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"

42482 results found.

  1. Konus-Wind detection of GRB 250920A
  2. Konus-Wind detection of GRB 250911A
  3. GRB 250916A: Swift/UVOT Detection
  4. GRB 250920B: Glowbug gamma-ray detection
  5. GRB 250916A: CrAO ZTSh R-band optical observations
  6. GRB 250920C: Swift-XRT refined Analysis
  7. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  8. GRB 250922A: Fermi GBM Final Localization
  9. GRB 250920B: Asiago optical observations
  10. GRB 250920B: Kitab-ISON optical upper limit
  11. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  12. GRB 250920C: SVOM/GRM observation
  13. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  14. GRB 250917B: KAIT optical upper limit
  15. GRB 250920A: NuSTAR detection of bright prompt emission
  16. GRB 250920C: GROWTH-India Telescope optical observations
  17. GRB 250920C: Swift-BAT refined analysis
  18. GRB 250920B: Swift-BAT refined analysis
  19. GRB 250920C: Enhanced Swift-XRT position
  20. GRB 250916A: FTW optical and NIR observations of the counterpart
  21. GRB 250920C: Swift/UVOT Detection
  22. GRB 250920B: Fermi GBM Observation
  23. GRB 250920A: Fermi GBM Detection
  24. GRB 250920C: Fermi GBM Observation
  25. Swift GRB 250920C: Global MASTER-Net observations report
  26. GRB 250920B: Swift/UVOT Detection
  27. GRB 250920B: FTW optical and NIR observations of the counterpart
  28. GRB 250920C: Optical counterpart detection by LCO
  29. GRB 250920A: SVOM/GRM observation
  30. GRB250920C: LCOGT Optical Detection
  31. GRB 250920B: Enhanced Swift-XRT position
  32. GRB 250920B: Swift-XRT refined Analysis
  33. GRB 250920B: SVOM/C-GFT optical observations
  34. GRB 250920C: GOTO optical counterpart candidate
  35. GRB 250919A / EP250919a: LCO optical observation
  36. Konus-Wind detection of GRB 250919A
  37. GRB 250920C: Swift detection of a burst
  38. GRB 250920C: Fermi GBM Final Real-time Localization
  39. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  40. Swift GRB 250920B: Global MASTER-Net observations report
  41. GRB 250919A / EP250919a: Insight-HXMT detection
  42. GRB 250920A: AstroSat CZTI detection
  43. GRB 250920B: Swift detection of a burst with a bright optical counterpart.
  44. GRB 250920B: Fermi GBM Final Real-time Localization
  45. GRB 250920A: BALROG localization (Fermi Trigger 780029651 / GRB 250920121)
  46. GRB 250920A: Fermi GBM Final Localization
  47. GRB 250919A/EP250919a: SVOM/VT optical observation
  48. GRB 250919A / EP250919a: MASTER bright afterglow detection 24h after GRB time
  49. GRB 250916A: Mondy R-band optical observations
  50. GRB 250919A: Glowbug gamma-ray detection
  51. GRB 250919A: Fermi GBM Observation
  52. Fermi GRB 250918A: Global MASTER-Net observations report
  53. GRB 250919A / EP250919a: NuSTAR detection of bright prompt emission
  54. GRB 250918A: SVOM/GRM observation
  55. GRB 250919A/EP250919A: Swift/UVOT afterglow detection
  56. GRB 250919A: Swift-XRT afterglow detection
  57. GRB 250919A: Fermi-LAT detection
  58. EP250919a/GRB 250919A: Gemini/GMOS-S spectroscopic redshift z = 1.145
  59. GRB 250919A: SVOM/GRM observation of a very bright GRB
  60. GRB 250919A: BALROG localization (Fermi Trigger 779934537 / GRB 250919020)
  61. EP250919a: Global MASTER-Net observations report
  62. EP250919a: Einstein Probe detection of an X-ray transient
  63. The EP-WXT trigger 01709243841: Las Cumbres discovery of the optical counterpart
  64. GRB 250916A: Fermi GBM Observation
  65. Fermi GRB 250919A: Global MASTER-Net observations report
  66. GRB 250919A: Fermi GBM Final Real-time Localization
  67. GRB 250916A: KAIT optical observations
  68. GRB 250917B: VLT/HAWK-I near-infrared observations
  69. GRB 250916A: NuSTAR detection of the prompt emission
  70. GRB 250916A: further SAO RAS optical observations
  71. GRB 250912A: SVOM/ECLAIRs refined analysis
  72. GRB 250917B: Swift-BAT refined analysis
  73. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  74. GRB 250918A: BALROG localization (Fermi Trigger 779891543 / GRB 250918522)
  75. GRB 250918A: Fermi GBM Final Real-time Localization
  76. GRB 250917B: Swift/UVOT Upper Limits
  77. GRB 250916A: OSIRIS+/GTC redshift z = 2.015
  78. GRB 250916A: Swift-XRT observations
  79. EP250916a: EP-FXT follow-up observation
  80. GRB 250916A: MAO/AZT-22 optical observations
  81. GRB 250916A: SAO RAS optical observations
  82. GRB 250916A : GIT optical observations
  83. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  84. GRB 250916A: Glowbug gamma-ray detection
  85. GRB250917B: WFST optical observations
  86. GRB 250916A: Swift ToO observations
  87. GRB 250917B: Fermi GBM Observation
  88. GRB 250917B: Swift-XRT observations
  89. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  90. Fermi GRB 250917B: Global MASTER-Net observations report
  91. GRB 250917B: Swift detection of a short burst
  92. GRB 250916A: GOTO optical counterpart candidate
  93. GRB 250917B: Fermi GBM Final Real-time Localization
  94. GRB 250917A: Fermi GBM Final Real-time Localization
  95. The EP-WXT trigger 01709241037 is likely a flaring star
  96. GRB 250916A: AstroSat CZTI detection of a bright long burst
  97. GRB 250910A: SVOM/ECLAIRs refined analysis
  98. EP250916a: Einstein Probe detection of an X-ray transient
  99. Fermi GRB 250916A: Global MASTER-Net observations report
  100. GRB 250916A: 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