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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"

5833 results found.

  1. Swift GRB 250129A: Global MASTER-Net OT detection
  2. GRB 250127A: EP-FXT afterglow detection
  3. Fermi GRB 250127B: Global MASTER-Net observations report
  4. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  5. IPN triangulation of GRB 250119B
  6. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  7. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  9. Integral GRB250114.55: Global MASTER-Net observations report
  10. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  11. GRB 250114A: Swift detection of a burst with an optical counterpart
  12. GRB 250101A: Terskol Zeiss-2000 optical observations
  13. GRB 250109A / EP250109a: GRBAlpha detection
  14. GRB 250109A / EP250109a: Mephisto optical upper limits
  15. EP250108a: Mephisto detection
  16. EP250111a: Global MASTER-Net observations report
  17. EP250108a: optical follow-up observations with the Liverpool Telescope
  18. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  19. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  20. GRB 250109A: Fermi GBM Observation
  21. EP250108a: NOT optical observations
  22. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  23. EP250109a: Swift/UVOT non-detection
  24. EP250108a: Liverpool Telescope likely optical counterpart
  25. GRB 250108B: REM optical/NIR upper limits
  26. EP250109a: Global MASTER-Net observations report
  27. GRB 250101A: Terskol K-800 optical observations
  28. EP250109a: GOTO optical upper limits
  29. EP250109a: Swift/XRT non-detection
  30. EP250108a: Global MASTER-Net observations report
  31. EP250109a: EP-WXT detection of an X-ray transient
  32. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  33. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  34. Fermi GRB 250107B: Global MASTER-Net observations report
  35. GRB 250103A: Fermi GBM Observation
  36. Fermi GRB 250102A: Global MASTER-Net observations report
  37. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  38. GRB 250101A: Swift detection of a burst with an optical counterpart
  39. GRB 240606B: 7DT Optical upper limits
  40. Fermi GRB 241228B: Global MASTER-Net observations report
  41. GRB 241228B: LCOGT photometry of the likely optical counterpart GOTO24jmz
  42. GRB 241228B: GOTO possible optical counterpart candidate
  43. GRB 241223A: GRBAlpha detection
  44. GRB 241212A: VZLUSAT-2 detection
  45. Fermi GRB 241226A: Global MASTER-Net observations report
  46. Fermi trigger No 756678579: Global MASTER-Net observations report
  47. IceCube Alert 241224.30: Global MASTER-Net observations report
  48. The EP-WXT trigger 01709129287 is likely a flaring star
  49. GRB 241217a/EP241217B: 1.6m Mephisto optical upper limits
  50. GRB 241217A / EP241217B: GRANDMA/T1MPicduMidi optical upperlimits
  51. GRB 241217A: refined SVOM/MXT data analysis. Long lasting X-ray emission.
  52. GRB 241217A / EP241217b: NOT optical upper limits
  53. GRB 241217a: Liverpool Telescope optical follow-up
  54. EP241217a: Global MASTER-Net observations report
  55. GRB 241209D: GRBAlpha detection
  56. GRB 241215A: Nanshan/HMT optical upper limit
  57. GRB 241212A: Fermi GBM detection
  58. EP241208a: NOT optical upper limits
  59. GRB 241212A: AstroSat CZTI detection
  60. GRB 241207A: TSHAO Zeiss-1000 optical observations
  61. GRB 241212A: Fermi GBM Final Real-time Localization
  62. GRB 241209B: GRBAlpha detection
  63. GRB 241209C: Fermi GBM Observation
  64. LIGO/Virgo/KAGRA S241210fu: Identification of a GW compact binary merger candidate
  65. GRB 241209D: AstroSat CZTI detection
  66. EP241208a: Global MASTER-Net observations report
  67. EP241208a: EP-FXT follow-up observations
  68. Fermi trigger No 755485387: Global MASTER-Net observations report
  69. GRB 241209D: Fermi GBM Observation
  70. GRB 241209A: VLT/HAWK-I near-IR counterpart candidate
  71. GRB 241209D: COLIBRÍ detection of the afterglow
  72. Fermi GRB 241209D: Global MASTER-Net observations report
  73. GRB 241209A: Fermi GBM Observation
  74. GRB 241209B: BOOTES-5 optical upper limit
  75. Swift GRB 241209D: Global MASTER-Net observations report
  76. Fermi GRB 241209C: Global MASTER-Net observations report
  77. Fermi GRB 241209E: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S241102br: continued GRAWITA observations and detection of an optical transient (AT2024adip)
  79. GRB 241209A: REM optical/NIR observations
  80. GRB 241209C: AstroSat CZTI detection
  81. Fermi GRB 241209A: Global MASTER-Net observations report
  82. GRB 241209A: GOTO optical upper limits
  83. GRB 241209B: SVOM/ECLAIRs and GRM detection of a long burst
  84. Swift GRB241209.23: Global MASTER-Net observations report
  85. Fermi GRB 241207B: Global MASTER-Net observations report
  86. GRB 241206A: DDOTI Upper Limit on the Afterglow
  87. GRB 241207C: MASTER optical observations
  88. Fermi trigger No 755225799: Global MASTER-Net observations report
  89. Fermi GRB 241207A: Global MASTER-Net observations report
  90. Fermi GRB 241206A: Global MASTER-Net observations report
  91. Fermi GRB 241204A: Global MASTER-Net observations report
  92. EP241201a: Global MASTER-Net observations report
  93. Fermi GRB 241201A: Global MASTER-Net observations report
  94. LIGO/Virgo S241127aj: GRANDMA/FRAM-CTA-N Observations
  95. GRB 241127A: Swift detection of a burst with an optical counterpart
  96. LIGO/Virgo/KAGRA S241127aj: NED Galaxies in the Localization Volume
  97. LIGO/Virgo/KAGRA S241125n: SAGUARO follow-up observations with the MMT
  98. LIGO/Virgo/KAGRA S241109bn: Upper limits from a two-week IceCube neutrino search
  99. IPN triangulation of GRB 241117A
  100. EP trigger ID 01709065118: Keck/LRIS spectroscopic observations

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