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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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submitter:"Judith Racusin"

32729 results found.

  1. EP251118a / GRB 251118C: SVOM/VT optical observation
  2. GRB 251118A: NuSTAR detection of bright prompt emission
  3. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  4. GRB 251116C: NOT optical observations
  5. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  6. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  7. EP251118A / GRB 251118C : MASTER optical counterpart observations
  8. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  9. Konus-Wind detection of GRB 251118C (EP251118a)
  10. EP251118a: FTW optical and NIR observations
  11. GRB 251117A: Insight-HXMT/HE detection
  12. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  13. EP251118a: VLT near-infrared observation
  14. GRB 251116D: SVOM/GRM observation of a long GRB
  15. EP251118a: GOTO optical afterglow detection
  16. EP251118a: NOT spectroscopic redshift of z = 1.216
  17. EP251118a: Global MASTER-Net observations report
  18. EP251118a: preliminary result of EP-FXT follow-up observation
  19. GRB 251118A: Fermi-LAT detection
  20. EP251118a: NOT candidate optical counterpart
  21. GRB 251118A: Swift ToO observations
  22. EP251118a: Einstein Probe detected of a fast X-ray transient
  23. Fermi GRB 251118B: Global MASTER-Net observations report
  24. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  25. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  26. GRB 251116C: SVOM/ECLAIRs refined analysis
  27. GRB 251116B: SVOM/ECLAIRs refined analysis
  28. GRB 251117A: AstroSat CZTI detection
  29. GRB 251114B: Insight-HXMT/HE detection
  30. GRB 251114B: GECAM-B detection of a short burst
  31. GRB 251117A: Fermi GBM observation
  32. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  33. LIGO/Virgo/KAGRA S251117dq: Updated Sky localization
  34. GRB 251116D: Insight-HXMT/HE detection
  35. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  36. GRB 251117A: SVOM/GRM observation of a short burst
  37. GRB 251117A: Tiled Swift observations
  38. GRB 251117A: Fermi-LAT detection
  39. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  40. GRB 251116C: Swift/BAT arcminute localization of a burst
  41. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  42. LIGO/Virgo/KAGRA S251112cm: Classification of reported candidates with SOAR/Goodman
  43. GRB 251116B: SVOM/VT optical upper limit
  44. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  45. LIGO/Virgo/KAGRA S251116en: Updated Sky localization
  46. GRB 251116D: Glowbug gamma-ray detection
  47. EP251023a: Assy AZT-20 optical observations
  48. EP251023a: UAFO and AbAO optical observations
  49. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  50. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  51. GRB 251116C: SVOM/VT optical upper limit
  52. GRB 251025B: further Mondy optical observations
  53. GRB 251111A: Mondy optical upper limit
  54. GRB 251116B: EP-FXT follow-up observation
  55. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  56. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  57. GRB 251116B: LCO optical upper limits
  58. GRB 251116C: LCO optical upper limits
  59. LIGO/Virgo/KAGRA S251112cm: GRANDMA observations of the skymap
  60. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  61. GRB 251115A: Tiled Swift observations
  62. GRB 251115A: Fermi-LAT detection
  63. GRB 251013C: joint SVOM/ECLAIRs-GRM refined analysis
  64. Fermi GRB 251115A: Global MASTER-Net observations report
  65. LIGO/Virgo/KAGRA S251112cm: DECam GW-MMADS candidates
  66. LIGO/Virgo/KAGRA S251112cm: Updated Sky localization and false alarm rate estimate
  67. GRB 251113A: Glowbug gamma-ray detection
  68. GRB 251113A: AstroSat CZTI detection
  69. GRB 251112A: Swift-BAT refined analysis
  70. Konus-Wind detection of GRB 251108C
  71. Konus-Wind detection of GRB 251103A
  72. LIGO/Virgo/KAGRA S251112cm: ATLAS targeted observations of the skymap
  73. IPN triangulation of GRB 251108C
  74. Fermi GRB 251114A: Global MASTER-Net observations report
  75. LIGO/Virgo/KAGRA S251112cm: Candidates from the Zwicky Transient Facility
  76. LIGO/Virgo/KAGRA S251112cm: TROVE Vetting of TNS Candidates
  77. LIGO/Virgo/KAGRA S251112cm: FTW observations of galaxies within localization region
  78. Fermi GRB 251113A: Global MASTER-Net observations report
  79. GRB 251111A: SVOM/ECLAIRs refined analysis
  80. GRB 251025B: SVOM/ECLAIRs refined analysis
  81. GRB 251112A: Swift/UVOT Upper Limits
  82. LIGO/Virgo/KAGRA S251112cm: ATLAS pre-detections of AT2025adgp and AT2025adgq
  83. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  84. LIGO/Virgo/KAGRA S251112cm: Coverage and upper limits from MAXI/GSC observations
  85. LIGO/Virgo/KAGRA S251112cm: Initial GOTO-South observations
  86. LIGO/Virgo/KAGRA S251112cm: Upper limits from Fermi-GBM Observations
  87. GRB251111A: 1.3m DFOT optical upper limit
  88. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  89. GRB 251106B: Glowbug gamma-ray detection of a likely short burst
  90. GRB 251111A: SVOM/VT optical observations with X-band data
  91. GRB 251111A: Swift-XRT observations
  92. GRB 251111A: EP-FXT counterpart detection
  93. GRB 251013C: Chandra X-ray observations and jet break detection
  94. GRB 251111A: SVOM/VT optical observations with VHF data
  95. GRB 251111A: KAIT optical upper limit
  96. GRB 251111A: LCO optical observation
  97. GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
  98. GRB 251103B: Swift-BAT refined analysis
  99. GRB 251106A: Swift/UVOT Upper Limits
  100. GRB 251105B: Insight-HXMT/HE detection

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