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"

22212 results found.

  1. EP/WXT 01709258378: NOT optical upper limits
  2. GRB 260211A - SVOM/ECLAIRs refined analysis
  3. GRB 260204A: SVOM/ECLAIRs refined analysis
  4. GRB 260211A: GOTO optical upper limit
  5. Fermi GRB 260212A: Global MASTER-Net observations report
  6. GRB 260211A: LAST optical upper limit
  7. GRB 260128B: SVOM/ECLAIRs refined analysis
  8. GRB260131A/B: 3.6m DOT Optical Observations
  9. GRB 260211A: SVOM/COLIBRÍ (FM-GFT) optical upper limits
  10. Fermi trigger No 792537871: Global MASTER-Net observations report
  11. Swift Operations Update + Community Forum (Friday, February 13 @ 10:00 AM EST)
  12. Konus-Wind detection of GRB 260209B
  13. GRB 260208A: Swift UVOT detection
  14. Fermi GRB 260210C: Global MASTER-Net observations report
  15. EP260209a: LCO optical upper limits
  16. EP260210a: Global MASTER-Net observations report
  17. EP260210a: refined analysis of the EP-FXT observation
  18. EP260209a: Global MASTER-Net observations report
  19. GRB 260208A: LCO detection of the optical counterpart
  20. EP260210a: Optical upper limits with Kinder observations
  21. EP260210a: SVOM/C-GFT upper limit
  22. GRB 260204A: Swift-XRT afterglow detection
  23. GRB260208A: Liverpool Telescope optical follow-up observations
  24. Fermi GRB 260209A: Global MASTER-Net observations report
  25. GRB 260208B: Swift-XRT observations
  26. GRB 260131A/B: continued Mondy optical observations
  27. GRB 260204A: Swift/UVOT Upper Limits
  28. GRB 260208B: COLIBRÍ optical observations
  29. GRB 260208A: Mondy optical observations (duplicate submission)
  30. GRB 260208A: Mondy optical observations
  31. GRB 260208A: 1.3m DFOT optical detection
  32. GRB 260208A: COLIBRÍ optical observations
  33. GRB 260208A: NOT spectroscopic redshift z = 2.36
  34. GRB 260208A: Liverpool Telescope optical detection
  35. Fermi GRB 260208C: Global MASTER-Net observations report
  36. GRB 260208B: SVOM/VT optical candidate
  37. GRB 260208A: Zwicky Transient Facility Follow-Up of a Fermi GRB (Trigger 792220053)
  38. GRB 260208A: SVOM/VT optical observation
  39. Fermi GRB 260208D: Global MASTER-Net observations report
  40. GRB 260208A: Swift-XRT observations
  41. GRB 260208B: Swift ToO observations
  42. LAT GRB 260208B: Global MASTER-Net observations report
  43. GRB 260208A: Swift ToO observations
  44. GRB 260208A: GOTO detection of a potential optical counterpart (GOTO26aob)
  45. GRB 260208A : MASTER bright optical transient inside retracted Fermi error-box
  46. Fermi GRB 260208A: Global MASTER-Net observations report
  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 260206A: Swift-XRT observations
  51. Fermi trigger No 792135758: Global MASTER-Net observations report
  52. EP260131a: VLA detection
  53. GRB 260206A: Tiled Swift observations
  54. GRB 260204A: Swift-XRT observations
  55. GRB 260204A: LCO optical afterglow detection
  56. GRB 260204A : MASTER Global robotic net optical observations
  57. GRB 260204A: GOTO optical upper limit
  58. EP260110a: Late GTC/EMIR near-infrared observations
  59. GRB 260204A: SVOM detection of a burst
  60. GRB 260121A: 239Alferov CubeSat detection
  61. Konus-Wind detection of GRB 260121A
  62. GRB 260131A/B: OHP/T193 optical observations
  63. GRB 260131A: KAIT optical observations
  64. GRB 251230A: MeerLICHT afterglow detection
  65. GRB 260131A: FTW optical and NIR observations
  66. GRB 260131A/AT2026bwg: Observations by the Zwicky Transient Facility
  67. GRB 260131A/B: GTC/OSIRIS+ redshift confimation
  68. GRB 260131A/B (AT2026bwg): J-band observations by SYSU 80cm infrared telescope
  69. GRB 260131A/B (AT2026bwg): COLIBRÍ further optical observations
  70. EP260131a: COLIBRÍ further observations
  71. Konus-Wind detection of GRB 260128A / EP260128a
  72. Konus-Wind detection of GRB 260131A/B
  73. GRB 260131A/B (AT2026bwg): COLIBRÍ optical observations and confirmation of fading
  74. GRB 260131A/B: GOTO candidate optical counterpart consistent with the MAXI localisation
  75. EP260131a: COLIBRÍ observations of slow optical fading
  76. EP260131a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  77. EP260131a: VLT/X-shooter spectroscopic redshift z = 0.937
  78. EP260131a: NOT early detection of the counterpart in "rapid response mode"
  79. EP260131a: COLIBRÍ optical observations of the counterpart
  80. Fermi GRB 260130A: Global MASTER-Net observations report
  81. EP260128a / GRB 260128A: NOT and TNG optical and NIR upper limits
  82. Fermi GRB 260129A: Global MASTER-Net observations report
  83. EP260128a: J band upper limit by SYSU 80cm infrared telescope
  84. GRB 260127B: Swift-XRT observations
  85. GRB 260127A: INASAN-Kislovodsk, SAO RAS, and Terskol K-800 optical observations
  86. EP260128a: NOT optical counterpart candidate
  87. EP260128a: refined analysis of the EP-WXT and autonomous EP-FXT observations
  88. EP260128a: Liverpool Telescope optical observations and possible counterpart
  89. EP260128a: Global MASTER-Net observations report
  90. Fermi GRB 260127A: Global MASTER-Net observations report
  91. IceCube-260125A: No Candidate Transients from the Zwicky Transient Facility
  92. GRB 260127A: COLIBRÍ optical observations
  93. GRB 260127A: NOT optical observations
  94. GRB 260127B: Swift ToO observations
  95. GRB 260127B: GOTO candidate optical counterpart
  96. GRB 260127A: SVOM/C-GFT optical observations
  97. Fermi GRB 260127B: Global MASTER-Net observations report
  98. Swift GRB 260127A: Global MASTER-Net observations report
  99. GRB 260127A: LCO optical afterglow discovery
  100. GRB 260125A: Swift-XRT 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