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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').
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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"

32184 results found.

  1. GRB 241209B: Swift-XRT afterglow detection
  2. GRB 241209C: Fermi GBM Observation
  3. GRB 241209A: Swift-XRT refined Analysis
  4. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  5. GRB 241128A: CrAO ZTSh and Mondy AZT-33IK optical observations
  6. GRB 241209D: AstroSat CZTI detection
  7. GRB 241209A: EP-FXT follow-up observations
  8. GRB 241209B: SVOM/VT afterglow detection
  9. GRB 241207B: Fermi GBM Observation
  10. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  11. GRB 241209D: Swift-XRT refined Analysis
  12. GRB 241209D: Fermi GBM Observation
  13. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  14. GRB 241209D: COLIBRÍ detection of the afterglow
  15. GRB 241209A: COLIBRÍ Optical Upper Limit
  16. Fermi GRB 241209D: Global MASTER-Net observations report
  17. GRB 241209A: Fermi GBM Observation
  18. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 241209A: GRANDMA/TAROT upper limit
  20. GRB 241209B: BOOTES-5 optical upper limit
  21. Swift GRB 241209D: Global MASTER-Net observations report
  22. Fermi GRB 241209C: Global MASTER-Net observations report
  23. Fermi GRB 241209E: Global MASTER-Net observations report
  24. GRB 241209E: Fermi GBM Final Real-time Localization
  25. GRB 241209B: Swift ToO observations
  26. GRB 241209A: REM optical/NIR observations
  27. GRB 241209D: Enhanced Swift-XRT position
  28. GRB 241209C: AstroSat CZTI detection
  29. GRB 241209D: Swift detection of a burst
  30. GRB 241209D: Fermi GBM Final Real-time Localization
  31. GRB 241209A: VLT/X-shooter spectroscopy
  32. GRB 241209A: Enhanced Swift-XRT position
  33. GRB 241114B: cubesat Avion detection
  34. GRB 241209A: VLT optical observations
  35. Fermi GRB 241209A: Global MASTER-Net observations report
  36. GRB 241209C: Fermi GBM Final Real-time Localization
  37. GRB 241209A: GOTO optical upper limits
  38. GRB 241209A: Prompt enhanced Swift-XRT position
  39. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  40. GRB 241209A: Swift detection of a short burst
  41. GRB 241209A: Fermi GBM Final Real-time Localization
  42. Fermi GRB 241207B: Global MASTER-Net observations report
  43. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  44. Fermi Gamma-ray Burst Monitor trigger 755277791/241207641 is not a GRB
  45. GRB 241201A: AstroSat CZTI detection
  46. GRB 241206A: DDOTI Upper Limit on the Afterglow
  47. GRB 241207C: MASTER optical observations
  48. GRB 241207C: Tiled Swift observations
  49. GRB 241207C: MAXI/GSC detection
  50. GRB 241207B: Fermi GBM Final Real-time Localization
  51. Fermi GRB 241207A: Global MASTER-Net observations report
  52. GRB 241206A: Fermi GBM observation
  53. GRB 241206C: SVOM/GRM observation of a likely short burst
  54. GRB 241207A: Fermi GBM Final Real-time Localization
  55. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  56. GRB 241206B: SVOM/MXT observations: a probable flare from the QSO 1ES 1959+650
  57. GRB 241206B: GWAC-F50A optical upper limit
  58. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  59. Fermi GRB 241206A: Global MASTER-Net observations report
  60. GRB 241206A: Fermi GBM Final Real-time Localization
  61. GRB 241204A: COLIBRÍ Optical Upper Limit
  62. EP241202b: KAIT optical upper limit
  63. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  64. GRB 241204A: DDOTI Upper Limits on the Afterglow
  65. GRB 241204A: Fermi GBM Observation
  66. Fermi GRB 241204A: Global MASTER-Net observations report
  67. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  68. GRB 241128A : RAPAS follow-up observations
  69. GRB 241201A: GRBAlpha detection
  70. GRB 241204A: Fermi-LAT detection
  71. EP241202b: Upper limits from Fermi-GBM Observations
  72. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  73. GRB 241113B : RAPAS follow-up observation
  74. Konus-Wind detection of GRB 241130A
  75. IPN triangulation of GRB 241130A
  76. GRB 241130A: EIRSAT-1 GMOD Detection
  77. GRB 241128A: Swift/UVOT Upper Limits
  78. GRB 241130A: Fermi GBM Detection
  79. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst
  80. LIGO/Virgo/KAGRA S241102br: GRAWITA wide-field optical observations
  81. GRB 241127B: detection of a long GRB by SVOM/ECLAIRs
  82. GRB241201B: Fermi GBM Final Localization
  83. GRB241201B: Fermi GBM Final Localization
  84. Fermi GRB 241201A: Global MASTER-Net observations report
  85. GRB 241201A: BALROG localization (Fermi Trigger 754757764 / GRB 241201622)
  86. GRB 241130A: Fermi GBM Final Real-time Localization
  87. GRB 241130A: Fermi GBM Final Real-time Localization
  88. GRB 241201A: Fermi GBM Final Real-time Localization
  89. IPN triangulation of GRB 241128B
  90. Konus-Wind detection of GRB 241114B
  91. GRB 241128A: AbAO optical upper limit
  92. GRB 241128C: SVOM/GRM observation
  93. GRB 241128B: SVOM/GRM observation
  94. GRB 241128A: Swift-BAT refined analysis
  95. GRB 241127A: Swift-BAT refined analysis
  96. GRB 241127A: PRIME near-infrared detection
  97. GRB 241128A: Mondy optical observations
  98. GRB 241128A: GRANDMA and Kilonova-Catcher Optical Afterglow Detections and Upperlimits
  99. Swift GRB 241128A: Global MASTER-Net observations report
  100. GRB 241128A: Swift-XRT refined Analysis

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