Skip to main content
New! BOOM Notices and Schema v7.0.0. 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"

35273 results found.

  1. GRB 250207A: REM optical afterglow detection
  2. GRB 250207A: Swift/UVOT Detection
  3. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  4. GRB 250129A: Continued AbAO and Mondy optical observations
  5. GRB 250207B: MAXI/GSC detection
  6. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  7. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  8. GRB 250207A: Swift detection of a burst with optical counterpart
  9. GRB 250207A: Fermi GBM Final Real-time Localization
  10. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  11. GRB 250206A: Fermi GBM Final Real-time Localization
  12. GRB 250205A: Fermi GBM Observation
  13. GRB 250205A: REM NIR upper limit
  14. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  15. GRB 250205A: Swift/UVOT Upper Limits
  16. EP250205a/GRB 250205A: correction to the source localization
  17. EP250205a/GRB 250205A: Einstein Probe observation
  18. GRB 250127C: SVOM/GRM observation of a burst
  19. GRB 250204B: SVOM/GRM observation of a likely short burst
  20. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  21. GRB 250205A: Swift/XRT detection
  22. GRB 250205A: Redshift from OSIRIS+/GTC z = 3.55
  23. GRB250205A: SVOM/VT optical afterglow detection
  24. GRB 250205A: GOTO optical upper limits
  25. GRB 250205A: OHP/T193 optical counterpart candidate
  26. GRB 250205A: Liverpool Telescope optical counterpart candidate detection
  27. GRB 250205A: SVOM detection of a burst
  28. Konus-Wind detection of GRB 250201A
  29. IPN triangulation of GRB 250201A
  30. Konus-Wind detection of GRB 250202B
  31. GRB 250129A: Swift-BAT refined analysis
  32. EP 250108A: Upper limits from Fermi-GBM Observations
  33. IPN triangulation of GRB 250204B (short/hard)
  34. IPN triangulation of GRB 250202B
  35. GRB 250204B: AstroSat CZTI detection of a short burst
  36. GRB 250204B: Fermi GBM Final Localization
  37. GRB 250129A: LCO late afterglow detection
  38. GRB 250129A: AbAO AS-32 and Mondy AZT-33IK optical observations
  39. GRB 250204A: Fermi GBM Final Real-time Localization
  40. GRB 250129A: COLIBRÍ/DDRAGO Afterglow Detection
  41. GRB 250202B: NuSTAR detection of the prompt emission
  42. GRB 250202C: GRBAlpha detection
  43. GRB 250202B: Fermi GBM Detection
  44. GRB 250129a: Liverpool Telescope optical follow-up
  45. GRB 240129A: further SAO RAS optical observations
  46. GRB 250129A: 7DT Detection and Medium-band SED of Afterglow
  47. GRB 250202C: Fermi GBM Final Real-time Localization
  48. GRB 250129A: SVOM/C-GFT optical observations
  49. GRB 250202B: AstroSat CZTI detection of a bright long GRB
  50. GRB 250202B: Fermi GBM Final Real-time Localization
  51. Swift GRB250129A: MASTER 4 days observations report
  52. GRB 250202A: Fermi GBM Final Real-time Localization
  53. GRB 250201A: INTEGRAL SPI/ACS detection
  54. Konus-Wind detection of GRB 250129A
  55. GRB 250129A: 1.3m DFOT Optical observations
  56. GRB 250129A: Liverpool Telescope observations suggest continued engine activity
  57. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  58. GRB 250201A: Fermi GBM Final Real-time Localization
  59. GRB 250129A: Skynet Continued Optical Observations
  60. GRB 250129A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations
  61. GRB 250129A: SAO RAS optical observations
  62. GRB 250129A: COLIBRÍ Continuing Detection of the Afterglow
  63. GRB 250129A: optical photometry from Konkoly
  64. GRB 250129A: COLIBRÍ Optical Observations
  65. GRB 250128B: VLA possible radio detection
  66. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  67. GRB 250129A: iTelescope optical observation
  68. GRB 250129A: NOT optical observations of continuining activity
  69. GRB 250129a: Liverpool Telescope optical follow-up
  70. GRB 250129A: TNG NIR afterglow detection
  71. GRB 250129A: AKO Optical Afterglow Detection
  72. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  73. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  74. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  75. GRB 250128B: VLA radio upper limit
  76. GRB 250129A: Skynet optical observations
  77. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  78. GRB 250129A: Swift-XRT refined Analysis
  79. GRB 250128B: Gemini-North optical extended source detection
  80. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  81. GRB 250128B: TNG optical upper limit
  82. GRB 250129A: Swift/UVOT Detection
  83. GRB 250128B: VLT/HAWKI near-infrared observations
  84. GRB 250127A: CrAO and Terskol optical upper limits
  85. GRB 250129A: Enhanced Swift-XRT position
  86. GRB 250128B: NOT optical upper limit
  87. GRB 250128B: VLT/FORS2 optical observations
  88. GRB 250129A: REM optical/NIR afterglow detection
  89. GRB 250129A: OHP/T193 optical and spectroscopy observations
  90. GRB 250129A: Early afterglow detection by LCO.
  91. GRB 250128B: OHP/T193 optical upper limit
  92. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  93. GRB 250129A: LCO optical observations
  94. GRB 250129A: NOT optical observations and redshift confirmation
  95. GRB 250129A: GOTO optical observations show brightening afterglow
  96. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  97. Swift GRB 250129A: Global MASTER-Net observations report
  98. GRB 250128B: Enhanced Swift-XRT position
  99. Fermi GRB 250128B: Global MASTER-Net observations report
  100. GRB 250129A: Swift detection of a burst with an optical counterpart

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