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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"

11529 results found.

  1. GRB 241228B: Fermi-LAT detection
  2. Fermi GRB 250107B: Global MASTER-Net observations report
  3. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  4. GRB 250107B: Fermi GBM Final Real-time Localization
  5. GRB 250107A: Fermi GBM Final Real-time Localization
  6. Fermi trigger No 757753930: Global MASTER-Net observations report
  7. GRB 241228B: 1.3m DFOT Optical observations
  8. GRB 250103A: NOT spectroscopic redshift
  9. GRB 250103A: TSHAO optical upper limit
  10. GRB 250103A: Fermi GBM Observation
  11. Fermi GRB 250102A: Global MASTER-Net observations report
  12. GRB 250101B: SVOM/GRM observation
  13. GRB 250102A: Fermi GBM Final Real-time Localization
  14. IceCube-250102A - IceCube observation of a high-energy neutrino candidate track-like event
  15. Fermi Gamma-ray Burst Monitor trigger 757464861/250101954 is not a GRB
  16. IceCube-250101A - IceCube observation of a high-energy neutrino candidate track-like event
  17. Fermi GRB 250101B: Global MASTER-Net observations report
  18. GRB 250101B: Fermi GBM Final Real-time Localization
  19. LIGO/Virgo/KAGRA S250101k: Upper limits from Fermi-GBM Observations
  20. GRB 241229B: Continued CrAO ZTSh observations
  21. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  22. GRB 241229B: SVOM/GRM observation
  23. GRB 241229B: SAO RAS optical upper limit
  24. GRB 241228B: SAO RAS optical observations
  25. GRB 241229B: CrAO ZTSh possible optical counterpart of SVOM/VT confirmation
  26. GRB 241229B: SVOM/VT optical candidate
  27. Konus-Wind detection of GRB 241228A
  28. Fermi trigger No 757231333: Global MASTER-Net observations report
  29. Fermi Gamma-ray Burst Monitor trigger 757207662/241229978 (GRB 241229C) is not a GRB
  30. GRB 241229C: Fermi GBM Final Real-time Localization
  31. GRB 241228B: D50 optical detection
  32. GRB 241228B: Fermi GBM Observation
  33. GRB 241228B: Swift-XRT afterglow detection
  34. GRB 241229B: Fermi GBM Observation
  35. GRB 241228A: Mondy optical afterglow observations
  36. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  37. GRB 241228B: LCO optical observation
  38. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  39. GRB 241229B: Fermi GBM Final Real-time Localization
  40. Fermi GRB 241228B: Global MASTER-Net observations report
  41. GRB 241228A: Fermi GBM Observation
  42. GRB241228B: GROWTH-India Telescope optical observations
  43. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  44. GRB 241228B: GOTO24jmz optical follow-up observations
  45. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 241228B: Swift ToO observations
  47. GRB 241228B: TRT optical counterpart confirmation
  48. GRB 241228B: GOTO possible optical counterpart candidate
  49. GRB 241228B: Fermi GBM Final Real-time Localization
  50. GRB 241223A: GRBAlpha detection
  51. GRB 241212A: VZLUSAT-2 detection
  52. Fermi GRB 241226A: Global MASTER-Net observations report
  53. GRB 241226A: Fermi GBM Final Real-time Localization
  54. GRB 241029A: LCO optical observation
  55. GRB 241223A: Swift-XRT observations
  56. GRB 241029A: AbAO AS-32 optical observations
  57. GRB 241223A: Fermi GBM Detection
  58. Fermi trigger No 756678579: Global MASTER-Net observations report
  59. IceCube-241224A - IceCube observation of a high-energy neutrino candidate track-like event
  60. Fermi Gamma-ray Burst Monitor trigger 756678579 / 241223854 is not a GRB
  61. Fermi GRB 241223A: Global MASTER-Net observations report
  62. GRB 241223A: GOTO optical observations summary
  63. GRB 241105A: JWST photometric observations of the host galaxy
  64. GRB 241223A: Swift ToO observations
  65. GRB 241223A: BALROG localization (Fermi Trigger 756648531 / GRB 241223506)
  66. GRB 241223A: Fermi GBM Final Real-time Localization
  67. Fermi trigger No 756447119: Global MASTER-Net observations report
  68. Fermi Gamma-ray Burst Monitor trigger 756447119/241221175 is not a GRB
  69. Fermi GRB 241221A: Global MASTER-Net observations report
  70. GRB 241221A: Fermi GBM Final Real-time Localization
  71. Konus-Wind detection of GRB 241204A (short/hard)
  72. GRB 241217A/EP241217B: Fermi-GBM Sub-Threshold Detection
  73. GRB 241209A: ATCA radio follow-up observations
  74. EP241217A: Non-detection from Fermi-GBM Observations
  75. GRB 241209D: GRBAlpha detection
  76. GRB 241214A: Swift/BAT-GUANO localization skymap of a burst
  77. GRB 241209D: CALET Gamma-Ray Burst Monitor detection
  78. GRB 241212A: Fermi GBM detection
  79. GRB241212A: OHP/T193 optical observations
  80. GRB 241212A : SVOM/C-GFT optical upper limit at early phase
  81. GRB 241212A : SVOM/VT bright optical afterglow
  82. GRB 241212A: AstroSat CZTI detection
  83. GRB 241207A: TSHAO Zeiss-1000 optical observations
  84. GRB 241212A: SVOM detection of a bright long burst
  85. GRB 241212A: Fermi GBM Final Real-time Localization
  86. GRB 241207A: EIRSAT-1 GMOD Detection
  87. GRB 241209A: Redshift of the likely host galaxy z = 0.784 from OSIRIS+/GTC
  88. GRB 241211A: Fermi GBM Final Real-time Localization
  89. GRB 241129A: Fermi GBM Observation
  90. GRB 241209B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 241209D: REM optical/NIR upper limits
  92. Konus-Wind detection of GRB 241209D
  93. GRB 241209C: Fermi GBM Observation
  94. Fermi Gamma-ray Burst Monitor trigger 755485387 / 241210044 is not a GRB
  95. GRB 241209D: AstroSat CZTI detection
  96. GRB 241209A: EP-FXT follow-up observations
  97. Fermi trigger No 755485387: Global MASTER-Net observations report
  98. GRB 241207B: Fermi GBM Observation
  99. GRB 241209A: BOOTES-7 and 2.2m CAHA early optical upper limits
  100. GRB 241209D: Fermi GBM Observation

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