Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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. GRB 240225C: Glowbug gamma-ray detection
  2. GRB 240225A (short): Glowbug gamma-ray detection
  3. GRB 240229A: DDOTI Upper Limits on the Afterglow
  4. GRB 240218A: NOEMA upper limit
  5. GRB 240229A: CALET Gamma-Ray Burst Monitor detection
  6. IceCube-240229A - IceCube observation of a high-energy neutrino candidate track-like event
  7. Swift BAT Triggers 1218081 and 1218082 are not astrophysical
  8. GRB 240225B: further SAO RAS optical observations
  9. Fermi GRB 240229A: Global MASTER-Net observations report
  10. IceCube Alert 240229.66: Global MASTER-Net observations report
  11. GRB 240225B: Swift ToO observations
  12. Konus-Wind detection of GRB 240225B (long)
  13. GRB 240229A: BALROG localization (Fermi Trigger 730908432 / GRB 240229588)
  14. GRB 240229A: Fermi GBM Final Real-time Localization
  15. GRB 240225B: VLT/X-shooter redshift
  16. GRB 240225B : MITSuME Akeno optical afterglow candidate detection
  17. GRB 240225B: 3.6m DOT observation
  18. GRB 240225B: WINTER near-IR observations and upper limits
  19. GRB 240225B: SAO RAS optical observations
  20. GRB 240226A: GRBAlpha detection
  21. GRB 240225B: Mondy afterglow observations
  22. Fermi GRB 240227A: Global MASTER-Net observations report
  23. GRB 240225B: Liverpool Telescope afterglow observations
  24. Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up
  25. Swift Trigger 1217799 is not a GRB
  26. IPN triangulation of GRB 240227A (short)
  27. GRB 240225B: Liverpool Telescope optical afterglow observations
  28. GRB 240225B: NOT optical observations
  29. GRB 240218A: CMO SAI NIR upper limit
  30. Fermi GRB 240226A: Global MASTER-Net observations report
  31. Swift-BAT triggers 1217733 - 1217736 are not astrophysical events
  32. Swift-BAT triggers 1217729-1217732 are not astrophysical
  33. GRB 240227A: Fermi GBM Final Real-time Localization
  34. Fermi Gamma-ray Burst Monitor trigger 730618809/240226236 is not a GRB
  35. GRB 240225B: Nanshan/HMT optical afterglow detection
  36. GRB 240225B: CALET Gamma-Ray Burst Monitor detection
  37. GRB 240225B: Swift-XRT observations
  38. GRB 240226B: Fermi GBM Final Real-time Localization
  39. Transient EPW20240219aa: Kp-band imaging observations with NIRES
  40. Transient EPW20240219aa: J-band upper limits from WINTER
  41. GRB 240225C: CALET Gamma-Ray Burst Monitor detection
  42. GRB 240225B: GOTO detection of a candidate optical afterglow
  43. GRB 240226A: Fermi GBM Final Real-time Localization
  44. Transient EPW20240219aa: REM optical/NIR upper limits
  45. GRB 240225C: GRBAlpha detection
  46. GRB 240222A: ATCA radio observations
  47. Fermi trigger No 730618809: Global MASTER-Net observations report
  48. GRB 240225C: AstroSat CZTI detection
  49. GRB 240225B: AstroSat CZTI detection
  50. GRB 240225B: Tiled Swift observations
  51. GRB 240225B: MAXI/GSC detection
  52. Transient EPW20240219aa: Xinglong-2.16m optical upper limit
  53. GRB 240218A: VLA detection
  54. GRB 240225A: Swift/BAT-GUANO detection of a short burst
  55. GRB 240222A: GRBAlpha detection
  56. Transient EPW20240219aa: GECKO: LOAO Optical Upper Limits
  57. Transient EPW20240219aa: 7DT Optical Upper Limits
  58. Swift-BAT triggers 1217218-1217222 are not astrophysical
  59. VLA X-band observation of EPW20240219aa
  60. Transient EPW20240219aa: Mondy optical observations
  61. Transient EPW20240219aa: upper limit in gamma-ray range from SPI-ACS/INTEGRAL observations
  62. Insight-HXMT/HE Sub-Threshold Detection of Transient EPW20240219aa
  63. Swift BAT Sub-Threshold Detection of EPW20240219aa
  64. Transient EPW20240219aa: Liverpool Telescope non-detection and limiting magnitude
  65. GRB 240222A: GECAM detection of a burst
  66. GRB 240222A: Swift-BAT refined analysis
  67. GRB 240222A: Swift-XRT refined Analysis
  68. Swift-BAT triggers 1216907-1216911 are not astrophysical
  69. GRB 240222A: Fermi GBM Observation
  70. GRB 240222A: Swift/UVOT Upper Limits
  71. Fermi GBM Sub-Threshold Detection of EPW20240219aa as a likely GRB
  72. Swift GRB 240222A: Global MASTER-Net observations report
  73. Fermi GRB 240222A: Global MASTER-Net observations report
  74. EPW20240219aa is Likely a GRB Event
  75. Swift Trigger 1216864 is not an astrophysical event
  76. GRB 240222A: REM optical and NIR early-time observations
  77. GRB 240222A: Swift detection of a burst
  78. GRB 240222A: Fermi GBM Final Real-time Localization
  79. Swift-BAT triggers 1216751 and 1216753 are not astrophysical events
  80. Swift-BAT triggers 1216743-1216748 are not astrophysical
  81. Swift GRB240221.92: Global MASTER-Net observations report
  82. GRB 240218A: MeerLICHT upper limits
  83. GRB 240216A: Glowbug gamma-ray detection
  84. GRB 240215B: Fermi GBM Observation
  85. GRB 240218A: LBT H-band detection
  86. GRB 240218A: Swift-BAT refined analysis
  87. Fermi GRB 240220A: Global MASTER-Net observations report
  88. GRB 240220A: Fermi GBM Final Real-time Localization
  89. Konus-Wind detection of GRB 240218A
  90. GRB 240218A: Swift-XRT refined Analysis
  91. GRB 240218A: VLT/X-shooter redshift of z = 6.782
  92. GRB 240218A: Fermi GBM Detection
  93. GRB 240215A: Fermi GBM Observation
  94. GRB 240216A: GRBAlpha detection
  95. GRB 240215B: GRBAlpha detection
  96. IPN triangulation of GRB 240209A
  97. Fermi trigger No 729914426: Global MASTER-Net observations report
  98. GRB 240218A: VLT/FORS2 z-band detection
  99. GRB 240218A: Enhanced Swift-XRT position
  100. GRB 240218A: REM detection of a NIR afterglow candidate

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