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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"

21866 results found.

  1. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  2. GRB251111A: 1.3m DFOT optical upper limit
  3. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  4. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  5. GRB 251111A: Swift-XRT afterglow detection
  6. GRB 251111A: SVOM/VT optical observations with X-band data
  7. GRB 251111A: Swift-XRT observations
  8. GRB 251111A: SVOM/VT optical observations with VHF data
  9. GRB 251111A: KAIT optical upper limit
  10. GRB 251111A: LCO optical observation
  11. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  12. GRB 251106A: Swift/UVOT Upper Limits
  13. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  14. GRB 251105A: AstroSat CZTI detection
  15. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  16. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  17. GRB 251102B: SVOM/GRM observation
  18. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  19. IPN triangulation of GRB 251105B (possible sGRB with EE)
  20. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  21. GRB 251106A: Swift-XRT afterglow detection
  22. GRB 251106A: Kilonova-Catcher optical upper limit
  23. GRB 251106A: Swift/BAT arcminute localization of a burst
  24. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  25. GRB 251106A: MASTER optical observations
  26. GRB 251025C: TERI Gamma-ray detection
  27. GRB 251016B: TERI Gamma-ray detection
  28. GRB 251016A: TERI Gamma-ray detection of a short burst
  29. GRB 250920C: TERI Gamma-ray detection
  30. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  31. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  32. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  33. GRB 251103B: Swift/UVOT Upper Limits
  34. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  35. GRB 251103A: WFST optical observations
  36. GRB 251103A: Xinglong 2.16m optical detection
  37. GRB 251103A: KAIT optical observations
  38. GRB 251103B: Nanshan/HMT optical upper limit
  39. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  40. GRB 251103B: MITSuME Akeno optical upper limits
  41. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  42. EP251102a: NIR observations with WINTER
  43. GRB 251103A: J-band detection with WINTER
  44. GRB 251103B: GROWTH-India Telescope optical upper limits
  45. GRB 251103A: Kilonova-Catcher optical afterglow detection
  46. GRB 251103B: Enhanced Swift-XRT position
  47. GRB 251103B: Swift detection of a burst
  48. GRB 251103B: Fermi GBM Final Real-time Localization
  49. GRB 251103A: Swift/UVOT Detection
  50. GRB 251103A: Fermi GBM Observation
  51. GRB 251103A: Swift-XRT afterglow detection
  52. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  53. EP251102a: Einstein Probe detection of a fast X-ray transient
  54. GRB 251025B: OHP/T193 optical upper limit
  55. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  56. GRB 251103A: LCO optical observation
  57. EP251102.890: COLIBRÍ optical counterpart candidate
  58. GRB 251103A: GOTO optical afterglow detection
  59. GRB 251102A: AstroSat CZTI detection
  60. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  61. GRB 251103A: BOOTES-2/TELMA optical afterglow
  62. GRB 251103A: LCO optical afterglow detection
  63. GRB 251103A: NOT optical afterglow candidate
  64. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  65. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  66. GRB 251025C: SVOM/GRM observation
  67. GRB 251028A: SVOM/GRM observation
  68. GRB 251022A: Swift-XRT confirmation of fading
  69. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  70. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  71. GRB 251028B: Glowbug gamma-ray detection
  72. GRB 251028A: Glowbug gamma-ray detection
  73. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  74. GRB251026B: PRIME H-band upper limit
  75. GRB251025B: 3.6m DOT Optical Observations
  76. SVOM trigger sb25102702/GRB 251027A is not a GRB
  77. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  78. GRB 251026B: Swift-XRT observations of GOTO25jgl/AT2025absf
  79. GRB 251025C: Glowbug gamma-ray detection
  80. GRB 251023B: Swift-UVOT Upper Limits
  81. GRB 251027A: Swift-XRT observations
  82. EP251027.145: COLIBRÍ optical upper limits
  83. GRB 251022A: SVOM/GRM observation
  84. GRB 251026A/EP251026a: Einstein Probe detection of a fast X-ray transient
  85. GRB 251027A: LCO optical upper limit
  86. GRB 251027A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  87. GRB 251023B / EP251023b: Mondy optical upper limit
  88. GRB 251017A: INASAN-Kislovodsk optical observations
  89. GRB 251026A: Mondy optical upper limit
  90. GRB 251025B: Mondy optical observations
  91. GRB 251025B: Kilonova-Catcher optical afterglow detection
  92. Konus-Wind detection of GRB 251016A (short/hard)
  93. GRB 251025B: VLT/MUSE spectroscopic redshift z = 2.003
  94. GRB 251026B: Tentative GOTO optical counterpart candidate
  95. EP251023a: Mondy optical observations
  96. GRB 251025B: MAO/AZT-22 optical observations
  97. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  98. GRB 251026A: Swift-XRT observations
  99. GRB 251025B: OHP/T193 optical detection
  100. GRB 251025B: J-band detection with WINTER

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