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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"

42531 results found.

  1. GRB 250806A: EP-FXT observation
  2. EP#01709198415/EP250806a: Swift-XRT observations
  3. EP250806a: Global MASTER-Net observations report
  4. EP250802a: EP-FXT follow-up observation
  5. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  6. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  7. EP250806a: SVOM /VT optical candidate
  8. GRB 250806A: J-band upper limit from WINTER
  9. GRB 250805A: Swift-BAT refined analysis
  10. GRB 250806A: KAIT optical upper limit
  11. GRB 250806A: SVOM/VT refined analysis
  12. GRB 250806A: Swift-XRT counterpart detection
  13. EP250806a: COLIBRÍ optical upper limit
  14. GRB 250806A: Kilonova-Catcher optical upper limits
  15. EP250806a: Einstein Probe detection of an X-ray transient
  16. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  17. GRB 250806A: SVOM/VT optical upper limit
  18. GRB 250806A: SVOM detection of a soft burst
  19. GRB 250805A: SVOM/VT optical counterpart
  20. GRB 250805A: ESO/VLT observations
  21. GRB 250805A: Swift-XRT refined Analysis
  22. GRB 250804B: Swift-XRT observations
  23. GRB 250805A: Enhanced Swift-XRT position
  24. GRB 250804C: AstroSat CZTI detection of a long burst
  25. GRB 250805A: TRT optical upper limits
  26. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  27. GRB 250805A: Swift-XRT observations
  28. GRB 250805A: Swift detection of a burst
  29. Swift GRB250805.26: Global MASTER-Net observations report
  30. GRB 250804B: Tiled Swift observations
  31. Fermi trigger No 776041355: Global MASTER-Net observations report
  32. GRB 250804B: SVOM/GRM observation of a short burst
  33. GRB 250804A: Fermi GBM Final Localization
  34. EP250802a: additional Liverpool Telescope upper limits
  35. EP250730a: SVOM/VT optical upper limit
  36. EP250802a: Liverpool Telescope optical upper limits
  37. EP250802a: Global MASTER-Net observations report
  38. EP250802a: GROWTH-India Telescope optical upper limit
  39. EP250802a: Einstein Probe detection of an X-ray transient
  40. The EP-WXT trigger 01709198251 is likely a flaring star
  41. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  42. The EP-WXT trigger 01709198202 is likely a flaring star
  43. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  44. GRB 250702B: SMA observations
  45. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  46. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  47. EP250711a: CrAO and Assy optical observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  49. EP250730a: Global MASTER-Net observations report
  50. EP250730a: COLIBRÍ optical upper limit
  51. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  52. EP250730a: Einstein Probe detection of an X-ray transient
  53. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  54. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  55. GRB 250725A: AstroSat CZTI detection
  56. GRB 250727A: EP-FXT follow-up observation
  57. GRB 250725A: PRIME near-infrared observations
  58. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  59. GRB: Clarification on Gamma-Ray Burst Naming Convention
  60. GRB 250728A: Swift-XRT observations
  61. GRB 250727A: SVOM/ECLAIRs refined analysis
  62. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  63. GRB 250728A: COLIBRÍ optical upper limit
  64. GRB 250728A: Fermi GBM Observation
  65. Fermi trigger No 775387550: Global MASTER-Net observations report
  66. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  67. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  68. GRB 250728A: Swift ToO observations
  69. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  70. GRB 250727A: AST3-2 Upper limit
  71. GRB 250727A: EP-FXT counterpart detection
  72. GRB250727A: SVOM/VT optical upper limit
  73. GRB 250727A: Swift-XRT observations
  74. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  75. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  77. GRB 250727A: SVOM detection of a burst
  78. The EP-WXT trigger 01709195487 is likely a flaring star
  79. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  80. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  81. GRB 250725A: Swift-XRT refined Analysis
  82. GRB 250725A: Fermi GBM Observation
  83. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  84. GRB 250725A: Swift-BAT refined analysis
  85. Konus-Wind detection of GRB 250725A
  86. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  87. GRB 250725A: SVOM/GRM observation
  88. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  89. GRB 250725A: Swift/UVOT Upper Limits
  90. GRB 250725A: Fermi-LAT detection
  91. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  92. GRB 250725A: BOOTES-7 early optical detection
  93. GRB 250725A: SVOM/VT optical candidate
  94. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  95. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  96. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  97. GRB 250725A: Enhanced Swift-XRT position
  98. GRB 250725A: Swift detection of a burst
  99. Swift GRB 250725A: Global MASTER-Net OT detection
  100. GRB 250725A: Fermi GBM Final Real-time Localization

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