Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! See news and announcements

GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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"

28052 results found.

  1. Fermi GRB 260604C: Global MASTER-Net observations report
  2. SVOM GRB260604.85: Global MASTER-Net observations report
  3. GRB 260603A: Simeiz Zeiss-1000 optical upper limit
  4. GRB 260601A: CALET Gamma-Ray Burst Monitor detection
  5. EP260602a: EP-FXT follow-up observation
  6. EP260603a: Global MASTER-Net observations report
  7. EP260603a: Einstein Probe detection of a fast X-ray transient
  8. EP260602d: Optical Upper limits with kinder observations
  9. EP260602b: Liverpool Telescope observations
  10. EP260602a: Liverpool Telescope optical upper limits
  11. EP260602b: Liverpool Telescope and LCO observations
  12. EP260602a: GTC and Liverpool Telescope optical observations
  13. EP260601a/GRB 260601B: EP-FXT follow-up observation
  14. GRB 260601B / EP260601a: Mondy optical upper limit
  15. EP260602b: EP-FXT follow-up observation
  16. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  17. GRB 260603A: Kilonova-Catcher optical upper limit
  18. GRB 260603A: SVOM/VT optical observations
  19. EP260602a: NOT NIR J-band observations
  20. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  21. EP260602d: Einstein Probe detection of a fast X-ray transient
  22. Fermi trigger No 802141998: Global MASTER-Net observations report
  23. GRB 260601A: SVOM/GRM observation of a short burst
  24. EP260602c: Einstein Probe detection of a fast X-ray transient
  25. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  26. EP260602a: COLIBRÍ optical observations
  27. GRB260601B/EP260601a: NOT near-infrared observations
  28. SVOM GRB260603.23: Global MASTER-Net observations report
  29. GRB 260603A: SVOM detection of a burst
  30. EP260602b: Einstein Probe detection of a fast X-ray transient
  31. Fermi GRB 260602B: Global MASTER-Net observations report
  32. Fermi GRB 260602B: Global MASTER-Net observations report
  33. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  34. EP260602a: SVOM/VT optical candidate
  35. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  36. GRB 260601B/EP260601a: J-band upper limit with WINTER
  37. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  38. EP260530a/AT 2026nwl: KAIT optical observations
  39. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  40. EP260602a: Optical upper limits with Kinder observations
  41. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  42. EP260602a: Einstein Probe detection of a fast X-ray transient
  43. GRB 260601B/EP260601a: SVOM/VT optical observations
  44. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  45. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  46. EP260601a: Einstein Probe detection of an X-ray transient
  47. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  48. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  49. GRB 260601A: Glowbug gamma-ray detection of a short burst
  50. GRB 260531B: Glowbug gamma-ray detection
  51. GRB 260601A: Fermi GBM Observation
  52. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  53. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  54. Fermi GRB 260601A: Global MASTER-Net observations report
  55. GRB 260601A: Fermi GBM Final Real-time Localization
  56. The EP-WXT trigger 01709266272 is likely a flaring star
  57. AT2026nik: EP-FXT X-ray counterpart
  58. Fermi trigger No 801900520: Global MASTER-Net observations report
  59. GRB 260531A: MAXI/GSC detection
  60. AT 2026nuz: COLIBRÍ optical observations
  61. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  62. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  63. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  64. Fermi GRB 260529A: Global MASTER-Net observations report
  65. EP260526a: SVOM/VT optical upper limits
  66. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  67. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  68. EP260527a/GRB 260527A: EP-FXT follow-up observation
  69. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  70. EP260527a: SVOM/VT optical observation
  71. EP260527a: COLIBRÍ optical detection
  72. EP260527a: Einstein Probe detection of a fast X-ray transient
  73. Fermi trigger No 801580882: Global MASTER-Net observations report
  74. EP260526a: LCO optical upper limits
  75. EP260526a: Einstein Probe detection of a fast X-ray transient
  76. EP260526.405: COLIBRÍ optical upper limits
  77. The EP-WXT trigger 01709266106 is not a real source
  78. Fermi GRB 260526A: Global MASTER-Net observations report
  79. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  80. EP-WXT 01709266106: NOT optical upper limits
  81. Fermi GRB 260525A: Global MASTER-Net observations report
  82. GRB 260523B: AstroSat CZTI detection
  83. Fermi GRB 260523A: Global MASTER-Net observations report
  84. GRB 260522A: Fermi GBM Observation
  85. GRB 260522B: NuSTAR detection of prompt emission
  86. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  87. Fermi trigger No 801135305: Global MASTER-Net observations report
  88. Fermi GRB 260522A: Global MASTER-Net observations report
  89. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  90. GRB 260511A: iTelescope T-75 optical detection
  91. GRB 260520B: SVOM/GRM observation
  92. GRB 260411B: TERI Gamma-ray detection
  93. GRB 260407A: TERI Gamma-ray detection
  94. GRB 260307A: TERI Gamma-ray detection
  95. GRB 260225D: TERI Gamma-ray detection
  96. GRB 251118A: TERI Gamma-ray detection
  97. GRB 251113A: TERI Gamma-ray detection
  98. GRB 260428A: TERI Gamma-ray detection
  99. GRB 260519C: NuSTAR detection of prompt emission
  100. Konus-Wind detection of GRB 260518A

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