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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"

5401 results found.

  1. SVOM GRB251108.54: Global MASTER-Net observations report
  2. SVOM GRB251106.83: Global MASTER-Net observations report
  3. GRB 251106A: MASTER optical observations
  4. GRB 251103B: AstroSat CZTI detection
  5. GRB 251103B: Fermi GBM observation
  6. GRB 251103A: Optical afterglow detection by ZTF’s public survey
  7. EP251102a: OHP/T193 optical observations
  8. GRB 251103A: OHP/T193 optical observations
  9. GRB 251103A: Xinglong 2.16m optical detection
  10. GRB 251103B: Nanshan/HMT optical upper limit
  11. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  12. GRB 251103B: MITSuME Akeno optical upper limits
  13. Fermi GRB 251103A: Global MASTER-Net observations report
  14. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  15. Swift GRB 251103B: Global MASTER-Net observations report
  16. GRB 251103B: GROWTH-India Telescope optical upper limits
  17. GRB 251103B: Prompt enhanced Swift-XRT position
  18. GRB 251103A: Fermi GBM Observation
  19. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  20. GRB 251103A: LCO optical observation
  21. EP251102.890: COLIBRÍ optical counterpart candidate
  22. GRB 251102A: AstroSat CZTI detection
  23. GRB 251103A: Fermi GBM Final Localization
  24. GRB 251103A: NOT optical afterglow candidate
  25. GRB 251102A: Fermi GBM Final Real-time Localization
  26. Konus-Wind detection of GRB 251028A
  27. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  28. GRB 251028A: Fermi GBM Observation
  29. GRB 251028A: Glowbug gamma-ray detection
  30. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  31. GRB 251028A: MAXI/GSC detection
  32. GRB 251028A: Fermi GBM Final Real-time Localization
  33. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  34. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  35. GRB 251026B: Tentative GOTO optical counterpart candidate
  36. Fermi GRB 251025C: Global MASTER-Net observations report
  37. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  38. EP251023a: OHP/T193 optical observations
  39. GRB 251022A: Swift-XRT detection of GOTO25iym
  40. GRB 251023B: CALET Gamma-Ray Burst Monitor detection
  41. GRB 251022A: MASTER OT detection
  42. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  43. Fermi GRB 251023A: Global MASTER-Net observations report
  44. GRB 251022A: GOTO optical counterpart detection
  45. LAT GRB251022A: Global MASTER-Net observations report
  46. EP251021b: BOOTES-7 optical upper limit
  47. GRB 250911A: MAXI/GSC detection
  48. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  49. IceCube-251018A: DDOTI Optical Upper Limit
  50. GRB 251018A: Fermi GBM Observation
  51. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  52. IceCube-251018A: Global MASTER-Net observations report
  53. GRB 251017A: COLIBRÍ photometric redshift
  54. GRB 251018A: MASTER OT detection
  55. GRB 251018A: TRT optical afterglow detection
  56. Swift GRB 251018A: Global MASTER-Net observations report
  57. GRB 251018A: Swift detection of a burst with an optical counterpart
  58. GRB 251018A: Fermi GBM Final Real-time Localization
  59. GRB 251011A: Fermi GBM Observation
  60. GRB 251013C: Leavitt Observatory optical photometry
  61. Fermi GRB 251016B: Global MASTER-Net observations report
  62. GRB 251017A: Swift detection of a burst with an optical counterpart
  63. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  64. GRB 251013C: VLA detection
  65. GRB 251013D: Swift/UVOT Observations
  66. GRB 251013C: Swift/UVOT Detection
  67. GRB 251014D: BOOTES-6/DPRT optical upper limit
  68. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  69. GRB 251013C: Bassano Bresciano Observatory optical observations
  70. GRB 251013C: ABObservatory optical observations
  71. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  72. GRB 251013C: ALMA detection
  73. GRB 251013C: DDOTI detection of the optical afterglow
  74. GRB 251013C: SLKT optical afterglow photometry
  75. GRB 251013C: Swift-XRT counterpart detection
  76. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  77. GRB 251011B inspection: MASTER orphan GRB detection
  78. GRB 251011A: AstroSat CZTI detection
  79. GRB 251011A: Fermi GBM Final Real-time Localization
  80. GRB 251003A: Fermi GBM Observation
  81. GRB 251007A: AKO Optical Upper Limit
  82. EP251003a: LCO and VST fading optical counterpart
  83. Fermi GRB 251006B: Global MASTER-Net observations report
  84. GRB 251003A: LAST optical observations
  85. GRB 251002A: Mondy/AZT-33IK optical observations
  86. GRB 251002A: NIR observations with WINTER
  87. Fermi GBM Sub-Threshold Detection of GRB 250910A
  88. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  89. GRB 251003A: COLIBRÍ photometric redshift
  90. GRB 251003A: GOTO detection of the optical counterpart
  91. GRB 251002A: GOTO detection of optical counterpart
  92. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  93. GRB 251002A: AbAO optical observations
  94. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  96. GRB 251003A: LCOGT Optical Detection
  97. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  98. Swift GRB251003A: Global MASTER-Net observations report
  99. GRB 251001B: SVOM/VT optical observation
  100. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592

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