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"

12191 results found.

  1. EP261030a: Einstein Probe detection of a fast X-ray transient
  2. GRB 261026A: Mondy, SAO RAS and Terskol optical observations
  3. GRB 261029A: Liverpool Telescope observations
  4. GRB 261029A: FRAM-ORM and FRAM-Auger optical afterglow light curve
  5. GRB 261029B : AstroSat CZTI detection
  6. GRB 261029A : AstroSat CZTI detection
  7. EP261010a: Xinglong optical follow-up
  8. GRB 261029A: Fermi-LAT detection
  9. GRB 261028B / MAXI J1609-487: MAXI GSC detection
  10. GRB 261026B: AstroSat CZTI detection
  11. GRB 261026A: SAO RAS optical observations
  12. GRB 261026B: NuSTAR detection of prompt emission
  13. GRB 261026A: Ondrejov D50 optical limit
  14. GRB 261026A: J-band observations by the SYSU 80cm infrared telescope
  15. GRB 261026A: SVOM/VT optical observations
  16. GRB 261024D: AstroSat CZTI detection of a long burst
  17. GRB 261024C: AstroSat CZTI detection of a long burst
  18. Fermi GRB 261026B: Global MASTER-Net observations report
  19. GRB 261026A: SVOM detection of a burst
  20. EP261023a: J-band upper limit with WINTER
  21. EP261025a: Einstein Probe detection of a fast X-ray transient
  22. EP261015a: MAO/AZT-22 optical observations
  23. IceCube-261020A: Upper limits from a search for additional neutrino events in IceCube
  24. NuSTAR 261020, a 830s hard X-ray transient
  25. EP261015a: GSP multiband optical follow-up observations
  26. EP261015a: Further optical observations with the 1.3m DFOT
  27. GRB 261020B: AstroSat CZTI detection of a short burst
  28. Fermi-LAT Gamma-ray Observations of IceCube-261020A
  29. EP261015a: AZT-20 Assy-Turgen optical observations
  30. GRB 261020A: Fermi GBM Observation
  31. EP261015a: Terskol Zeiss-2000 optical upper limit
  32. GRB 261017A: COLIBRÍ optical upper limit
  33. IceCube-261020A - IceCube observation of a high-energy neutrino candidate track-like event
  34. GRB 261020A: MAXI GSC detection
  35. GRB 261020A: Fermi GBM Final Real-time Localization
  36. EP261015a: COLIBRÍ optical observations of a rebrightening
  37. Konus-Wind detection of GRB 261017A
  38. GRB 261017A: J band upper limit by the SYSU 80cm infrared telescope
  39. GRB 261017A: Swift-XRT refined Analysis
  40. EP261015a: Tentative fading of the candidate optical counterpart from the NOT
  41. EP261015b: Refined analysis of EP-FXT observations
  42. EP261015b: J-band upper limit by the SYSU 80cm infrared telescope
  43. EP261015a: refined analysis of EP-FXT observations
  44. EP261015c: J-band upper limit with WINTER
  45. GRB 261010A: VLA radio observations
  46. EP261015a: Einstein Probe detection of a fast X-ray transient
  47. GRB 261010A: LBT tentative near-infrared detection
  48. GRB 261011A: SAO RAS and AbAO optical observations
  49. EP261006a : MeerKAT radio observations.
  50. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  51. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  52. GRB 261010A: Swift-XRT refined Analysis
  53. GRB 261011A: Swift-XRT refined Analysis
  54. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  55. Konus-Wind detection of GRB 261010A
  56. Konus-Wind detection of GRB 261011A
  57. Konus-Wind detection of GRB 261007A/EP261007a
  58. GRB 261012A: MAXI GSC detection
  59. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  60. GRB 261011A: Optical follow-up observations with Kinder
  61. GRB 261011A: SVOM/VT optical observation from VHF data
  62. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  63. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  64. EP261010a: SVOM/VT optical upper limits
  65. EP261010a Einstein Probe detection of an X-ray transient
  66. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  67. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  68. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  69. GRB 261007A: NOT optical observations
  70. EP261007b: NOT optical observations, variable source outside the FXT region
  71. GRB 261007A / EP261007a: AstroSat CZTI detection
  72. EP261007a/GRB 261007A：Xinglong optical observation
  73. GRB 261007A/EP261007a: Optical follow-up observations with Kinder
  74. EP261006a: Optical follow-up observations with Kinder
  75. EP261006a: Liverpool Telescope optical observations
  76. EP261006a: Early Optical Observations by WFST
  77. GRB 261007A: Swift-XRT afterglow detection
  78. EP261007b: Einstein Probe detection of an X-ray transient
  79. GRB 261007A: SVOM/C-GFT optical observations
  80. GRB 261007B: Fermi GBM Final Real-time Localization
  81. EP261007a/GRB 261007A: Einstein Probe detection of an X-ray transient
  82. EP261006a: Einstein Probe detection of an X-ray transient
  83. GRB 261007A: SVOM detection of a burst
  84. GRB 261005B: Swift-XRT refined Analysis
  85. EP trigger 01709320985: Ondrejov D50 optical upper limits
  86. GRB 261005A: Glowbug gamma-ray detection
  87. GRB 261005A: Fermi GBM Final Real-time Localization
  88. GRB 261002A: Fermi GBM Final Localization
  89. EP#01709320865: Swift-XRT observations
  90. Konus-Wind detection of GRB 260919A / EP 260920a
  91. Fermi GRB 261003A: Global MASTER-Net observations report
  92. EP261003a: Einstein Probe detection of an X-ray transient
  93. EP Alert 261003.01: Global MASTER-Net observations report
  94. Fermi-LAT Gamma-ray Observations of IceCube-260930A
  95. Fermi GRB 260930B: Global MASTER-Net observations report
  96. IceCube Alert 260930A: Global MASTER-Net observations report
  97. GRB 260926C: AstroSat CZTI detection
  98. GRB 260926A: GECAM-B observation
  99. EP260927a: Einstein Probe detection of a fast X-ray transient
  100. GRB 260926A: Glowbug gamma-ray 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