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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

21009 results found.

  1. Swift GRB 251007A: Global MASTER-Net observations report
  2. GRB 251007B: SVOM detection of a faint burst
  3. GRB 251007B: Swift detection of a burst
  4. GRB 250702B/EP250702a: JWST/NIRCam Observations
  5. GRB 251006B/EP251006a: SVOM/VT optical candidate
  6. Fermi GRB 251006B: Global MASTER-Net observations report
  7. GRB 251005C: COLIBRÍ optical observations
  8. Fermi GRB 251006A: Global MASTER-Net observations report
  9. GRB 251005C: VLT/X-shooter Imaging
  10. GRB 251003A: LAST optical observations
  11. GRB 251002A: LAST optical observations
  12. GRB 251005C: Swift/UVOT Upper Limits
  13. Swift GRB 251005A: Global MASTER-Net observations report
  14. GRB 251005C: GOTO optical upper limits
  15. Fermi trigger No 781367244: Global MASTER-Net observations report
  16. GRB 251002A: Mondy/AZT-33IK optical observations
  17. EP251003a: Einstein Probe detection of an X-ray transient
  18. GRB 251003A: J-band detection with WINTER
  19. GRB 251002A: NIR observations with WINTER
  20. GRB 251001B: NIR observations with WINTER
  21. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  22. GRB 251003A: Swift/UVOT Upper Limits
  23. GRB 251002A: Swift/UVOT detection
  24. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  25. GRB 251003A: COLIBRÍ photometric redshift
  26. GRB 251003A: GOTO detection of the optical counterpart
  27. GRB 251002A: GOTO detection of optical counterpart
  28. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  29. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  30. GRB 251003A: Kilonova-Catcher optical afterglow detection
  31. GRB 251002A: Swift-XRT afterglow detection
  32. GRB 251001B: AbAO optical upper limit
  33. GRB 251002A: Kilonova-Catcher optical afterglow detection
  34. GRB 251002A: AbAO optical observations
  35. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  36. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  37. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  38. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  39. GRB 251003A: LCOGT Optical Detection
  40. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  41. GRB 251003A: 1.5m OSN afterglow candidate
  42. Swift GRB251003A: Global MASTER-Net observations report
  43. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  44. GRB 251002A: SAO RAS optical observations
  45. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  46. GRB 251002A: LCO optical observation
  47. Fermi GRB 251002A: Global MASTER-Net observations report
  48. GRB 251001B: Swift/UVOT Detection
  49. GRB 251001B: COLIBRÍ optical observations
  50. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  51. GRB 251001B: NOT optical observations
  52. Swift GRB 251001B: Global MASTER-Net observations report
  53. GRB 251001B: Further GOTO observations of optical counterpart.
  54. GRB 251001B: LCOGT Optical Observations
  55. GRB 251001B: GOTO optical counterpart detection
  56. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  57. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  58. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  59. GRB 250925A: MAO/AZT-22 optical observations
  60. Fermi GRB 250929A: Global MASTER-Net observations report
  61. GRB 250925A: Mondy I-band optical observations
  62. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  63. Fermi trigger No 780609036: Global MASTER-Net observations report
  64. IceCube Alert 250926.52: Global MASTER-Net observations report
  65. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  66. GRB 250925A: Swift/UVOT Upper Limits
  67. GRB 250925A: Mondy and AbAO optical observations
  68. GRB 250925A: COLIBRÍ photometric redshift
  69. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  70. GRB 250925A: JinShan optical observations
  71. GRB 250925A: 1.5m OSN optical detection and redshift with the 10.4m GTC/OSIRIS+
  72. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  73. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  74. Fermi GRB 250926A: Global MASTER-Net observations report
  75. GRB 250925A: Optical Observations via Virtual Telescope Project, Italy
  76. GRB250925A: Liverpool Telescope optical observations
  77. GRB 250925A: NOT optical afterglow candidate
  78. GRB 250925A: Leavitt Observatory optical upper limit
  79. Swift GRB 250925A: Global MASTER-Net observations report
  80. GRB 250924A: 1.6m Mephisto optical upper limits
  81. GRB 250924A: SAO RAS optical observations
  82. GRB 250924A: NOT optical observations
  83. GRB 250924A: Swift/UVOT Detection
  84. GRB 250924A: J-band detection with WINTER
  85. GRB 250924A: GROWTH-India Telescope Upper Limits
  86. GRB 250924A: KAIT optical observations
  87. GRB 250924A: Mondy optical observations, afterglow fading
  88. GRB 250924A: Kilonova-Catcher optical afterglow detection
  89. GRB 250920C: Kilonova-Catcher optical afterglow detection
  90. GRB 250920C: TRT optical observation
  91. GRB 250924A: COLIBRÍ optical observations
  92. Swift GRB 250924A: Global MASTER-Net observations report
  93. GRB 250919A / EP250919a: further LCO optical observation
  94. GRB 250924A: DDOTI Detection of the Optical Counterpart
  95. GRB 250920C: KAIT optical observations
  96. EP250911a: e-MERLIN radio observations
  97. GRB 250920B: CrAO ZTSH optical observations
  98. GRB 250920C: SALT redshift confirmation
  99. GRB 250920C: COLIBRÍ optical observations
  100. Fermi GRB 250922B: Global MASTER-Net observations report

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