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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').
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"

32501 results found.

  1. IPN triangulation of GRB 250703A
  2. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  3. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  4. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  5. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  6. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  7. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  8. GRB 250702F: Kilonova-Catcher optical afterglow detection
  9. GRB 250702F: Monte Agliale Observatory optical observations
  10. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  11. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  12. EP250704a / GRB 250704B: JinShan optical observations
  13. GRB 250704A: SVOM/VT optical observation
  14. EP250704a / GRB 250704B: SAO RAS optical observations
  15. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  16. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  17. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  18. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  19. EP 250704a: BOOTES-5 optical detection
  20. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  21. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  22. GRB 250702A: Insight-HXMT detection
  23. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  24. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  25. EP250704a / GRB250704B: Swift-XRT counterpart detection
  26. GRB 250704A: Swift-XRT afterglow detection
  27. GRB 250702B / EP2050702a: FTW optical and NIR observations
  28. Konus-Wind detection of GRB 250702F
  29. EP250704a / GRB 250704B - REM observations
  30. GRB 250702F: GROWTH-India Telescope optical observations
  31. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  32. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  33. EP250702a: WFST optical observations
  34. EP250704a: COLIBRÍ optical counterpart candidate
  35. EP250704a: Einstein Probe detection of an X-ray transient
  36. GRB 250702F: optical photometry from Konkoly
  37. GRB 250704A: REM detection of the optical afterglow
  38. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  39. GRB 250702F: SVOM/VT optical observation
  40. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  41. GRB 250702F: Swift/UVOT Detection
  42. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  43. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  44. Fermi GRB 250703A: Global MASTER-Net observations report
  45. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  46. GRB 250702F: Fermi GBM Observation
  47. GRB 250702F: Leavitt Observatory optical observations
  48. GRB 250702F: AKO Optical Afterglow Detection
  49. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  50. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  51. GRB 250702A: GECAM-B detection
  52. GRB 250702F: Skynet Optical Observations
  53. GRB 250424A: VIRT Optical Upper Limit
  54. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  55. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  56. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  57. GRB 250702F: TRT Optical Observation
  58. GRB 250703A: DDOTI Optical Upper Limit
  59. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  60. GRB 250702F: REM optical afterglow detection
  61. EP250702a: Global MASTER-Net observations report
  62. GRB 250702F: DDOTI Optical Observation
  63. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  64. GRB 250702F: COLIBRÍ Observations of the Afterglow
  65. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  66. Fermi GRB 250702E: Global MASTER-Net observations report
  67. Fermi GRB 250702B: Global MASTER-Net observations report
  68. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  69. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  70. GRB 250702F: NOT observations of the optical afterglow
  71. GRB 250702F: MASTER optical afterglow observation
  72. Fermi GRB 250702F: Global MASTER-Net observations report
  73. Fermi GRB 250702C: Global MASTER-Net observations report
  74. GRB 250702F: GOTO optical counterpart detection
  75. GRB 250702F: Swift detection of a burst with an optical counterpart
  76. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  77. Konus-Wind detection of GRB 250627A
  78. IPN triangulation of GRB 250627A (short)
  79. GRB 250702A: Fermi GBM Detection
  80. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  81. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  82. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  83. GRB 250628B: Swift-XRT observations
  84. GRB 250628B: SVOM/VT optical upper limit
  85. GRB 250628B: EP-FXT counterpart detection
  86. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  87. GRB 250627A: Insight-HXMT detection
  88. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  89. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  90. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  91. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  92. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  93. GRB 250628A: REM optical/NIR upper limits
  94. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate
  95. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  96. GRB 250628A: VLT/X-shooter upper limits
  97. GRB 250628A: Swift/UVOT Upper Limits
  98. Fermi GRB 250626A: Global MASTER-Net observations report
  99. Swift GRB 250628A: Global MASTER-Net observations report
  100. GRB 250625A: Swift-BAT refined analysis

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