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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"

41979 results found.

  1. GRB 250805A: TRT optical upper limits
  2. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  3. GRB 250805A: Swift-XRT observations
  4. GRB 250805A: Swift detection of a burst
  5. Swift GRB250805.26: Global MASTER-Net observations report
  6. GRB 250804B: Tiled Swift observations
  7. Fermi trigger No 776041355: Global MASTER-Net observations report
  8. GRB 250804B: SVOM/GRM observation of a short burst
  9. GRB 250804A: Fermi GBM Final Localization
  10. EP250802a: additional Liverpool Telescope upper limits
  11. EP250730a: SVOM/VT optical upper limit
  12. EP250802a: Liverpool Telescope optical upper limits
  13. EP250802a: Global MASTER-Net observations report
  14. EP250802a: GROWTH-India Telescope optical upper limit
  15. EP250802a: Einstein Probe detection of an X-ray transient
  16. The EP-WXT trigger 01709198251 is likely a flaring star
  17. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  18. The EP-WXT trigger 01709198202 is likely a flaring star
  19. LIGO/Virgo/KAGRA S250727dc: GRANDMA/OPD observations of AT2025smm
  20. GRB 250702B: SMA observations
  21. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS candidates
  22. LIGO/Virgo/KAGRA S250725j: GOTO pre-trigger detection of AT2025sib
  23. EP250711a: CrAO and Assy optical observations
  24. LIGO/Virgo/KAGRA S250727dc: DECam DESGW Epoch 1 Candidates
  25. EP250730a: Global MASTER-Net observations report
  26. EP250730a: COLIBRÍ optical upper limit
  27. GRB 250727A: Swift-XRT afterglow confirmation and refined analysis
  28. EP250730a: Einstein Probe detection of an X-ray transient
  29. LIGO/Virgo/KAGRA S250725j: DECam DESGW Epoch 1-2 Candidates
  30. LIGO/Virgo/KAGRA S250727dc: Swift-XRT observations, 8 X-ray sources
  31. GRB 250725A: AstroSat CZTI detection
  32. GRB 250727A: EP-FXT follow-up observation
  33. GRB 250725A: PRIME near-infrared observations
  34. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  35. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  36. GRB: Clarification on Gamma-Ray Burst Naming Convention
  37. GRB 250728A: Swift-XRT observations
  38. GRB 250727A: SVOM/ECLAIRs refined analysis
  39. EP-WXT trigger 01709195487: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
  40. GRB 250728A: COLIBRÍ optical upper limit
  41. GRB 250728A: Fermi GBM Observation
  42. Fermi trigger No 775387550: Global MASTER-Net observations report
  43. LIGO/Virgo/KAGRA S250727dc: Updated Sky localization
  44. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  45. GRB 250728A: Swift ToO observations
  46. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  47. GRB 250727A: AST3-2 Upper limit
  48. GRB 250727A: EP-FXT counterpart detection
  49. GRB250727A: SVOM/VT optical upper limit
  50. GRB 250727A: Swift-XRT observations
  51. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  52. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  53. LIGO/Virgo/KAGRA S250725j: DECam GW-MMADS candidates
  54. GRB 250727A: SVOM detection of a burst
  55. The EP-WXT trigger 01709195487 is likely a flaring star
  56. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  57. LIGO/Virgo/KAGRA S250726ak: Identification of a GW compact binary merger candidate
  58. GRB 250725A: Swift-XRT refined Analysis
  59. GRB 250725A: Fermi GBM Observation
  60. LIGO/Virgo/KAGRA S250725j: Updated Sky localization
  61. GRB 250725A: Swift-BAT refined analysis
  62. Konus-Wind detection of GRB 250725A
  63. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  64. GRB 250725A: SVOM/GRM observation
  65. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  66. GRB 250725A: Swift/UVOT Upper Limits
  67. GRB 250725A: Fermi-LAT detection
  68. GRB 250725A: VLT/FORS2 spectroscopic redshift z = 5.26
  69. GRB 250725A: BOOTES-7 early optical detection
  70. GRB 250725A: SVOM/VT optical candidate
  71. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  72. LIGO/Virgo/KAGRA S250725j: Identification of a GW compact binary merger candidate
  73. GRB 250725A: Enhanced Swift-XRT position
  74. GRB 250725A: Swift detection of a burst
  75. GRB 250725A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 250725A: Global MASTER-Net observations report
  77. Swift GRB 250725A: Global MASTER-Net observations report
  78. EP250702a/GRB250702 B,E,D: MeerKAT radio observations at 3.06 GHz
  79. EP250702a/GRB250702 B,D,E: uGMRT Radio detection in 1.26 GHz
  80. SVOM J195836+32283/sb25072103: Second VT observation
  81. SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
  82. GRB 250723B: Fermi GBM Final Real-time Localization
  83. GRB 250721A: Fermi GBM Observation
  84. GRB 250723A: Fermi GBM Final Real-time Localization
  85. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  86. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  87. GRB 250721A: Swift-XRT observations
  88. GRB 250722A: Fermi GBM Final Real-time Localization
  89. GRB 250713A : SVOM/ECLAIRs refined analysis
  90. GRB 250717B: SVOM/GRM observation
  91. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  92. GRB 250721A: Tiled Swift observations
  93. GRB 250721A: MAXI/GSC detection
  94. GRB 250721A: Fermi GBM Final Localization
  95. GRB 250720B: Fermi GBM Final Localization Correction
  96. GRB 250720A: Fermi GBM Final Localization
  97. Fermi trigger No 774730635: Global MASTER-Net observations report
  98. LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
  99. EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
  100. GRB 250717B: COLIBRÍ optical upper limit

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