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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"

42534 results found.

  1. EP250806a: Liverpool telescope optical upper limit
  2. GRB 250807A: Swift detection of a burst with an optical counterpart
  3. IceCube Alert 250804.84: Global MASTER-Net observations report
  4. GRB 250806A: EP-FXT observation
  5. EP#01709198415/EP250806a: Swift-XRT observations
  6. EP250806a: Global MASTER-Net observations report
  7. EP250802a: EP-FXT follow-up observation
  8. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  9. EP250806a: Earlier Detection of the VT Candidate by COLIBRÍ and LS
  10. EP250806a: SVOM /VT optical candidate
  11. GRB 250806A: J-band upper limit from WINTER
  12. GRB 250805A: Swift-BAT refined analysis
  13. GRB 250806A: KAIT optical upper limit
  14. GRB 250806A: SVOM/VT refined analysis
  15. GRB 250806A: Swift-XRT counterpart detection
  16. EP250806a: COLIBRÍ optical upper limit
  17. GRB 250806A: Kilonova-Catcher optical upper limits
  18. EP250806a: Einstein Probe detection of an X-ray transient
  19. GRB 250806A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  20. GRB 250806A: SVOM/VT optical upper limit
  21. GRB 250806A: SVOM detection of a soft burst
  22. GRB 250805A: SVOM/VT optical counterpart
  23. GRB 250805A: ESO/VLT observations
  24. GRB 250805A: Swift-XRT refined Analysis
  25. GRB 250804B: Swift-XRT observations
  26. GRB 250805A: Enhanced Swift-XRT position
  27. GRB 250804C: AstroSat CZTI detection of a long burst
  28. GRB 250805A: TRT optical upper limits
  29. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  30. GRB 250805A: Swift-XRT observations
  31. GRB 250805A: Swift detection of a burst
  32. Swift GRB250805.26: Global MASTER-Net observations report
  33. GRB 250804B: Tiled Swift observations
  34. Fermi trigger No 776041355: Global MASTER-Net observations report
  35. GRB 250804B: SVOM/GRM observation of a short burst
  36. GRB 250804A: Fermi GBM Final Localization
  37. EP250802a: additional Liverpool Telescope upper limits
  38. EP250730a: SVOM/VT optical upper limit
  39. EP250802a: Liverpool Telescope optical upper limits
  40. EP250802a: Global MASTER-Net observations report
  41. EP250802a: GROWTH-India Telescope optical upper limit
  42. EP250802a: Einstein Probe detection of an X-ray transient
  43. The EP-WXT trigger 01709198251 is likely a flaring star
  44. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  45. The EP-WXT trigger 01709198202 is likely a flaring star
  46. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  47. GRB 250702B: SMA observations
  48. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  49. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  50. EP250711a: CrAO and Assy optical observations
  51. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  52. EP250730a: Global MASTER-Net observations report
  53. EP250730a: COLIBRÍ optical upper limit
  54. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  55. EP250730a: Einstein Probe detection of an X-ray transient
  56. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  57. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  58. GRB 250725A: AstroSat CZTI detection
  59. GRB 250727A: EP-FXT follow-up observation
  60. GRB 250725A: PRIME near-infrared observations
  61. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  62. GRB: Clarification on Gamma-Ray Burst Naming Convention
  63. GRB 250728A: Swift-XRT observations
  64. GRB 250727A: SVOM/ECLAIRs refined analysis
  65. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  66. GRB 250728A: COLIBRÍ optical upper limit
  67. GRB 250728A: Fermi GBM Observation
  68. Fermi trigger No 775387550: Global MASTER-Net observations report
  69. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  70. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  71. GRB 250728A: Swift ToO observations
  72. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  73. GRB 250727A: AST3-2 Upper limit
  74. GRB 250727A: EP-FXT counterpart detection
  75. GRB250727A: SVOM/VT optical upper limit
  76. GRB 250727A: Swift-XRT observations
  77. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  78. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  80. GRB 250727A: SVOM detection of a burst
  81. The EP-WXT trigger 01709195487 is likely a flaring star
  82. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  83. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  84. GRB 250725A: Swift-XRT refined Analysis
  85. GRB 250725A: Fermi GBM Observation
  86. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  87. GRB 250725A: Swift-BAT refined analysis
  88. Konus-Wind detection of GRB 250725A
  89. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  90. GRB 250725A: SVOM/GRM observation
  91. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  92. GRB 250725A: Swift/UVOT Upper Limits
  93. GRB 250725A: Fermi-LAT detection
  94. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  95. GRB 250725A: BOOTES-7 early optical detection
  96. GRB 250725A: SVOM/VT optical candidate
  97. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  98. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  100. GRB 250725A: Enhanced Swift-XRT position

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