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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"

26332 results found.

  1. Fermi trigger No 784621743: Global MASTER-Net observations report
  2. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  3. GRB251111A: 1.3m DFOT optical upper limit
  4. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  5. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  6. GRB 251111A: Swift-XRT afterglow detection
  7. GRB 251111A: SVOM/VT optical observations with X-band data
  8. SVOM GRB251111.42: Global MASTER-Net observations report
  9. GRB 251111A: Swift-XRT observations
  10. SVOM GRB251111.22: Global MASTER-Net observations report
  11. GRB 251111A: EP-FXT counterpart detection
  12. GRB 251013C: Chandra X-ray observations and jet break detection
  13. GRB 251111A: SVOM/VT optical observations with VHF data
  14. GRB 251111A: LCO optical observation
  15. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  16. GRB 251103B: Swift-BAT refined analysis
  17. GRB 251106A: Swift/UVOT Upper Limits
  18. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  19. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  20. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  21. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  22. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  23. Fermi trigger No 784329591: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  25. Fermi trigger No 784279167: Global MASTER-Net observations report
  26. SVOM GRB251108.54: Global MASTER-Net observations report
  27. GRB 251102B: SVOM/GRM observation
  28. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  29. SVOM GRB251106.83: Global MASTER-Net observations report
  30. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  31. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  32. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) fading of the optical counterpart
  33. GRB 251106A: Swift-XRT afterglow detection
  34. GRB 251106A: Kilonova-Catcher optical upper limit
  35. Fermi GBM Sub-Threshold Detection of GRB 251106A
  36. GRB 251106A: SVOM/COLIBRÍ (FM-GFT) detection of a likely optical counterpart
  37. GRB 251106A: MASTER optical observations
  38. GRB 251025C: TERI Gamma-ray detection
  39. GRB 251016B: TERI Gamma-ray detection
  40. GRB 251016A: TERI Gamma-ray detection of a short burst
  41. GRB 250920C: TERI Gamma-ray detection
  42. Fermi trigger No 784034269: Global MASTER-Net observations report
  43. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  44. GRB 251105A: Fermi GBM Observation
  45. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  46. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  47. Fermi GBM Sub-Threshold Detection of GRB 251105B
  48. GRB 251103B: Swift/UVOT Upper Limits
  49. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  50. GRB 251103B: Fermi GBM observation
  51. GRB 251103A: WFST optical observations
  52. GRB 251103A: OHP/T193 optical observations
  53. GRB 251103A: Xinglong 2.16m optical detection
  54. GRB 251103A: KAIT optical observations
  55. GRB 251103B: Nanshan/HMT optical upper limit
  56. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  57. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  58. GRB 251103B: MITSuME Akeno optical upper limits
  59. GRB 251103B: Swift-XRT refined Analysis
  60. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  61. EP251102a: NIR observations with WINTER
  62. GRB 251103A: J-band detection with WINTER
  63. GRB 251103B: GROWTH-India Telescope optical upper limits
  64. GRB 251103A: Kilonova-Catcher optical afterglow detection
  65. GRB 251103B: Enhanced Swift-XRT position
  66. GRB 251103B: Swift detection of a burst
  67. GRB 251103A: Swift/UVOT Detection
  68. GRB 251103A: Fermi GBM Observation
  69. GRB 251103A: Swift-XRT afterglow detection
  70. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  71. GRB 251103A: SVOM/COLIBRÍ (FM-GFT) optical observations
  72. EP251102a: Einstein Probe detection of a fast X-ray transient
  73. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  74. GRB 251103A: LCO optical observation
  75. EP251102.890: COLIBRÍ optical counterpart candidate
  76. GRB 251026A: SVOM/COLIBRÍ (FM-GFT) confirmation of the optical counterpart
  77. GRB 251103A: LCO optical afterglow detection
  78. GRB 251103A: NOT optical afterglow candidate
  79. GRB 251031A: Fermi GBM Observation
  80. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  81. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  82. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  83. GRB 251025C: SVOM/GRM observation
  84. GRB 251028A: SVOM/GRM observation
  85. GRB 251028A: Fermi GBM Observation
  86. GRB 251022A: Swift-XRT confirmation of fading
  87. GRB 250926A: VZLUSAT-2 detection
  88. GRB 251026B: Fermi GBM Observation
  89. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  90. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  91. GRB 251028B: Glowbug gamma-ray detection
  92. GRB 251028A: Glowbug gamma-ray detection
  93. GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
  94. GRB251026B: PRIME H-band upper limit
  95. GRB251025B: 3.6m DOT Optical Observations
  96. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  97. GRB 251028A: MAXI/GSC detection
  98. SVOM trigger sb25102702/GRB 251027A is not a GRB
  99. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  100. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations

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