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"
  1. GRB261010A: Keck/MOSFIRE detection of a near-IR source
  2. EP261015a: Einstein Probe detection of a fast X-ray transient
  3. EP261015a (WXT 11900947714): Possible optical counterpart from NOT and LCO
  4. The EP-WXT trigger 01709321333 is likely a flaring star
  5. GRB 261010A: ASKAP non-detection of a radio afterglow
  6. GRB 261010A: LBT tentative near-infrared detection
  7. GRB 261011A: SAO RAS and AbAO optical observations
  8. GRB 261010A: Glowbug gamma-ray detection
  9. GRB 261008A: SVOM/GRM observation
  10. GRB 261009A: GECAM-B detection of a burst
  11. EP261006a : MeerKAT radio observations.
  12. IceCube-261012A: Upper limits from a search for additional neutrino events in IceCube
  13. GRB 261010A: initial pulse rest-frame energetics from Konus-Wind detection
  14. GRB 261010A: a short minimum variability timescale and a distinct pulse evolution compatible with a merger origin
  15. GRB 261013A: Fermi GBM Final Real-time Localization
  16. GRB 261011A: Later-epoch J-band upper limit from the SYSU 80 cm infrared telescope
  17. Fermi-LAT Gamma-ray Observations of IceCube-261012A
  18. GRID detection of GRB 261010A
  19. GRB 261011A: GECAM-B observation
  20. GRB 261011B: GECAM-B observation
  21. GRB 261010A: J-band upper limit by the SYSU 80cm infrared telescope
  22. IceCube-260919A: No transient candidates from the Zwicky Transient Facility
  23. GRB 261010A: Swift-XRT refined Analysis
  24. GRB 261011A: Swift-XRT refined Analysis
  25. GRB 261011A: Enhanced Swift-XRT position
  26. GRB 261010A: a Type I-L (merger-driven) GRB candidate
  27. GRB 261011A: 10.4m GTC spectroscopic redshift (z = 2.407)
  28. GRB 261011A: Swift-BAT refined analysis
  29. IceCube-261012A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 261010A: 10.4m GTC spectroscopy of the galaxy 2" from the afterglow
  31. MAXI GRB261012.23: Global MASTER-Net observations report
  32. GRB 261011A: REM optical/NIR observations
  33. Konus-Wind detection of GRB 261010A
  34. Konus-Wind detection of GRB 261011A
  35. Konus-Wind detection of GRB 261007A/EP261007a
  36. GRB 261011A: SOAR optical afterglow observations at ~17 hours
  37. EP261006a: 10 GHz VLA observations
  38. GRB 261011A: VLT/X-shooter redshift constraints
  39. GRB 261012A: MAXI GSC detection
  40. GRB 261010A: Swift-BAT refined analysis
  41. GRB 261011A : MITSuME Akeno optical afterglow candidate detection
  42. GRB 261011A: Optical followup from Sichuan South Observatory
  43. GRB 261011A: GMG Optical Observation
  44. GRB 261011A: Liverpool Telescope optical observations
  45. GRB 261011A: J-band observations by the SYSU 80cm infrared telescope
  46. GRB 261010A: NOT confirmation of the optical afterglow
  47. GRB 261010A: Fermi GBM Observation
  48. GRB 261011B: Fermi GBM Final Localization
  49. GRB 261011A: continued LCO optical observations
  50. EP261007b: Global MASTER-Net observations report
  51. GRB 261011A: GROWTH-India Telescope optical observations
  52. GRB 261011A: Luminance-band upper limit from a 28cm telescope in Chengde
  53. Swift GRB 261011A: Global MASTER-Net observations report
  54. GRB 261011A: Optical follow-up observations with Kinder
  55. GRB 261011A: SVOM/C-GFT optical observations
  56. EP261007b: Second EP-FXT follow-up observation and a possible X-ray counterpart to the optical transient
  57. GRB 261011A: LCO optical observations
  58. GRB 261011A: SVOM/VT optical observation from VHF data
  59. GRB 261011A: LCO optical observations
  60. GRB 261011A: TRT optical afterglow detection
  61. GRB 261011A: GOTO optical counterpart detection
  62. GRB 261011A: Swift detection of an unusual burst
  63. GRB 261011A: SVOM detection of a long bright burst
  64. GRB 261010A: Enhanced Swift-XRT position
  65. EP261010a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  66. EP261006a / AT 2026aetp: Luminance-band optical follow-up with small-aperture telescopes
  67. GRB 261010A: possible optical afterglow detected with the 1.5m OSN
  68. GRB 261010A: NOT possible optical counterpart
  69. GRB 261010A: Swift detection of a burst
  70. GRB 261010A: Fermi GBM Final Real-time Localization
  71. EP261006a: Kilonova-Catcher optical follow-up and detection
  72. GRB 261001A: SVOM/GRM observation
  73. EP261006a / AT 2026aetp: Multiband optical follow-up with the PKU 60cm Telescope
  74. EP261010a: SVOM/VT optical upper limits
  75. EP261006a: Liverpool Telescope optical follow-up
  76. EP261010a: NOT optical upper limits
  77. EP261010a: Global MASTER-Net observations report
  78. EP261010a Einstein Probe detection of an X-ray transient
  79. GRB 261009A: Fermi GBM Final Real-time Localization
  80. GRB261007A: Lesedi optical afterglow detection
  81. EP261006a: Xinglong 2.16m/BFOSC optical follow-up observations
  82. EP261007b: SVOM/ECLAIRs Upper Limit
  83. GRB 261008A: GECAM-B observation
  84. EP261006a: Optical follow-up observations with MATCH
  85. EP261007b: J-band upper limit by SYSU 80cm infrared telescope
  86. EP261007b: Refined analysis of the EP-WXT and autonomous EP-FXT observations
  87. GRB 261007A: SVOM/ECLAIRs refined analysis
  88. EP261007b: SVOM/VT optical detection of the NOT transient
  89. GRB 261007A / EP261007a: SVOM/GWAC-F60A/B observations
  90. EP261006a / AT 2026aetp: VLT/X-shooter spectroscopic redshift z = 0.1853
  91. GRB 261007A: Glowbug gamma-ray detection
  92. GRB 261008A: Fermi GBM Final Real-time Localization
  93. GRB 261007A: NOT optical observations
  94. EP261007b: NOT optical observations, variable source outside the FXT region
  95. GRB 261007A: SVOM/GRM observation
  96. EP261007b: SVOM/C-GFT optical upper limits
  97. EP261007b: J-band upper limit with WINTER
  98. The EP-WXT trigger 01709321008/EP261007b：Xinglong optical upper limit
  99. GRB 261007A / EP261007a: AstroSat CZTI detection
  100. GRB 261005A: GECAM-B observation

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