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"

37967 results found.

  1. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  2. Fermi GRB 250702E: Global MASTER-Net observations report
  3. Fermi GRB 250702B: Global MASTER-Net observations report
  4. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  5. GRB 250702F: Enhanced Swift-XRT position
  6. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  7. GRB 250702F: NOT observations of the optical afterglow
  8. GRB 250702F: MASTER optical afterglow observation
  9. Fermi GRB 250702F: Global MASTER-Net observations report
  10. Fermi GRB 250702C: Global MASTER-Net observations report
  11. GRB 250702F: GOTO optical counterpart detection
  12. GRB 250702F: Ondrejov D50 optical afterglow detection
  13. GRB 250702F: Swift detection of a burst with an optical counterpart
  14. Swift GRB 250702F: Global MASTER-Net observations report
  15. GRB 250702F: Fermi GBM Final Real-time Localization
  16. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  17. GRB 250702E: Fermi GBM Final Real-time Localization
  18. Konus-Wind detection of GRB 250627A
  19. IPN triangulation of GRB 250627A (short)
  20. GRB 250702A: Fermi GBM Detection
  21. GRB 250702D: Fermi GBM Final Localization Correction
  22. GRB 250702C: Fermi GBM Final Real-time Localization
  23. GRB 250702B: Fermi GBM Final Real-time Localization
  24. GRB 250702A: BALROG localization (Fermi Trigger 773142852 / GRB 250702413)
  25. GRB 250702A: Fermi GBM Final Real-time Localization
  26. Fermi Gamma-ray Burst Monitor trigger 772838080/250628885 is not a GRB
  27. GRB 250628B: Swift-XRT observations
  28. Fermi Gamma-ray Burst Monitor trigger 772981768/250630548 is not a GRB
  29. GRB 250628B: SVOM/VT optical upper limit
  30. GRB 250628B: EP-FXT counterpart detection
  31. GRB 250627A: Insight-HXMT detection
  32. GRB 250627A: SVOM/GRM detection of a short burst
  33. GRB 250628A: REM optical/NIR upper limits
  34. GRB 250628C: Fermi GBM Final Real-time Localization
  35. GRB 250628B: SVOM detection of a long burst
  36. Fermi Gamma-ray Burst Monitor trigger 772811638/250628579 is not a GRB
  37. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  38. GRB 250628A: VLT/X-shooter upper limits
  39. GRB 250628A: Swift/UVOT Upper Limits
  40. GRB 250628A: Swift-XRT refined Analysis
  41. Fermi GRB 250626A: Global MASTER-Net observations report
  42. Swift GRB 250628A: Global MASTER-Net observations report
  43. GRB 250628A: Enhanced Swift-XRT position
  44. GRB 250628A: Swift detection of a burst
  45. GRB 250625A: Swift-BAT refined analysis
  46. GRB 250625A: Leavitt Observatory afterglow detection
  47. Fermi Gamma-ray Burst Monitor trigger 772732642/250627665 is not a GRB
  48. Fermi Gamma-ray Burst Monitor trigger 772720540/250627525 is not a GRB
  49. GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
  50. GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
  51. GRB 250626A: Fermi GBM Final Real-time Localization
  52. Fermi Gamma-ray Burst Monitor trigger 772647532/250626680 is not a GRB
  53. GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  54. GRB 250625A: SVOM/C-GFT upper limit in early phase
  55. GRB 250625A: GECAM-B detection
  56. GRB 250625A: Swift/UVOT Upper Limits
  57. GRB 250625A: ABObservatory afterglow detection
  58. GRB 250625A: OHP/T193 optical detection
  59. GRB 250625A: COLIBRÍ optical observations
  60. GRB 250625A: Fermi-LAT detection
  61. GRB 250625A: Swift-XRT refined Analysis
  62. GRB 250625A: JinShan optical observations
  63. GRB250625A: Fermi GBM Observation
  64. Swift GRB 250625A: Global MASTER-Net observations report
  65. GRB 250625A: NOT z-band upper limit
  66. GRB 250625A: SVOM/VT optical confirmation
  67. GRB 250620B: Fermi GBM Observation
  68. GRB 250625A: SAO RAS possible optical afterglow
  69. GRB 250625A: Enhanced Swift-XRT position
  70. Fermi GRB 250625A: Global MASTER-Net observations report
  71. GRB 250625A: Swift detection of a burst
  72. GRB 250625A: Fermi GBM Final Real-time Localization
  73. GRB 250617B: Mondy and SAO RAS optical observations on 2025-06-23, 2025-06-24
  74. GRB 250620A: AstroSat CZTI detection
  75. GRB 241018A: Maidanak optical observations
  76. GRB 250620C: AstroSat CZTI detection
  77. Fermi GRB 250624A: Global MASTER-Net observations report
  78. GRB 250624A: Fermi GBM Final Real-time Localization
  79. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  80. Fermi GRB 250623A: Global MASTER-Net observations report
  81. GRB 250623A: Fermi GBM Final Real-time Localization
  82. GRB 250521A: VZLUSAT-2 detection
  83. GRB 250617B: Swift-BAT refined analysis
  84. Konus-Wind detection of GRB 250620C
  85. IPN triangulation of GRB 250620C (long/bright)
  86. GRB 250621B: SVOM/GRM detection of a possible magnetar X-ray burst
  87. GRB 250620C: SVOM/GRM observation
  88. GRB 250620A: SVOM/GRM observation of a short burst
  89. GRB250620A: Fermi GBM Observation
  90. GRB 250617B: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  91. Fermi GRB 250621A: Global MASTER-Net observations report
  92. GRB 250619B: Fermi GBM Observation
  93. GRB 250621A: Fermi GBM Final Real-time Localization
  94. GRB 250620B: Swift/BAT-GUANO localization skymap of a burst
  95. GRB250620C: Fermi GBM Observation
  96. GRB 250506A - SVOM/ECLAIRs Refined analysis
  97. GRB 250620A: Swift/BAT-GUANO subthreshold detection of a possibly short burst
  98. GRB 250619B: Swift/BAT-GUANO localization skymap of a burst
  99. GRB 250620C: Fermi GBM Final Real-time Localization
  100. GRB 250620B: Fermi GBM Final Real-time Localization

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