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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').
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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"
body:"GRB"
submitter:"Judith Racusin"

32531 results found.

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

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