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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').
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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

37216 results found.

  1. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  2. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  3. GRB 251125B: GECAM-B detection
  4. Fermi GRB 251127A: Global MASTER-Net observations report
  5. GRB 251127A: Fermi GBM Final Real-time Localization
  6. GRB 251126A: Enhanced Swift-XRT position
  7. GRB 251126A: Kilonova-Catcher optical afterglow detection
  8. GRB 251126A: Asiago i-band detection
  9. GRB 251126A: Nanshan/HMT optical afterglow detection
  10. Swift GRB 251126A: Global MASTER-Net observations report
  11. GRB 251121A: Fermi GBM Observation
  12. GRB 251126A: Prompt enhanced Swift-XRT position
  13. GRB 251126A: GIT discovery of the likely optical afterglow
  14. GRB 251126A: Swift detection of a burst
  15. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  16. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  17. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  18. Fermi GRB 251125B: Global MASTER-Net observations report
  19. GRB 251125B: Fermi GBM Final Real-time Localization
  20. Fermi GRB 251125A: Global MASTER-Net observations report
  21. GRB 251125A: Fermi GBM Final Real-time Localization
  22. GRB 251124A: Fermi GBM Localization by automated pipeline
  23. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  24. EP251124a: Optical upper limit with Kinder observations
  25. GRB 251122B: Fermi GBM Final Localization
  26. Fermi GRB 251124a: Global MASTER-Net observations report
  27. GRB 251124a: Fermi GBM Final Localization
  28. GRB 251116C: Swift-XRT confirmation of fading
  29. GRB 251122A/EP251122a: FTW optical and NIR observations
  30. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  31. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  32. GRB 251122A / EP251122a: EP-FXT counterpart detection
  33. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  34. GRB 251122A / EP251122a: WFST optical observations
  35. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  36. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  37. GRB 251122A / EP251122a: LCO optical upper limits
  38. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  39. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  40. GRB 251122A / EP251122a: SVOM detection of a long burst
  41. EP251118a: Continued Optical Detection with Kinder observations
  42. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  43. GRB 251121A: Glowbug gamma-ray detection of a likely short burst
  44. EP251118a: Xinglong-2.16m optical observation
  45. GRB 251115A: Fermi GBM Observation
  46. GRB 251121A: Fermi GBM Final Real-time Localization
  47. Fermi Gamma-ray Burst Monitor trigger 785388351 / 251121143 is not a GRB
  48. GRB 251118A: Swift/UVOT Detection
  49. EP251118a / GRB 251118C: SAO RAS optical observations
  50. GRB 251118A: Glowbug gamma-ray detection
  51. GRB 251118A: Fermi GBM Observation
  52. GRB 251118A: Swift-XRT afterglow detection
  53. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  54. EP251118a: Optical detection with Kinder observations
  55. GRB 251118A: GECAM-B detection
  56. EP251118a / GRB 251118C: SVOM/VT optical observation
  57. GRB 251118A: NuSTAR detection of bright prompt emission
  58. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  59. GRB 251116C: NOT optical observations
  60. GRB 251118C: Glowbug gamma-ray detection of the fast X-ray transient EP251118A
  61. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  62. GRB 251018A: FRAM-Auger optical detection
  63. GRB 251117A: Swift-XRT observations
  64. EP251118A / GRB 251118C : MASTER optical counterpart observations
  65. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  66. Konus-Wind detection of GRB 251118C (EP251118a)
  67. GRB 251117A: Insight-HXMT/HE detection
  68. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  69. GRB 251116D: SVOM/GRM observation of a long GRB
  70. EP251118a: GOTO optical afterglow detection
  71. GRB 251119A: SVOM detection of a possible burst
  72. EP251118a: NOT spectroscopic redshift of z = 1.216
  73. GRB 251118A: Fermi-LAT detection
  74. EP251118a: NOT candidate optical counterpart
  75. GRB 251118A: Swift ToO observations
  76. Fermi GRB 251118B: Global MASTER-Net observations report
  77. GRB 251118B: Fermi GBM Final Real-time Localization
  78. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  79. GRB 251118A: BALROG localization (Fermi Trigger 785190695 / GRB 251118855)
  80. GRB 251117A: FTW Observations of Swift candidate X-ray sources
  81. GRB 251118A: Fermi GBM Final Real-time Localization
  82. GRB 251116C: SVOM/ECLAIRs refined analysis
  83. GRB 251116B: SVOM/ECLAIRs refined analysis
  84. GRB 251117A: AstroSat CZTI detection
  85. GRB 251114B: Insight-HXMT/HE detection
  86. GRB 251114B: GECAM-B detection of a short burst
  87. GRB 251117A: Fermi GBM observation
  88. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  89. GRB 251116D: Insight-HXMT/HE detection
  90. GRB 251115A: Swift-XRT observations
  91. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  92. GRB 251117A: SVOM/GRM observation of a short burst
  93. GRB 251117A: Tiled Swift observations
  94. GRB 251117A: Fermi-LAT detection
  95. GRB 251116C: Swift/BAT arcminute localization of a burst
  96. GRB 251116B: SVOM/VT optical upper limit
  97. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  98. GRB 251116C: Swift-XRT observations
  99. GRB 251117A: Fermi GBM Final Localization Correction
  100. GRB 251116D: Glowbug gamma-ray detection

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