Skip to main content
New! Browse Circulars by Event, Advanced Search, Sample Codes, Schema Release. 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"

3360 results found.

  1. LIGO/Virgo/KAGRA S240422ed: Continued Magellan Observations
  2. S240422ed: BlackGEM/MeerLICHT transient detection AT2024hgl/MLTJ080628.10-250116.4
  3. LIGO/Virgo/KAGRA S240422ed: Second night Pan-STARRS observations of the skymap
  4. LIGO/Virgo/KAGRA S240422ed: Further near-infrared observations with Subaru/MOIRCS by J-GEM Collaboration
  5. Fermi trigger No 735697285: Global MASTER-Net observations report
  6. LIGO/Virgo/KAGRA S240422ed: No significant candidates in GRANDMA/FRAM Observations
  7. LIGO/Virgo S240422ed: Swift-XRT detection of 3 possible counterparts
  8. LIGO/Virgo/KAGRA S240422ed: Continued Imaging of Mag24a
  9. IceCube Alert 240424.08: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S240422ed: Subaru/MOIRCS near-infrared observations by J-GEM Collaboration
  11. LIGO/Virgo/KAGRA S240422ed: Magellan Observations
  12. Fermi GRB 240421B: Global MASTER-Net observations report
  13. Fermi trigger No 735280430: Global MASTER-Net observations report
  14. IceCube Alert 240419.98: Global MASTER-Net observations report
  15. EP240420a: EP-WXT detection of a fast X-ray transient
  16. Fermi GRB 240417A: Global MASTER-Net observations report
  17. LIGO/Virgo/KAGRA S240413p: STEP - T80S Search and Candidate Counterpart Identification
  18. GRB 240414A: GAD Observatory, La Spezia, Italy ,upper limit
  19. Fermi GRB 240415A: Global MASTER-Net observations report
  20. GRB 240414A: Photometric observation from 2.2m CAHA
  21. Fermi trigger No 734754044: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S240413p: Global MASTER-Net observations report
  23. GRB 240411B: 1.3m DFOT Optical observations
  24. X-ray transient EP240315a: second epoch e-MERLIN radio observations
  25. Fermi GRB 240407A: Global MASTER-Net observations report
  26. X-ray transient LXT 240402A: WFST optical upper limits​
  27. X-ray transient LXT240402A: AST3-3 optical upper limits
  28. LXT 240402A: MASTER optical observations with AGN in error-box
  29. IceCube-240327B: Upper limits from a search for additional neutrino events in IceCube
  30. IceCube-240327A: Upper limits from a search for additional neutrino events in IceCube
  31. Fermi GRB 240329A: Global MASTER-Net observations report
  32. IceCube-240327B: No candidates from the Zwicky Transient Facility
  33. GRB 240328C: Glowbug gamma-ray detection
  34. GRB 240328B: Fermi GBM Final Real-time Localization
  35. GRB 240328A: Fermi GBM Final Real-time Localization
  36. IceCube Alert 240327.68: Global MASTER-Net observations report
  37. Fermi GRB 240320A: Global MASTER-Net observations report
  38. GRB 240315B: AstroSat CZTI detection
  39. Fermi trigger No 732299243: Global MASTER-Net observations report
  40. Fermi trigger No 731839490: Global MASTER-Net observations report
  41. Fermi trigger No 731571927: Global MASTER-Net observations report
  42. GRB 231215A: further radio observations with the VLA
  43. GRB 231028C: Glowbug gamma-ray confirmation of a prior burst
  44. Swift detection of Swift J151857.0-572147
  45. Fermi trigger No 731161136: Global MASTER-Net observations report
  46. IceCube-240229A: Upper limits from a search for additional neutrino events in IceCube
  47. Fermi GRB 240229A: Global MASTER-Net observations report
  48. IceCube Alert 240229.66: Global MASTER-Net observations report
  49. GRB 240225B: 3.6m DOT observation
  50. GRB 240225B: SAO RAS optical observations
  51. Fermi GRB 240227A: Global MASTER-Net observations report
  52. GRB 240225B: MAXI/GSC detection
  53. Fermi trigger No 729914426: Global MASTER-Net observations report
  54. Gamma-ray flaring activity from the blazar 1ES 1959+650 observed by the Fermi-LAT
  55. GRB 240213A: GRBAlpha detection
  56. Fermi trigger No 729703985: Global MASTER-Net observations report
  57. Fermi GRB 240213A: Global MASTER-Net observations report
  58. Fermi trigger No 729152364: Global MASTER-Net observations report
  59. Fermi trigger No 729012023: Global MASTER-Net observations report
  60. Konus-Wind detection of GRB 240205B (long / very soft)
  61. Fermi trigger No 728749569: Global MASTER-Net observations report
  62. Fermi trigger No 728796365: Global MASTER-Net observations report
  63. Fermi GRB 240204A: Global MASTER-Net observations report
  64. Fermi trigger No 728706420: Global MASTER-Net observations report
  65. IceCube Alert 240204.38: Global MASTER-Net observations report
  66. GRB 240129A: Fermi GBM Observation
  67. GRB 240128A: Glowbug gamma-ray detection
  68. GRB 240128A: GRBAlpha detection
  69. GRB 240128A: CALET Gamma-Ray Burst Monitor detection
  70. GRB 240128A: MAXI/GSC detection
  71. GRB 240122A: MAXI/GSC detection
  72. Fermi GRB 240115B: Global MASTER-Net observations report
  73. GRB 240114A: MAXI/GSC detection
  74. Fermi trigger No 726774492: Global MASTER-Net observations report
  75. GRB 230818A: further radio observations with the VLA
  76. IceCube Alert 240105.52: Global MASTER-Net observations report
  77. GRB 240101B: MarSEC Observatory, Vicenza, Italy, UPPER LIMIT
  78. GRB 231230A: GOTO optical upper limits
  79. Fermi trigger No 725592555: Global MASTER-Net observations report
  80. Swift Triggers 1205103, 1205104, 1205107 and 1205110 are not astrophysical events
  81. LIGO/Virgo/KAGRA S231223j: Identification of a GW compact binary merger candidate
  82. Fermi trigger No 724781422: Global MASTER-Net observations report
  83. GRB 231215A: Osservatorio Astronomico Nastro Verde upper limit
  84. GRB 231216A: BOOTES-2/TELMA optical upper limit
  85. GRB 231214A: AstroSat CZTI detection
  86. Fermi trigger No 724278269: Global MASTER-Net observations report
  87. Fermi trigger No 724233240: Global MASTER-Net observations report
  88. GRB 231214A: Swift detection of a burst
  89. GRB 231210B: detection of the optical counterpart with the LCOGT 40cm telescope at Sutherland Observatory
  90. GRB 231129C: ASIM MXGS observation and localization
  91. Fermi trigger No 723435916: Global MASTER-Net observations report
  92. Fermi trigger No 723326169: Global MASTER-Net observations report
  93. Fermi trigger No 723149952: Global MASTER-Net observations report
  94. GRB 231128A: VZLUSAT-2 detection
  95. GRB 231129C: MAXI/GSC detection
  96. GRB 231128A: Fermi GBM Final Real-time Localization
  97. Fermi trigger No 722507896: Global MASTER-Net observations report
  98. GRB230728A: VIRT optical upper limit
  99. Fermi trigger No 722400249: Global MASTER-Net observations report
  100. GRB 231118A: MeerLICHT afterglow detection

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