Skip to main content
Retirement of GCN Classic VOEvent Brokers. 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 230812B: Fermi-LAT detection
  2. GRB 230812B: Fermi GBM Observation of a very bright burst
  3. LAT GRB230812.79: Global MASTER-Net observations report
  4. Fermi GRB 230812B: Global MASTER-Net observations report
  5. GRB 230812B: Tiled Swift observations
  6. GRB 230812B: Fermi GBM detection of an extremely bright GRB
  7. GRB 230812B: Fermi GBM Final Real-time Localization
  8. ZTF23aaoohpy/AT2023lcr: JWST spectroscopy confirmation of an associated type Ic-BL supernova
  9. Fermi trigger No 713525317: Global MASTER-Net observations report
  10. GRB 230812A: Fermi GBM Final Real-time Localization
  11. LIGO/Virgo/KAGRA S230811n: Updated Sky localization
  12. GRB 230808A: Fermi GBM Detection
  13. LIGO/Virgo/KAGRA S230811n: Identification of a GW compact binary merger candidate
  14. GRB 230805B: Swift-BAT refined analysis
  15. LIGO/Virgo/KAGRA S230810af: Retraction of GW compact binary merger candidate
  16. GRB 230805B: Iota Scorpii Observatory, La Spezia, Italy upper limit
  17. GRB 230805B: AstroSat CZTI detection
  18. GRB 230808A: Swift/BAT-GUANO detection of a burst
  19. Fermi trigger No 713136868: Global MASTER-Net observations report
  20. GRB 230808B: Fermi GBM Final Real-time Localization
  21. The Fermi GBM Trigger 713134237 / 230807868 is not associated with LIGO/Virgo/KAGRA S230807f.
  22. Fermi trigger No 713205976: Global MASTER-Net observations report
  23. ZTF23aaoohpy/AT2023lcr: JWST observations consistent with the presence of a supernova
  24. GRB 230808A: Fermi GBM Final Real-time Localization
  25. GRB 230805B : MITSuME Akeno optical upper limits
  26. LIGO/Virgo/KAGRA S230808i: retraction of a GW unmodeled transient candidate
  27. LIGO/Virgo/KAGRA S230808i: Identification of a GW unmodeled transient candidate
  28. LIGO/Virgo/KAGRA S230807f: Updated Sky localization and EM Bright Classification
  29. transient SPT-SVJ025406.5-702837: ATCA follow-up observations
  30. Fermi GRB 230807A: Global MASTER-Net observations report
  31. Fermi trigger No 713134237: Global MASTER-Net observations report
  32. GRB 230807A: Fermi GBM Final Real-time Localization
  33. LIGO/Virgo/KAGRA S230807f: Identification of a GW compact binary merger candidate
  34. LIGO/Virgo/KAGRA S230805x: Upper limits from Swift/BAT-GUANO
  35. Konus-Wind detection of GRB 230803A
  36. GRB 230805B: Fermi GBM observation
  37. GRB 230805B : OHP/T193 optical upper limit
  38. LIGO/Virgo/KAGRA S230806ak: Updated Sky localization and EM Bright Classification
  39. GRB 230806A: Fermi GBM Final Localization
  40. GRB 230805B: Enhanced Swift-XRT position
  41. LIGO/Virgo/KAGRA S230806ak: Identification of a GW compact binary merger candidate
  42. GRB 230805B: Swift/UVOT Upper Limits
  43. Fermi trigger No 712991593: Global MASTER-Net observations report
  44. GRB 230805B: Bassano Bresciano observatory upper limit
  45. Fermi trigger No 712987357: Global MASTER-Net observations report
  46. GRB 230805B: BOOTES-6/DPRT optical upper limit and 1.5m OSN detection
  47. GRB 230805B: NOT optical afterglow confirmation
  48. GRB 230805B: Swift-XRT refined Analysis
  49. Fermi GRB 230805A: Global MASTER-Net observations report
  50. GRB 230805B: SAO RAS optical observations
