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"
  1. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  2. Fermi GRB 260223A: Global MASTER-Net observations report
  3. GRB 260223A: Fermi GBM Final Real-time Localization
  4. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  5. EP260221a: COLIBRÍ optical counterpart candidate
  6. EP260221a: Gemini South z-band upper limit
  7. GRB 260222A: Fermi GBM Final Real-time Localization
  8. EP260221a: Global MASTER-Net observations report
  9. EP260221a: EP-FXT follow-up observation
  10. Fermi GRB 260221B: Global MASTER-Net observations report
  11. GRB 260221B: Fermi GBM Final Real-time Localization
  12. EP-WXT01709258519: Xinglong optical upper limit
  13. EP260221a: Xinglong optical upper limit
  14. Fermi GRB 260221A: Global MASTER-Net observations report
  15. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  16. GRB 260221A: Fermi GBM Final Real-time Localization
  17. EP260221a: GOTO optical upper limit
  18. EP260221a: COLIBRÍ optical upper limit
  19. SVOM alert sb26021801: LCO optical upper limit
  20. EP260221a: Einstein Probe detection of an X-ray transient
  21. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  22. GRB 260219A: AstroSat CZTI detection
  23. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 260219A: GECAM-B observation of a long burst
  25. Fermi GRB 260219A: Global MASTER-Net observations report
  26. GRB 260219A: Fermi GBM Final Real-time Localization
  27. SVOM alert sb26021801: LAST optical upper limit
  28. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. IceCube Alert 260217A: Global MASTER-Net observations report
  30. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  31. GRB 260217A: Fermi GBM Final Localization
  32. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  33. sb26021801: SVOM detection of a long faint X-ray transient
  34. The EP-WXT trigger 01709258455 is likely a flaring star
  35. EP-WXT 01709258455: NOT optical upper limits
  36. EP260214b: Mondy optical observations
  37. EP260214b: 1.3m DFOT optical upper limit
  38. EP260210a: Mondy optical upper limits
  39. Konus-Wind detection of GRB 260212A
  40. GRB 260208A: AbAO and Terskol optical upper limits
  41. GRB 260208A: continued Mondy optical observations
  42. IPN triangulation of GRB 260212A
  43. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  44. GRB 260213A: GECAM-B observation of a short burst
  45. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  46. GRB 260216A: Fermi GBM Final Real-time Localization
  47. EP260214b: Liverpool Telescope optical observations
  48. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  49. EP260214b: Optical upper limit with Kinder observations
  50. EP260214a: Optical upper limits with Kinder observations
  51. EP260214b: EP-FXT follow-up observation
  52. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  53. EP260214b: DDOTI Optical Detection
  54. EP260214b: GROWTH-India Telescope optical upper limit
  55. EP260214a: VLT near-infrared observation
  56. EP260214b: SVOM/VT optical observation
  57. EP260214a: NOT optical upper limits
  58. EP260214a: COLIBRÍ optical upper limits
  59. EP260214b: OHP/T120 optical observations
  60. EP260214a: refined analysis of the EP-FXT observation
  61. EP260214b: LCO optical counterpart detection
  62. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  63. GRB 260211A: SVOM/VT optical counterpart
  64. EP260214b: COLIBRÍ optical observations
  65. EP260214a: SVOM/VT optical upper limits
  66. EP260214b: NOT optical counterpart detection
  67. EP260214b: Einstein Probe detection of a fast X-ray transient
  68. EP260214a: Global MASTER-Net observations report
  69. EP260214a: Einstein Probe detection of an X-ray transient
  70. GRB 260212A: AstroSat CZTI detection
  71. GRB 260212A: Fermi GBM Observation
  72. EP260213a: Liverpool Telescope optical upper limits
  73. EP260213a: Global MASTER-Net observations report
  74. EP260213a: COLIBRÍ optical upper limits
  75. GRB 260212A: GECAM-B observation
  76. EP260213a: Optical upper limits with Kinder observations
  77. EP260213a: SVOM/VT optical upper limit
  78. EP260213a: Mondy R-band optical upper limit
  79. EP260213a: NUTTelA-TAO Early Optical Limits
  80. EP260213a: SVOM/C-GFT upper limit
  81. EP260213a: refined analysis of the EP-FXT observation
  82. EP260213a: Einstein Probe detection of a fast X-ray transient
  83. EP/WXT 01709258378: NOT optical upper limits
  84. GRB 260212A: SVOM/GRM observation of a long burst
  85. GRB 260213B: Fermi GBM Final Localization
  86. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  87. GRB 260211A - SVOM/ECLAIRs refined analysis
  88. GRB 260204A: SVOM/ECLAIRs refined analysis
  89. GRB 260213A: Fermi GBM Final Localization
  90. GRB 260211A: EP-FXT follow-up observation
  91. GRB 260211A: SVOM/VT optical observation
  92. GRB 260212A: Glowbug gamma-ray detection
  93. GRB 260211A: GOTO optical upper limit
  94. Fermi GRB 260212A: Global MASTER-Net observations report
  95. GRB 260212A: Fermi GBM Final Real-time Localization
  96. GRB 260211A: LAST optical upper limit
  97. GRB 260210A: SVOM/GRM observation
  98. Fermi GBM Sub-Threshold Detection of GRB 260211A
  99. Konus-Wind detection of GRB 260207B
  100. GRB 260128B: SVOM/ECLAIRs refined analysis

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