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"

28049 results found.

  1. EP260602a: EP-FXT follow-up observation
  2. EP260603a: Global MASTER-Net observations report
  3. EP260603a: Einstein Probe detection of a fast X-ray transient
  4. EP260602d: Optical Upper limits with kinder observations
  5. EP260602b: Liverpool Telescope observations
  6. EP260602a: Liverpool Telescope optical upper limits
  7. EP260602b: Liverpool Telescope and LCO observations
  8. EP260602a: GTC and Liverpool Telescope optical observations
  9. EP260601a/GRB 260601B: EP-FXT follow-up observation
  10. GRB 260601B / EP260601a: Mondy optical upper limit
  11. EP260602b: EP-FXT follow-up observation
  12. GRB 260601B/EP260601a: Glowbug gamma-ray detection
  13. GRB 260603A: Kilonova-Catcher optical upper limit
  14. GRB 260603A: SVOM/VT optical observations
  15. EP260602a: NOT NIR J-band observations
  16. GRB 260603A: SVOM/COLIBRÍ (FM-GFT) photometric redshift z = 3.57
  17. EP260602d: Einstein Probe detection of a fast X-ray transient
  18. Fermi trigger No 802141998: Global MASTER-Net observations report
  19. GRB 260601A: SVOM/GRM observation of a short burst
  20. EP260602c: Einstein Probe detection of a fast X-ray transient
  21. GRB 260603A: SVOM/COLIBRÍ (GFT-FM) optical counterpart candidate
  22. EP260602a: COLIBRÍ optical observations
  23. GRB260601B/EP260601a: NOT near-infrared observations
  24. SVOM GRB260603.23: Global MASTER-Net observations report
  25. GRB 260603A: SVOM detection of a burst
  26. EP260602b: Einstein Probe detection of a fast X-ray transient
  27. Fermi GRB 260602B: Global MASTER-Net observations report
  28. Fermi GRB 260602B: Global MASTER-Net observations report
  29. EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
  30. EP260602a: SVOM/VT optical candidate
  31. EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
  32. GRB 260601B/EP260601a: J-band upper limit with WINTER
  33. EP260530a/AT 2026nwl: COLIBRÍ optical follow up
  34. EP260530a/AT 2026nwl: KAIT optical observations
  35. GRB 260601B: CALET Gamma-Ray Burst Monitor detection
  36. EP260602a: Optical upper limits with Kinder observations
  37. GRB 260601B / EP260601a: NuSTAR detection of prompt emission
  38. EP260602a: Einstein Probe detection of a fast X-ray transient
  39. GRB 260601B/EP260601a: SVOM/VT optical observations
  40. GRB 260601B/EP260601a: GECAM-B analysis suggests a possible long duration Type I burst
  41. GRB 260601B: GECAM-B detection of a burst probably associated with EP260601a
  42. EP260601a: Einstein Probe detection of an X-ray transient
  43. EP-WXT trigger 01709266307 (EP260601a): COLIBRÍ optical observations
  44. EP-WXT trigger 01709266307 (EP260601a): JinShan optical counterpart detection
  45. GRB 260601A: Glowbug gamma-ray detection of a short burst
  46. GRB 260531B: Glowbug gamma-ray detection
  47. GRB 260601A: Fermi GBM Observation
  48. EP260530a/AT 2026nwl: COLIBRÍ optical observations
  49. GRB 260527A/EP260527a: Glowbug gamma-ray detection
  50. Fermi GRB 260601A: Global MASTER-Net observations report
  51. GRB 260601A: Fermi GBM Final Real-time Localization
  52. The EP-WXT trigger 01709266272 is likely a flaring star
  53. AT2026nik: EP-FXT X-ray counterpart
  54. Fermi trigger No 801900520: Global MASTER-Net observations report
  55. GRB 260531A: MAXI/GSC detection
  56. AT 2026nuz: COLIBRÍ optical observations
  57. EP260527a/GRB 260527A: optical upper limit with Kinder observations
  58. GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
  59. GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
  60. Fermi GRB 260529A: Global MASTER-Net observations report
  61. EP260526a: SVOM/VT optical upper limits
  62. EP260527a / GRB 260527A: VLT detection of the optical and nIR counterpart
  63. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  64. EP260527a/GRB 260527A: EP-FXT follow-up observation
  65. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  66. EP260527a: SVOM/VT optical observation
  67. EP260527a: COLIBRÍ optical detection
  68. EP260527a: Einstein Probe detection of a fast X-ray transient
  69. Fermi trigger No 801580882: Global MASTER-Net observations report
  70. EP260526a: LCO optical upper limits
  71. EP260526a: Einstein Probe detection of a fast X-ray transient
  72. EP260526.405: COLIBRÍ optical upper limits
  73. The EP-WXT trigger 01709266106 is not a real source
  74. Fermi GRB 260526A: Global MASTER-Net observations report
  75. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  76. EP-WXT 01709266106: NOT optical upper limits
  77. Fermi GRB 260525A: Global MASTER-Net observations report
  78. GRB 260523B: AstroSat CZTI detection
  79. Fermi GRB 260523A: Global MASTER-Net observations report
  80. GRB 260522A: Fermi GBM Observation
  81. GRB 260522B: NuSTAR detection of prompt emission
  82. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  83. Fermi trigger No 801135305: Global MASTER-Net observations report
  84. Fermi GRB 260522A: Global MASTER-Net observations report
  85. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  86. GRB 260511A: iTelescope T-75 optical detection
  87. GRB 260520B: SVOM/GRM observation
  88. GRB 260411B: TERI Gamma-ray detection
  89. GRB 260407A: TERI Gamma-ray detection
  90. GRB 260307A: TERI Gamma-ray detection
  91. GRB 260225D: TERI Gamma-ray detection
  92. GRB 251118A: TERI Gamma-ray detection
  93. GRB 251113A: TERI Gamma-ray detection
  94. GRB 260428A: TERI Gamma-ray detection
  95. GRB 260519C: NuSTAR detection of prompt emission
  96. Konus-Wind detection of GRB 260518A
  97. GRB 260516D: SVOM/ECLAIRs refined analysis
  98. GRB 260421B: radio detection with the VLA
  99. GRB 260509A: CrAO ZTSh optical upper limit
  100. GRB 260516D: GOTO optical counterpart 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