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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"

27919 results found.

  1. GRB 250717B: SVOM/GRM observation
  2. GRB 250721A: Tiled Swift observations
  3. GRB 250721A: MAXI/GSC detection
  4. GRB 250721A: Fermi GBM Final Localization
  5. GRB 250720B: Fermi GBM Final Localization Correction
  6. GRB 250720A: Fermi GBM Final Localization
  7. GRB 250717B: COLIBRÍ optical upper limit
  8. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  9. GRB 250717B: Swift-XRT observations
  10. GRB 250718B: Fermi GBM Final Localization Correction
  11. GRB 250718B: Fermi GBM Final Real-time Localization
  12. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  13. Swift Trigger 1334535: a possible GRB 250718A
  14. Swift GRB250718.01: Global MASTER-Net observations report
  15. GRB 250717B: Swift ToO observations
  16. GRB 270713A: Kitab and AbAO Optical Observations
  17. GRB 250717B: Fermi GBM Observation
  18. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  19. Konus-Wind detection of GRB 250716A
  20. GRB 250716A: Swift-XRT afterglow detection
  21. GRB 250717B: Fermi GBM Final Real-time Localization
  22. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  23. GRB 250717A: Fermi GBM Final Real-time Localization
  24. GRB 250716A: Swift ToO observations
  25. GRB 250716A: Fermi GBM Final Real-time Localization
  26. GRB 250715A: Fermi GBM Final Real-time Localization
  27. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  28. GRB 250713A: SVOM/C-GFT upper limit
  29. GRB 250714A: Fermi GBM Final Real-time Localization
  30. GRB 250706B/C: 7DT Follow-up Observations
  31. GRB 250713A: Swift-XRT observations
  32. GRB 250713A: EP-FXT counterpart detection
  33. GRB 250706A: Swift-BAT refined analysis
  34. GRB 250702F: Swift-BAT refined analysis
  35. GRB 250628A: Swift-BAT refined analysis
  36. GRB 250713A: SVOM detection of a long burst
  37. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  38. GRB 250711A: Fermi GBM Final Real-time Localization
  39. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  40. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  41. GRB 250702B,D,E / EP250702a: ALMA detection
  42. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  43. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  44. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  45. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  46. GRB 250709A: Fermi GBM Final Localization
  47. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  48. GRB 250706B/C: Insight-HXMT detection
  49. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  50. EP250704a/GRB 250704B: 10 GHz VLA detection
  51. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  52. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  53. IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
  54. GRB 250704B / EP250704a: VLA radio detection
  55. GRB 250708A: Fermi GBM Final Real-time Localization
  56. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  57. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  58. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  59. GRB 250702F: radio detection with the VLA
  60. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  61. GRB 250706B/C: Fermi-LAT detection
  62. GRB 250706B: Swift/UVOT Detection
  63. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  64. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  65. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 250702F: GRANDMA observations
  67. GRB 250706A: Swift-XRT refined Analysis
  68. GRB 250706A: Swift/UVOT Upper Limits
  69. GRB 250706A: REM optical/NIR observations
  70. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  71. IceCube-250416A: DDOTI Optical Upper Limit
  72. Swift GRB 250706A: Global MASTER-Net observations report
  73. GRB 250706A: JinShan optical upper limits
  74. GRB 250706A: SAO RAS optical observations
  75. EP250704A: NOWT Detection
  76. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  77. GRB250706B: Swift-XRT counterpart detection
  78. IceCube-250706A - IceCube observation of a high-energy neutrino candidate track-like event
  79. GRB 250706B: TRT bright optical counterpart detection
  80. GRB 250706A: GROWTH-India Telescope optical upper limit
  81. GRB 250706B: SVOM detection of a long burst
  82. GRB 250706A: Swift detection of a burst
  83. GRB 250704B: Swift-XRT refined Analysis
  84. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  85. EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
  86. GRB 250703A: EIRSAT-1 GMOD Detection
  87. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  88. GRB 250704B: Swift/UVOT Upper Limits
  89. GRB 250704A: Swift/UVOT Detection
  90. GRB 250704B: Insight-HXMT detection
  91. Konus-Wind detection of GRB 250703A
  92. IPN triangulation of GRB 250703A
  93. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  94. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  95. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  96. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  97. GRB 250702F: Kilonova-Catcher optical afterglow detection
  98. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  99. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  100. GRB 250704A: SVOM/VT optical observation

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