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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"

1583 results found.

  1. GRB 251116D: Insight-HXMT/HE detection
  2. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  3. GRB 251117A: SVOM/GRM observation of a short burst
  4. GRB 251116C: Swift/BAT arcminute localization of a burst
  5. GRB 251116B: SVOM/VT optical upper limit
  6. GRB 251116C: Swift-XRT observations
  7. GRB 251116C: SVOM/VT optical upper limit
  8. GRB 251116B: EP-FXT follow-up observation
  9. GRB 251116B: LCO optical upper limits
  10. GRB 251116C: LCO optical upper limits
  11. SVOM GRB251116C: Global MASTER-Net observations report
  12. GRB 251116C: SVOM detection of a burst
  13. GRB 251116B: SVOM detection of a burst
  14. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  15. Konus-Wind detection of GRB 251103A
  16. GRB 251111A: SVOM/ECLAIRs refined analysis
  17. GRB 251025B: SVOM/ECLAIRs refined analysis
  18. GRB251111A: 1.3m DFOT optical upper limit
  19. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  20. GRB 251111A: Swift-XRT afterglow detection
  21. GRB 251111A: SVOM/VT optical observations with X-band data
  22. SVOM GRB251111.42: Global MASTER-Net observations report
  23. GRB 251111A: Swift-XRT observations
  24. SVOM GRB251111.22: Global MASTER-Net observations report
  25. GRB 251111A: EP-FXT counterpart detection
  26. GRB 251111A: SVOM/VT optical observations with VHF data
  27. GRB 251111A: KAIT optical upper limit
  28. GRB 251111A: LCO optical observation
  29. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  30. GRB 251111A: SVOM detection of a soft burst
  31. GRB 251106A: Swift/UVOT Upper Limits
  32. GRB 251105B: Insight-HXMT/HE detection
  33. GRB 251106B: Insight-HXMT detection
  34. SVOM GRB251108.54: Global MASTER-Net observations report
  35. GRB 251102B: SVOM/GRM observation
  36. SVOM GRB251106.83: Global MASTER-Net observations report
  37. IPN triangulation of GRB 251105B (possible sGRB with EE)
  38. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  39. GRB 251106B: SVOM/GRM observation of a short burst
  40. GRB 251106A: Swift-XRT afterglow detection
  41. GRB 251106A: Kilonova-Catcher optical upper limit
  42. Fermi GBM Sub-Threshold Detection of GRB 251106A
  43. GRB 251106A: Swift/BAT arcminute localization of a burst
  44. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  45. GRB 251106A: MASTER optical observations
  46. GRB 251106A: SVOM detection of a burst
  47. GRB 251016A: TERI Gamma-ray detection of a short burst
  48. GRB 250920C: TERI Gamma-ray detection
  49. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  50. GRB 251105B: AstroSat CZTI detection of a short burst with extended emission
  51. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  52. Fermi GBM Sub-Threshold Detection of GRB 251105B
  53. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  54. GRB 251104A: SVOM detection of a burst
  55. GRB 251028A: Insight-HXMT/HE detection
  56. GRB 251103A: WFST optical observations
  57. GRB 251103A: Xinglong 2.16m optical detection
  58. GRB 251103A: Insight-HXMT detection
  59. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  60. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  61. GRB 251103A: Kilonova-Catcher optical afterglow detection
  62. GRB 251103A: Swift/UVOT Detection
  63. GRB 251103A: Fermi GBM Observation
  64. GRB 251103A: SVOM/GRM observation
  65. GRB 251103A: Swift-XRT afterglow detection
  66. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  67. GRB 251103A: LCO optical observation
  68. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  69. GRB 251103A: BOOTES-2/TELMA optical afterglow
  70. GRB 251103A: LCO optical afterglow detection
  71. GRB 251103A: SVOM detection of a bright burst
  72. Konus-Wind detection of GRB 251028A
  73. GRB 251025C: SVOM/GRM observation
  74. GRB 251028A: GECAM-B detection
  75. GRB 251028A: SVOM/GRM observation
  76. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  77. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  78. GRB251025B: 3.6m DOT Optical Observations
  79. SVOM trigger sb25102702/GRB 251027A is not a GRB
  80. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  81. Konus-Wind detection of GRB 251022A
  82. GRB 251027A: Swift-XRT observations
  83. GRB 251022A: SVOM/GRM observation
  84. GRB 251027A: LCO optical upper limit
  85. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  86. GRB 251026A: Mondy optical upper limit
  87. GRB 251025B: Kilonova-Catcher optical afterglow detection
  88. Konus-Wind detection of GRB 251016A (short/hard)
  89. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  90. GRB 251027A: SVOM detection of a faint burst
  91. GRB 251026A: Swift-XRT observations
  92. GRB 251026A: SVOM/C-GFT upper limit
  93. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  94. GRB 251026A: SVOM detection of a long burst
  95. GRB 251025B: SVOM/VT optical bump
  96. GRB 251025B: SVOM/COLIBRÍ (FM-GFT) strong rebrightening of the optical counterpart
  97. GRB 251023A: SVOM/GRM observation
  98. GRB 251025B: ULL-ASTRO-MASTER optical counterpart detection with IAC80 telescope at Teide Observatory
  99. GRB 251025B: GROWTH-India Telescope optical observations
  100. GRB 251025B: Swift-XRT afterglow detection

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