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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 trigger No 742317942: Global MASTER-Net observations report
  2. EP240708a: KAIT optical upper limit
  3. Fermi GRB 240710A: Global MASTER-Net observations report
  4. GRB 240710A: Fermi GBM Final Real-time Localization
  5. EP240708a: NOT optical observations
  6. EP240708a: SVOM/C-GFT optical upper limit
  7. EP240708a: X-ray follow-up observations with EP/FXT and Swift/XRT
  8. EP240708a: Optical upper limits with Kinder observations
  9. EP240708a: EP-WXT detection of a fast X-ray transient
  10. LIGO/Virgo S240615dg: Swift XRT observations, 28 futher X-ray sources
  11. EP240703b: GSP optical upper limit
  12. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  13. GRB 240705A: Fermi GBM Final Real-time Localization
  14. EP240703b: TRT optical upper limits
  15. EP240703a: TRT further optical observation
  16. EP240702a: TRT optical upper limits
  17. Konus-Wind detection of GRB 240627A
  18. IPN triangulation of GRB 240628B (short)
  19. LIGO/Virgo/KAGRA S240705at: Updated Sky localization
  20. EP240703a and EP240703b: Swift/XRT upper limits
  21. LIGO/Virgo/KAGRA S240705at: Identification of a GW compact binary merger candidate
  22. EP240703a: KAIT optical upper limit
  23. EP240703a: BTA observations
  24. EP240703c: Kinder optical follow-up and Swift XRT observations
  25. EP240703a: BOOTES-3 optical upper limit
  26. EP240703a: Liverpool Telescope optical follow-up observations
  27. EP240703a/GRB 240703A: TRT optical candidate likely not real
  28. EP240703a: Kinder optical follow-up observations
  29. EP240703c: EP-WXT detection of an X-ray transient
  30. LIGO/Virgo/KAGRA S240703ad: Updated Sky localization
  31. LIGO/Virgo/KAGRA S240703ad: Identification of a GW compact binary merger candidate
  32. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  33. IPN triangulation of GRB 240627A
  34. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  35. LIGO/Virgo/KAGRA S240422ed: Updated significance estimate
  36. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  37. EP240703b: EP-WXT detection of a fast X-ray transient
  38. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  39. EP240702a: Swift/XRT upper limit
  40. EP240703a: EP-WXT detection of a fast X-ray transient
  41. EP240702a: GSP optical upper limit
  42. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  43. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  44. Fermi GRB 240702A: Global MASTER-Net observations report
  45. GRB 240702A: Fermi GBM Final Real-time Localization
  46. EP240702a: EP-WXT detection of a fast X-ray transient
  47. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  48. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  49. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  50. Fermi trigger No 741448122: Global MASTER-Net observations report
  51. LIGO/Virgo/KAGRA S240630t: Updated Sky localization
  52. LIGO/Virgo/KAGRA S240629by: Updated Sky localization
  53. LIGO/Virgo/KAGRA S240630t: Identification of a GW compact binary merger candidate
  54. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  55. LIGO/Virgo/KAGRA S240629by: Coverage and upper limits from MAXI/GSC observations
  56. Fermi trigger No 741356809: Global MASTER-Net observations report
  57. Fermi GRB 240629A: Global MASTER-Net observations report
  58. Fermi Gamma-ray Burst Monitor trigger 741362867/240629589 is not a GRB
  59. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  60. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  61. GRB 240629A: Fermi GBM Final Real-time Localization
  62. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  63. LIGO/Virgo/KAGRA S240629by: Identification of a GW compact binary merger candidate
  64. Fermi trigger No 741296200: Global MASTER-Net observations report
  65. Fermi trigger No 741251380: Global MASTER-Net observations report
  66. IPN triangulation of GRB 240619C
  67. IceCube-Cascade 240626A: Upper limits from a search for additional neutrino events in IceCube
  68. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  69. GRB 240627A: NuSTAR Detection of the long GRB
  70. GRB 240615A: SAI CMO J- band observations
  71. GRB 240627A: AstroSat CZTI detection
  72. Fermi trigger No 741211696: Global MASTER-Net observations report
  73. EP240626a: Montarrenti Observatory optical upper limit
  74. EP240626a: KAIT optical upper limit
  75. LIGO/Virgo/KAGRA S240627by: Identification of a GW compact binary merger candidate
  76. EP240625a: GRANDMA Optical Upper Limits
  77. EP240626a: EP-FXT detection of the X-ray emission
  78. GRB 240624A: Swift-BAT refined analysis
  79. Konus-Wind detection of GRB 240619A
  80. EP240626a: BOOTES-7 optical upper limit
  81. EP240626a: EP-WXT detection of a fast X-ray transient
  82. Fermi GRB 240625B: Global MASTER-Net observations report
  83. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  84. GRB 240625B: Fermi GBM Final Real-time Localization
  85. GRB 240625A: Fermi GBM Observation
  86. EP240625a: NOT optical counterpart candidate
  87. EP240625a: EP-FXT detection of the X-ray emission
  88. GRB 240624B: GRBAlpha detection
  89. GRB 240625A: Fermi GBM Final Real-time Localization
  90. EP240625a: EP-WXT detection of a fast X-ray transient
  91. GRB240624A: Fermi GBM Observation
  92. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  94. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  95. Swift GRB 240624A: Global MASTER-Net observations report
  96. GRB240615A: Gemini-North observations of the BAT and XRT positions
  97. Fermi GRB 240624A: Global MASTER-Net observations report
  98. GRB 240624B: Fermi GBM Final Real-time Localization
  99. Fermi trigger No 740949590: Global MASTER-Net observations report
  100. LIGO/Virgo/KAGRA S240624cd: Retraction of GW unmodeled transient candidate

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