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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"

36367 results found.

  1. Fermi GRB 250217C: Global MASTER-Net observations report
  2. GRB 250217C: Fermi GBM Final Real-time Localization
  3. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  4. Fermi GRB 250217A: Global MASTER-Net observations report
  5. GRANDMA/OPD observations of GRB250215A
  6. GRB 250217B: Fermi GBM Final Real-time Localization
  7. GRB 250217A: Fermi GBM Final Real-time Localization
  8. Fermi GRB 250216A: Global MASTER-Net observations report
  9. GRB 250215A / EP250215a: LCO detection of the afterglow
  10. GRB 250216A: Fermi GBM Final Real-time Localization
  11. GRB 250215A: Swift/UVOT Upper Limits
  12. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  13. EP250215a / GRB 250215A : GTC redshift z = 4.61
  14. GRB 250215A: Fermi GBM Observation
  15. EP250215a / GRB 250215A : NOT optical observations
  16. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  17. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  18. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  19. GRB 250215A: Swift-XRT refined Analysis
  20. GRB 250215A: SVOM/GRM observation
  21. EP250215a / GRB 250215A: AstroSat CZTI detection
  22. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  23. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  24. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  25. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  26. Fermi GRB 250215A: Global MASTER-Net observations report
  27. GRB 250215A: Fermi GBM Final Real-time Localization
  28. GRB 250213A：SVOM/VT optical candidate
  29. Fermi Gamma-ray Burst Monitor trigger 761206993/250214266 is not a GRB
  30. Fermi GRB 250214A: Global MASTER-Net observations report
  31. GRB 250213A: Swift ToO observations
  32. GRB 250214A: Fermi GBM Final Real-time Localization
  33. GRB 250213A: SVOM detection of a burst
  34. GRB 250205A: VIRT Optical Upper Limit
  35. GRB 250205A: Leavitt Observatory optical upper limit
  36. GRB 250210A: GRBAlpha detection
  37. Fermi GRB 250212A: Global MASTER-Net observations report
  38. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  39. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  40. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  41. GRB 250211B: A long GRB detected by INTEGRAL
  42. GRB 250211A: Swift ToO observations
  43. GRB 250212A: Fermi GBM Final Real-time Localization
  44. GRB 250207A: Fermi GBM Observation
  45. GRB 250206A: Fermi GBM Observation
  46. GRB 250205A / EP250205A: radio detection with the VLA
  47. Konus-Wind detection of GRB 250207A
  48. Konus-Wind detection of GRB 250206A
  49. GRB 250210A: SVOM/GRM observation of a long burst
  50. Fermi Gamma-ray Burst Monitor trigger 760945500/250211240 is not a GRB
  51. GRB 250207A: Skynet optical afterglow observations
  52. GRB 241128A: VIRT Optical Upper Limit
  53. EP250207A: Upper limits from Fermi-GBM Observations
  54. GRB 250210A: INTEGRAL SPI-ACS detection
  55. GRB 250210A: AstroSat CZTI detection
  56. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  57. Fermi GRB 250210A: Global MASTER-Net observations report
  58. GRB 250210A: Fermi GBM Final Real-time Localization
  59. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  60. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  61. GRB 250204B: GRBAlpha detection
  62. GRB 250204A: GRBAlpha detection
  63. GRB 250207A: 1.3m DFOT Optical observations
  64. GRB 250206A: Swift-XRT observations
  65. GRB 250129A: GRANDMA Continued Afterglow Detection
  66. GRB 250207A: Swift-BAT refined analysis
  67. GRB 250205A: 1.3m DFOT optical upper limit
  68. GRB 250206A: Tiled Swift observations
  69. GRB 250206A: EIRSAT-1 GMOD Detection
  70. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Observations
  71. GRB 250206A: Fermi-LAT detection
  72. GRB 250207B: Swift-XRT observations
  73. GRB 250208A: Fermi GBM Final Real-time Localization
  74. GRB 250207A: Swift-XRT refined Analysis
  75. GRB 250207A: Enhanced Swift-XRT position
  76. GRB 250129A: ABObservatory SLOAN r’ afterglow detection
  77. GRB 250207A: REM IR afterglow detection
  78. GRB 250207A: FRAM-Auger optical detection
  79. GRB 250207B: Tiled Swift observations
  80. Konus-Wind detection of GRB 250204B
  81. GRB 250207A: REM optical afterglow detection
  82. GRB 250207A: Swift/UVOT Detection
  83. LIGO/Virgo/KAGRA S250206dm: No counterpart candidates in INTEGRAL SPI-ACS prompt observation
  84. GRB 250129A: Continued AbAO and Mondy optical observations
  85. GRB 250207B: MAXI/GSC detection
  86. GRB 250207A: COLIBRÍ/DDRAGO Optical Afterglow Detection
  87. LIGO/Virgo/KAGRA S250206dm: Upper limits from Fermi-GBM Observations
  88. GRB 250207A: Swift detection of a burst with optical counterpart
  89. GRB 250207A: Fermi GBM Final Real-time Localization
  90. GRB 250206A: BALROG localization (Fermi Trigger 760564296 / GRB 250206827)
  91. GRB 250206A: Fermi GBM Final Real-time Localization
  92. GRB 250205A: Fermi GBM Observation
  93. GRB 250205A: REM NIR upper limit
  94. EP250205a/GRB 250205A: FTW optical and NIR observations of the counterpart
  95. GRB 250205A: Swift/UVOT Upper Limits
  96. EP250205a/GRB 250205A: correction to the source localization
  97. EP250205a/GRB 250205A: Einstein Probe observation
  98. GRB 250127C: SVOM/GRM observation of a burst
  99. GRB 250204B: SVOM/GRM observation of a likely short burst
  100. GRB 250205A: COLIBRÍ/DDRAGO Optical Afterglow Detection

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