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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"

19566 results found.

  1. EP251130A: Optical observation from 1.3m DFOT
  2. EP251130a: refined analysis of the EP-WXT and EP-FXT observations
  3. EP251130a: JinShan optical observations
  4. GRB 251127A: SVOM/GRM observation
  5. EP251130a: COLIBRÍ optical counterpart candidate
  6. EP251130a: Einstein Probe detection of an X-ray transient
  7. GRB 251129A / EP251129a: SAO RAS optical observations
  8. GRB 251126A: SAO RAS optical observations
  9. GRB 251128A: SVOM/GRM observation of a long burst
  10. SVOM GRB 251129A : MASTER optical counterpart detection
  11. GRB 251129A: Swift-XRT afterglow detection
  12. GRB 251129A: Swift ToO observations
  13. EP251129a/GRB 251129A : Einstein Probe detection of an X-ray transient
  14. GRB 251129A: SVOM/COLIBRÍ (FM-GFT) optical counterpart candidate
  15. GRB 251129A: SVOM detection of a burst
  16. GRB 251129A: SVOM detection of a burst
  17. GRB 251126A: TShAO, Mondy, and AbAO optical observations
  18. GRB 251128A: Swift/BAT-GUANO localization skymap of a burst
  19. GRB 251126A: further SAO RAS optical observations
  20. LIGO/Virgo/KAGRA S251112cm: GECKO/KMTNet tiling observations and transient candidates
  21. GRB251126A: MAO/AZT-22 optical observations
  22. GRB251126A: Continued optical observation from 1.3m DFOT
  23. GRB 251126A: Swift/UVOT Detection
  24. GRB 251126A: Mondy and SAO RAS optical observations
  25. GRB 251126A : MITSuME Akeno optical afterglow candidate detection
  26. GRB 251126A: 1.3m DFOT optical afterglow detection
  27. GRB 251126A: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at McDonald Observatory
  28. GRB 251126A: COLIBRÍ photometric redshift z = 3.5
  29. GRB 251126A: Enhanced Swift-XRT position
  30. GRB 251126A: Kilonova-Catcher optical afterglow detection
  31. GRB 251126A: Nanshan/HMT optical afterglow detection
  32. GRB 251126A: GIT discovery of the likely optical afterglow
  33. GRB 251126A: Swift detection of a burst
  34. GRB 251125B: COLIBRÍ further observations and photometric redshift upper limit of z < 3
  35. GRB 251125B: COLIBRÍ observations of fading of the MASTER OT candidate
  36. EP251124b: NOT r- and z-band optical upper limits
  37. Fermi GRB 251125B : MASTER OT J155558.56+581224.1 optical counterpart discovery
  38. EP251124b: EP-WXT detection of a fast X-ray transient
  39. EP251124a: Xinglong GWAC-F60A optical observation
  40. EP251124a: NOT r- and z-band optical upper limits
  41. EP251124a: Swift-XRT observations
  42. LIGO/Virgo/KAGRA S251112cm: AT 2025adht Kinder follow-up observations
  43. EP251124a: Optical upper limit with Kinder observations
  44. LIGO/Virgo/KAGRA S251105aj: SVOM/VT optical observations and preliminary results on SVOM J2320.0-2901
  45. LIGO/Virgo/KAGRA S251105aj: EP-FXT follow-up observations and preliminary results on SVOM J2320.0-2901
  46. EP251124a: GROWTH-India Telescope optical upper limits
  47. EP251124a: Einstein Probe detection of an X-ray transient
  48. GRB 251116C: Swift-XRT confirmation of fading
  49. GRB 251122A/EP251122A: 1.3m DFOT optical detection
  50. GRB 251122A / EP251122a: Xinglong 2.16m optical observation
  51. EP251118A: 3.6m DOT optical afterglow detection
  52. EP251122a: refined analysis of the EP-WXT and EP-FXT observations
  53. GRB 251122A / EP251122a: WFST optical observations
  54. GRB 251122A/EP251122a: SVOM/VT optical observations with VHF data
  55. GRB 251122A/EP251122a: Additional, deeper LCO optical r band upper limit
  56. GRB 251122A / EP251122a: LCO optical upper limits
  57. EP251122a / GRB 251122A: optical counterpart candidate with Kinder observations
  58. GRB 251122A/EP251122a: SVOM/C-GFT upper limit
  59. GRB 251122A / EP251122a: SVOM detection of a long burst
  60. EP251122a: Einstein Probe detection of an X-ray transient
  61. EP251118a: Continued Optical Detection with Kinder observations
  62. LIGO/Virgo/KAGRA S251105aj: SVOM/ECLAIRs detection of a high-energy transient SVOM J2320.0-2901 through targeted search
  63. GRB 251121A: Swift/BAT-GUANO localization skymap of a short burst
  64. EP251118a: Xinglong-2.16m optical observation
  65. Fermi trigger No 785388351: Global MASTER-Net observations report
  66. EP251118A: 1.3m DFOT optical afterglow detection
  67. GRB 251118A: Swift/UVOT Detection
  68. EP251118a / GRB 251118C: SAO RAS optical observations
  69. GRB 251118A: Swift-XRT afterglow detection
  70. GRB 251103A: SVOM/ECLAIRs and SVOM/GRM joint refined analysis
  71. EP251118a: Optical detection with Kinder observations
  72. LIGO/Virgo/KAGRA S251112cm: SVOM/VT optical observations and preliminary results
  73. EP251118a / GRB 251118C: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 1-m telescope at CTIO
  74. GRB 251118C: Swift/BAT rates detection of a burst with a possible association with EP 251118A
  75. GRB 251117A: Swift-XRT observations
  76. GRB 251118C: SVOM/GRM observation of a possible gamma-ray counterpart of EP251118a
  77. GRB 251119A: SVOM trigger sb25111901 is not a GRB
  78. EP251118a: VLT near-infrared observation
  79. GRB 251116D: SVOM/GRM observation of a long GRB
  80. GRB 251119A: SVOM detection of a possible burst
  81. EP251118a: NOT candidate optical counterpart
  82. GRB 251118A: Swift ToO observations
  83. EP251118a: Einstein Probe detected of a fast X-ray transient
  84. LIGO/Virgo/KAGRA S251112cm: Upper limits from Glowbug gamma-ray observations
  85. GRB 251117A: Swift/BAT-GUANO localization skymap of a short burst
  86. GRB 251117A: SVOM/GRM observation of a short burst
  87. GRB 251117A: Tiled Swift observations
  88. LIGO/Virgo/KAGRA S251117dq: Identification of a GW compact binary merger candidate
  89. LIGO/Virgo/KAGRA S251112cm: WFST follow-up observations and preliminary results
  90. EP251023a: Assy AZT-20 optical observations
  91. EP251023a: UAFO and AbAO optical observations
  92. LIGO/Virgo/KAGRA S251112cm: EP-FXT follow-up observations
  93. The EP-WXT trigger 01709247588: more evidence of flaring star from Mondy optical observations
  94. GRB 251025B: further Mondy optical observations
  95. GRB 251111A: Mondy optical upper limit
  96. LIGO/Virgo/KAGRA S251116en: Identification of a GW compact binary merger candidate
  97. LIGO/Virgo/KAGRA S251112cm: Observations with the NSF-DOE Vera C. Rubin Observatory
  98. GRB 251116B: LCO optical upper limits
  99. GRB 251116C: LCO optical upper limits
  100. GRB 251116B: SVOM detection of a burst

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