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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"

35270 results found.

  1. GRB 250219A: NOT optical observations
  2. GRB 250219A: COLIBRÍ/DDRAGO Detection of the Optical Counterpart
  3. GRB 250219A: 1.6m Mephisto optical upper limits
  4. GRB 250219A: SVOM/VT optical counterpart
  5. GRB 250219A: Swift-XRT observations
  6. GRB 250219A: Swift ToO observations
  7. GRB 250219A: SVOM detection of a burst
  8. Konus-Wind detection of GRB 250215A / EP250215a
  9. GRB 250217C: Swift-XRT observations
  10. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  11. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  12. GRB 250217C: SVOM/GRM observation
  13. GRB 250217C: Tiled Swift observations
  14. GRB 250217C: Fermi GBM Observation
  15. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  16. IPN triangulation of GRB 250217C (short)
  17. GRB 250213A: Swift-XRT observations
  18. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  19. GRB 250216A: AstroSat CZTI detection
  20. GRB 250217C: AstroSat CZTI detection of a short burst
  21. Fermi GRB 250217C: Global MASTER-Net observations report
  22. GRB 250217C: Fermi GBM Final Real-time Localization
  23. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  24. Fermi GRB 250217A: Global MASTER-Net observations report
  25. GRANDMA/OPD observations of GRB250215A
  26. GRB 250217B: Fermi GBM Final Real-time Localization
  27. GRB 250217A: Fermi GBM Final Real-time Localization
  28. Fermi GRB 250216A: Global MASTER-Net observations report
  29. GRB 250215A / EP250215a: LCO detection of the afterglow
  30. GRB 250216A: Fermi GBM Final Real-time Localization
  31. GRB 250215A: Swift/UVOT Upper Limits
  32. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  33. EP250215a / GRB 250215A : GTC redshift z = 4.61
  34. GRB 250215A: Fermi GBM Observation
  35. EP250215a / GRB 250215A : NOT optical observations
  36. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  37. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  38. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  39. GRB 250215A: Swift-XRT refined Analysis
  40. GRB 250215A: SVOM/GRM observation
  41. EP250215a / GRB 250215A: AstroSat CZTI detection
  42. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  43. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  44. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  45. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  46. Fermi GRB 250215A: Global MASTER-Net observations report
  47. GRB 250215A: Fermi GBM Final Real-time Localization
  48. GRB 250213A：SVOM/VT optical candidate
  49. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  50. Fermi GRB 250214A: Global MASTER-Net observations report
  51. GRB 250213A: Swift ToO observations
  52. GRB 250214A: Fermi GBM Final Real-time Localization
  53. GRB 250213A: SVOM detection of a burst
  54. GRB 250205A: VIRT Optical Upper Limit
  55. GRB 250205A: Leavitt Observatory optical upper limit
  56. GRB 250210A: GRBAlpha detection
  57. Fermi GRB 250212A: Global MASTER-Net observations report
  58. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  59. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  60. GRB 250211B: A long GRB detected by INTEGRAL
  61. GRB 250211A: Swift ToO observations
  62. GRB 250212A: Fermi GBM Final Real-time Localization
  63. GRB 250207A: Fermi GBM Observation
  64. GRB 250206A: Fermi GBM Observation
  65. GRB 250205A / EP250205A: radio detection with the VLA
  66. Konus-Wind detection of GRB 250207A
  67. Konus-Wind detection of GRB 250206A
  68. GRB 250210A: SVOM/GRM observation of a long burst
  69. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  70. GRB 250207A: Skynet optical afterglow observations
  71. GRB 241128A: VIRT Optical Upper Limit
  72. EP250207A: Upper limits from Fermi-GBM Observations
  73. GRB 250210A: INTEGRAL SPI-ACS detection
  74. GRB 250210A: AstroSat CZTI detection
  75. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  76. Fermi GRB 250210A: Global MASTER-Net observations report
  77. GRB 250210A: Fermi GBM Final Real-time Localization
  78. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  79. GRB 250204B: GRBAlpha detection
  80. GRB 250204A: GRBAlpha detection
  81. GRB 250207A: 1.3m DFOT Optical observations
  82. GRB 250206A: Swift-XRT observations
  83. GRB 250129A: GRANDMA Continued Afterglow Detection
  84. GRB 250207A: Swift-BAT refined analysis
  85. GRB 250205A: 1.3m DFOT optical upper limit
  86. GRB 250206A: Tiled Swift observations
  87. GRB 250206A: EIRSAT-1 GMOD Detection
  88. GRB 250206A: Fermi-LAT detection
  89. GRB 250207B: Swift-XRT observations
  90. GRB 250208A: Fermi GBM Final Real-time Localization
  91. GRB 250207A: Swift-XRT refined Analysis
  92. GRB 250207A: Enhanced Swift-XRT position
  93. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  94. GRB 250207A: REM IR afterglow detection
  95. GRB 250207A: FRAM-Auger optical detection
  96. GRB 250207B: Tiled Swift observations
  97. Konus-Wind detection of GRB 250204B
  98. GRB 250207A: REM optical afterglow detection
  99. GRB 250207A: Swift/UVOT Detection
  100. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation

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