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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"

5544 results found.

  1. Swift GRB250129A: MASTER 4 days observations report
  2. Konus-Wind detection of GRB 250129A
  3. GRB 250201A: BALROG localization (Fermi Trigger 760096791 / GRB 250201417)
  4. GRB 250201A: Fermi GBM Final Real-time Localization
  5. LIGO/Virgo/KAGRA S250201i: Coverage and upper limits from MAXI/GSC observations
  6. GRB 250127A: EP-FXT second observation epoch and confirmation of the x-ray afterglow fading
  7. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  8. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  9. Swift GRB 250129A: Global MASTER-Net observations report
  10. Fermi GRB 250128B: Global MASTER-Net observations report
  11. GRB 250129A: Swift detection of a burst with an optical counterpart
  12. Swift GRB 250129A: Global MASTER-Net OT detection
  13. GRB 250127A: EP-FXT afterglow detection
  14. Fermi GRB 250127B: Global MASTER-Net observations report
  15. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  16. IPN triangulation of GRB 250119B
  17. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  18. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  20. Integral GRB250114.55: Global MASTER-Net observations report
  21. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  22. GRB 250114A: Swift detection of a burst with an optical counterpart
  23. GRB 250101A: Terskol Zeiss-2000 optical observations
  24. GRB 250109A / EP250109a: GRBAlpha detection
  25. GRB 250109A / EP250109a: Mephisto optical upper limits
  26. EP250108a: Mephisto detection
  27. EP250111a: Global MASTER-Net observations report
  28. EP250108a: optical follow-up observations with the Liverpool Telescope
  29. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  30. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  31. GRB 250109A: Fermi GBM Observation
  32. EP250108a: NOT optical observations
  33. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  34. EP250109a: Swift/UVOT non-detection
  35. EP250108a: Liverpool Telescope likely optical counterpart
  36. GRB 250108B: REM optical/NIR upper limits
  37. EP250109a: Global MASTER-Net observations report
  38. GRB 250101A: Terskol K-800 optical observations
  39. EP250109a: GOTO optical upper limits
  40. EP250109a: Swift/XRT non-detection
  41. EP250108a: Global MASTER-Net observations report
  42. EP250109a: EP-WXT detection of an X-ray transient
  43. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  45. Fermi GRB 250107B: Global MASTER-Net observations report
  46. GRB 250103A: Fermi GBM Observation
  47. Fermi GRB 250102A: Global MASTER-Net observations report
  48. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  49. GRB 250101A: Swift detection of a burst with an optical counterpart
  50. GRB 240606B: 7DT Optical upper limits
  51. Fermi GRB 241228B: Global MASTER-Net observations report
  52. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  53. GRB 241228B: GOTO possible optical counterpart candidate
  54. GRB 241223A: GRBAlpha detection
  55. GRB 241212A: VZLUSAT-2 detection
  56. Fermi GRB 241226A: Global MASTER-Net observations report
  57. Fermi trigger No 756678579: Global MASTER-Net observations report
  58. IceCube Alert 241224.30: Global MASTER-Net observations report
  59. The EP-WXT trigger 01709129287 is likely a flaring star
  60. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  61. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  62. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  63. GRB 241217A / EP241217b: NOT optical upper limits
  64. GRB 241217a: Liverpool Telescope optical follow-up
  65. EP241217a: Global MASTER-Net observations report
  66. GRB 241209D: GRBAlpha detection
  67. GRB 241215A: Nanshan/HMT optical upper limit
  68. GRB 241212A: Fermi GBM detection
  69. EP241208a: NOT optical upper limits
  70. GRB 241212A: AstroSat CZTI detection
  71. GRB 241207A: TSHAO Zeiss-1000 optical observations
  72. GRB 241212A: Fermi GBM Final Real-time Localization
  73. GRB 241209B: GRBAlpha detection
  74. GRB 241209C: Fermi GBM Observation
  75. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  76. GRB 241209D: AstroSat CZTI detection
  77. EP241208a: Global MASTER-Net observations report
  78. EP241208a: EP-FXT follow-up observations
  79. Fermi trigger No 755485387: Global MASTER-Net observations report
  80. GRB 241209D: Fermi GBM Observation
  81. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  82. GRB 241209D: COLIBRÍ detection of the afterglow
  83. Fermi GRB 241209D: Global MASTER-Net observations report
  84. GRB 241209A: Fermi GBM Observation
  85. GRB 241209B: BOOTES-5 optical upper limit
  86. Swift GRB 241209D: Global MASTER-Net observations report
  87. Fermi GRB 241209C: Global MASTER-Net observations report
  88. Fermi GRB 241209E: Global MASTER-Net observations report
  89. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  90. GRB 241209A: REM optical/NIR observations
  91. GRB 241209C: AstroSat CZTI detection
  92. Fermi GRB 241209A: Global MASTER-Net observations report
  93. GRB 241209A: GOTO optical upper limits
  94. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  95. Swift GRB241209.23: Global MASTER-Net observations report
  96. Fermi GRB 241207B: Global MASTER-Net observations report
  97. GRB 241206A: DDOTI Upper Limit on the Afterglow
  98. GRB 241207C: MASTER optical observations
  99. Fermi trigger No 755225799: Global MASTER-Net observations report
  100. Fermi GRB 241207A: Global MASTER-Net observations report

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