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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"

32510 results found.

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

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