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"

29092 results found.

  1. GRB 260208B: refined analysis of the EP-FXT observation
  2. GRB 260207B: AstroSat CZTI detection
  3. GRB 260208C: SVOM/GRM observation
  4. GRB 260208B: AstroSat CZTI detection of a bright long burst
  5. GRB260208A: Liverpool Telescope optical follow-up observations
  6. GRB 260208A: Glowbug gamma-ray detection
  7. GRB 260208A: NuSTAR detection of prompt emission
  8. GRB 260208A: Fermi GBM Observation
  9. Fermi GRB 260209A: Global MASTER-Net observations report
  10. GRB 260208B: Swift-XRT observations
  11. GRB 260131A/B: continued Mondy optical observations
  12. GRB 260204A: Swift/UVOT Upper Limits
  13. GRB 260208B: COLIBRÍ optical observations
  14. GRB 260208A: Mondy optical observations
  15. GRB 260208A: 1.3m DFOT optical detection
  16. GRB 260208A: COLIBRÍ optical observations
  17. GRB 260208B: EP-FXT observation
  18. GRB 260208A: NOT spectroscopic redshift z = 2.36
  19. GRB 260208A: Liverpool Telescope optical detection
  20. Fermi GRB 260208C: Global MASTER-Net observations report
  21. GRB 260208B: SVOM/VT optical candidate
  22. GRB 260208A: GECAM-B observation of a bright burst
  23. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  24. GRB 260209A: Fermi GBM Final Real-time Localization
  25. GRB 260208A: SVOM/VT optical observation
  26. Fermi GRB 260208D: Global MASTER-Net observations report
  27. GRB 260208D: Fermi GBM Final Real-time Localization
  28. GRB 260208A: Swift-XRT observations
  29. GRB 260208B: Swift ToO observations
  30. GRB 260208B: SVOM/GRM observation of a bright burst
  31. GRB 260208B: Fermi GBM Detection
  32. LAT GRB 260208B: Global MASTER-Net observations report
  33. GRB 260208B: Fermi-LAT detection
  34. GRB 260208C: Fermi GBM Final Real-time Localization
  35. GRB 260208A: Fermi-LAT detection
  36. GRB 260207B: GECAM-B observation
  37. GRB 260208A: Swift ToO observations
  38. GRB 260208A: Fermi GBM Classification Correction
  39. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  40. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  41. GRB 260208B: BALROG localization (Fermi Trigger 792237169 / GRB 260208412)
  42. GRB 260208B: Fermi GBM Final Real-time Localization
  43. Fermi GRB 260208A: Global MASTER-Net observations report
  44. Fermi Gamma-ray Burst Monitor trigger 792220053/260208214 is not a GRB
  45. GRB 260208A: Fermi GBM Final Real-time Localization
  46. GRB 260207B: Fermi GBM Detection of a Short Burst with Extended Emission
  47. GRB 260207A : MASTER optical counterpart discovery
  48. GRB 260131A/B: Mondy and Terskol optical observations
  49. Fermi GRB 260207B: Global MASTER-Net observations report
  50. GRB 260207B: Fermi GBM Final Real-time Localization
  51. GRB 260207A: Fermi GBM Final Localization
  52. Fermi trigger No 792135758: Global MASTER-Net observations report
  53. GRB 260204A: SVOM/VT confirms fading of the optical afterglow
  54. GRB 260204A: Swift-XRT observations
  55. GRB 260204A: LCO optical afterglow detection
  56. GRB 260204A: SVOM/VT optical candidate
  57. GRB 260204A : MASTER Global robotic net optical observations
  58. Fermi GBM Sub-Threshold Detection of GRB 260204A
  59. GRB 260204A: GOTO optical upper limit
  60. GRB 260204A: LCO optical upper limits
  61. EP260110a: Late GTC/EMIR near-infrared observations
  62. GRB 260204B: Fermi GBM Final Real-time Localization
  63. GRB 260204A: SVOM detection of a burst
  64. GRB 260131A/B: OHP/T193 optical observations
  65. GRB 260131A: KAIT optical observations
  66. GRB 251230A: MeerLICHT afterglow detection
  67. GRB 260131A: FTW optical and NIR observations
  68. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  69. GRID detection of GRB 260131A/B
  70. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  71. GRB 260130A: Insight-HXMT/HE detection
  72. GRB 260130A: GECAM-B observation of a short burst
  73. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  74. GRB 260131A/B: EP/FXT X-ray afterglow detection
  75. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  76. GRB 260127B: Insight-HXMT/HE detection
  77. GRB 260127B: GECAM-B observation of a short burst
  78. GRB 260127A: GECAM-B observation
  79. GRB 260131A: NOT spectroscopic redshift z = 1.434
  80. EP260131a: Liverpool Telescope optical upper limits
  81. EP260131a: COLIBRÍ further observations
  82. Konus-Wind detection of GRB 260128A / EP260128a
  83. GRB 260131A: Insight-HXMT/HE detection
  84. Konus-Wind detection of GRB 260131A/B
  85. EP260131a: Xinglong optical upper limit
  86. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  87. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  88. GRB 260131A/B: Fermi GBM Observation
  89. EP260131a: COLIBRÍ observations of slow optical fading
  90. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  91. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  92. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  93. GRB 260131A: Fermi GBM Final Real-time Localization
  94. EP260131a: COLIBRÍ optical observations of the counterpart
  95. EP260131a: Las Cumbres detection of an optical counterpart
  96. GRB 260127B: AstroSat CZTI detection
  97. GRB 260130A: Fermi GBM Detection
  98. GRB 260127B: Fermi GBM Detection
  99. EP260128a / GRB 260128A: COLIBRÍ optical upper limit
  100. Fermi GRB 260130A: Global MASTER-Net observations report

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