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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"

32491 results found.

  1. GRB 251001B: Swift/UVOT Detection
  2. GRB 251001B: COLIBRÍ optical observations
  3. GRB 251001B: GTC/OSIRIS+ spectroscopic redshift z = 2.162
  4. GRB 251001B: SVOM/VT optical observation
  5. GRB 251001B: NOT optical observations
  6. Swift GRB 251001B: Global MASTER-Net observations report
  7. GRB 251001B: Fermi GBM Observation
  8. GRB 251001B: Further GOTO observations of optical counterpart.
  9. GRB 251001B: LCOGT Optical Observations
  10. GRB 251001B: TRT optical afterglow detection and potential host galaxy
  11. GRB 251001B: GOTO optical counterpart detection
  12. GRB 250910A / EP250910a: VLT limits on the possible associated supernova
  13. LIGO/Virgo/KAGRA S250830bp: SOAR spectroscopy of two DESGW candidates
  14. LIGO/Virgo/KAGRA S250818k: further MeerKAT monitoring
  15. GRB 250910A / EP250910a: VLT/X-shooter host galaxy redshift z = 0.592
  16. GRB 250925A: MAO/AZT-22 optical observations
  17. Fermi GRB 250929A: Global MASTER-Net observations report
  18. GRB 250926A: CALET Gamma-Ray Burst Monitor detection
  19. LIGO/Virgo/KAGRA S250929c: Updated Sky localization
  20. GRB 250925A: Mondy I-band optical observations
  21. GRB 250916A: SVOM/VT optical observation
  22. LIGO/Virgo/KAGRA S250929c: Identification of a GW compact binary merger candidate
  23. LIGO/Virgo/KAGRA S250927cy: Updated Sky localization
  24. LIGO/Virgo/KAGRA S250927ck: Updated Sky localization
  25. Fermi-LAT Gamma-ray Observations of IceCube-250926A
  26. GRB 250926A: triangulation location with Insight-HXMT/HE and Fermi/GBM
  27. GRB 250924A: SVOM/GRM observation
  28. LIGO/Virgo/KAGRA S250927cy: Identification of a GW compact binary merger candidate
  29. LIGO/Virgo/KAGRA S250927ck: Identification of a GW compact binary merger candidate
  30. IceCube-250926A: Upper limits from a search for additional neutrino events in IceCube
  31. GRB 250926A: Insight-HXMT detection
  32. GRB 250920C: ULL-ASTRO-MASTER early detection of the optical afterglow with LCO 40-cm telescope at Siding Spring Observatory
  33. GRB 250926A: AstroSat CZTI detection
  34. GRB 250925A: Swift/UVOT Upper Limits
  35. GRB 250925A: Swift-BAT refined analysis
  36. GRB 250925A: Mondy and AbAO optical observations
  37. GRB 250925A: COLIBRÍ photometric redshift
  38. GRB 250925A: SVOM/GWAC-F60A upper limit
  39. GRB 250925A/EP250925a: EP-WXT detection
  40. GRB 250926A: DDOTI Optical Observations and Spatial Coincidence with the Orion Nebula
  41. GRB 250925A : MITSuME Akeno optical upper limits
  42. GRB 250925A: JinShan optical observations
  43. GRB 250919A / EP250919a: Global MASTER Net before, during and after trigger optical observations
  44. GRB 250925A: COLIBRÍ optical photometry of the afterglow
  45. Fermi GRB 250926A: Global MASTER-Net observations report
  46. GRB 250925A: Optical Observations via Virtual Telescope Project, Italy
  47. GRB250925A: Liverpool Telescope optical observations
  48. GRB 250925A: NOT optical afterglow candidate
  49. GRB 250925A: Leavitt Observatory optical upper limit
  50. GRB 250924A: Swift-BAT refined analysis
  51. GRB 250925A: GROWTH-India Telescope Upper Limits
  52. GRB 250922A: SVOM/GRM observation
  53. GRB 250924A: 1.6m Mephisto optical upper limits
  54. GRB 250924A: SAO RAS optical observations
  55. GRB 250924A: NOT optical observations
  56. GRB 250924A: AstroSat CZTI detection
  57. GRB 250914A: AstroSat CZTI detection
  58. GRB 250920B: AstroSat CZTI detection
  59. GRB 250924A: SVOM/VT optical observation
  60. GRB 250924A: Swift/UVOT Detection
  61. GRB 250924A: J-band detection with WINTER
  62. GRB 250924A: GROWTH-India Telescope Upper Limits
  63. GRB 250924A: KAIT optical observations
  64. GRB 250924A: Mondy optical observations, afterglow fading
  65. GRB 250924A: Kilonova-Catcher optical afterglow detection
  66. GRB 250920C: Kilonova-Catcher optical afterglow detection
  67. GRB 250922B: SVOM/GRM observation
  68. GRB 250920C: TRT optical observation
  69. GRB 250924A: COLIBRÍ optical observations
  70. Swift GRB 250924A: Global MASTER-Net observations report
  71. GRB 250919A / EP250919a: further LCO optical observation
  72. GRB 250924A: DDOTI Detection of the Optical Counterpart
  73. GRB 250920B: AbAO optical upper limits
  74. Konus-Wind detection of GRB 250920C
  75. GRB 250920C: KAIT optical observations
  76. GRB 250920C: VLT redshift confirmation z = 1.399
  77. EP250911a: e-MERLIN radio observations
  78. GRB 250920B: CrAO ZTSH optical observations
  79. GRB 250920C: SALT redshift confirmation
  80. GRB 250920C: COLIBRÍ optical observations
  81. Fermi GRB 250922B: Global MASTER-Net observations report
  82. GRB 250920B: SAO RAS optical observations
  83. GRB 250920C: NIR observations with WINTER
  84. GRB 250920B: NIR observations with WINTER
  85. GRB 250920C: PRIME near-infrared detection
  86. Konus-Wind detection of GRB 250920B
  87. Konus-Wind detection of GRB 250920A
  88. IPN triangulation of GRB 250920A (long/bright)
  89. Konus-Wind detection of GRB 250911A
  90. GRB 250916A: Swift/UVOT Detection
  91. GRB 250920B: Glowbug gamma-ray detection
  92. GRB 250916A: CrAO ZTSh R-band optical observations
  93. GRB 250916A: SAO RAS Zeiss-1000 optical observations
  94. GRB 250920B: Asiago optical observations
  95. GRB 250920B: Kitab-ISON optical upper limit
  96. GRB 250917B: Mondy and Zeiss-1000 SAO RAS optical observations, optical observations, afterglow candidate
  97. GRB 250920C: SVOM/GRM observation
  98. GRB 250920C: GTC/OSIRIS+ spectroscopic redshift z = 1.40
  99. GRB 250917B: KAIT optical upper limit
  100. GRB 250920A: NuSTAR detection of bright prompt emission

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