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"

35422 results found.

  1. GRB 250129A: continued KAIT observations indicating steep decay after 28.5h
  2. GRB 250129A: iTelescope optical observation
  3. GRB 250129A: NOT optical observations of continuining activity
  4. GRB 250129a: Liverpool Telescope optical follow-up
  5. GRB 250129A: TNG NIR afterglow detection
  6. GRB 250129A: AKO Optical Afterglow Detection
  7. GRB 250129A: GRANDMA/TAROT optical afterglow detection
  8. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  9. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  10. GRB 250128B: VLA radio upper limit
  11. GRB 250129A: Skynet optical observations
  12. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  13. GRB 250129A: Swift-XRT refined Analysis
  14. GRB 250128B: Gemini-North optical extended source detection
  15. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  16. GRB 250128B: TNG optical upper limit
  17. GRB 250129A: Swift/UVOT Detection
  18. GRB 250128B: VLT/HAWKI near-infrared observations
  19. GRB 250127A: CrAO and Terskol optical upper limits
  20. GRB 250129A: Enhanced Swift-XRT position
  21. GRB 250128B: NOT optical upper limit
  22. GRB 250128B: VLT/FORS2 optical observations
  23. GRB 250129A: REM optical/NIR afterglow detection
  24. GRB 250129A: OHP/T193 optical and spectroscopy observations
  25. GRB 250129A: Early afterglow detection by LCO.
  26. GRB 250128B: OHP/T193 optical upper limit
  27. Swift GRB 250129A: Global MASTER-Net Slowly evolving LC detection
  28. GRB 250129A: LCO optical observations
  29. GRB 250129A: NOT optical observations and redshift confirmation
  30. GRB 250129A: GOTO optical observations show brightening afterglow
  31. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  32. Swift GRB 250129A: Global MASTER-Net observations report
  33. GRB 250128B: Enhanced Swift-XRT position
  34. Fermi GRB 250128B: Global MASTER-Net observations report
  35. GRB 250129A: Swift detection of a burst with an optical counterpart
  36. Swift GRB 250129A: Global MASTER-Net OT detection
  37. GRB 250128B: Swift-XRT refined Analysis
  38. GRB 250128B: Fermi GBM Observation
  39. GRB 250128B: GOTO optical upper limit
  40. Swift GRB 250128B: Global MASTER-Net observations report
  41. EP250125a: Upper limits from Swift/BAT-GUANO
  42. GRB 250128B: LCO optical observations
  43. GRB 250128B: Swift detection of a short burst
  44. GRB 250128B: Fermi GBM Final Real-time Localization
  45. GRB 250127A: Swift-XRT observations
  46. GRB 250127B: DDOTI Upper Limit on the Afterglow
  47. GRB 250127A: EP-FXT afterglow detection
  48. Fermi GRB 250128A: Global MASTER-Net observations report
  49. GRB 250128A: Fermi GBM Final Real-time Localization
  50. GRB 250117A: Fermi GBM Observation
  51. Fermi GRB 250127B: Global MASTER-Net observations report
  52. GRB 250127A: SVOM/VT upper limit
  53. GRB 250127B: Fermi GBM Final Real-time Localization
  54. IPN triangulation of GRB 250119C
  55. GRB 250127A: Swift ToO observations
  56. GRB 250127A: LCO optical upper limit
  57. GRB 241223A: cubesat Avion detection
  58. GRB 250127A: SVOM detection of a long burst
  59. GRB 250126A: CALET Gamma-Ray Burst Monitor detection
  60. EP250125A: Non-detection from Fermi-GBM Observations
  61. GRB 250126A: MAXI/GSC detection
  62. GRB 250126A: BALROG localization (Fermi Trigger 759560335 / GRB 250126208)
  63. GRB 250126A: Fermi GBM Final Real-time Localization
  64. GRB 250118A: Fermi GBM Observation
  65. GRB 250119C: Fermi GBM Observation
  66. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  67. IPN triangulation of a bright burst from SGR 1E1841-045
  68. GRB 250121A: CALET Gamma-Ray Burst Monitor detection
  69. EP250108a: AbAO, CMO and Terskol optical upper limits
  70. Konus-Wind detection of GRB 250118B
  71. GRB 250121A: Fermi GBM Observation
  72. IPN triangulation of GRB 250118B
  73. Konus-Wind detection of GRB 250119B
  74. IPN triangulation of GRB 250119B
  75. GRB 250122A: Fermi GBM Final Real-time Localization
  76. Improved IPN triangulation of GRB 250107C
  77. GRB 250114A: Swift-BAT refined analysis
  78. GRB 250121A: INTEGRAL/SPI-ACS detection
  79. GRB 250121A: Fermi-LAT detection
  80. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  81. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  82. GRB 250121A: Fermi GBM Final Real-time Localization
  83. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  84. GRB 250119B: Fermi GBM Observation
  85. Konus-Wind detection of GRB 250117A
  86. IPN triangulation of GRB 250117A (short)
  87. ATCA detection of possible radio counterpart to GRB 250114A
  88. GRB 250119B: INTEGRAL/SPI-ACS detection
  89. EP 250108A: Late-time optical observation by LCO
  90. GRB 250117A: SVOM/GRM observation of a short burst
  91. GRB 250119C: Fermi GBM Final Real-time Localization
  92. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  93. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  94. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  95. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  96. GRB 250117A: GECAM observation of a short burst
  97. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  98. GRB 250119B: Fermi GBM Final Real-time Localization
  99. GRB 250119A: Fermi GBM Final Real-time Localization
  100. GRB 250118A: Fermi GBM Final Real-time Localization

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