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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"

26216 results found.

  1. GRB 250728A: COLIBRÍ optical upper limit
  2. GRB 250728A: Fermi GBM Observation
  3. Fermi trigger No 775387550: Global MASTER-Net observations report
  4. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  5. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  6. GRB 250727A: EP-FXT counterpart detection
  7. GRB250727A: SVOM/VT optical upper limit
  8. GRB 250727A: Swift-XRT observations
  9. GRB 250727A: SVOM detection of a burst
  10. The EP-WXT trigger 01709195487 is likely a flaring star
  11. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  12. GRB 250725A: Swift-XRT refined Analysis
  13. GRB 250725A: Fermi GBM Observation
  14. GRB 250725A: Swift-BAT refined analysis
  15. GRB 250725A: SVOM/GRM observation
  16. GRB 250725A: Swift/UVOT Upper Limits
  17. GRB 250725A: Fermi-LAT detection
  18. GRB 250725A: SVOM/VT optical candidate
  19. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  20. GRB 250725A: Swift detection of a burst
  21. Swift GRB 250725A: Global MASTER-Net OT detection
  22. GRB 250725A: Fermi GBM Final Real-time Localization
  23. Fermi GRB 250725A: Global MASTER-Net observations report
  24. Swift GRB 250725A: Global MASTER-Net observations report
  25. SVOM J195836+32283/sb25072103: Second VT observation
  26. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  27. GRB 250723B: Fermi GBM Final Real-time Localization
  28. GRB 250721A: Fermi GBM Observation
  29. GRB 250723A: Fermi GBM Final Real-time Localization
  30. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  31. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  32. Swift-BAT trigger 1334535 is not a GRB
  33. GRB 250722A: Fermi GBM Final Real-time Localization
  34. GRB 250713A : SVOM/ECLAIRs refined analysis
  35. GRB 250717B: SVOM/GRM observation
  36. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  37. GRB 250721A: Fermi GBM Final Localization
  38. GRB 250720B: Fermi GBM Final Localization Correction
  39. GRB 250720A: Fermi GBM Final Localization
  40. Fermi trigger No 774730635: Global MASTER-Net observations report
  41. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  42. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  43. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  44. GRB 250717B: COLIBRÍ optical upper limit
  45. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  46. GRB 250718B: Fermi GBM Final Localization Correction
  47. GRB 250718B: Fermi GBM Final Real-time Localization
  48. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  49. Swift Trigger 1334535: a possible GRB 250718A
  50. Swift GRB250718.01: Global MASTER-Net observations report
  51. GRB 270713A: Kitab and AbAO Optical Observations
  52. GRB 250717B: Fermi GBM Observation
  53. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  54. GRB 250717B: Fermi GBM Final Real-time Localization
  55. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  56. GRB 250717A: Fermi GBM Final Real-time Localization
  57. GRB 250716A: GOTO tentative optical counterpart candidate
  58. GRB 250716A: Fermi GBM Observation
  59. GRB 250714A: SVOM/GRM observation
  60. Fermi GRB 250716A: Global MASTER-Net observations report
  61. GRB 250716A: Fermi GBM Final Real-time Localization
  62. Fermi GRB 250715A: Global MASTER-Net observations report
  63. GRB 250715A: Fermi GBM Final Real-time Localization
  64. GRB 250713A: Mephisto optical upper limits
  65. Fermi GRB 250714A: Global MASTER-Net observations report
  66. GRB 250713A: SVOM/VT optical upper limit
  67. GRB 250713A: NOT optical upper limits
  68. GRB 250713A: OHP/T193 upper limit
  69. GRB 250713A: SVOM/C-GFT upper limit
  70. GRB 250714A: Fermi GBM Final Real-time Localization
  71. GRB 250713A: Swift-XRT observations
  72. GRB 250713A: EP-FXT counterpart detection
  73. EP250711a: COLIBRÍ continuous optical observations
  74. GRB 250706A: Swift-BAT refined analysis
  75. GRB 250702F: Swift-BAT refined analysis
  76. GRB 250628A: Swift-BAT refined analysis
  77. GRB 250713A: JinShan optical upper limits
  78. GRB 250713A: SVOM detection of a long burst
  79. EP250711a: Global MASTER-Net observations report
  80. GRB 250711A: DDOTI Optical Upper Limit
  81. EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
  82. GRB 250711A: SVOM/GRM observation
  83. EP250711a: NOT optical counterpart candidate
  84. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  85. EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
  86. Fermi GRB 250711A: Global MASTER-Net observations report
  87. GRB 250704A: GRANDMA observations
  88. GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
  89. GRB 250711A: Fermi GBM Final Real-time Localization
  90. GRB 250704A: SVOM/ECLAIRs refined analysis
  91. GRB 250702B,D,E / EP250702a: ALMA detection
  92. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  93. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  94. GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
  95. GRB 250709A: Fermi GBM Final Localization
  96. EP/WXT 01709181970: GOTO observations confirm stellar variability
  97. EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
  98. The EP-WXT trigger 01709181970 is likely a flaring star
  99. Fermi GRB 250708A: Global MASTER-Net observations report
  100. IceCube-250708A: Global MASTER-Net observations report

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