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

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