Skip to main content
Updates to LVK & CHIME Notices, Schema v7.2.3! 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 240619A: J-band detection with WINTER
  2. LIGO/Virgo/KAGRA S240622h: Updated Sky localization and Source Classification
  3. Fermi trigger No 740744838: Global MASTER-Net observations report
  4. EP240618a: NOT optical counterpart candidate
  5. LIGO/Virgo/KAGRA S240621em: Updated Sky localization and Source Classification
  6. GRB 240529A: JinShan optical observations
  7. LIGO/Virgo/KAGRA S240621dy: Updated Sky localization and Source Classification
  8. LIGO/Virgo/KAGRA S240621eb: Updated Sky localization and Source Classification
  9. EP240618a: GSP optical upper limit
  10. LIGO/Virgo/KAGRA S240622h: Identification of a GW compact binary merger candidate
  11. LIGO/Virgo/KAGRA S240621em: Identification of a GW compact binary merger candidate
  12. LIGO/Virgo/KAGRA S240621eb: Identification of a GW compact binary merger candidate
  13. LIGO/Virgo/KAGRA S240621dy: Identification of a GW compact binary merger candidate
  14. IPN triangulation of GRB 240615A (short)
  15. X-ray transient EP240618a: Fermi/GBM non-detection
  16. GRB 240619A: GRBAlpha detection
  17. EP240618a: Swift/XRT upper limit
  18. EP240617a: tentative Swift/XRT detection of the afterglow
  19. GRB 240619A: Swift-XRT probable afterglow detection
  20. GRB 240619A: Swift ToO observations
  21. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  22. GRB 240619C: NuSTAR automated detection of the GRB
  23. GRB 240619A: Fermi GBM Observation
  24. Fermi GBM Sub-Threshold Detection of GRB 240619C
  25. GRB 240619A: GOTO candidate optical afterglow
  26. EP240618a: Abastumani optical observationsEP240618a
  27. GRB 240615A: NOT optical observations
  28. EP240618a: GRANDMA Optical Upper Limits
  29. GRB 240619C: AstroSat CZTI detection
  30. EP240618a: TRT optical upper limit
  31. Fermi trigger No 740474239: Global MASTER-Net observations report
  32. Fermi GRB 240619A: Global MASTER-Net observations report
  33. EP240617a: STEP/T80S optical limits
  34. GRB 240615A: possible transient detection from Wendelstein observations
  35. LIGO/Virgo S240615dg: GRANDMA/FRAM-CTA-N Observations
  36. LIGO/Virgo/KAGRA S240615dg: Updated Sky localization
  37. LIGO/Virgo/KAGRA S240618ah: Updated Sky localization
  38. EP240618a: OHP/T193 MISTRAL i' and Y band upper limits
  39. EP240618a: BOOTES-6/DPRT optical upper limit
  40. Fermi Gamma-ray Burst Monitor trigger 740474239/240619304 is not a GRB
  41. GRB 240619B: Fermi GBM Final Real-time Localization
  42. LIGO/Virgo S240615dg: Swift XRT observations, 39 X-ray sources
  43. Fermi trigger No 740430582: Global MASTER-Net observations report
  44. GRB240615A: 1.3m DFOT optical upper limit
  45. GRB 240619A: BALROG localization (Fermi Trigger 740461416 / GRB 240619155)
  46. GRB 240619A: Fermi GBM Final Real-time Localization
  47. EP240617a: BOOTES-6/DPRT optical upper limit
  48. EP240617a is likely a GRB event
  49. EP240617a: EP-WXT detection of a fast X-ray transient
  50. EP240618a: EP-WXT detection of a fast X-ray transient and EP-FXT quick follow-up
  51. LIGO/Virgo/KAGRA S240618ah: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S240615ea: Upper limits from Swift/BAT-GUANO
  53. LIGO/Virgo/KAGRA S240615dg: Upper limits from Swift/BAT-GUANO
  54. GRB 240615A: J-band upper limits from WINTER
  55. GRB 240615A: Fermi GBM Observation
  56. LIGO/Virgo/KAGRA S240615ea: Updated Sky localization
  57. GRB 240615A: Swift-XRT observations
  58. GRB 240615A: GECAM detection
  59. X-ray transient EP240414a: Chandra late time observation
  60. GRB 240615A: FLWO-1.2m optical upper limits
  61. Fermi trigger No 740221779: Global MASTER-Net observations report
  62. Fermi GRB 240616A: Global MASTER-Net observations report
  63. Konus-Wind detection of GRB 240615A (short/hard)
  64. GRB 240615A: GOTO optical upper limits
  65. Fermi trigger No 740166710: Global MASTER-Net observations report
  66. GRB 240616A: Fermi GBM Final Real-time Localization
  67. GRB 240615A: Swift ToO observations
  68. GRB 240615A: Swift/BAT-GUANO arcminute localization of a short burst
  69. GRB 240615A: Fermi GBM Final Real-time Localization
  70. LIGO/Virgo/KAGRA S240615ea: Identification of a GW compact binary merger candidate
  71. LIGO/Virgo/KAGRA S240615dg: Identification of a GW compact binary merger candidate
  72. GRB 240603A: VZLUSAT-2 detection
  73. GRB 240612A: GRBAlpha detection
  74. GRB 240613A: Fermi GBM Final Real-time Localization
  75. Fermi GRB 240612B: Global MASTER-Net observations report
  76. Fermi GRB 240612A: Global MASTER-Net observations report
  77. GRB 240612B: Fermi GBM Final Real-time Localization
  78. GRB 240612A: Fermi GBM Final Real-time Localization
  79. GRB 240607A: GECAM detection of a bright long burst
  80. Fermi GRB 240611A: Global MASTER-Net observations report
  81. Konus-Wind detection of GRB 240607A
  82. GRB 240611A: Fermi GBM Final Real-time Localization
  83. EXO 0748-676: Swift-BAT refined analysis
  84. GRB240529A: 3.6m TNG NIR detection 8d after the burst
  85. GRB 240529A: LBT optical detection and late temporal decay
  86. GRB 240529A : MITSuME Akeno optical afterglow detection
  87. Trigger 1236151: Swift detection of EXO 0748-676
  88. Fermi GRB 240610A: Global MASTER-Net observations report
  89. GRB 240610A: Fermi GBM Final Real-time Localization
  90. IPN triangulation of GRB 240607A
  91. Fermi Gamma-ray Burst Monitor trigger 739632045/240609556 is not a GRB
  92. Fermi trigger No 739632045: Global MASTER-Net observations report
  93. Fermi GRB 240608A: Global MASTER-Net observations report
  94. Konus-Wind detection of GRB 240606B
  95. Fermi trigger No 739506569: Global MASTER-Net observations report
  96. GRB 240608A: Fermi GBM Final Real-time Localization
  97. Fermi GRB 240607A: Global MASTER-Net observations report
  98. GRB 240529A: NOEMA detection
  99. GRB 240607A: Fermi GBM Observation
  100. GRB 240606B: Fermi GBM Observation

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