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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"

32534 results found.

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

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