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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"

39156 results found.

  1. GRB 250217C: SVOM/GRM observation
  2. GRB 250217C: Tiled Swift observations
  3. GRB 250217C: Fermi GBM Observation
  4. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  5. IPN triangulation of GRB 250217C (short)
  6. SVOM/sb25021804: SVOM detection of a long X-ray transient
  7. GRB 250213A: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  9. GRB 250216A: AstroSat CZTI detection
  10. GRB 250217C: AstroSat CZTI detection of a short burst
  11. Fermi GRB 250217C: Global MASTER-Net observations report
  12. GRB 250217C: Fermi GBM Final Real-time Localization
  13. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  14. Fermi GRB 250217A: Global MASTER-Net observations report
  15. GRANDMA/OPD observations of GRB250215A
  16. GRB 250217B: Fermi GBM Final Real-time Localization
  17. GRB 250217A: Fermi GBM Final Real-time Localization
  18. Fermi GRB 250216A: Global MASTER-Net observations report
  19. GRB 250215A / EP250215a: LCO detection of the afterglow
  20. GRB 250216A: Fermi GBM Final Real-time Localization
  21. GRB 250215A: Swift/UVOT Upper Limits
  22. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  23. EP250215a / GRB 250215A : GTC redshift z = 4.61
  24. GRB 250215A: Fermi GBM Observation
  25. EP250215a / GRB 250215A : NOT optical observations
  26. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  27. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  28. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  29. GRB 250215A: Swift-XRT refined Analysis
  30. GRB 250215A: SVOM/GRM observation
  31. EP250215a / GRB 250215A: AstroSat CZTI detection
  32. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  33. EP250215a: Global MASTER-Net observations report
  34. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  35. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  36. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  37. Fermi GRB 250215A: Global MASTER-Net observations report
  38. GRB 250215A: Fermi GBM Final Real-time Localization
  39. Fermi trigger No 761206993: Global MASTER-Net observations report
  40. GRB 250213A：SVOM/VT optical candidate
  41. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  42. EP250207b: Xinglong optical upper limit
  43. Fermi GRB 250214A: Global MASTER-Net observations report
  44. GRB 250213A: Swift ToO observations
  45. GRB 250214A: Fermi GBM Final Real-time Localization
  46. EP250212a: Xinglong optical upper limit
  47. GRB 250213A: SVOM detection of a burst
  48. EP250212a: Global MASTER-Net observations report
  49. GRB 250205A: VIRT Optical Upper Limit
  50. GRB 250205A: Leavitt Observatory optical upper limit
  51. GRB 250210A: GRBAlpha detection
  52. Fermi GRB 250212A: Global MASTER-Net observations report
  53. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  54. Fermi trigger No 760945500: Global MASTER-Net observations report
  55. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  56. GRB 250211B: A long GRB detected by INTEGRAL
  57. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  58. GRB 250211A: Swift ToO observations
  59. Integral GRB250211.89: Global MASTER-Net observations report
  60. GRB 250212A: Fermi GBM Final Real-time Localization
  61. GRB 250207A: Fermi GBM Observation
  62. GRB 250206A: Fermi GBM Observation
  63. GRB 250205A / EP250205A: radio detection with the VLA
  64. EP250207b: Tentative z-band brightening source
  65. Konus-Wind detection of GRB 250207A
  66. Konus-Wind detection of GRB 250206A
  67. GRB 250210A: SVOM/GRM observation of a long burst
  68. EP250207b: Liverpool Telescope possible optical counterpart
  69. EP250207b: Global MASTER-Net observations report
  70. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  71. GRB 250207A: Skynet optical afterglow observations
  72. GRB 241128A: VIRT Optical Upper Limit
  73. EP250207A: Upper limits from Fermi-GBM Observations
  74. GRB 250210A: INTEGRAL SPI-ACS detection
  75. GRB 250210A: AstroSat CZTI detection
  76. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  77. Fermi GRB 250210A: Global MASTER-Net observations report
  78. GRB 250210A: Fermi GBM Final Real-time Localization
  79. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  80. LIGO/Virgo/KAGRA S250206dm: Global MASTER-Net observations report
  81. IceCube Alert 250207.09: Global MASTER-Net observations report
  82. GRB 250204B: GRBAlpha detection
  83. GRB 250204A: GRBAlpha detection
  84. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  85. GRB 250207A: 1.3m DFOT Optical observations
  86. GRB 250206A: Swift-XRT observations
  87. GRB 250129A: GRANDMA Continued Afterglow Detection
  88. GRB 250207A: Swift-BAT refined analysis
  89. LIGO/Virgo/KAGRA S250206dm: GECKO Observation with 7DT and KMTNet
  90. GRB 250205A: 1.3m DFOT optical upper limit
  91. GRB 250206A: Tiled Swift observations
  92. GRB 250206A: EIRSAT-1 GMOD Detection
  93. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  94. GRB 250206A: Fermi-LAT detection
  95. GRB 250207B: Swift-XRT observations
  96. GRB 250208A: Fermi GBM Final Real-time Localization
  97. GRB 250207A: Swift-XRT refined Analysis
  98. EP trigger 01709131361 (possible EP250207a): NOT optical observations and flaring star
  99. GRB 250207A: Enhanced Swift-XRT position
  100. GRB 250129A: ABObservatory SLOAN r’ afterglow detection

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