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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

28105 results found.

  1. GRB 250718B: Fermi GBM Final Real-time Localization
  2. Swift Trigger 1334535: a possible GRB 250718A
  3. GRB 250717B: Swift ToO observations
  4. GRB 270713A: Kitab and AbAO Optical Observations
  5. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  6. Konus-Wind detection of GRB 250716A
  7. GRB 250716A: Swift-XRT afterglow detection
  8. GRB 250717B: Fermi GBM Final Real-time Localization
  9. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  10. GRB 250717A: Fermi GBM Final Real-time Localization
  11. GRB 250716A: Swift ToO observations
  12. GRB 250716A: Fermi GBM Final Real-time Localization
  13. GRB 250715A: Fermi GBM Final Real-time Localization
  14. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  15. GRB 250713A: SVOM/VT optical upper limit
  16. GRB 250713A: SVOM/C-GFT upper limit
  17. GRB 250714A: Fermi GBM Final Real-time Localization
  18. GRB 250706B/C: 7DT Follow-up Observations
  19. GRB 250713A: Swift-XRT observations
  20. GRB 250713A: EP-FXT counterpart detection
  21. GRB 250713A: SVOM detection of a long burst
  22. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  23. GRB 250711A: Fermi GBM Final Real-time Localization
  24. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  25. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  26. GRB 250702B,D,E / EP250702a: ALMA detection
  27. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  28. GRB 250709A: Fermi GBM Final Localization
  29. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  30. GRB 250706B/C: Insight-HXMT detection
  31. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  32. EP250704a/GRB 250704B: 10 GHz VLA detection
  33. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  34. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  35. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  36. GRB 250704B / EP250704a: VLA radio detection
  37. GRB 250708A: Fermi GBM Final Real-time Localization
  38. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  39. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  40. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  41. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  42. GRB 250702F: radio detection with the VLA
  43. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  44. GRB 250706B/C: Fermi-LAT detection
  45. GRB 250706B: Swift/UVOT Detection
  46. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  47. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  48. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  49. GRB 250702F: GRANDMA observations
  50. GRB 250706A: Swift-XRT refined Analysis
  51. GRB 250706B: refined SVOM/MXT data analysis
  52. GRB 250706A: Swift/UVOT Upper Limits
  53. GRB 250706B: REM optical observations
  54. GRB 250706A: REM optical/NIR observations
  55. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  56. IceCube-250416A: DDOTI Optical Upper Limit
  57. GRB 250706A: JinShan optical upper limits
  58. GRB 250706A: SAO RAS optical observations
  59. EP250704A: NOWT Detection
  60. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  61. GRB250706B: Swift-XRT counterpart detection
  62. GRB 250706B: iTelescope optical observations
  63. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  64. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  65. GRB 250706B: SVOM/VT optical observation
  66. GRB 250706B: TRT bright optical counterpart detection
  67. GRB 250706A: GROWTH-India Telescope optical upper limit
  68. GRB 250706B: SVOM detection of a long burst
  69. GRB 250706A: Swift detection of a burst
  70. GRB 250704B: Swift-XRT refined Analysis
  71. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  72. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  73. GRB 250703A: EIRSAT-1 GMOD Detection
  74. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  75. GRB 250704B: Swift/UVOT Upper Limits
  76. GRB 250704A: Swift/UVOT Detection
  77. GRB 250704B: Insight-HXMT detection
  78. Konus-Wind detection of GRB 250703A
  79. IPN triangulation of GRB 250703A
  80. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  81. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  82. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  83. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  84. GRB 250702F: Kilonova-Catcher optical afterglow detection
  85. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  86. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  87. EP250704a / GRB 250704B: JinShan optical observations
  88. GRB 250704A: SVOM/VT optical observation
  89. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  90. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  91. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  92. EP 250704a: BOOTES-5 optical detection
  93. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  94. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  95. GRB 250702A: Insight-HXMT detection
  96. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  97. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  98. EP250704a / GRB250704B: Swift-XRT counterpart detection
  99. GRB 250704A: Swift-XRT afterglow detection
  100. GRB 250702B / EP2050702a: FTW optical and NIR observations

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