  51. Fermi trigger No 712927418: Global MASTER-Net observations report
  52. Swift GRB 230805B: Global MASTER-Net observations report
  53. LIGO/Virgo/KAGRA S230805x: Updated Sky localization
  54. GRB 230805B: Swift detection of a burst
  55. GRB 230805A: Fermi GBM Final Real-time Localization
  56. LIGO/Virgo/KAGRA S230805x: Identification of a GW compact binary merger candidate
  57. LIGO/Virgo/KAGRA S230802aq: Updated Sky localization and EM Bright Classification
  58. GRB 230802B: AstroSat CZTI detection
  59. GRB 230802A: Fermi GBM observation
  60. GRB 230802A: Swift-BAT refined analysis
  61. GRB 230804A: Fermi GBM Final Real-time Localization
  62. Fermi trigger No 712798043: Global MASTER-Net observations report
  63. IPN triangulation of GRB 230803A
  64. GRB 230802A: Swift/UVOT Upper Limits
  65. GRB 230803A: AstroSat CZTI detection
  66. LIGO/Virgo/KAGRA S230802aq: AstroSat CZTI non-detection and upper limits
  67. Fermi trigger No 712718833: Global MASTER-Net observations report
  68. GRB 230803A: Fermi GBM Final Real-time Localization
  69. Fermi trigger No 712713532: Global MASTER-Net observations report
  70. Fermi trigger No 712651827: Global MASTER-Net observations report
  71. GRB 230802B: Fermi GBM Final Localization
  72. Swift GRB 230802A: Global MASTER-Net observations report
  73. GRB 230802A: BOOTES-5/JGT optical upper limit
  74. LIGO/Virgo/KAGRA S230802aq: Upper limits from Fermi-GBM Observations
  75. GRB 230802A: Swift-XRT refined Analysis
  76. GRB 230802A: Enhanced Swift-XRT position
  77. LIGO/Virgo S230802aq: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  78. LIGO/Virgo/KAGRA S230802aq: Coverage and upper limits from MAXI/GSC observations
  79. LIGO/Virgo/KAGRA S230802aq: Identification of a GW compact binary merger candidate
  80. GRB 230802A: Swift detection of a burst
  81. IceCube-230724A: JCMT/SCUBA-2 submm observations
  82. IceCube-230707A: JCMT/SCUBA-2 submm observations
  83. LIGO/Virgo/KAGRA S230731an: Upper limits from Swift/BAT-GUANO
  84. GRB 230723A: SPT-3G millimeter-band transient event inconsistent with IPN position
  85. LIGO/Virgo/KAGRA S230731an: AstroSat CZTI non-detection and upper limits
  86. LIGO/Virgo/KAGRA S230731an: not observable by Fermi-GBM
  87. LIGO/Virgo/KAGRA S230731an: Updated Sky Localization and EM Bright Classification, and Correction to Source Classification
  88. GRB 230731A: Fermi GBM Final Real-time Localization
  89. LIGO/Virgo/KAGRA S230731an: Coverage and upper limits from MAXI/GSC observations
  90. LIGO/Virgo/KAGRA S230731an: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S230729z: Updated Sky localization
  92. GRB 230723A: Detection of candidate millimeter-band radiation by SPT-3G
  93. Fermi trigger No 712390645: Global MASTER-Net observations report
  94. GRB 230728A: Swift-BAT refined analysis
  95. Fermi-LAT gamma-ray observations of IceCube-230727A
  96. GRB 230723B: Swift-BAT refined analysis
  97. Fermi trigger No 712306969: Global MASTER-Net observations report
  98. GRB 230723B: MITSuME Ishigaki optical observation
  99. IceCube-230727A: No candidates from the Zwicky Transient Facility
  100. LIGO/Virgo/KAGRA S230729z: Identification of a GW compact binary merger candidate

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