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. EP240708a: NOT optical observations
  2. EP240708a: SVOM/C-GFT optical upper limit
  3. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  4. EP240708a: Optical upper limits with Kinder observations
  5. EP240708a: EP-WXT detection of a fast X-ray transient
  6. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  7. EP240703b: GSP optical upper limit
  8. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  9. GRB 240705A: Fermi GBM Final Real-time Localization
  10. EP240703b: TRT optical upper limits
  11. EP240703a: TRT further optical observation
  12. EP240702a: TRT optical upper limits
  13. Konus-Wind detection of GRB 240627A
  14. IPN triangulation of GRB 240628B (short)
  15. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  16. EP240703a and EP240703b: Swift/XRT upper limits
  17. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  18. EP240703a: KAIT optical upper limit
  19. EP240703a: BTA observations
  20. EP240703c: Kinder optical follow-up and Swift XRT observations
  21. EP240703a: BOOTES-3 optical upper limit
  22. EP240703a: Liverpool Telescope optical follow-up observations
  23. EP240703a/GRB 240703A: TRT optical candidate likely not real
  24. EP240703a: Kinder optical follow-up observations
  25. EP240703c: EP-WXT detection of an X-ray transient
  26. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  27. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  28. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  29. IPN triangulation of GRB 240627A
  30. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  31. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  32. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  33. EP240703b: EP-WXT detection of a fast X-ray transient
  34. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  35. EP240702a: Swift/XRT upper limit
  36. EP240703a: EP-WXT detection of a fast X-ray transient
  37. EP240702a: GSP optical upper limit
  38. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  39. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  40. Fermi GRB 240702A: Global MASTER-Net observations report
  41. GRB 240702A: Fermi GBM Final Real-time Localization
  42. EP240702a: EP-WXT detection of a fast X-ray transient
  43. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  44. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  45. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  46. Fermi trigger No 741448122: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  48. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  49. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  50. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  51. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  52. Fermi trigger No 741356809: Global MASTER-Net observations report
  53. Fermi GRB 240629A: Global MASTER-Net observations report
  54. Fermi Gamma-ray Burst Monitor trigger 741362867/240629589 is not a GRB
  55. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  56. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  57. GRB 240629A: Fermi GBM Final Real-time Localization
  58. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  59. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  60. Fermi trigger No 741296200: Global MASTER-Net observations report
  61. Fermi trigger No 741251380: Global MASTER-Net observations report
  62. IPN triangulation of GRB 240619C
  63. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  64. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  65. GRB 240627A: NuSTAR Detection of the long GRB
  66. GRB 240615A: SAI CMO J- band observations
  67. GRB 240627A: AstroSat CZTI detection
  68. Fermi trigger No 741211696: Global MASTER-Net observations report
  69. EP240626a: Montarrenti Observatory optical upper limit
  70. EP240626a: KAIT optical upper limit
  71. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  72. EP240625a: GRANDMA Optical Upper Limits
  73. EP240626a: EP-FXT detection of the X-ray emission
  74. GRB 240624A: Swift-BAT refined analysis
  75. Konus-Wind detection of GRB 240619A
  76. EP240626a: BOOTES-7 optical upper limit
  77. EP240626a: EP-WXT detection of a fast X-ray transient
  78. Fermi GRB 240625B: Global MASTER-Net observations report
  79. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  80. GRB 240625B: Fermi GBM Final Real-time Localization
  81. GRB 240625A: Fermi GBM Observation
  82. EP240625a: NOT optical counterpart candidate
  83. EP240625a: EP-FXT detection of the X-ray emission
  84. GRB 240624B: GRBAlpha detection
  85. GRB 240625A: Fermi GBM Final Real-time Localization
  86. EP240625a: EP-WXT detection of a fast X-ray transient
  87. GRB240624A: Fermi GBM Observation
  88. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  89. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  90. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  91. Swift GRB 240624A: Global MASTER-Net observations report
  92. GRB240615A: Gemini-North observations of the BAT and XRT positions
  93. Fermi GRB 240624A: Global MASTER-Net observations report
  94. GRB 240624B: Fermi GBM Final Real-time Localization
  95. Fermi trigger No 740949590: Global MASTER-Net observations report
  96. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate
  97. GRB240615A: Gemini-North observations of the BAT and XRT positions
  98. GRB 240624A: Fermi GBM Final Real-time Localization
  99. GRB 240619A: detection of a radio counterpart with AMI-LA
  100. GRB 240624A: Swift detection of a burst

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