Skip to main content
New! Super-Kamiokande JSON Notices and Schema v4.5.0. 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"
  1. GRB 240101A: Swift/UVOT Upper Limits
  2. GRB 240101A: Swift-XRT refined Analysis
  3. GRB 240101B: Enhanced Swift-XRT position
  4. GRB 240101B: KAIT Optical Upper Limit
  5. GRB 240101A: KAIT Optical Upper Limit
  6. GRB 240101A: Enhanced Swift-XRT position
  7. GRB 240101C: Fermi GBM Final Localization
  8. Swift GRB240101.85: Global MASTER-Net observations report
  9. GRB 240101B: Swift detection of a burst
  10. GRB 240101A: Swift detection of a burst
  11. Fermi trigger No 725806648: Global MASTER-Net observations report
  12. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  13. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  14. GRB231230A: Fermi GBM Observation
  15. GRB 231230A: Swift-XRT refined Analysis
  16. GRB 231230A: GOTO optical upper limits
  17. GRB 231230A: Enhanced Swift-XRT position
  18. GRB 231230A: Swift/UVOT Upper Limits
  19. GRB 231230A: NOT optical upper limits
  20. Fermi trigger No 725592555: Global MASTER-Net observations report
  21. GRB 231230A: Prompt enhanced Swift-XRT position
  22. GRB 231230A: Swift detection of a burst
  23. Swift GRB231230.06: Global MASTER-Net observations report
  24. GRB 231230A: Fermi GBM Final Real-time Localization
  25. GRB 231210B: BOOTES-7 optical upper limit
  26. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  27. LIGO/Virgo/KAGRA S231224e: Upper limits from Swift/BAT-GUANO
  28. IPN triangulation of GRB 231224A (short)
  29. LIGO/Virgo/KAGRA S231226av: Updated Sky localization
  30. LIGO/Virgo/KAGRA S231226av: Identification of a GW compact binary merger candidate
  31. Fermi trigger No 725143760: Global MASTER-Net observations report
  32. GRB 231224A: Fermi GBM Final Real-time Localization
  33. GRB 231222B: GRBAlpha detection
  34. LIGO/Virgo/KAGRA S231224e: Updated Sky localization and Source Classification
  35. LIGO/Virgo/KAGRA S231224e: Identification of a GW compact binary merger candidate
  36. LIGO/Virgo/KAGRA S231223j: Updated Sky localization
  37. GRB 231222B: Swift-XRT afterglow detection
  38. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  39. Fermi trigger No 724921799: Global MASTER-Net observations report
  40. GRB 231222B: Fermi GBM Detection
  41. LAT GRB231222.31: Global MASTER-Net observations report
  42. GRB 231222B: Fermi-LAT detection
  43. GRB 231222A: Tiled Swift observations
  44. IceCube-231211A: GRANDMA observations of PKS2047+098
  45. GRID detection of GRB 231215A
  46. GRB 231222A: Fermi GBM Final Real-time Localization
  47. GRB 231220A: Swift-XRT follow-up observations
  48. GRB 231220A: Swift ToO observations
  49. GRB 231220A: Swift/BAT-GUANO arcminute localization of a long burst
  50. Fermi trigger No 724781422: Global MASTER-Net observations report
  51. GRB 231220A: Fermi GBM Final Real-time Localization
  52. GRB 231210B: new optical transient detected with the Greenhill Observatory University of Tasmania within the BAT-Swift enhanced position
  53. Fermi trigger No 724698747: Global MASTER-Net observations report
  54. GRB 231219A: Fermi GBM Final Real-time Localization
  55. GRID detection of GRB 231205B
  56. GRID detection of GRB 231205A
  57. GRB 231216A: GAD Observatory, La Spezia, Italy upper limit
  58. GRB 231214B: Fermi GBM observation
  59. GRB 231216A: optical upper limits from the INAF Asiago Observatory
  60. GRB 231216A: 10.4 m GTC optical upper limit
  61. GRB 231215A: AMI-LA radio detection
  62. GRB 231216A: Nanshan/HMT optical upper limit
  63. GRB 231216A: LCOGT Optical Upper Limits
  64. GRB 231216A: Osservatorio Astronomico Nastro Verde upper limit
  65. GRB 231216A: Swift-XRT refined analysis correction
  66. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  67. GRB 231216A: Swift-XRT refined Analysis
  68. GRB 231216A: AST3-3 YaoAn Optical Upper Limit
  69. GRB 231216A: REM NIR upper limits
  70. GRB 231216A: Swift/UVOT Upper Limits
  71. GRB 231216A: Swift-BAT refined analysis
  72. GRB 231215A: Swift-BAT refined analysis
  73. GRB 231214A: Swift-BAT refined analysis
  74. GRB 231216A: R-band observations from T120 at Observatoire de Haute-Provence
  75. GRB 231216A: GIT optical upper limit
  76. GRB 231216A: NOT optical upper limits
  77. GRB 231216A: BOOTES-2/TELMA optical upper limit
  78. GRB 231215A: GRBAlpha detection
  79. Swift GRB231216.77: Global MASTER-Net observations report
  80. GRB 231216A: Swift detection of a burst
  81. Konus-Wind detection of GRB 231215A
  82. GRB 231215A: optical afterglow detection from the INAF Asiago Observatory
  83. GRB 231215A: NOT optical observations
  84. GRB 231214A: Swift/UVOT Upper Limits
  85. GRB 231215A: Redshift from OSIRIS+ / GTC
  86. GRB 231205B: VZLUSAT-2 detection
  87. GRB 231204A: VZLUSAT-2 detection
  88. GRB 231215A: GAD Observatory, La Spezia, Italy upper limit;
  89. GRB 231215A: Fermi GBM observation
  90. GRB 231215A: CALET Gamma-Ray Burst Monitor detection
  91. GRB 231215A : OHP/T193 optical afterglow detection
  92. GRB 231215A: Swift/UVOT Detection
  93. LIGO/Virgo/KAGRA S231215i: 3 counterpart neutrino candidate events from an IceCube neutrino search
  94. GRB 231215A: Swift-XRT refined Analysis
  95. GRB 231215A: BOOTES-4/MET optical detection
  96. GRB 231215A: AKO Optical Upper Limit
  97. GRB 231215A: AGILE detection
  98. GRB 231214A: Fermi GBM observation
  99. Konus-Wind detection of GRB 231210B
  100. ATCA observations of GRB 231210B

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