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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"

32495 results found.

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

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