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"

32707 results found.

  1. IPN triangulation of GRB 260127B (short)
  2. GRB 260127B: Swift-XRT observations
  3. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  4. GRB 260128A / EP260128a: Fermi-GBM Sub-Threshold Detection
  5. EP260128a: NOT optical counterpart candidate
  6. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  7. EP260128a: Liverpool Telescope optical observations and possible counterpart
  8. EP260128a: LCO optical upper limits
  9. EP260126a: SVOM/VT optical upperlimit
  10. EP260128a: Global MASTER-Net observations report
  11. Fermi GRB 260127A: Global MASTER-Net observations report
  12. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  13. GRB 260127A: Fermi GBM Observation
  14. IceCube-260125A: Upper limits from a search for additional neutrino events in IceCube
  15. GRB 260127A: COLIBRÍ optical observations
  16. GRB 260127A: NOT optical observations
  17. GRB 260127B: Swift ToO observations
  18. EP260126a: Seimei/TriCCS optical upper limit
  19. GRB 260127A : MITSuME Akeno optical afterglow candidate detection
  20. GRB 260127B: GOTO candidate optical counterpart
  21. GRB 260127A: SVOM/C-GFT optical observations
  22. Fermi GRB 260127B: Global MASTER-Net observations report
  23. Swift GRB 260127A: Global MASTER-Net observations report
  24. GRB 260127A: LCO optical afterglow discovery
  25. GRB 260125A: Swift-XRT observations
  26. EP260126a: EP-FXT follow-up observation
  27. EP260126a: Optical upper limit with Kinder observations
  28. EP260126a: Liverpool Telescope optical upper limits
  29. EP260126a: Further NOT optical upper limits
  30. EP260126a: COLIBRÍ optical upper limits
  31. EP260126a: NOT optical observations
  32. Fermi-LAT Gamma-ray Observations of IceCube-260125A
  33. GRB 260125A: NOT optical observations on GOTO26acv / AT 2026bjf
  34. Konus-Wind detection of GRB 260120B
  35. GRB 251222A: SVOM/ECLAIRs refined analysis
  36. GRB 260125A: Swift ToO observations
  37. GRB 260125A: GOTO candidate optical counterpart
  38. Fermi GRB 260125B: Global MASTER-Net observations report
  39. IceCube-260125A - IceCube observation of a high-energy neutrino candidate track-like event
  40. GRB 260114A: SVOM/VT optical upper limits
  41. GRB 260120A: AstroSat CZTI detection
  42. GRB 260122B: Swift-BAT refined analysis
  43. GRB 260120B: SVOM/GRM observation
  44. GRB 260120A: GECAM-B observation
  45. GRB 260120B: AstroSat CZTI detection
  46. GRB 260114A: Insight-HXMT/HE detection
  47. EP260119a: Assy AZT-20 optical observations
  48. EP260119a: Mondy and SAO RAS optical upper limits
  49. IceCube-260115A: No Candidate Transients from the Zwicky Transient Facility
  50. EP260119a: Xinglong optical upper limit
  51. Fermi GRB 260120C: Global MASTER-Net observations report
  52. GRB 260120B: Swift-BAT refined analysis
  53. EP260116a: COLIBRÍ further observations
  54. GRB 251122A / EP251122a: VLT/X-shooter host redshift z = 1.765
  55. GRB 260120B: Fermi GBM Observation
  56. EP260105a: GTC/HiPERCAM optical observations
  57. GRB 260120B: Swift/UVOT Detection
  58. GRB 260120B: COLIBRÍ optical upper limits
  59. GRB 260120B: SVOM/C-GFT optical counterpart detection
  60. GRB 260101A: 239Alferov CubeSat detection
  61. EP260116a: COLIBRÍ observations of a tentative optical rebrightening
  62. EP260119A: Mondy I-Band Observations
  63. GRB 260114A: Swift/UVOT Upper Limits
  64. EP260119a: Liverpool Telescope optical follow-up observations
  65. GRB 251202A: further radio observations with the VLA
  66. Trigger 1442421: Swift detection of HMXB 1A 1118-61
  67. EP260119A: GTC/OSIRIS+ spectroscopic redshift z = 5.47
  68. EP260119a: KAIT optical observations
  69. EP260119a: SVOM/VT optical observation
  70. EP260119a: update of EP-FXT follow-up observation
  71. EP260119a: NOT optical observations
  72. EP260119a: SAO RAS optical observations
  73. EP260116a: COLIBRÍ detection of a fading optical source
  74. GRB 251208D: SVOM/ECLAIRs refined analysis
  75. GRB 251208D: SVOM/ECLAIRs refined analysis
  76. GRB 260117A: Swift-XRT afterglow detection
  77. EP260119a: COLIBRÍ photometric redshift z ≈ 5.6
  78. EP260119a: Global MASTER-Net observations report
  79. GRB 260115A: AstroSat CZTI detection
  80. EP260119a: LCO optical observations
  81. GRB 260117A: ZTSh optical upper limit
  82. EP260119a: COLIBRÍ optical counterpart candidate
  83. EP260119a: preliminary result from the EP-FXT observation
  84. GRB 260117A: SVOM/COLIBRÍ (FM-GFT) optical observations
  85. Fermi-LAT Gamma-ray Observations of IceCube-260115A
  86. Swift trigger on the HMXB 1A 1118-61
  87. GRB 260117A: SVOM/VT optical candidate
  88. GRB 260117A: SVOM/C-GFT upper limit
  89. GRB 260117A: Swift ToO observations
  90. EP 260116a: COLIBRÍ optical upper limit
  91. GRB 260115A: GECAM-B observation
  92. FRB 20251229A: COLIBRÍ further inspection of the updated localization
  93. EP260116a: Liverpool Telescope upper limits
  94. FRB 20251229A: Updated CHIME/FRB Baseband Localization of FRB 20251229A
  95. EP260116A: 1.3m DFOT optical upper limit
  96. GRB 260114A: VLT/MUSE spectroscopic observations
  97. IceCube-260115A: Upper limits from a search for additional neutrino events in IceCube
  98. EP260116a: Global MASTER-Net observations report
  99. GRB 260111A: COLIBRÍ fading of the optical counterpart candidate
  100. EP260116a: Xinglong optical upper limit

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