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"

14824 results found.

  1. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  2. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  3. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  4. GRB 250702F: Kilonova-Catcher optical afterglow detection
  5. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  6. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  7. EP250704a / GRB 250704B: JinShan optical observations
  8. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  9. EP 250704a: BOOTES-5 optical detection
  10. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  11. GRB 250702A: Insight-HXMT detection
  12. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  13. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  14. EP250704a / GRB250704B: Swift-XRT counterpart detection
  15. GRB 250704A: Swift-XRT afterglow detection
  16. Konus-Wind detection of GRB 250702F
  17. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  18. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  19. EP250702a: WFST optical observations
  20. EP250704a: Einstein Probe detection of an X-ray transient
  21. GRB 250702F: optical photometry from Konkoly
  22. GRB 250704A: REM detection of the optical afterglow
  23. GRB 250704A: SVOM detection of a burst
  24. GRB 250702F: Swift/UVOT Detection
  25. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  26. GRB 250702F: AKO Optical Afterglow Detection
  27. GRB 250702A: GECAM-B detection
  28. GRB 250702F: Skynet Optical Observations
  29. GRB 250424A: VIRT Optical Upper Limit
  30. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  31. GRB 250702F: TRT Optical Observation
  32. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  33. GRB 250702F: REM optical afterglow detection
  34. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  35. GRB 250703A: Fermi GBM Final Real-time Localization
  36. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  37. GRB 250702F: GOTO optical counterpart detection
  38. GRB 250702F: Ondrejov D50 optical afterglow detection
  39. GRB 250702F: Swift detection of a burst with an optical counterpart
  40. GRB 250702F: Fermi GBM Final Real-time Localization
  41. GRB 250702E: Fermi GBM Final Real-time Localization
  42. Konus-Wind detection of GRB 250627A
  43. IPN triangulation of GRB 250627A (short)
  44. GRB 250702A: Fermi GBM Detection
  45. GRB 250702D: Fermi GBM Final Localization Correction
  46. GRB 250702C: Fermi GBM Final Real-time Localization
  47. GRB 250702B: Fermi GBM Final Real-time Localization
  48. GRB 250702A: Fermi GBM Final Real-time Localization
  49. GRB 250628B: EP-FXT counterpart detection
  50. GRB 250627A: Insight-HXMT detection
  51. GRB 250627A: SVOM/GRM detection of a short burst
  52. GRB 250628C: Fermi GBM Final Real-time Localization
  53. GRB 250628B: SVOM detection of a long burst
  54. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  55. GRB 250628A: VLT/X-shooter upper limits
  56. GRB 250628A: Swift detection of a burst
  57. GRB 250625A: Leavitt Observatory afterglow detection
  58. GRB 250626A: Fermi GBM Final Real-time Localization
  59. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  60. GRB 250625A: GECAM-B detection
  61. GRB 250625A: ABObservatory afterglow detection
  62. GRB 250625A: OHP/T193 optical detection
  63. GRB 250625A: COLIBRÍ optical observations
  64. GRB 250625A: Fermi-LAT detection
  65. GRB 250625A: JinShan optical observations
  66. GRB 250625A: Swift detection of a burst
  67. GRB 250625A: Fermi GBM Final Real-time Localization
  68. GRB 250620A: AstroSat CZTI detection
  69. GRB 241018A: Maidanak optical observations
  70. GRB 250620C: AstroSat CZTI detection
  71. GRB 250624A: Fermi GBM Final Real-time Localization
  72. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  73. GRB 250623A: Fermi GBM Final Real-time Localization
  74. GRB 250521A: VZLUSAT-2 detection
  75. Konus-Wind detection of GRB 250620C
  76. IPN triangulation of GRB 250620C (long/bright)
  77. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  78. GRB 250621A: Fermi GBM Final Real-time Localization
  79. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  80. GRB 250620C: Fermi GBM Final Real-time Localization
  81. GRB 250620B: Fermi GBM Final Real-time Localization
  82. GRB 250620A: Fermi GBM Final Real-time Localization
  83. EP-WXT trigger 01709179036: a new outburst of GRS 1739-278
  84. GRB 250619B: Fermi GBM Final Real-time Localization
  85. GRB 250619A: Fermi GBM Final Real-time Localization
  86. GRB 250612A / Swift J1643.6−3854: Swift-BAT refined analysis
  87. sb25061218/SVOM: OHP/T120 and OHP/T193 optical imaging and spectroscopic observations
  88. GRB 250617B: Swift/UVOT Detection
  89. GRB 250617B: Kilonova-Catcher optical afterglow detection
  90. GRB 250617B: VLT/X-shooter spectroscopic redshift z = 1.396
  91. GRB 250617B: NUTTelA-TAO early time optical observations
  92. GRB 250617B: Fermi GBM Final Localization
  93. GRB 250617B: Ondrejov D50 optical afterglow detection
  94. GRB 250617B: Swift detection of a burst with an optical counterpart
  95. GRB 250617A: Fermi GBM Final Real-time Localization
  96. IPN triangulation of GRB 250612C (short/hard)
  97. EP#01709178975: Swift-XRT counterpart detection
  98. Konus-Wind detection of GRB 250615A / EP250615a
  99. GRB 250615A / EP250615a: AstroSat CZTI detection
  100. GRB 250615A: COLIBRÍ optical upper limit

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