Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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"

11755 results found.

  1. GRB 251211B: Fermi GBM Final Real-time Localization
  2. GRB 251209A: AstroSat CZTI detection
  3. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  4. EP251130a: Mondy and AbAO optical observations
  5. GRB 251208A: AstroSat CZTI detection
  6. GRB 251208B: Swift-XRT afterglow detection
  7. GRB 251208B: Fermi GBM Observation
  8. GRB 251208D: Swift-XRT observations
  9. GRB 251208B: Fermi-LAT detection
  10. GRB 251206A: SVOM detection of a burst through offline search
  11. GRB 251205A: Swift-XRT refined Analysis
  12. Konus-Wind detection of GRB 251118A
  13. Swift GRB251205A: Global MASTER-Net observations report
  14. GRB 251203A: SVOM/GRM observation
  15. GRB 251203A: AstroSat CZTI detection
  16. GRB 251203C: EP-FXT follow-up observation
  17. GRB 251203B: Swift-XRT observations
  18. GRB 251203B: confirmation of a stellar flare by BOOTES-2
  19. GRB 251203B: SVOM detection of a burst
  20. EP251130a: MAO/AZT-22 optical observations
  21. EP251202a / GRB251202A: AstroSat CZTI detection
  22. Fermi GRB 251202B: Global MASTER-Net observations report
  23. GRB 251129B: AstroSat CZTI detection
  24. GRB 251201B: Swift/UVOT Detection
  25. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  26. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  27. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  28. GRB 251202A: Swift-XRT afterglow detection
  29. EP251129a/GRB 251129A: NOWT Detection
  30. GRB 251126A: SVOM/VT optical observation
  31. EP251202a/GRB 251202A: Einstein Probe detection of an X-ray transient
  32. GRB 251201B: Swift-XRT refined Analysis
  33. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  34. GRB 251130B: AstroSat CZTI detection
  35. EP251130a: Optical detections with Kinder observations
  36. GRB 251201A: MAXI/GSC detection
  37. EP251130a: Swift-XRT counterpart detection
  38. EP251130a: Einstein Probe detection of an X-ray transient
  39. EP251129a/GRB 251129A: EP-FXT follow-up observations
  40. GRB 251128A: AstroSat CZTI detection
  41. GRB 251129A: Swift-XRT afterglow detection
  42. EP251129a: Global MASTER-Net observations report
  43. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  44. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  45. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 251126A: further SAO RAS optical observations
  47. GRB 251126A: Mondy and SAO RAS optical observations
  48. GRB 251126A: Swift-XRT refined Analysis
  49. Fermi GRB 251127A: Global MASTER-Net observations report
  50. Swift GRB 251126A: Global MASTER-Net observations report
  51. GRB 251126A: Swift detection of a burst
  52. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  53. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  54. Fermi GRB 251125B: Global MASTER-Net observations report
  55. GRB 251125B: Fermi GBM Final Real-time Localization
  56. Fermi GRB 251125A: Global MASTER-Net observations report
  57. EP251124a: Swift-XRT observations
  58. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  59. EP251124a: Optical upper limit with Kinder observations
  60. EP251118A: 6 GHz VLA Detection
  61. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  62. EP251124a: Einstein Probe detection of an X-ray transient
  63. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  64. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  65. GRB 251122A / EP251122a: SVOM detection of a long burst
  66. EP251122a: Einstein Probe detection of an X-ray transient
  67. EP251118a: Continued Optical Detection with Kinder observations
  68. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  69. GRB 251115A: Fermi GBM Observation
  70. EP251118A: 1.3m DFOT optical afterglow detection
  71. GRB 251118A: Glowbug gamma-ray detection
  72. GRB 251118A: Fermi GBM Observation
  73. GRB 251118A: Swift-XRT afterglow detection
  74. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  75. EP251118a: Optical detection with Kinder observations
  76. EP251118a / GRB 251118C: SVOM/VT optical observation
  77. GRB 251118A: NuSTAR detection of bright prompt emission
  78. Konus-Wind detection of GRB 251118C (EP251118a)
  79. GRB 251116D: SVOM/GRM observation of a long GRB
  80. EP251118a: Global MASTER-Net observations report
  81. EP251118a: preliminary result of EP-FXT follow-up observation
  82. LAT GRB251118.86: Global MASTER-Net observations report
  83. GRB 251118A: Fermi-LAT detection
  84. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  85. GRB 251118A: Fermi GBM Final Real-time Localization
  86. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  87. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  88. GRB 251117A: Fermi-LAT detection
  89. LAT GRB251117.51: Global MASTER-Net observations report
  90. GRB 251116C: Swift/BAT arcminute localization of a burst
  91. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  92. GRB 251116C: Swift-XRT observations
  93. EP251023a: Assy AZT-20 optical observations
  94. GRB 251116D: AstroSat CZTI detection
  95. GRB 251025B: further Mondy optical observations
  96. SVOM GRB251116C: Global MASTER-Net observations report
  97. GRB 251116C: SVOM detection of a burst
  98. GRB 251115A: Fermi-LAT detection
  99. Fermi GRB 251115A: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 4-Update Localization Volume

Advanced

Download all Circulars as a .tar.gz archive (updated once a day):
Looking for U.S. government information and services? Visit USA.gov