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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"

27777 results found.

  1. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  2. GRB 241213A: SVOM/VT optical candidate
  3. GRB 241213B: Tiled Swift observations
  4. GRB 241213A: Swift/UVOT Upper Limits
  5. GRB 241213B: CALET Gamma-Ray Burst Monitor detection
  6. GRB 241213A: Swift-XRT refined Analysis
  7. GRB 241212A: Fermi GBM detection
  8. GRB 241212A: Swift ToO observations
  9. GRB 241213A: LCOGT Optical Upper Limits
  10. EP 241208A : Detection of a long soft transient by SVOM/ECLAIRs
  11. EP241213a/GRB241213a: Likely joint detection and INTEGRAL/SPI-ACS counterpart
  12. GRB 241213B: MAXI/GSC detection
  13. EP241213a: EP detection of An X-ray Transient
  14. GRB 241213A: REM optical/NIR upper limits
  15. GRB 241213A: Enhanced Swift-XRT position
  16. GRB241212A: OHP/T193 optical observations
  17. Swift GRB 241213A: Global MASTER-Net observations report
  18. GRB 241213A: Swift detection of a burst
  19. GRB 241212A: AstroSat CZTI detection
  20. GRB 241212A: SVOM detection of a bright long burst
  21. GRB 241212A: Fermi GBM Final Real-time Localization
  22. GRB 241209A: Chandra X-ray Detection
  23. Konus-Wind detection of GRB 241209B
  24. GRB 241207A: EIRSAT-1 GMOD Detection
  25. GRB 241209B: GRBAlpha detection
  26. GRB 241206C: GRBAlpha detection
  27. GRB 241211A: Fermi GBM Final Real-time Localization
  28. GRB 241129A: Fermi GBM Observation
  29. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  30. GRB 241209D: REM optical/NIR upper limits
  31. Konus-Wind detection of GRB 241209D
  32. GRB 241209B: Swift-XRT afterglow detection
  33. GRB 241209C: Fermi GBM Observation
  34. GRB 241209A: Swift-XRT refined Analysis
  35. GRB 241209D: AstroSat CZTI detection
  36. GRB 241209A: EP-FXT follow-up observations
  37. GRB 241209B: SVOM/VT afterglow detection
  38. EP241208a: EP-FXT follow-up observations
  39. GRB 241207B: Fermi GBM Observation
  40. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  41. GRB 241209D: Swift-XRT refined Analysis
  42. GRB 241209D: Fermi GBM Observation
  43. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  44. GRB 241209D: COLIBRÍ detection of the afterglow
  45. GRB 241209A: COLIBRÍ Optical Upper Limit
  46. GRB 241209A: Fermi GBM Observation
  47. GRB 241209C: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 241209A: GRANDMA/TAROT upper limit
  49. GRB 241209B: BOOTES-5 optical upper limit
  50. Swift GRB 241209D: Global MASTER-Net observations report
  51. GRB 241209E: Fermi GBM Final Real-time Localization
  52. GRB 241209B: Swift ToO observations
  53. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  54. GRB 241209A: REM optical/NIR observations
  55. GRB 241209D: Enhanced Swift-XRT position
  56. GRB 241209C: AstroSat CZTI detection
  57. GRB 241209D: Swift detection of a burst
  58. GRB 241209D: Fermi GBM Final Real-time Localization
  59. GRB 241209A: Enhanced Swift-XRT position
  60. GRB 241114B: cubesat Avion detection
  61. GRB 241209C: Fermi GBM Final Real-time Localization
  62. GRB 241209A: GOTO optical upper limits
  63. EP241206a: 1.5m OSN optical limit
  64. GRB 241209A: Prompt enhanced Swift-XRT position
  65. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  66. EP241208a: EP detection of a fast X-ray transient
  67. GRB 241209A: Swift detection of a short burst
  68. Swift GRB241209.23: Global MASTER-Net observations report
  69. GRB 241209A: Fermi GBM Final Real-time Localization
  70. GRB 241207B: Swift/BAT-GUANO localization skymap of a short burst
  71. GRB 241201A: AstroSat CZTI detection
  72. GRB 241206A: DDOTI Upper Limit on the Afterglow
  73. AT2024adec: X-ray Upper Limits from EP-FXT Observation
  74. EP241206a: BOOTES Global Network optical limits
  75. GRB 241207C: Tiled Swift observations
  76. GRB 241207C: MAXI/GSC detection
  77. GRB 241207B: Fermi GBM Final Real-time Localization
  78. EP241206a: EP detection of a fast X-ray transient
  79. GRB 241206A: Fermi GBM observation
  80. GRB 241207A: Fermi GBM Final Real-time Localization
  81. GRB 241206A: Swift/BAT-GUANO localization skymap of a burst
  82. GRB 241206B: SVOM/ECLAIRs detection of a long soft transient
  83. EP241113a: Keck/LRIS spectroscopic observation and tentative redshift
  84. GRB 241206A: Fermi GBM Final Real-time Localization
  85. LIGO/Virgo/KAGRA S241125n: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  86. GRB 241130A: CALET Gamma-Ray Burst Monitor detection
  87. GRB 241201A: GRBAlpha detection
  88. GRB 241204A: Fermi-LAT detection
  89. IceCube-241127A: No transient candidates from the Zwicky Transient Facility
  90. EP241202b: Kinder optical counterpart candidate
  91. Fermi-GBM Sub-Threshold Detection of GRB 241128A
  92. EP241201a: EP-FXT follow-up observations
  93. Konus-Wind detection of GRB 241130A
  94. EP241201a: BOOTES-5 optical upper limit
  95. EP241202b: EP detection of a fast X-ray transient
  96. IPN triangulation of GRB 241130A
  97. GRB 241130A: EIRSAT-1 GMOD Detection
  98. GRB 241128A: Swift/UVOT Upper Limits
  99. GRB 241130A: Fermi GBM Detection
  100. GRB 241129A: Swift/BAT-GUANO localization skymap of a burst

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