Skip to main content
Due to the lapse in federal government funding, NASA is not updating this website. See the Operations FAQ for GCN impacts.
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. Fermi GRB 240115A: Global MASTER-Net observations report
  2. GRB 240115A: Fermi GBM Final Real-time Localization
  3. GRB 240112C: GRBAlpha detection
  4. GRB 240114A: MAXI/GSC detection
  5. GRB 240112C: Swift/UVOT Detection
  6. GRB 240112C: Fermi GBM Detection
  7. Fermi trigger No 726773850: Global MASTER-Net observations report
  8. GRB 240112C: Swift-XRT refined Analysis
  9. GRB 240112C: SAO RAS optical observations
  10. GRB 240112E: Fermi GBM Final Localization
  11. Fermi GRB 240112D: Global MASTER-Net observations report
  12. GRB 240112D: Fermi GBM Final Real-time Localization
  13. Fermi trigger No 726774492: Global MASTER-Net observations report
  14. Swift GRB 240112C: Global MASTER-Net observations report
  15. Fermi GRB 240112B: Global MASTER-Net observations report
  16. GRB 240109A: Swift-BAT refined analysis
  17. GRB 240112C: Swift detection of a burst with an optical counterpart
  18. GRB 240112B: Fermi GBM Final Real-time Localization
  19. GRB 240112A: GECAM detection of a burst
  20. GRB 240109A: Fermi GBM Observation
  21. GRB 240110A: AstroSat CZTI detection
  22. Fermi-LAT detection of increased gamma-ray activity of blazar PKS 0446+11, located inside the IceCube-240105A error region
  23. GRB 240108A: Glowbug gamma-ray detection
  24. GRB 231214A: ATCA Radio Upper Limits
  25. GRB 240106B: Glowbug gamma-ray detection
  26. GRB 240106A: Glowbug gamma-ray detection
  27. IceCube-240105A: Upper limits from a search for additional neutrino events in IceCube
  28. GRB 240109B: Fermi GBM Final Real-time Localization
  29. IceCube-240105A: Three candidates from the Zwicky Transient Facility
  30. LIGO/Virgo/KAGRA S240109a: Updated Sky localization
  31. Konus-Wind detection of GRB 240101C
  32. GRB 231215A: radio detection with the VLA
  33. GRB 230818A: further radio observations with the VLA
  34. GRB 230812B: further radio observations with the VLA
  35. Swift GRB240109.17: Global MASTER-Net observations report
  36. GRB 240107A: AstroSat CZTI detection
  37. LIGO/Virgo/KAGRA S240109a: Identification of a GW compact binary merger candidate
  38. GRB 240109A: Swift detection of a short burst
  39. LIGO/Virgo/KAGRA S240104bl: Upper limits from Swift/BAT-GUANO
  40. IceCube-240105A: JCMT SCUBA2 Detection of Two Bright Submillimeter Sources
  41. Update of IceCube-240105A - Corrected errors
  42. GRB 240106A: GRBAlpha detection
  43. LIGO/Virgo/KAGRA S240107b: Updated Sky localization and Source Classification
  44. GRB 240107A: MAXI/GSC detection
  45. Fermi trigger No 726347794: Global MASTER-Net observations report
  46. LIGO/Virgo/KAGRA S240107b: Identification of a GW compact binary merger candidate
  47. GRB 240106B: Fermi GBM Final Real-time Localization
  48. Fermi trigger No 726194053: Global MASTER-Net observations report
  49. GRB 240106A: Fermi GBM Final Real-time Localization
  50. IPN triangulation of GRB 240101C (short)
  51. GRB GRB240101C: Fermi GBM observation
  52. IceCube Alert 240105.52: Global MASTER-Net observations report
  53. GRB 240101A: 1.3m DFOT optical observations
  54. IceCube-240105A - IceCube observation of a high-energy neutrino candidate track-like event
  55. GRB 240102A: 1.3m DFOT optical upper limit
  56. GRB 240101B: 1.3m DFOT optical upper limit
  57. GRB 240101C: Swift/BAT-GUANO detection of a short burst
  58. LIGO/Virgo/KAGRA S240104bl: Updated Sky localization
  59. LIGO/Virgo/KAGRA S240104bl: Identification of a GW compact binary merger candidate
  60. GRB 240102C: AstroSat CZTI detection
  61. GRB 240101C: AstroSat CZTI detection
  62. GRB 231220A: Swift-UVOT upper limit
  63. GRB 240102A: Swift-BAT refined analysis
  64. GRB 240102A: Swift/UVOT Upper Limits
  65. GRB 231230A: Swift-BAT refined analysis
  66. GRB 240101A: Swift-BAT refined analysis
  67. GRB 240101B: Swift-BAT refined analysis
  68. GRB 240102A: Enhanced Swift-XRT position
  69. GRB 240101B: Swift-XRT refined Analysis
  70. GRB 240102A: Swift-XRT refined Analysis
  71. GRB 240102B (Fermi GBM trigger 725926335/240102925) is not a GRB
  72. GRB 240102A: LCOGT Optical Upper Limits
  73. Fermi trigger No 725857207: Global MASTER-Net observations report
  74. GRB240102A: BOOTES-6/DPRT optical upper limit
  75. GRB 240102B: Fermi GBM Final Real-time Localization
  76. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  77. IceCube-Cascade 231230A: Upper limits from a search for additional neutrino events in IceCube
  78. GRB 240102A: Swift detection of a burst
  79. GRB 240101A: Terskol Zeiss-2000 optical observations
  80. GRB 240101C: GRBAlpha detection
  81. GRB 240101B: Swift/UVOT Upper Limits
  82. GRB 240101A: Swift/UVOT Upper Limits
  83. GRB 240101A: Swift-XRT refined Analysis
  84. GRB 240101B: Enhanced Swift-XRT position
  85. GRB 240101B: KAIT Optical Upper Limit
  86. GRB 240101A: KAIT Optical Upper Limit
  87. GRB 240101A: Enhanced Swift-XRT position
  88. GRB 240101C: Fermi GBM Final Localization
  89. Swift GRB240101.85: Global MASTER-Net observations report
  90. GRB 240101B: Swift detection of a burst
  91. GRB 240101A: Swift detection of a burst
  92. Fermi trigger No 725806648: Global MASTER-Net observations report
  93. LIGO/Virgo/KAGRA S231231ag: Updated Sky localization and Source Classification
  94. LIGO/Virgo/KAGRA S231231ag: Identification of a GW compact binary merger candidate
  95. GRB231230A: Fermi GBM Observation
  96. GRB 231230A: Swift-XRT refined Analysis
  97. GRB 231230A: GOTO optical upper limits
  98. GRB 231230A: Enhanced Swift-XRT position
  99. GRB 231230A: Swift/UVOT Upper Limits
  100. GRB 231230A: NOT optical upper limits

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