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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"

23559 results found.

  1. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  2. GRB 251108B: Glowbug gamma-ray detection
  3. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  4. Fermi trigger No 784621743: Global MASTER-Net observations report
  5. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  6. GRB251111A: 1.3m DFOT optical upper limit
  7. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  8. GRB 251111A: SVOM/VT optical observations with X-band data
  9. SVOM GRB251111.42: Global MASTER-Net observations report
  10. SVOM GRB251111.22: Global MASTER-Net observations report
  11. GRB 251111A: EP-FXT counterpart detection
  12. GRB 251111A: LCO optical observation
  13. GRB 251111A: SVOM detection of a soft burst
  14. GRB 251103B: Swift-BAT refined analysis
  15. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  16. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  17. IceCube-Cascade 251107A: Upper limits from a search for additional neutrino events in IceCube
  18. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  19. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  20. GRB 251108A: Fermi GBM Final Localization Correction
  21. Fermi trigger No 784329591: Global MASTER-Net observations report
  22. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  23. Fermi trigger No 784279167: Global MASTER-Net observations report
  24. SVOM GRB251108.54: Global MASTER-Net observations report
  25. GRB 251102B: SVOM/GRM observation
  26. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  27. The EP-WXT trigger 01709248051 is likely a flaring star
  28. SVOM GRB251106.83: Global MASTER-Net observations report
  29. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  30. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  31. IPN triangulation of GRB 251105B (possible sGRB with EE)
  32. Fermi GBM Sub-Threshold Detection of GRB 251106A
  33. GRB 251106A: Swift/BAT arcminute localization of a burst
  34. GRB 251106A: MASTER optical observations
  35. GRB 251106A: SVOM detection of a burst
  36. GRB 251103B: AstroSat CZTI detection
  37. Fermi trigger No 784034269: Global MASTER-Net observations report
  38. EP251102a: Xinglong 2.16-m clear-band observations of the optical counterpart
  39. GRB 251105A: Fermi GBM Observation
  40. GRB 251105C: Fermi GBM Final Localization Correction
  41. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  42. GRB 251105A: Swift/BAT-GUANO localization skymap of a burst
  43. GRB 251104A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  44. GRB 251023A: SVOM/ECLAIRs detection of a burst through targeted search
  45. Fermi GBM Sub-Threshold Detection of GRB 251105B
  46. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  47. GRB 251105B: SVOM/GRM observation of a possible short burst with extended emission
  48. Fermi GRB 251105A: Global MASTER-Net observations report
  49. GRB 251105A: Fermi GBM Final Real-time Localization
  50. GRB 251103B: Fermi GBM observation
  51. GRB 251104A: SVOM detection of a burst
  52. EP251102a: update of EP-FXT follow-up observation
  53. GRB 251103A: Xinglong 2.16m optical detection
  54. GRB 251103A: KAIT optical observations
  55. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  56. GRB 251103A: Swift/BAT-GUANO arcminute localization of a burst
  57. GRB 251103B: MITSuME Akeno optical upper limits
  58. GRB 251103B: Swift-XRT refined Analysis
  59. Fermi GRB 251103A: Global MASTER-Net observations report
  60. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  61. Swift GRB 251103B: Global MASTER-Net observations report
  62. GRB 251103B: GROWTH-India Telescope optical upper limits
  63. GRB 251103B: Fermi GBM Final Real-time Localization
  64. GRB 251103A: Fermi GBM Observation
  65. GRB 251103A: SVOM/GRM observation
  66. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  67. EP251102a (WXT 11900459650): LCO observations confirm COLIBRÍ candidate
  68. GRB 251103A: LCO optical afterglow detection
  69. GRB 251103A: Fermi GBM Final Localization
  70. GRB 251103A: SVOM detection of a bright burst
  71. GRB 251102B: Fermi GBM Final Real-time Localization
  72. Fermi GRB 251102A: Global MASTER-Net observations report
  73. GRB 251102A: Fermi GBM Final Real-time Localization
  74. GRB 251031A: Fermi GBM Observation
  75. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  76. GRB 251031A: Swift/BAT-GUANO localization skymap of a burst
  77. Konus-Wind detection of GRB 251028A
  78. GRB 251031A: BALROG localization (Fermi Trigger 783588065 / GRB 251031306)
  79. GRB 251031A: Fermi GBM Final Real-time Localization
  80. GRB 251025C: SVOM/GRM observation
  81. GRB 251028A: GECAM-B detection
  82. GRB 251028A: SVOM/GRM observation
  83. IceCube-251025A: Two Transient Candidates from the Zwicky Transient Facility
  84. GRB 251028A: Fermi GBM Observation
  85. GRB 251022A: Swift-XRT confirmation of fading
  86. GRB 250926B: VZLUSAT-2 detection
  87. GRB 250926A: VZLUSAT-2 detection
  88. GRB 250925A: VZLUSAT-2 detection
  89. GRB 251026B: Fermi GBM Observation
  90. GRB 251026A/EP251026a: SVOM/VT optical counterpart
  91. GRB 251026A/EP251026a: EP-FXT follow-up observation
  92. The EP-WXT trigger 01709247588 is likely a flaring star
  93. GRB 251028B: Fermi/GBM observation
  94. GRB 251028B: Swift/BAT-GUANO localization skymap of a burst
  95. GRB 251028B: CALET Gamma-Ray Burst Monitor detection
  96. Fermi GRB 251028B: Global MASTER-Net observations report
  97. GRB 251028B: Fermi GBM Final Localization Correction
  98. GRB251025B: 3.6m DOT Optical Observations
  99. GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
  100. GRB 251028A: Fermi GBM Final Real-time Localization

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