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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"

37261 results found.

  1. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  2. GRB 250725A: Enhanced Swift-XRT position
  3. GRB 250725A: Swift detection of a burst
  4. Swift GRB 250725A: Global MASTER-Net OT detection
  5. GRB 250725A: Fermi GBM Final Real-time Localization
  6. Fermi GRB 250725A: Global MASTER-Net observations report
  7. Swift GRB 250725A: Global MASTER-Net observations report
  8. SVOM J195836+32283/sb25072103: Second VT observation
  9. GRB 250723B: Fermi GBM Final Real-time Localization
  10. GRB 250721A: Fermi GBM Observation
  11. GRB 250723A: Fermi GBM Final Real-time Localization
  12. Swift-BAT trigger 1334535 is not a GRB
  13. GRB 250721A: Swift-XRT observations
  14. GRB 250722A: Fermi GBM Final Real-time Localization
  15. GRB 250713A : SVOM/ECLAIRs refined analysis
  16. GRB 250717B: SVOM/GRM observation
  17. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  18. GRB 250721A: Tiled Swift observations
  19. GRB 250721A: MAXI/GSC detection
  20. GRB 250721A: Fermi GBM Final Localization
  21. GRB 250720B: Fermi GBM Final Localization Correction
  22. GRB 250720A: Fermi GBM Final Localization
  23. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  24. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  25. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  26. GRB 250717B: COLIBRÍ optical upper limit
  27. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  28. GRB 250717B: Swift-XRT observations
  29. GRB 250718B: Fermi GBM Final Localization Correction
  30. GRB 250718B: Fermi GBM Final Real-time Localization
  31. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  32. Swift Trigger 1334535: a possible GRB 250718A
  33. GRB 250717B: Swift ToO observations
  34. GRB 270713A: Kitab and AbAO Optical Observations
  35. GRB 250717B: Fermi GBM Observation
  36. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  37. Konus-Wind detection of GRB 250716A
  38. GRB 250716A: Swift-XRT afterglow detection
  39. GRB 250717B: Fermi GBM Final Real-time Localization
  40. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  41. GRB 250717A: Fermi GBM Final Real-time Localization
  42. GRB 250716A: Swift ToO observations
  43. GRB 250716A: GOTO tentative optical counterpart candidate
  44. GRB 250716A: Fermi GBM Observation
  45. GRB 250714A: SVOM/GRM observation
  46. Fermi GRB 250716A: Global MASTER-Net observations report
  47. GRB 250716A: Fermi GBM Final Real-time Localization
  48. Fermi GRB 250715A: Global MASTER-Net observations report
  49. GRB 250715A: Fermi GBM Final Real-time Localization
  50. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  51. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  52. GRB 250713A: Mephisto optical upper limits
  53. Fermi GRB 250714A: Global MASTER-Net observations report
  54. GRB 250713A: SVOM/VT optical upper limit
  55. GRB 250713A: NOT optical upper limits
  56. GRB 250713A: OHP/T193 upper limit
  57. GRB 250713A: SVOM/C-GFT upper limit
  58. GRB 250714A: Fermi GBM Final Real-time Localization
  59. GRB 250706B/C: 7DT Follow-up Observations
  60. GRB 250713A: Swift-XRT observations
  61. GRB 250713A: EP-FXT counterpart detection
  62. GRB 250706A: Swift-BAT refined analysis
  63. GRB 250702F: Swift-BAT refined analysis
  64. GRB 250628A: Swift-BAT refined analysis
  65. GRB 250713A: JinShan optical upper limits
  66. GRB 250713A: SVOM detection of a long burst
  67. GRB 250711A: DDOTI Optical Upper Limit
  68. GRB 250711A: SVOM/GRM observation
  69. Fermi GRB 250711A: Global MASTER-Net observations report
  70. GRB 250704A: GRANDMA observations
  71. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  72. GRB 250711A: Fermi GBM Final Real-time Localization
  73. GRB 250704A: SVOM/ECLAIRs refined analysis
  74. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  75. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  76. GRB 250702B,D,E / EP250702a: ALMA detection
  77. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  78. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  79. IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
  80. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  81. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  82. GRB 250709A: Fermi GBM Final Localization
  83. IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
  84. GRB 250706B/C: Insight-HXMT detection
  85. EP250704a/GRB 250704B: 10 GHz VLA detection
  86. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  87. IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
  88. GRB 250704B / EP250704a: VLA radio detection
  89. Fermi GRB 250708A: Global MASTER-Net observations report
  90. EP250704a/GRB250704B : HCT optical and NIR upper limits
  91. GRB 250708A: Fermi GBM Final Real-time Localization
  92. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  93. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  94. GRB 250704B: CALET Gamma-Ray Burst Monitor detection
  95. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  96. GRB 250702F: radio detection with the VLA
  97. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  98. IceCube-250706A: EP-FXT follow-up observations
  99. GRB 250706B/C: Fermi-LAT detection
  100. GRB 250704A: SVOM/COLIBRÍ (FM-GFT) optical observations

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