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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"

4258 results found.

  1. EP251229a: Global MASTER-Net observations report
  2. Fermi GRB 251228A: Global MASTER-Net observations report
  3. SVOM GRB251227.07: Global MASTER-Net observations report
  4. GRB 251129A / EP251129a: VLA detection of a radio counterpart
  5. EP251222b/GRB 251222A: SVOM/GRM observation
  6. GRB 251222A: SVOM detection of a long burst
  7. GRB 251219A: GECAM-B detection of a possible magnetar X-ray burst from SGR 1830-0645
  8. IceCube-251218A: Upper limits from a search for additional neutrino events in IceCube
  9. SVOM GRB251219.11: Global MASTER-Net observations report
  10. Fermi GRB 251217A: Global MASTER-Net observations report
  11. Fermi GRB 251216A: Global MASTER-Net observations report
  12. Fermi GRB 251215A: Global MASTER-Net observations report
  13. EP251212a: Global MASTER-Net observations report
  14. GRB 251129A/EP251129a: AbAO and Mondy optical observations
  15. Fermi GRB 251208C: Global MASTER-Net observations report
  16. GRB 251208D: Swift-XRT observations
  17. GRB 251205A: ZTF and ATLAS optical afterglow detections
  18. GRB 251205A: Swift/UVOT Detection
  19. GRB 251205A: GTC/OSIRIS+ redshift z = 1.100
  20. GRB 251205A: Swift detection of a burst with an optical afterglow
  21. GRB 251202A / EP251202a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm and 1-m telescopes at McDonald Observatory
  22. GRB 251129B: Glowbug gamma-ray detection of a short burst
  23. EP251130a: JinShan near-infrared observations
  24. GRB 251129B: AstroSat CZTI detection
  25. EP251129a/GRB 251129A: NOWT Detection
  26. IceCube-251130A: Upper limits from a search for additional neutrino events in IceCube
  27. EP251130a: SAO RAS optical observations
  28. GRB 251201A: MAXI/GSC detection
  29. Fermi GRB 251130B: Global MASTER-Net observations report
  30. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  31. GRB 251129A / EP251129a: SAO RAS optical observations
  32. GRB 251126A: SAO RAS optical observations
  33. SVOM GRB 251129A : MASTER optical counterpart detection
  34. EP251129a: Global MASTER-Net observations report
  35. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  36. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  37. SVOM GRB251129A: Global MASTER-Net observations report
  38. Fermi GRB 251125B: Global MASTER-Net observations report
  39. Fermi GRB 251125A: Global MASTER-Net observations report
  40. Fermi GRB 251124a: Global MASTER-Net observations report
  41. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  42. Konus-Wind detection of GRB 251118C (EP251118a)
  43. LAT GRB251118.86: Global MASTER-Net observations report
  44. EP251118a: Einstein Probe detected of a fast X-ray transient
  45. GRB 251013C: Koshka, SAO RAS, Mondy, and CrAO optical observations, possible SN detection
  46. LAT GRB251117.51: Global MASTER-Net observations report
  47. LIGO/Virgo/KAGRA S251112cm: J-GEM follow-up observations
  48. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  49. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  50. GRB 251025B: further Mondy optical observations
  51. LIGO/Virgo/KAGRA S251112cm: AT2025adht follow-up at Maidanak observatory by GRANDMA
  52. Konus-Wind detection of GRB 251108C
  53. Fermi trigger No 784717756: Global MASTER-Net observations report
  54. Fermi GRB 251114A: Global MASTER-Net observations report
  55. LIGO/Virgo/KAGRA S251112cm: Detection of two young transients by BlackGEM/MeerLICHT: AT2025adgp and AT2025adgq
  56. LIGO/Virgo/KAGRA S251112cm: Identification of a GW compact binary merger candidate
  57. SVOM GRB251108.54: Global MASTER-Net observations report
  58. SVOM GRB251106.83: Global MASTER-Net observations report
  59. GRB 251106A: MASTER optical observations
  60. GRB 251103A: WFST optical observations
  61. GRB 251013C: 7DT detection and Medium-band SED of Afterglow
  62. Fermi GRB 251103A: Global MASTER-Net observations report
  63. Fermi GRB 251102A: Global MASTER-Net observations report
  64. GRB 251027A: Swift-XRT observations
  65. GRB 251026B: Tentative GOTO optical counterpart candidate
  66. Fermi GRB 251026B: Global MASTER-Net observations report
  67. Fermi GRB 251025C: Global MASTER-Net observations report
  68. LIGO/Virgo/KAGRA S251026bn: Identification of a GW compact binary merger candidate
  69. GRB 251003A: VLA Detection
  70. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  71. EP251023a: COLIBRÍ optical observations
  72. Fermi GRB 251023A: Global MASTER-Net observations report
  73. GRB 250911A: MAXI/GSC detection
  74. IceCube-251018A: Global MASTER-Net observations report
  75. Fermi GRB 251016B: Global MASTER-Net observations report
  76. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  77. Fermi GRB 251013C: Global MASTER-Net observations report
  78. Fermi GRB 251013B: Global MASTER-Net observations report
  79. GRB 251011B : MASTER optical observations
  80. GRB 251011A: AstroSat CZTI detection
  81. GRB 250916A: TERI Gamma-ray detection
  82. EP251006a: Global MASTER-Net observations report
  83. GRB 251007B: SVOM/C-GFT upper limit
  84. EP251003a: LCO and VST fading optical counterpart
  85. Fermi GRB 251006B: Global MASTER-Net observations report
  86. GRB 251003A: Enhanced Swift-XRT position
  87. GRB 251003A: Prompt enhanced Swift-XRT position
  88. GRB 251003A: Swift detection of a burst
  89. Fermi GRB 250929A: Global MASTER-Net observations report
  90. GRB 250929A: Fermi GBM Final Real-time Localization
  91. GRB 250916A: SVOM/VT optical observation
  92. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  93. Fermi trigger No 780609036: Global MASTER-Net observations report
  94. GRB 250924A: COLIBRÍ optical observations
  95. GRB 250924A: Swift detection of a burst with an optical counterpart
  96. Konus-Wind detection of GRB 250911A
  97. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  98. GRB 250917B: KAIT optical upper limit
  99. GRB 250920B: Swift/UVOT Detection
  100. GRB250920C: LCOGT Optical Detection

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