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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"

35437 results found.

  1. Fermi GRB 250716A: Global MASTER-Net observations report
  2. GRB 250716A: Fermi GBM Final Real-time Localization
  3. Fermi GRB 250715A: Global MASTER-Net observations report
  4. GRB 250715A: Fermi GBM Final Real-time Localization
  5. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  6. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  7. GRB 250713A: Mephisto optical upper limits
  8. Fermi GRB 250714A: Global MASTER-Net observations report
  9. GRB 250713A: SVOM/VT optical upper limit
  10. GRB 250713A: NOT optical upper limits
  11. GRB 250713A: OHP/T193 upper limit
  12. GRB 250713A: SVOM/C-GFT upper limit
  13. GRB 250714A: Fermi GBM Final Real-time Localization
  14. GRB 250706B/C: 7DT Follow-up Observations
  15. GRB 250713A: Swift-XRT observations
  16. GRB 250713A: EP-FXT counterpart detection
  17. GRB 250706A: Swift-BAT refined analysis
  18. GRB 250702F: Swift-BAT refined analysis
  19. GRB 250628A: Swift-BAT refined analysis
  20. GRB 250713A: JinShan optical upper limits
  21. GRB 250713A: SVOM detection of a long burst
  22. GRB 250711A: DDOTI Optical Upper Limit
  23. GRB 250711A: SVOM/GRM observation
  24. Fermi GRB 250711A: Global MASTER-Net observations report
  25. GRB 250704A: GRANDMA observations
  26. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  27. GRB 250711A: Fermi GBM Final Real-time Localization
  28. GRB 250704A: SVOM/ECLAIRs refined analysis
  29. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  30. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  31. GRB 250702B,D,E / EP250702a: ALMA detection
  32. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  33. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  34. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  35. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  36. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  37. GRB 250709A: Fermi GBM Final Localization
  38. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  39. GRB 250706B/C: Insight-HXMT detection
  40. EP250704a/GRB 250704B: 10 GHz VLA detection
  41. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  42. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  43. GRB 250704B / EP250704a: VLA radio detection
  44. Fermi GRB 250708A: Global MASTER-Net observations report
  45. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  46. EP250704a/GRB250704B : HCT optical and NIR upper limits
  47. GRB 250708A: Fermi GBM Final Real-time Localization
  48. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  49. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  50. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  51. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  52. GRB 250702F: radio detection with the VLA
  53. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  54. GRB 250706B/C: Fermi-LAT detection
  55. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  56. GRB 250706B: Swift/UVOT Detection
  57. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  58. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  59. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  60. GRB 250702F: GRANDMA observations
  61. GRB 250706A: Swift-XRT refined Analysis
  62. GRB 250706B: refined SVOM/MXT data analysis
  63. GRB 250706A: Swift/UVOT Upper Limits
  64. GRB 250706B: REM optical observations
  65. GRB 250706A: REM optical/NIR observations
  66. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  67. Swift GRB 250706A: Global MASTER-Net observations report
  68. GRB 250706A: JinShan optical upper limits
  69. GRB 250706A: SAO RAS optical observations
  70. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  71. GRB250706B: Swift-XRT counterpart detection
  72. GRB 250706B: iTelescope optical observations
  73. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  74. GRB 250706B: SVOM/VT optical observation
  75. GRB 250706B: TRT bright optical counterpart detection
  76. GRB 250706A: GROWTH-India Telescope optical upper limit
  77. GRB 250706B: SVOM detection of a long burst
  78. GRB 250706A: Swift detection of a burst
  79. GRB 250704B: Swift-XRT refined Analysis
  80. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  81. GRB 250703A: EIRSAT-1 GMOD Detection
  82. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  83. GRB 250704B: Swift/UVOT Upper Limits
  84. GRB 250704A: Swift/UVOT Detection
  85. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  86. GRB 250704B: Insight-HXMT detection
  87. Konus-Wind detection of GRB 250703A
  88. IPN triangulation of GRB 250703A
  89. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  90. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  91. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  92. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  93. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  94. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  95. GRB 250702F: Kilonova-Catcher optical afterglow detection
  96. GRB 250702F: Monte Agliale Observatory optical observations
  97. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  98. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  99. EP250704a / GRB 250704B: JinShan optical observations
  100. GRB 250704A: SVOM/VT optical observation

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