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"

27215 results found.

  1. GRB 250320C : SVOM detection of a burst through offline search
  2. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  3. GRB 250330A: VLT/FORS2 Afterglow Detection
  4. GRB20250327B: 45th Parallel Observatory upper limit
  5. GRB 250328A: Swift/UVOT Detection
  6. GRB 250328A: Swift-XRT refined Analysis
  7. SVOM/sb25033102 is a false trigger
  8. GRB 250330A: Fermi GBM Observation
  9. GRB 250331C: COLIBRÍ/DDRAGO optical upper limit
  10. GRB 250331B: COLIBRÍ/DDRAGO optical upper limit
  11. GRB 250331D: Fermi GBM Final Real-time Localization
  12. GRB 250331C: Swift detection of a burst
  13. GRB 250331B: Swift detection of a burst
  14. GRB 250330A: SVOM/VT optical upper limit
  15. SVOM/sb25033102: SVOM detection of an X-ray transient
  16. Fermi GRB 250330B: Global MASTER-Net observations report
  17. GRB 250330B: Fermi GBM Final Real-time Localization
  18. Fermi GRB 250330A: Global MASTER-Net observations report
  19. GRB 250330A: BOOTES-7 early optical upper limit
  20. GRB 250330A: Swift/UVOT Upper Limits
  21. GRB 250328A: 1.6m Mephisto optical observations
  22. GRB 250329B: SVOM/COLIBRÍ (F-GFT) optical upper limit
  23. GRB 250330A: Fermi GBM Final Localization
  24. IceCube Alert 250330.35: Global MASTER-Net observations report
  25. GRB 250330A: VLT/FORS2 Optical Observations
  26. GRB 250330A: Prompt Swift-XRT position
  27. GRB 250329B: Swift-XRT afterglow detection
  28. GRB 250330A: Swift detection of a burst
  29. Swift GRB250330.26: Global MASTER-Net observations report
  30. GRB 250328A: A fading optical afterglow confirmed by SVOM/VT
  31. GRB 250329B: SVOM/C-GFT optical upper limit
  32. GRB 250329B: SVOM/VT optical upper limit
  33. GRB 250327B: SVOM/COLIBRÍ (F-GFT) Further Observations
  34. GRB 250329B: 1.6m Mephisto Optical Upper Limits
  35. LIGO/Virgo/KAGRA S250329fl: 2 counterpart neutrino candidate events from an IceCube neutrino search
  36. GRB250329A: REM optical afterglow detection
  37. GRB 250329B: SVOM detection of a faint transient
  38. GRB 250329A: Swift-XRT afterglow detection
  39. GRB 250328A: SVOM/VT optical observation
  40. GRB 250329A: Fading optical counterpart detection by LCO.
  41. GRB 250328A: SVOM/C-GFT optical upper limit
  42. GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
  43. GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
  44. GRB 250329A: VLT/X-shooter redshift z = 2.921
  45. GRB 250329A: SVOM/VT optical counterpart confirmation
  46. GRB 250329A: SVOM detection of a burst
  47. GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
  48. GRB 250327B: MASTER detection of OT rebrightening
  49. GRB 250327B: LCO optical counterpart detection
  50. GRB 250328A: SVOM detection of a burst
  51. GRB 250327B: CrAO and SAO RAS Optical Observations
  52. GRB 250327B: OHP/T193 spectroscopic observations and redshift confirmation
  53. GRB 250327b: Liverpool Telescope optical observations
  54. GRB 250322A: GRANDMA/TNOT optical upper limits
  55. GRB 250327A: SVOM/VT upper limits on the XRT position
  56. GRB 250327B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  57. GRB 250327B: Las Cumbres optical counterpart detection
  58. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  59. GRB 250327B: 1.6m Mephisto optical observations
  60. GRB 250327B: NOT spectroscopic redshift z = 3.035
  61. GRB 250327A: Swift-XRT refined Analysis
  62. GRB 250327B: GOTO optical counterpart detection
  63. GRB 250327B: SVOM/VT optically bright counterpart
  64. GRB 250327B: SAO RAS optical candidate
  65. GRB 250327B: SVOM detection of a burst
  66. GRB 250327A: SVOM/VT optical candidate
  67. GRB 250327A: Fermi GBM observation
  68. Fermi GRB 250327A: Global MASTER-Net observations report
  69. Swift GRB 250327A: Global MASTER-Net observations report
  70. GRB 250327A: DDOTI Optical Observations
  71. GRB 250327A: COLIBRÍ optical upper limit
  72. GRB 250327A: Swift detection of a burst
  73. GRB 250327A: Fermi GBM Final Real-time Localization
  74. Fermi trigger No 764700395: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 250322A (short)
  76. EP250321a: Mondy AZT-33IK Continued Optical Observations
  77. GRB 250322A: Swift-BAT refined analysis
  78. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  79. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  80. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  81. GRB 250322A: Swift/UVOT Upper Limits
  82. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  83. GRB 250322A: Swift-XRT refined Analysis
  84. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  85. SVOM/sb25032302: SVOM detection of a long X-ray transient
  86. GRB250322A: STEP/T80S optical limits
  87. GRB 250322A: Gemini-South optical observations
  88. GRB 250322A: VLT optical observations
  89. GRB 250322A: NOT optical upper limits
  90. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  91. GRB 250322A: MASTER optical observation
  92. EP250321a: Liverpool Telescope optical follow-up
  93. EP250321a: Mondy AZT-33IK Optical Observations
  94. GRB 250322A: Swift detection of a short burst
  95. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  96. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  97. EP250321a: KAIT optical observations
  98. EP250321A: COLIBRÍ Continuing Optical Observations
  99. GRB 250225B: GECAM-A detection
  100. GRB 250312A: GECAM-A detection

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