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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"

38289 results found.

  1. JinShan confirmation of the EP-WXT source triggered on July 14th due to a flaring star
  2. GRB 240715A: Fermi GBM Final Real-time Localization
  3. GRB 240713A: Tiled Swift observations
  4. GRB 240713A: J-band upper limit from WINTER
  5. GRB 240713A: NOT optical upper limits on three EP/FXT candidates
  6. GRB 240713A: JinShan optical upper limits
  7. GRB 240713A: OHP/T120 optical upper limit
  8. GRB240713A: X-ray follow-up observation with EP-FXT
  9. GRB 240713B: AstroSat CZTI detection of a long burst
  10. GRB240713A: Optical upper limit with Kinder observations
  11. Fermi Sub-threshold Observation of GRB240713A
  12. GRB240713A : The first probable GRB Located on-Board SVOM by ECLAIRs
  13. Fermi Gamma-ray Burst Monitor trigger 742413075/240711744 is not a GRB
  14. EP240708a: GSP optical upper limit
  15. GRB 240712A: Swift detection of a burst
  16. GRB 240711A: Fermi GBM Final Real-time Localization
  17. Fermi trigger No 742405878: Global MASTER-Net observations report
  18. Fermi trigger No 742317942: Global MASTER-Net observations report
  19. EP240708a: KAIT optical upper limit
  20. Fermi GRB 240710A: Global MASTER-Net observations report
  21. GRB 240710A: Fermi GBM Final Real-time Localization
  22. EP240708a: SVOM/C-GFT optical upper limit
  23. EP240703b: GSP optical upper limit
  24. Fermi Gamma-ray Burst Monitor trigger 741911057/240705933 is not a GRB
  25. GRB 240705A: Fermi GBM Final Real-time Localization
  26. EP240703b: TRT optical upper limits
  27. EP240703a: TRT further optical observation
  28. EP240702a: TRT optical upper limits
  29. Konus-Wind detection of GRB 240627A
  30. IPN triangulation of GRB 240628B (short)
  31. EP240703a: KAIT optical upper limit
  32. EP240703a: BTA observations
  33. EP240703a: Liverpool Telescope optical follow-up observations
  34. EP240703a/GRB 240703A: TRT optical candidate likely not real
  35. EP240703a/GRB 240703A: TRT and JinShan decaying optical afterglow candidate
  36. IPN triangulation of GRB 240627A
  37. GRB 240619A: Host galaxy redshift from VLT/X-shooter
  38. The first three GRBs detected by SVOM: X-ray Upper Limits from EP-WXT
  39. Konus-Wind detection of GRB 240703A (a counterpart of EP240703a)
  40. EP240702a: GSP optical upper limit
  41. The first three GRBs detected by SVOM: GRB 240627B, GRB 240629A and GRB 240702A
  42. GRB 240702A: BALROG localization (Fermi Trigger / GRB 240702885)
  43. Fermi GRB 240702A: Global MASTER-Net observations report
  44. GRB 240702A: Fermi GBM Final Real-time Localization
  45. LIGO/Virgo/KAGRA S240627by: Upper limits from Swift/BAT-GUANO
  46. Fermi Gamma-ray Burst Monitor trigger 741448122/240630575 is not a GRB
  47. GRB 240627A: CALET Gamma-Ray Burst Monitor detection
  48. Fermi trigger No 741448122: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S240629by: Upper limits from Fermi-GBM Observations
  50. Fermi trigger No 741356809: Global MASTER-Net observations report
  51. Fermi GRB 240629A: Global MASTER-Net observations report
  52. Fermi Gamma-ray Burst Monitor trigger 741362867/240629589 is not a GRB
  53. Fermi Gamma-ray Burst Monitor trigger 741288821/240628732 is not a GRB
  54. GRB 240629A: BALROG localization (Fermi Trigger 741372837 / GRB 240629704)
  55. GRB 240629A: Fermi GBM Final Real-time Localization
  56. Fermi Gamma-ray Burst Monitor trigger 741356809/240629519 is not a GRB
  57. Fermi trigger No 741296200: Global MASTER-Net observations report
  58. Fermi trigger No 741251380: Global MASTER-Net observations report
  59. IPN triangulation of GRB 240619C
  60. GRB 240628A: BALROG localization (Fermi Trigger 741288821 / GRB 240628732)
  61. GRB 240627A: NuSTAR Detection of the long GRB
  62. GRB 240615A: SAI CMO J- band observations
  63. GRB 240627A: AstroSat CZTI detection
  64. Fermi trigger No 741211696: Global MASTER-Net observations report
  65. EP240626a: Montarrenti Observatory optical upper limit
  66. EP240626a: KAIT optical upper limit
  67. GRB 240624A: Swift-BAT refined analysis
  68. Konus-Wind detection of GRB 240619A
  69. Fermi GRB 240625B: Global MASTER-Net observations report
  70. GRB 240624B: CALET Gamma-Ray Burst Monitor detection
  71. GRB 240625B: Fermi GBM Final Real-time Localization
  72. GRB 240625A: Fermi GBM Observation
  73. GRB 240624B: GRBAlpha detection
  74. GRB 240625A: Fermi GBM Final Real-time Localization
  75. GRB240624A: Fermi GBM Observation
  76. LIGO/Virgo/KAGRA S240622h: Upper limits from Swift/BAT-GUANO
  77. LIGO/Virgo/KAGRA S240621dy: Upper limits from Swift/BAT-GUANO
  78. LIGO/Virgo/KAGRA S240618ah: Upper limits from Swift/BAT-GUANO
  79. Swift GRB 240624A: Global MASTER-Net observations report
  80. GRB240615A: Gemini-North observations of the BAT and XRT positions
  81. Fermi GRB 240624A: Global MASTER-Net observations report
  82. GRB 240624B: Fermi GBM Final Real-time Localization
  83. Fermi trigger No 740949590: Global MASTER-Net observations report
  84. GRB240615A: Gemini-North observations of the BAT and XRT positions
  85. GRB 240624A: Fermi GBM Final Real-time Localization
  86. GRB 240619A: detection of a radio counterpart with AMI-LA
  87. GRB 240624A: Swift detection of a burst
  88. GRB 240619A: J-band detection with WINTER (duplicate submission of GCN 36739)
  89. GRB 240619A: J-band detection with WINTER
  90. Fermi trigger No 740744838: Global MASTER-Net observations report
  91. EP240618a: NOT optical counterpart candidate
  92. GRB 240529A: JinShan optical observations
  93. EP240618a: GSP optical upper limit
  94. IPN triangulation of GRB 240615A (short)
  95. GRB 240619A: GRBAlpha detection
  96. GRB 240619A: Swift-XRT probable afterglow detection
  97. GRB 240619A: Swift ToO observations
  98. GRB 240619A: CALET Gamma-Ray Burst Monitor detection
  99. GRB 240619C: NuSTAR automated detection of the GRB
  100. GRB 240619A: Fermi GBM Observation

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