Skip to main content
JSON Notices via Email, Kafka Cron Jobs, Submitter Profile, GCN is Hiring. See news and announcements

GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28235 results found.

  1. GRB 251001C: Glowbug gamma-ray detection
  2. GRB 251001B: Fermi GBM Observation
  3. GRB 251001B: Enhanced Swift-XRT position
  4. GRB 251001B: LCOGT Optical Observations
  5. GRB 250930A: SVOM/GRM observation
  6. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  7. GRB 251001B: Swift detection of a burst
  8. GRB 251001B: Fermi GBM Final Real-time Localization
  9. GRB 251001A: Fermi GBM Detection
  10. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  11. GRB 251001A: BALROG localization (Fermi Trigger 780979261 / GRB 251001112)
  12. GRB 251001A: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  14. GRB 250925A: MAO/AZT-22 optical observations
  15. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  16. GRB 250925A: Mondy I-band optical observations
  17. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  18. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  19. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  20. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  21. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  22. GRB 250924A: SVOM/GRM observation
  23. GRB 250925A: Swift-XRT refined Analysis
  24. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  26. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  27. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  28. GRB 250926A: AstroSat CZTI detection
  29. GRB 250925A: Swift-BAT refined analysis
  30. GRB 250925A: Mondy and AbAO optical observations
  31. GRB 250925A: COLIBRÍ photometric redshift
  32. GRB 250925A: SVOM/GWAC-F60A upper limit
  33. GRB 250925A/EP250925a: EP-WXT detection
  34. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  35. GRB 250925A : MITSuME Akeno optical upper limits
  36. GRB 250925A: JinShan optical observations
  37. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  38. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  39. GRB250925A: Liverpool Telescope optical observations
  40. GRB 250925A: NOT optical afterglow candidate
  41. GRB 250925A: Leavitt Observatory optical upper limit
  42. GRB 250925A: Enhanced Swift-XRT position
  43. GRB 250924A: Swift-BAT refined analysis
  44. GRB 250925A: GROWTH-India Telescope Upper Limits
  45. GRB 250925A: Swift detection of a burst
  46. GRB 250922A: SVOM/GRM observation
  47. GRB 250924A: 1.6m Mephisto optical upper limits
  48. GRB 250924A: SAO RAS optical observations
  49. GRB 250924A: AstroSat CZTI detection
  50. GRB 250924A: SVOM/VT optical observation
  51. GRB 250924A: Swift/UVOT Detection
  52. GRB 250924A: Swift-XRT refined Analysis
  53. GRB 250924A: Enhanced Swift-XRT position
  54. GRB 250924A: J-band detection with WINTER
  55. GRB 250924A: GROWTH-India Telescope Upper Limits
  56. GRB 250924A: KAIT optical observations
  57. GRB 250924A: Mondy optical observations, afterglow fading
  58. GRB 250924A: Kilonova-Catcher optical afterglow detection
  59. GRB 250920C: Kilonova-Catcher optical afterglow detection
  60. GRB 250922B: SVOM/GRM observation
  61. GRB 250920C: TRT optical observation
  62. GRB 250924A: COLIBRÍ optical observations
  63. GRB 250919A / EP250919a: further LCO optical observation
  64. GRB 250924A: DDOTI Detection of the Optical Counterpart
  65. GRB 250924A: Swift detection of a burst with an optical counterpart
  66. GRB 250920B: AbAO optical upper limits
  67. GRB 250920C: KAIT optical observations
  68. GRB 250920B: CrAO ZTSH optical observations
  69. GRB 250920C: COLIBRÍ optical observations
  70. GRB 250922C: AstroSat CZTI detection of a short burst
  71. GRB 250920B: SAO RAS optical observations
  72. GRB 250920C: NIR observations with WINTER
  73. GRB 250920B: NIR observations with WINTER
  74. Fermi trigger No 780156732: Global MASTER-Net observations report
  75. GRB 250920C: PRIME near-infrared detection
  76. GRB 250916A: Swift/UVOT Detection
  77. GRB 250920B: Glowbug gamma-ray detection
  78. GRB 250916A: CrAO ZTSh R-band optical observations
  79. GRB 250920C: Swift-XRT refined Analysis
  80. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  81. GRB 250920B: Asiago optical observations
  82. GRB 250920B: Kitab-ISON optical upper limit
  83. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  84. GRB 250920C: SVOM/GRM observation
  85. GRB 250917B: KAIT optical upper limit
  86. GRB 250920A: NuSTAR detection of bright prompt emission
  87. GRB 250920C: GROWTH-India Telescope optical observations
  88. GRB 250920C: Swift-BAT refined analysis
  89. GRB 250920B: Swift-BAT refined analysis
  90. GRB 250920C: Enhanced Swift-XRT position
  91. GRB 250920C: Swift/UVOT Detection
  92. GRB 250920B: Fermi GBM Observation
  93. GRB 250920A: Fermi GBM Detection
  94. GRB 250920C: Fermi GBM Observation
  95. GRB 250920B: Swift/UVOT Detection
  96. GRB 250920C: Optical counterpart detection by LCO
  97. GRB 250920A: SVOM/GRM observation
  98. GRB250920C: LCOGT Optical Detection
  99. GRB 250920B: Enhanced Swift-XRT position
  100. GRB 250920B: Swift-XRT refined Analysis

Advanced

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