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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
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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.

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subject:"Swift"
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4066 results found.

  1. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  2. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  3. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  4. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  5. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  6. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  7. LIGO/Virgo/KAGRA S251112cm: NED Galaxies in the 3-Initial Localization Volume
  8. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  9. LIGO/Virgo/KAGRA S251108fi: DDOTI Optical Candidate
  10. LIGO/Virgo/KAGRA S251108fi: One counterpart neutrino candidate from IceCube neutrino searches
  11. LIGO/Virgo/KAGRA S251108fi: Updated Sky localization
  12. LIGO/Virgo/KAGRA S251108dn: Updated Sky localization
  13. LIGO/Virgo/KAGRA S251108fi: Identification of a GW compact binary merger candidate
  14. LIGO/Virgo/KAGRA S251108dn: Identification of a GW compact binary merger candidate
  15. LIGO/Virgo/KAGRA S251105aj: Updated Sky localization
  16. LIGO/Virgo/KAGRA S251103f: Updated Sky localization
  17. LIGO/Virgo/KAGRA S251031dw: Candidates from the Zwicky Transient Facility
  18. LIGO/Virgo/KAGRA S251105aj: Identification of a GW compact binary merger candidate
  19. LIGO/Virgo/KAGRA S251103f: Identification of a GW compact binary merger candidate
  20. LIGO/Virgo/KAGRA S251031cq: Updated Sky localization
  21. GRB 251103A: NOT optical afterglow candidate (duplicate submission)
  22. LIGO/Virgo/KAGRA S251031cq: Identification of a GW compact binary merger candidate
  23. IceCube-251025A: Upper limits from a search for additional neutrino events in IceCube
  24. GRB 251013C : 3.4-m telescope of Iranian National Observatory (INO340) optical observations
  25. LIGO/Virgo/KAGRA S251026bn: Updated Sky localization
  26. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  27. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  28. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  30. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  31. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S251017di: Retraction of GW compact binary merger candidate
  33. GRB 251013C: Leavitt Observatory optical photometry
  34. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  35. Upper limits from a search for additional neutrino events in IceCube
  36. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  37. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  38. LIGO/Virgo/KAGRA S251014cn: Identification of a GW compact binary merger candidate
  39. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  40. LIGO/Virgo/KAGRA S251013x: Updated Sky localization and Source Classification
  41. LIGO/Virgo/KAGRA S251013x: Identification of a GW compact binary merger candidate
  42. LIGO/Virgo/KAGRA S251006dd: Identification of a GW compact binary merger candidate
  43. LIGO/Virgo/KAGRA S251003at: Retraction of GW compact binary merger candidate
  44. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  45. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  46. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  49. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  50. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  51. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  52. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  53. LIGO/Virgo/KAGRA S250920bq: Coverage and upper limits from MAXI/GSC observations
  54. LIGO/Virgo/KAGRA S250918aw: 1 counterpart neutrino candidate event from an IceCube neutrino search
  55. LIGO/Virgo/KAGRA S250917aq: Three counterpart neutrino candidates from IceCube neutrino searches
  56. LIGO/Virgo/KAGRA S250917aq: Updated Sky localization
  57. LIGO/Virgo/KAGRA S250917aq: Identification of a GW compact binary merger candidate
  58. LIGO/Virgo/KAGRA S250818k: HCT optical follow-up
  59. LIGO/Virgo/KAGRA S250912s: 2 counterpart neutrino candidate events from an IceCube neutrino search
  60. LIGO/Virgo/KAGRA S250912f: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250912f: Identification of a GW compact binary merger candidate
  62. LIGO/Virgo/KAGRA S250911ac: Updated Sky localization and Source Classification
  63. LIGO/Virgo/KAGRA S250908y: Updated Sky localization
  64. LIGO/Virgo/KAGRA S250911ac: Identification of a GW compact binary merger candidate
  65. LIGO/Virgo/KAGRA S250906ca: Updated Sky localization
  66. LIGO/Virgo/KAGRA S250910b: Retraction of GW compact binary merger candidate
  67. LIGO/Virgo/KAGRA S250908y: Identification of a GW compact binary merger candidate
  68. LIGO/Virgo/KAGRA S250906ca: Identification of a GW compact binary merger candidate
  69. IceCube-250905A: Upper limits from a search for additional neutrino events in IceCube
  70. LIGO/Virgo/KAGRA S250830bp: DECam/SOAR GW-MMADS updates
  71. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 2 Candidates
  72. LIGO/Virgo/KAGRA S250904cv: Updated Sky localization
  73. LIGO/Virgo/KAGRA S250904br: Updated Sky localization
  74. LIGO/Virgo/KAGRA S250904ae: Updated Sky localization
  75. LIGO/Virgo/KAGRA S250904cv: Identification of a GW compact binary merger candidate
  76. LIGO/Virgo/KAGRA S250904br: Identification of a GW compact binary merger candidate
  77. LIGO/Virgo/KAGRA S250904ae: Identification of a GW compact binary merger candidate
  78. LIGO/VIRGO/KAGRA S250818k: No evidence for radio variability of AT2025ulz in MeerKAT 3 GHz data
  79. IceCube-250831A: Upper limits from a search for additional neutrino events in IceCube
  80. LIGO/Virgo/KAGRA S250902av: 1 counterpart neutrino candidate event from an IceCube neutrino search
  81. LIGO/Virgo/KAGRA S250901cb: Updated Sky localization
  82. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  83. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  84. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  85. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  86. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  87. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  88. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  89. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  90. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  91. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  93. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  94. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  95. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  96. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  97. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  98. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  99. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  100. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz

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