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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"

45444 results found.

  1. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  2. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  3. The EP-WXT trigger 01709195487 is likely a flaring star
  4. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  5. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  6. GRB 250725A: Swift-XRT refined Analysis
  7. GRB 250725A: Fermi GBM Observation
  8. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  9. GRB 250725A: Swift-BAT refined analysis
  10. Konus-Wind detection of GRB 250725A
  11. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  12. GRB 250725A: SVOM/GRM observation
  13. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  14. GRB 250725A: Swift/UVOT Upper Limits
  15. GRB 250725A: Fermi-LAT detection
  16. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  17. GRB 250725A: BOOTES-7 early optical detection
  18. GRB 250725A: SVOM/VT optical candidate
  19. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  20. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  21. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  23. GRB 250725A: Enhanced Swift-XRT position
  24. GRB 250725A: Swift detection of a burst
  25. Swift GRB 250725A: Global MASTER-Net OT detection
  26. GRB 250725A: Fermi GBM Final Real-time Localization
  27. Fermi GRB 250725A: Global MASTER-Net observations report
  28. Swift GRB 250725A: Global MASTER-Net observations report
  29. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  30. SVOM J195836+32283 is not a real source
  31. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  32. SVOM J195836+32283/sb25072103: Second VT observation
  33. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  34. GRB 250723B: Fermi GBM Final Real-time Localization
  35. GRB 250721A: Fermi GBM Observation
  36. GRB 250723A: Fermi GBM Final Real-time Localization
  37. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  38. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  39. Swift-BAT trigger 1334535 is not a GRB
  40. GRB 250721A: Swift-XRT observations
  41. GRB 250722A: Fermi GBM Final Real-time Localization
  42. GRB 250713A : SVOM/ECLAIRs refined analysis
  43. GRB 250717B: SVOM/GRM observation
  44. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  45. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  46. GRB 250721A: Tiled Swift observations
  47. GRB 250721A: MAXI/GSC detection
  48. GRB 250721A: Fermi GBM Final Localization
  49. GRB 250720B: Fermi GBM Final Localization Correction
  50. GRB 250720A: Fermi GBM Final Localization
  51. Fermi trigger No 774730635: Global MASTER-Net observations report
  52. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  53. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  54. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  55. GRB 250717B: COLIBRÍ optical upper limit
  56. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  57. GRB 250717B: Swift-XRT observations
  58. GRB 250718B: Fermi GBM Final Localization Correction
  59. GRB 250718B: Fermi GBM Final Real-time Localization
  60. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  61. Swift Trigger 1334535: a possible GRB 250718A
  62. Swift GRB250718.01: Global MASTER-Net observations report
  63. GRB 250717B: Swift ToO observations
  64. GRB 270713A: Kitab and AbAO Optical Observations
  65. GRB 250717B: Fermi GBM Observation
  66. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  67. Konus-Wind detection of GRB 250716A
  68. GRB 250716A: Swift-XRT afterglow detection
  69. GRB 250717B: Fermi GBM Final Real-time Localization
  70. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  71. GRB 250717A: Fermi GBM Final Real-time Localization
  72. GRB 250716A: Swift ToO observations
  73. GRB 250716A: GOTO tentative optical counterpart candidate
  74. GRB 250716A: Fermi GBM Observation
  75. GRB 250714A: SVOM/GRM observation
  76. Fermi GRB 250716A: Global MASTER-Net observations report
  77. GRB 250716A: Fermi GBM Final Real-time Localization
  78. Fermi GRB 250715A: Global MASTER-Net observations report
  79. GRB 250715A: Fermi GBM Final Real-time Localization
  80. EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
  81. GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
  82. GRB 250713A: Mephisto optical upper limits
  83. Fermi GRB 250714A: Global MASTER-Net observations report
  84. GRB 250713A: SVOM/VT optical upper limit
  85. GRB 250713A: NOT optical upper limits
  86. GRB 250713A: OHP/T193 upper limit
  87. GRB 250713A: SVOM/C-GFT upper limit
  88. GRB 250714A: Fermi GBM Final Real-time Localization
  89. GRB 250706B/C: 7DT Follow-up Observations
  90. GRB 250713A: Swift-XRT observations
  91. GRB 250713A: EP-FXT counterpart detection
  92. EP250711a: COLIBRÍ continuous optical observations
  93. GRB 250706A: Swift-BAT refined analysis
  94. GRB 250702F: Swift-BAT refined analysis
  95. GRB 250628A: Swift-BAT refined analysis
  96. LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
  97. GRB 250713A: JinShan optical upper limits
  98. GRB 250713A: SVOM detection of a long burst
  99. EP250711a: Global MASTER-Net observations report
  100. GRB 250711A: DDOTI Optical Upper Limit

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