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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"

36128 results found.

  1. GRB 250713A: NOT optical upper limits
  2. GRB 250713A: OHP/T193 upper limit
  3. GRB 250713A: SVOM/C-GFT upper limit
  4. GRB 250714A: Fermi GBM Final Real-time Localization
  5. GRB 250706B/C: 7DT Follow-up Observations
  6. GRB 250713A: Swift-XRT observations
  7. GRB 250713A: EP-FXT counterpart detection
  8. GRB 250706A: Swift-BAT refined analysis
  9. GRB 250702F: Swift-BAT refined analysis
  10. GRB 250628A: Swift-BAT refined analysis
  11. GRB 250713A: JinShan optical upper limits
  12. GRB 250713A: SVOM detection of a long burst
  13. GRB 250711A: DDOTI Optical Upper Limit
  14. GRB 250711A: SVOM/GRM observation
  15. Fermi GRB 250711A: Global MASTER-Net observations report
  16. GRB 250704A: GRANDMA observations
  17. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  18. GRB 250711A: Fermi GBM Final Real-time Localization
  19. GRB 250704A: SVOM/ECLAIRs refined analysis
  20. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  21. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  22. GRB 250702B,D,E / EP250702a: ALMA detection
  23. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  24. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  25. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  26. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  27. IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
  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. EP250704a/GRB 250704B: 10 GHz VLA detection
  32. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  33. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  34. GRB 250704B / EP250704a: VLA radio detection
  35. Fermi GRB 250708A: Global MASTER-Net observations report
  36. IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
  37. EP250704a/GRB250704B : HCT optical and NIR upper limits
  38. GRB 250708A: Fermi GBM Final Real-time Localization
  39. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  40. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  41. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  42. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  43. GRB 250702F: radio detection with the VLA
  44. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  45. GRB 250706B/C: Fermi-LAT detection
  46. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations
  47. GRB 250706B: Swift/UVOT Detection
  48. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  49. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  50. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  51. GRB 250702F: GRANDMA observations
  52. GRB 250706A: Swift-XRT refined Analysis
  53. GRB 250706B: refined SVOM/MXT data analysis
  54. GRB 250706A: Swift/UVOT Upper Limits
  55. GRB 250706B: REM optical observations
  56. GRB 250706A: REM optical/NIR observations
  57. EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
  58. Swift GRB 250706A: Global MASTER-Net observations report
  59. GRB 250706A: JinShan optical upper limits
  60. GRB 250706A: SAO RAS optical observations
  61. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  62. GRB250706B: Swift-XRT counterpart detection
  63. GRB 250706B: iTelescope optical observations
  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. GRB 250703A: EIRSAT-1 GMOD Detection
  73. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  74. GRB 250704B: Swift/UVOT Upper Limits
  75. GRB 250704A: Swift/UVOT Detection
  76. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  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. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  82. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  83. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  84. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  85. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  86. GRB 250702F: Kilonova-Catcher optical afterglow detection
  87. GRB 250702F: Monte Agliale Observatory optical observations
  88. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  89. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  90. EP250704a / GRB 250704B: JinShan optical observations
  91. GRB 250704A: SVOM/VT optical observation
  92. EP250704a / GRB 250704B: SAO RAS optical observations
  93. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  94. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  95. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  96. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  97. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  98. GRB 250702A: Insight-HXMT detection
  99. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  100. EP250704a / GRB250704B: Swift-XRT counterpart detection

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