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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"

26030 results found.

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

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