Skip to main content
New! BOOM Notices and Schema v7.0.0. 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. EP260527a / GRB 260527A: NOT optical observations
  2. GRB 260527A/EP260527a: FTW optical and NIR observations
  3. EP260527a/GRB 260527A: Infrared J upper limit with MDM/MIRAGE
  4. GRB 260527A: CALET Gamma-Ray Burst Monitor detection
  5. EP260527a/GRB 260527A: EP-FXT follow-up observation
  6. GRB 260527A: GECAM-B detection of a short burst probably associated with EP260527a
  7. GRB 260526A: GECAM-B observation
  8. Konus-Wind detection of GRB 260527A (short/hard) ~4 min before EP260527a
  9. EP260526a: EP-FXT follow-up observation
  10. EP260527a: SVOM/VT optical observation
  11. EP260527a: COLIBRÍ optical detection
  12. EP260527a: Einstein Probe detection of a fast X-ray transient
  13. The EP-WXT trigger 01709266172 is likely a flaring star
  14. The EP-WXT trigger 01709266147 is likely a flaring star
  15. Fermi trigger No 801580882: Global MASTER-Net observations report
  16. GRB 260524A: SVOM/ECLAIRs detection of a burst through on-ground search
  17. EP260526a: LCO optical upper limits
  18. EP260526a: Einstein Probe detection of a fast X-ray transient
  19. GRB 260525A: AstroSat CZTI detection
  20. EP260526.405: COLIBRÍ optical upper limits
  21. The EP-WXT trigger 01709266106 is not a real source
  22. Fermi GRB 260526A: Global MASTER-Net observations report
  23. GRB 260526A: Fermi GBM Final Real-time Localization
  24. EP01709266106 (EP260526a?): Liverpool Telescope upper limits
  25. EP-WXT 01709266106: NOT optical upper limits
  26. Fermi GRB 260525A: Global MASTER-Net observations report
  27. GRB 260525A: Fermi GBM Final Real-time Localization
  28. GRB 260523B: AstroSat CZTI detection
  29. GRB 260523B: GECAM-B observation
  30. Fermi GRB 260523A: Global MASTER-Net observations report
  31. GRB 260523B: Fermi GBM Final Real-time Localization
  32. GRB 260523A: Fermi GBM Final Real-time Localization
  33. GRB 260522A: Fermi GBM Observation
  34. GRB 260522B: NuSTAR detection of prompt emission
  35. EP260518a (AT2026ndp): LCO observations and Gemini-South Redshift z = 2.28
  36. GRB 260522B: Fermi GBM Final Real-time Localization
  37. GRB 260522A: GOTO optical upper limit
  38. Fermi trigger No 801135305: Global MASTER-Net observations report
  39. Fermi GRB 260522A: Global MASTER-Net observations report
  40. EP260518a: Einstein Probe detection of an sub-threshold X-ray transient with counterpart AT 2026ndp
  41. GRB 260522A: Fermi-LAT detection
  42. GRB 260519C: SVOM/GRM observation
  43. GRB 260522A: Fermi GBM Final Real-time Localization
  44. GRB 260511A: iTelescope T-75 optical detection
  45. GRB 260520B: SVOM/GRM observation
  46. GRB 260411B: TERI Gamma-ray detection
  47. GRB 260407A: TERI Gamma-ray detection
  48. GRB 260307A: TERI Gamma-ray detection
  49. GRB 260225D: TERI Gamma-ray detection
  50. GRB 251118A: TERI Gamma-ray detection
  51. GRB 251113A: TERI Gamma-ray detection
  52. GRB 260428A: TERI Gamma-ray detection
  53. Konus-Wind detection of GRB 260519C
  54. GRB 260520B: Fermi GBM Final Localization
  55. GRB 260509A: SVOM/ECLAIRs refined analysis
  56. GRB 260520A: Fermi GBM Final Localization
  57. GRB 260519D: Fermi GBM Final Localization Correction
  58. GRB 260519C: NuSTAR detection of prompt emission
  59. Konus-Wind detection of GRB 260518A
  60. GRB 260519B: Fermi GBM Final Localization
  61. GRB 260519A: Fermi GBM Final Localization
  62. GRB 260518A: AstroSat CZTI detection of a long burst
  63. GRB 260516D: SVOM/ECLAIRs refined analysis
  64. GRB 260515A: SVOM/ECLAIRs refined analysis
  65. GRB 260421B: radio detection with the VLA
  66. GRID detection of GRB 260511A
  67. GRB 260509A: CrAO ZTSh optical upper limit (Duplicate Submission)
  68. GRB 260509A: CrAO ZTSh optical upper limit
  69. GRB 260516D: EP-FXT follow-up observation
  70. GRB 260516D: GOTO optical counterpart detection
  71. GRB 260516D: LCO optical observations
  72. GRB 260515A: further Liverpool Telescope observations
  73. GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
  74. GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
  75. GRB 260516D: GROWTH-India Telescope optical detection
  76. GRB 260516D: SVOM/VT optical bright candidate
  77. GRB 260516D: FRAM-ORM optical limit
  78. GRB 260515A: CrAO ZTSh BVRI optical observations
  79. Fermi GRB 260516C: Global MASTER-Net observations report
  80. SVOM GRB260516D: Global MASTER-Net observations report
  81. GRB 260516D: SVOM possible detection of a burst
  82. GRB 260516C: Fermi GBM Final Real-time Localization
  83. Konus-Wind detection of GRB 260515A
  84. GRB 260515A: Liverpool Telescope optical detection
  85. GRB 260515A: LCO optical counterpart detection
  86. Fermi Gamma-ray Burst Monitor trigger 800627191/260516518 is not a GRB
  87. GRB 260515A: SVOM/COLIBRÍ (FM-GFT) optical observations
  88. GRB 260515A: EP-FXT follow-up observation
  89. EP260514a: refined analysis of the EP-WXT and follow-up EP-FXT observations
  90. EP260514a: NOT optical counterpart confirmation
  91. EP260514a: TRT optical counterpart candidate
  92. EP260514a: SVOM/VT optical candidate
  93. Fermi GRB 260516B: Global MASTER-Net observations report
  94. GRB 260516B: Fermi GBM Final Real-time Localization
  95. Fermi Gamma-ray Burst Monitor trigger 800592653/260516119 is not a GRB
  96. GRB 260515A: SVOM/VT optical observations
  97. GRB 260515A: OHP/T193 optical observations
  98. EP260514a: COLIBRÍ optical upper limits
  99. GRB 260516A: Fermi GBM Final Real-time Localization
  100. GRID detection of GRB 260507A

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