Skip to main content
New! CHIME and DSA-110 FRB Notices, IceCube Notices and Schema v6.1.1. 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. EP260223a: COLIBRÍ optical upper limits
  2. EP260223a: Einstein Probe detection of an X-ray transient
  3. GRB 260223A: SVOM/VT optical observation
  4. GRB 260223A: SVOM/GRM observation
  5. GRB 260223A: COLIBRÍ further optical observations and a brightening
  6. EP260221a: Optical upper limit with Kinder observations
  7. GRB 260223A: COLIBRÍ optical observations
  8. GRB 260223A: DDOTI Optical Candidate
  9. GRB 260223A: BALROG localization (Fermi Trigger 793512674 / GRB 260223174)
  10. Fermi GRB 260223A: Global MASTER-Net observations report
  11. GRB 260223A: Fermi GBM Final Real-time Localization
  12. EP260221a: Liverpool Telescope detection of COLIBRÍ counterpart candidate
  13. EP260221a: COLIBRÍ optical counterpart candidate
  14. EP260221a: Gemini South z-band upper limit
  15. GRB 260222A: Fermi GBM Final Real-time Localization
  16. EP260221a: Global MASTER-Net observations report
  17. EP260221a: EP-FXT follow-up observation
  18. Fermi GRB 260221B: Global MASTER-Net observations report
  19. GRB 260221B: Fermi GBM Final Real-time Localization
  20. EP-WXT01709258519: Xinglong optical upper limit
  21. EP260221a: Xinglong optical upper limit
  22. Fermi GRB 260221A: Global MASTER-Net observations report
  23. ZTF26aaglqak/AT2026dbl: COLIBRÍ Optical Observations
  24. GRB 260221A: Fermi GBM Final Real-time Localization
  25. EP260221a: GOTO optical upper limit
  26. EP260221a: COLIBRÍ optical upper limit
  27. SVOM alert sb26021801: LCO optical upper limit
  28. EP260221a: Einstein Probe detection of an X-ray transient
  29. The EP-WXT trigger 01709258519 is likely caused by Mrk 421
  30. GRB 260219A: AstroSat CZTI detection
  31. IceCube-260217A: Upper limits from a search for additional neutrino events in IceCube
  32. GRB 260219A: GECAM-B observation of a long burst
  33. Fermi GRB 260219A: Global MASTER-Net observations report
  34. GRB 260219A: Fermi GBM Final Real-time Localization
  35. SVOM alert sb26021801: LAST optical upper limit
  36. sb26021801: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  37. IceCube Alert 260217A: Global MASTER-Net observations report
  38. Fermi-LAT Gamma-ray Observations of IceCube-260217A
  39. GRB 260217A: Fermi GBM Final Localization
  40. GRB 260214B/EP260214b: SVOM/ECLAIRs detection through targeted search
  41. sb26021801: SVOM detection of a long faint X-ray transient
  42. The EP-WXT trigger 01709258455 is likely a flaring star
  43. EP-WXT 01709258455: NOT optical upper limits
  44. EP260214b: Mondy optical observations
  45. EP260214b: 1.3m DFOT optical upper limit
  46. EP260210a: Mondy optical upper limits
  47. Konus-Wind detection of GRB 260212A
  48. GRB 260208A: AbAO and Terskol optical upper limits
  49. GRB 260208A: continued Mondy optical observations
  50. IPN triangulation of GRB 260212A
  51. IceCube-260217A - IceCube observation of a high-energy neutrino candidate track-like event
  52. GRB 260213A: GECAM-B observation of a short burst
  53. GRB 260216A: Fermi Gamma-ray Burst Monitor trigger 792969362/260216886 is not a GRB
  54. GRB 260216A: Fermi GBM Final Real-time Localization
  55. EP260214b: Liverpool Telescope optical observations
  56. GRB 260206A: probable hard X-ray burst from 4U 0513-40
  57. EP260214b: Optical upper limit with Kinder observations
  58. EP260214a: Optical upper limits with Kinder observations
  59. EP260214b: EP-FXT follow-up observation
  60. EP260214a / GRB 260214A: Fermi-GBM Sub-Threshold Detection
  61. EP260214b: DDOTI Optical Detection
  62. EP260214b: GROWTH-India Telescope optical upper limit
  63. EP260214a: VLT near-infrared observation
  64. EP260214b: SVOM/VT optical observation
  65. EP260214a: NOT optical upper limits
  66. EP260214a: COLIBRÍ optical upper limits
  67. EP260214b: OHP/T120 optical observations
  68. EP260214a: refined analysis of the EP-FXT observation
  69. EP260214b: LCO optical counterpart detection
  70. EP260214b: VLT/X-shooter spectroscopic redshift z = 1.208
  71. GRB 260211A: SVOM/VT optical counterpart
  72. EP260214b: COLIBRÍ optical observations
  73. EP260214a: SVOM/VT optical upper limits
  74. EP260214b: NOT optical counterpart detection
  75. EP260214b: Einstein Probe detection of a fast X-ray transient
  76. EP260214a: Global MASTER-Net observations report
  77. EP260214a: Einstein Probe detection of an X-ray transient
  78. GRB 260212A: AstroSat CZTI detection
  79. GRB 260212A: Fermi GBM Observation
  80. EP260213a: Liverpool Telescope optical upper limits
  81. EP260213a: Global MASTER-Net observations report
  82. EP260213a: COLIBRÍ optical upper limits
  83. GRB 260212A: GECAM-B observation
  84. EP260213a: Optical upper limits with Kinder observations
  85. EP260213a: SVOM/VT optical upper limit
  86. EP260213a: Mondy R-band optical upper limit
  87. EP260213a: NUTTelA-TAO Early Optical Limits
  88. EP260213a: SVOM/C-GFT upper limit
  89. EP260213a: refined analysis of the EP-FXT observation
  90. EP260213a: Einstein Probe detection of a fast X-ray transient
  91. EP/WXT 01709258378: NOT optical upper limits
  92. GRB 260212A: SVOM/GRM observation of a long burst
  93. GRB 260213B: Fermi GBM Final Localization
  94. GRB 260213B: BALROG localization (Fermi Trigger 792697214 / GRB 260213736)
  95. GRB 260211A - SVOM/ECLAIRs refined analysis
  96. GRB 260204A: SVOM/ECLAIRs refined analysis
  97. GRB 260213A: Fermi GBM Final Localization
  98. GRB 260211A: EP-FXT follow-up observation
  99. GRB 260211A: SVOM/VT optical observation
  100. GRB 260212A: Glowbug gamma-ray detection

Advanced

Download all Circulars as a .tar.gz archive:
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