Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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 240331A: AstroSat CZTI detection
  2. GRB 240329A: AstroSat CZTI detection
  3. GRB 240331A: Fermi GBM Final Real-time Localization
  4. GRB 240329A: GRBAlpha detection
  5. Fermi trigger No 733366352: Global MASTER-Net observations report
  6. Fermi GRB 240329A: Global MASTER-Net observations report
  7. GRB 240329A: BALROG localization (Fermi Trigger 733441392 / GRB 240329905)
  8. GRB 240329A: Fermi GBM Final Real-time Localization
  9. Fermi GRB 240328B: Global MASTER-Net observations report
  10. Fermi GRB 240328A: Global MASTER-Net observations report
  11. X-ray transient EP240315a: continued ATCA monitoring
  12. IceCube-240327B: No candidates from the Zwicky Transient Facility
  13. GRB 240328C: Glowbug gamma-ray detection
  14. GRB 240328B: Fermi GBM Final Real-time Localization
  15. GRB 240328A: Fermi GBM Final Real-time Localization
  16. IceCube Alert 240327.68: Global MASTER-Net observations report
  17. IceCube-240327B - IceCube observation of a high-energy neutrino candidate track-like event
  18. IceCube-240327A - IceCube observation of a high-energy neutrino candidate track-like event
  19. X-ray transient EP 240315a: Second epoch Chandra observations
  20. Fermi trigger No 733097506: Global MASTER-Net observations report
  21. X-ray transient EP240315a: e-MERLIN radio observations
  22. X-ray transient EP240315a: Ondrejov D50 optical limit
  23. Transient EPW20240219aa: REM optical/NIR further observations
  24. Fermi trigger No 733092476: Global MASTER-Net observations report
  25. GRB 240320A: Glowbug gamma-ray detection
  26. Fermi trigger No 732937833: Global MASTER-Net observations report
  27. GRB 240318A: Fermi GBM Observation
  28. Fermi GRB 240320A: Global MASTER-Net observations report
  29. Konus-Wind detection of GRB 240315C (possible counterpart of EP240315a)
  30. GRB 240315C / X-ray transient EP240315a: Swift/BAT detection
  31. Fermi trigger No 732657380: Global MASTER-Net observations report
  32. GRB 240318A: Swift/BAT-GUANO detection of a burst outside the coded FOV
  33. X-ray transient EP240315a: ATCA detection of radio counterpart
  34. GRB 240320A: Fermi GBM Final Real-time Localization
  35. IPN triangulation of GRB 240315C (consistent with a fast X-ray transient EP240315a)
  36. GRB 240317B: Swift/BAT-GUANO Angular Error Correction
  37. Fermi Gamma-ray Burst Monitor trigger 732299243/240316686 is not a GRB
  38. X-ray transient EP 240315a: Chandra observations
  39. X-ray transient EP240315a: GTC/HiPERCAM photometry
  40. X-ray transient EP240315a: MeerKAT radio detection
  41. X-ray transient EP240315a: GTC/OSIRIS spectroscopic redshift confirmation
  42. GRB 240318A: Glowbug gamma-ray detection
  43. GRB 240317C: Glowbug gamma-ray detection
  44. GRB 240318B: Glowbug gamma-ray detection
  45. X-ray transient EP240315a: PRIME near infrared detection
  46. GRB 240317B: Fermi GBM Observation
  47. X-ray transient EP240315a: 3.6 m TNG NIR detection
  48. Swift satellite in safe mode
  49. X-ray transient EP240315a/AT2024eju: TShAO (Zeiss-1000) observatory optical upper limit
  50. X-ray transient EP240315a: EP-FXT detection of the X-ray afterglow
  51. Fermi GRB 240318A: Global MASTER-Net observations report
  52. GRB 240318A: Fermi GBM Final Real-time Localization
  53. GRB 240317B: Swift/BAT-GUANO arcminute localization of a burst
  54. GRB 240317A: AstroSat CZTI detection
  55. GRB 240315B: AstroSat CZTI detection
  56. X-ray transient EP240315a: Kitab observatory optical upper limitns
  57. X-ray transient EP240315a: Montarrenti Observatory optical upper limit
  58. Fermi GRB 240317B: Global MASTER-Net observations report
  59. Fermi GRB 240317A: Global MASTER-Net observations report
  60. GRB 240317B: Fermi GBM Final Real-time Localization
  61. X-ray transient EP240315a: orphan FXT?
  62. GRB 240317A: Fermi GBM Final Real-time Localization
  63. X-ray transient EP240315a: Kinder follow-up observations for AT 2024eju with Lulin observatory
  64. X-ray transient EP240315a: GROND J-band detection
  65. X-ray transient EP240315a: VLT/X-shooter spectroscopic redshift of z = 4.859
  66. X-ray transient EP240315a: Nanshan/HMT optical upper limit
  67. Fermi trigger No 732299243: Global MASTER-Net observations report
  68. AT2024eju: followup observations with Liverpool Telescope suggest a fading transient
  69. X-ray transient EP240315a: ATLAS detection of a possible optical counterpart AT2024eju
  70. Einstein Probe detected of a fast X-ray transient EP240315a
  71. GRID detection of GRB 240306A
  72. Changes to the Fermi-GBM Triggering Thresholds
  73. Swift Triggers 1220155, 1220156, 1220157, 1220158, 1220160 and 1220161 were not astrophysical
  74. GRB 240315A: Fermi GBM Final Real-time Localization
  75. Swift Triggers 1220093, 1220094, 1220095 and 1220096 are not astrophysical
  76. Swift Triggers 1220090, 1220091 and 1220092 are not astrophysical
  77. Fermi GRB 240314A: Global MASTER-Net observations report
  78. GRB 240314A: Fermi GBM Final Real-time Localization
  79. GRB240204A: VIRT optical upper limit
  80. GRB 240312A: Glowbug gamma-ray detection
  81. Swift triggers 1219917, 1219917 and 1219922 were not astrophysical
  82. Swift Trigger 1219909 and 1219910 are not a astrophysical
  83. Swift Trigger 1219905 is not a GRB
  84. GRB 240312A: GECAM detection of a long burst
  85. Swift Trigger 1219874 is not astrophysical
  86. GRB 240303C: VZLUSAT-2 detection
  87. GRB 240310A: MASTER OT J200702.72-263928.7 inside 3sigma
  88. Fermi trigger No 731839490: Global MASTER-Net observations report
  89. Fermi-LAT gamma-ray observations of IceCube-240307A
  90. GRB 240310B: Glowbug gamma-ray detection
  91. Fermi GRB 240310A: Global MASTER-Net observations report
  92. Swift GRB240309.61: Global MASTER-Net observations report
  93. GRB 240310A: Fermi GBM Final Real-time Localization
  94. GRB 240309A: MAXI/GSC detection
  95. Swift Trigger 1219325 is not a GRB
  96. IceCube-240307A: Upper limits from a search for additional neutrino events in IceCube
  97. GRID detection of GRB 240229A (Updated Report)
  98. GRID detection of GRB 240229A
  99. GRB 240308A: Fermi GBM Final Localization
  100. Fermi trigger No 731571927: Global MASTER-Net observations report

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