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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"

37676 results found.

  1. GRB 251007A: AKO Optical Upper Limit
  2. GRB 251007A: CALET Gamma-Ray Burst Monitor detection
  3. GRB 251006B: Insight-HXMT detection
  4. GRB 251007A: SVOM/C-GFT optical observations
  5. GRB 251005C: PRIME J-band upper limit
  6. Swift GRB 251007B: Global MASTER-Net observations report
  7. GRB 251007A: Glowbug gamma-ray detection
  8. GRB 251007B: SVOM/C-GFT upper limit
  9. Swift GRB 251007A: Global MASTER-Net observations report
  10. GRB 251007B: SVOM detection of a faint burst
  11. GRB 251007B: Swift detection of a burst
  12. GRB 251007A: Swift detection of a burst with an optical counterpart
  13. GRB 250702B/EP250702a: JWST/NIRCam Observations
  14. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  15. GRB 251005B: Glowbug gamma-ray detection
  16. GRB 251006B/EP251006a: SVOM/VT optical candidate
  17. GRB 251006B/EP251006a: EP-FXT follow-up observation
  18. GRB 251006B: SVOM/GRM observation
  19. GRB 251006B: COLIBRÍ optical upper limit
  20. GRB 251006B/EP251006a: EP-WXT detection
  21. GRB 251005C: SVOM/VT optical fading
  22. GRB 251005C: SVOM/GRM observation of a likely short GRB
  23. Fermi GRB 251006B: Global MASTER-Net observations report
  24. GRB 251006B: BALROG localization (Fermi Trigger 781473909 / GRB 251006837)
  25. GRB 251006B: Fermi GBM Final Real-time Localization
  26. GRB 251006A (short): Glowbug gamma-ray detection
  27. GRB 251005C: COLIBRÍ optical observations
  28. Fermi GRB 251006A: Global MASTER-Net observations report
  29. GRB 251005C: VLT/X-shooter Imaging
  30. GRB 251003A: LAST optical observations
  31. GRB 251002A: LAST optical observations
  32. GRB 251006A: Fermi GBM Final Real-time Localization
  33. GRB 251005C: SVOM/VT optical candidate
  34. GRB 251005C: AstroSat CZTI detection
  35. GRB 251005C: Swift/UVOT Upper Limits
  36. GRB 250902A: MSU cubesats detection
  37. GRB 251005C: Swift-XRT refined Analysis
  38. GRB 251005C: Fermi GBM Observation
  39. Swift GRB 251005A: Global MASTER-Net observations report
  40. GRB 251005C: Enhanced Swift-XRT position
  41. GRB 251005C: GOTO optical upper limits
  42. Fermi trigger No 781367244: Global MASTER-Net observations report
  43. GRB 251005C: Swift detection of a burst
  44. GRB 251005B: Fermi GBM Final Real-time Localization
  45. GRB 251005A: Fermi GBM Final Localization
  46. GRB 251002A: Mondy/AZT-33IK optical observations
  47. GRB 251002A: Insight-HXMT detection
  48. GRB 251002A: Insight-HXMT detection
  49. GRB 251003A: J-band detection with WINTER
  50. GRB 251002A: NIR observations with WINTER
  51. Fermi GBM Sub-Threshold Detection of GRB 250910A
  52. GRB 251003A: Swift-BAT refined analysis
  53. GRB 251001B: NIR observations with WINTER
  54. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  55. GRB 251003A: Swift/UVOT Upper Limits
  56. GRB 251002A: Swift/UVOT detection
  57. GRB 251001A: AstroSat CZTI detection
  58. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  59. GRB 251003A: Swift-XRT refined Analysis
  60. GRB 251003A: COLIBRÍ photometric redshift
  61. GRB 251003A: GOTO detection of the optical counterpart
  62. GRB 251002A: Fermi GBM Observation
  63. GRB 251002A: GOTO detection of optical counterpart
  64. GRB 251001C: SVOM/GRM observation
  65. GRB 251003A: Enhanced Swift-XRT position
  66. GRB 251002A: AKO Early Optical Afterglow Detection
  67. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  68. GRB 251003A: Kilonova-Catcher optical afterglow detection
  69. GRB 251002A: Swift-XRT afterglow detection
  70. GRB 251001B: AbAO optical upper limit
  71. GRB 251002A: Kilonova-Catcher optical afterglow detection
  72. GRB 251002A: AbAO optical observations
  73. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  74. GRB 251001C: CALET Gamma-Ray Burst Monitor detection
  75. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  76. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  77. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  78. GRB 251002A: EP-FXT counterpart detection
  79. GRB 251003A: LCOGT Optical Detection
  80. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  81. GRB 251003A: 1.5m OSN afterglow candidate
  82. GRB 251003A: Prompt enhanced Swift-XRT position
  83. GRB 251003A: Swift detection of a burst
  84. GRB 251003A: Fermi GBM Final Real-time Localization
  85. Fermi/SVOM GRB 251002A : MASTER OT earlier detection in 2 polarization filters
  86. GRB 251002A: BOOTES-6 early optical detection
  87. GRB 251002A: SAO RAS optical observations
  88. GRB 251002A: ULL-ASTRO-MASTER early detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  89. GRB 251002A: FRAM-ORM afterglow detection
  90. GRB 251002A: LCO optical observation
  91. GRB 251002A: SVOM/VT optical observation
  92. GRB 251002A: SVOM detection of a burst
  93. Fermi GRB 251002A: Global MASTER-Net observations report
  94. GRB 251001B: Swift-BAT refined analysis
  95. GRB 251001A: SVOM/GRM observation
  96. GRB 251001A: Insight-HXMT detection
  97. GRB 251001B: Swift/UVOT Detection
  98. GRB 251001B: COLIBRÍ optical observations
  99. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  100. GRB 251001B: Swift-XRT refined Analysis

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