
  58. GRB 251230A / EP251230a: NOT observations and spectroscopic redshift upper limit z < 2.2
  59. EP251229a: BOOTES-2 early optical upper limit
  60. GRB 251230A: GOTO optical upper limit
  61. EP251229a: NOT optical upper limits
  62. GRB 251230A / EP251230a: SVOM/VT optical observation
  63. EP251229a: refined analysis of the EP-WXT and EP-FXT observations
  64. GRB 251230A: Early optical counterpart detection by LCO.
  65. EP-WXT trigger 01709250662 Mephisto and 50cm telescope follow-up
  66. GRB 251230A: Optical Observations via Virtual Telescope Project, Italy
  67. EP251230a / GRB 251230A: Einstein Probe detection of an X-ray transient
  68. GRB 251230A/EP#01709250693 (likely EP251230a): FTW optical and NIR observations
  69. LIGO/Virgo/KAGRA S251112cm: Candidates from the NSF-DOE Vera C. Rubin Observatory
  70. Swift GRB 251230A: Global MASTER-Net observations report
  71. The EP-WXT trigger 01709250693/GRB 251230A: Las Cumbres detection of the optical counterpart
  72. EP251229a: Global MASTER-Net observations report
  73. GRB 251226A: Glowbug gamma-ray detection
  74. GRB 251222A/EP251222b: 1.6m Mephisto optical followup
  75. GRB 251129A: redshift correction and SN detection at z = 0.505 with GTC
  76. Fermi GRB 251228A: Global MASTER-Net observations report
  77. GRB 251226A: SVOM/GRM observation
  78. IceCube-251225A: Upper limits from a search for additional neutrino events in IceCube
  79. GRB 251222A: NUTTelA-TAO Early Measurements
  80. GRB 251222A/EP251222b: Optical detection with Kinder observations
  81. EP251222a: Optical upper limit with Kinder observations
  82. GRB 251221A: Swift-BAT refined analysis
  83. GRB 251222A/EP251222b: FTW optical and NIR observations
  84. EP251222a: FTW optical and NIR observations
  85. GRB 251205A: Kilonova-Catcher optical afterglow detection
  86. GRB 251222A: AbAO optical observations
  87. GRB 251222A / EP251222b: Kilonova-Catcher optical afterglow detection
  88. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  89. EP251222a: VLT/FORS2 spectroscopic redshift z = 0.505
  90. GRB 251222A: ZTSH BVRI optical observations
  91. GRB 251222A: SVOM/COLIBRÍ (FM-GFT) optical observations
  92. GRB 251222A: Continued 1.3m DFOT optical observation
  93. EP251220a: 3.6m DOT optical afterglow detection
  94. GRB 251222A: Fermi GBM Observation
  95. EP251220a: CrAO ZTSh optical observations
  96. EP251221a: PRIME upper limit
  97. EP251222a: Global MASTER-Net observations report
  98. GRB 251222A / EP251222b: GECAM-B observation
  99. EP251221a: Liverpool Telescope upper limits
  100. EP251222a: refined analysis of the EP-WXT and EP-FXT 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