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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"

32509 results found.

  1. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  2. GRB 250704B: Swift/UVOT Upper Limits
  3. GRB 250704A: Swift/UVOT Detection
  4. LIGO/Virgo/KAGRA S250705cb: Identification of a GW compact binary merger candidate
  5. Radio observation of GRBs 250702B,C,E / EP250702a with the Allen Telescope Array
  6. GRB 250704B: Insight-HXMT detection
  7. Konus-Wind detection of GRB 250703A
  8. IPN triangulation of GRB 250703A
  9. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  10. EP250704a/GRB 250704B: FTW optical and NIR observations of the counterpart
  11. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  12. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  13. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  14. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  15. GRB 250702F: Kilonova-Catcher optical afterglow detection
  16. GRB 250702F: Monte Agliale Observatory optical observations
  17. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  18. EP250704a / GRB 250704B: VLT/X-shooter spectroscopic redshift z = 0.661
  19. EP250704a / GRB 250704B: JinShan optical observations
  20. GRB 250704A: SVOM/VT optical observation
  21. EP250704a / GRB 250704B: SAO RAS optical observations
  22. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  23. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  24. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  25. EP250704a / GRB 250704B: Pan-STARRS iz-band imaging and photometry
  26. EP 250704a: BOOTES-5 optical detection
  27. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  28. LIGO/Virgo/KAGRA S250704ab: Upper limits from Fermi-GBM Observations
  29. GRB 250702A: Insight-HXMT detection
  30. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  31. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  32. EP250704a / GRB250704B: Swift-XRT counterpart detection
  33. GRB 250704A: Swift-XRT afterglow detection
  34. GRB 250702B / EP2050702a: FTW optical and NIR observations
  35. Konus-Wind detection of GRB 250702F
  36. EP250704a / GRB 250704B - REM observations
  37. GRB 250702F: GROWTH-India Telescope optical observations
  38. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  39. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  40. EP250702a: WFST optical observations
  41. EP250704a: COLIBRÍ optical counterpart candidate
  42. EP250704a: Einstein Probe detection of an X-ray transient
  43. GRB 250702F: optical photometry from Konkoly
  44. GRB 250704A: REM detection of the optical afterglow
  45. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  46. GRB 250702F: SVOM/VT optical observation
  47. LIGO/Virgo/KAGRA S250704ab: Identification of a GW compact binary merger candidate
  48. GRB 250702F: Swift/UVOT Detection
  49. GRB 250702A: CALET Gamma-Ray Burst Monitor detection
  50. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  51. Fermi GRB 250703A: Global MASTER-Net observations report
  52. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  53. GRB 250702F: Fermi GBM Observation
  54. GRB 250702F: Leavitt Observatory optical observations
  55. GRB 250702F: AKO Optical Afterglow Detection
  56. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  57. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  58. GRB 250702A: GECAM-B detection
  59. GRB 250702F: Skynet Optical Observations
  60. GRB 250424A: VIRT Optical Upper Limit
  61. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  62. GRB 250702B,C,D,E/EP250702a: COLIBRÍ optical upper limit
  63. EP250702a/GRB 250702B, C, D, E: EP-FXT follow-up observation
  64. GRB 250702F: TRT Optical Observation
  65. GRB 250703A: DDOTI Optical Upper Limit
  66. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  67. GRB 250702F: REM optical afterglow detection
  68. EP250702a: Global MASTER-Net observations report
  69. GRB 250702F: DDOTI Optical Observation
  70. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  71. GRB 250702F: COLIBRÍ Observations of the Afterglow
  72. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  73. Fermi GRB 250702E: Global MASTER-Net observations report
  74. Fermi GRB 250702B: Global MASTER-Net observations report
  75. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  76. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  77. GRB 250702F: NOT observations of the optical afterglow
  78. GRB 250702F: MASTER optical afterglow observation
  79. Fermi GRB 250702F: Global MASTER-Net observations report
  80. Fermi GRB 250702C: Global MASTER-Net observations report
  81. GRB 250702F: GOTO optical counterpart detection
  82. GRB 250702F: Swift detection of a burst with an optical counterpart
  83. Fermi GBM Triggers 250702B, C, D and E are likely from the same source
  84. Konus-Wind detection of GRB 250627A
  85. IPN triangulation of GRB 250627A (short)
  86. GRB 250702A: Fermi GBM Detection
  87. LIGO/Virgo/KAGRA S250702n: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S250701bq: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  90. GRB 250628B: Swift-XRT observations
  91. GRB 250628B: SVOM/VT optical upper limit
  92. GRB 250628B: EP-FXT counterpart detection
  93. LIGO/Virgo/KAGRA S250629bs: Updated Sky localization
  94. GRB 250627A: Insight-HXMT detection
  95. LIGO/Virgo/KAGRA S250629ae: Updated Sky localization
  96. LIGO/Virgo/KAGRA S250629bs: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S250628am: Identification of a GW compact binary merger candidate (duplicate submission)
  98. LIGO/Virgo/KAGRA S250629ae: Identification of a GW compact binary merger candidate
  99. LIGO/Virgo/KAGRA S250628am: Updated Sky localization
  100. GRB 250628A: REM optical/NIR upper limits

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