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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

22215 results found.

  1. EP251130a: continued NOT optical observations indicate steep fading phase
  2. GRB 251122A/EP251122a: CrAO ZTSh optical observations
  3. Fermi-LAT Gamma-ray Observations of IceCube-251130A
  4. EP251202a / GRB 251202A: LCO r- and i-band optical detection
  5. GRB 251202A: GOTO optical afterglow detection
  6. EP251202a/GRB 251202A: refined analysis of the EP-WXT observations
  7. GRB 251202A: Swift-XRT afterglow detection
  8. Fermi GRB 251202A: Global MASTER-Net observations report
  9. GRB 251201B: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at Sutherland Observatory
  10. Swift GRB 251201B: Global MASTER-Net observations report
  11. EP251118a: Mondy, CrAO, Assy and SAO RAS/Zeiss-1000 optical observations
  12. EP251130a: Mondy optical observations
  13. EP251130a: Optical detections with Kinder observations
  14. SVOM GRB251201.19: Global MASTER-Net observations report
  15. EP251130a: SAO RAS optical observations
  16. EP251130a: GTC OSIRIS+ redshift z = 4.035 and rebrightening
  17. EP251130a: KAIT optical observations
  18. EP251130A: Optical observation from 1.3m DFOT
  19. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  20. EP251130a: JinShan optical observations
  21. Fermi GRB 251130B: Global MASTER-Net observations report
  22. IceCube Alert 251130.75: Global MASTER-Net observations report
  23. EP251130a: Swift-XRT counterpart detection
  24. EP251130a: Global MASTER-Net observations report
  25. EP251129a/GRB 251129A: EP-FXT follow-up observations
  26. GRB 251129A / EP251129a: GTC/OSIRIS+ spectroscopic redshift z = 1.460
  27. GRB 251129A / EP251129a: SAO RAS optical observations
  28. GRB 251126A: SAO RAS optical observations
  29. GRB 251129A: Swift-XRT afterglow detection
  30. GRB 251129A: Swift ToO observations
  31. EP251129a: Global MASTER-Net observations report
  32. GRB 251129A: Optical Observations via Virtual Telescope Project, Italy
  33. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  34. SVOM GRB251129A: Global MASTER-Net observations report
  35. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  36. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  37. Fermi GRB 251128A: Global MASTER-Net observations report
  38. GRB 251126A: OHP/T193 optical observations and tentative spectroscopic redshift
  39. GRB 251126A: further SAO RAS optical observations
  40. GRB 250702B: detection of the compact radio counterpart 139 days after the burst
  41. GRB 251126A NUTTelA-TAO Early Measurements
  42. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  43. GRB251126A: MAO/AZT-22 optical observations
  44. GRB251126A: Continued optical observation from 1.3m DFOT
  45. GRB 251126A: Swift/UVOT Detection
  46. GRB 251126A: Mondy and SAO RAS optical observations
  47. GRB 251126A: NOT optical observations
  48. GRB 251126A: 1.3m DFOT optical afterglow detection
  49. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  50. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  51. Fermi GRB 251127A: Global MASTER-Net observations report
  52. GRB 251126A: Kilonova-Catcher optical afterglow detection
  53. GRB 251126A: Asiago i-band detection
  54. GRB 251126A: Nanshan/HMT optical afterglow detection
  55. Swift GRB 251126A: Global MASTER-Net observations report
  56. GRB 251126A: GIT discovery of the likely optical afterglow
  57. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  58. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  59. EP251124b: NOT r- and z-band optical upper limits
  60. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  61. Fermi GRB 251125B: Global MASTER-Net observations report
  62. EP251124b: Global MASTER-Net observations report
  63. Fermi GRB 251125A: Global MASTER-Net observations report
  64. EP251124a: NOT r- and z-band optical upper limits
  65. EP251124a: Global MASTER-Net observations report
  66. EP251124a: Swift-XRT observations
  67. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  68. EP251124a: Optical upper limit with Kinder observations
  69. EP251118A: 6 GHz VLA Detection
  70. Fermi GRB 251124a: Global MASTER-Net observations report
  71. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  72. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  73. GRB 251116C: Swift-XRT confirmation of fading
  74. GRB 251122A/EP251122a: FTW optical and NIR observations
  75. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  76. EP251118A: 3.6m DOT optical afterglow detection
  77. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  78. GRB 251122A / EP251122a: WFST optical observations
  79. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  80. GRB 251122A / EP251122a: LCO optical upper limits
  81. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  82. EP251122a: Global MASTER-Net observations report
  83. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  84. EP251118a: Continued Optical Detection with Kinder observations
  85. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  86. LIGO/Virgo/KAGRA S251112cm: SOAR spectroscopy of three TROVE TNS candidates
  87. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  88. EP251118a: Xinglong-2.16m optical observation
  89. Fermi trigger No 785388351: Global MASTER-Net observations report
  90. EP251118A: 1.3m DFOT optical afterglow detection
  91. GRB 251118A: Swift/UVOT Detection
  92. EP251118a / GRB 251118C: SAO RAS optical observations
  93. GRB 251118A: Swift-XRT afterglow detection
  94. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  95. EP251118a: Optical detection with Kinder observations
  96. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  97. EP251118a / GRB 251118C: SVOM/VT optical observation
  98. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  99. GRB 251116C: NOT optical observations
  100. GRB 251117A: Swift-XRT observations

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