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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"

43892 results found.

  1. GRB 250727A: EP-FXT follow-up observation
  2. GRB 250725A: PRIME near-infrared observations
  3. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  4. GRB: Clarification on Gamma-Ray Burst Naming Convention
  5. GRB 250728A: Swift-XRT observations
  6. GRB 250727A: SVOM/ECLAIRs refined analysis
  7. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  8. GRB 250728A: COLIBRÍ optical upper limit
  9. GRB 250728A: Fermi GBM Observation
  10. Fermi trigger No 775387550: Global MASTER-Net observations report
  11. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  12. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  13. GRB 250728A: Swift ToO observations
  14. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  15. GRB 250727A: AST3-2 Upper limit
  16. LIGO/Virgo/KAGRA S250727cl: Updated Sky localization
  17. GRB 250727A: EP-FXT counterpart detection
  18. GRB250727A: SVOM/VT optical upper limit
  19. GRB 250727A: Swift-XRT observations
  20. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  21. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  22. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  23. GRB 250727A: SVOM detection of a burst
  24. LIGO/Virgo/KAGRA S250725l: Updated Sky localization
  25. LIGO/Virgo/KAGRA S250726ak: Updated Sky localization
  26. The EP-WXT trigger 01709195487 is likely a flaring star
  27. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  28. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  29. GRB 250725A: Swift-XRT refined Analysis
  30. GRB 250725A: Fermi GBM Observation
  31. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  32. GRB 250725A: Swift-BAT refined analysis
  33. Konus-Wind detection of GRB 250725A
  34. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  35. GRB 250725A: SVOM/GRM observation
  36. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  37. GRB 250725A: Swift/UVOT Upper Limits
  38. GRB 250725A: Fermi-LAT detection
  39. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  40. GRB 250725A: BOOTES-7 early optical detection
  41. GRB 250725A: SVOM/VT optical candidate
  42. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  43. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate (duplicate submission)
  44. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  45. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  46. GRB 250725A: Enhanced Swift-XRT position
  47. GRB 250725A: Swift detection of a burst
  48. Swift GRB 250725A: Global MASTER-Net OT detection
  49. GRB 250725A: Fermi GBM Final Real-time Localization
  50. Fermi GRB 250725A: Global MASTER-Net observations report
  51. Swift GRB 250725A: Global MASTER-Net observations report
  52. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  53. SVOM J195836+32283 is not a real source
  54. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  55. SVOM J195836+32283/sb25072103: Second VT observation
  56. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  57. GRB 250723B: Fermi GBM Final Real-time Localization
  58. GRB 250721A: Fermi GBM Observation
  59. GRB 250723A: Fermi GBM Final Real-time Localization
  60. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  61. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  62. Swift-BAT trigger 1334535 is not a GRB
  63. GRB 250721A: Swift-XRT observations
  64. GRB 250722A: Fermi GBM Final Real-time Localization
  65. GRB 250713A : SVOM/ECLAIRs refined analysis
  66. GRB 250717B: SVOM/GRM observation
  67. LIGO/Virgo/KAGRA S250711q: Updated Sky localization
  68. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  69. GRB 250721A: Tiled Swift observations
  70. GRB 250721A: MAXI/GSC detection
  71. GRB 250721A: Fermi GBM Final Localization
  72. GRB 250720B: Fermi GBM Final Localization Correction
  73. GRB 250720A: Fermi GBM Final Localization
  74. Fermi trigger No 774730635: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  76. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  77. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  78. GRB 250717B: COLIBRÍ optical upper limit
  79. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  80. GRB 250717B: Swift-XRT observations
  81. GRB 250718B: Fermi GBM Final Localization Correction
  82. GRB 250718B: Fermi GBM Final Real-time Localization
  83. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  84. Swift Trigger 1334535: a possible GRB 250718A
  85. Swift GRB250718.01: Global MASTER-Net observations report
  86. GRB 250717B: Swift ToO observations
  87. GRB 270713A: Kitab and AbAO Optical Observations
  88. GRB 250717B: Fermi GBM Observation
  89. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  90. Konus-Wind detection of GRB 250716A
  91. GRB 250716A: Swift-XRT afterglow detection
  92. GRB 250717B: Fermi GBM Final Real-time Localization
  93. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  94. GRB 250717A: Fermi GBM Final Real-time Localization
  95. GRB 250716A: Swift ToO observations
  96. GRB 250716A: GOTO tentative optical counterpart candidate
  97. GRB 250716A: Fermi GBM Observation
  98. GRB 250714A: SVOM/GRM observation
  99. Fermi GRB 250716A: Global MASTER-Net observations report
  100. GRB 250716A: Fermi GBM Final Real-time Localization

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