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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').
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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"

45697 results found.

  1. EP250831a: EP-WXT detection of a fast X-ray transient
  2. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  3. GRB 250831A: Swift-XRT counterpart detection
  4. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  5. GRB 250831A: SVOM/VT upper limit with VHF data
  6. GRB 250831A: SVOM detection of a soft burst
  7. GRB 250830B: Swift-XRT observations
  8. EP250830a: Global MASTER-Net observations report
  9. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  10. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  11. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  12. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  13. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  14. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  15. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  16. GRB 250830B: Swift ToO observations
  17. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  18. GRB 250830B: MAXI/GSC detection
  19. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  20. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  21. The EP-WXT trigger 01709200994 is likely a flaring star
  22. GRB 250828B: Swift-BAT refined analysis
  23. EP250821a: SOAR observations
  24. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  25. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  26. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  27. GRB 250808B: SVOM detection of a burst through offline search
  28. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  29. EP250828a: Optical counterpart detection with Kinder observations
  30. EP250828a: Liverpool Telescope upper limits
  31. Swift GRB 250828B: Global MASTER-Net observations report
  32. EP250828a: Global MASTER-Net observations report
  33. EP-WXT trigger 01709200800 : KAIT optical observations
  34. EP250828a: KAIT optical upper limit
  35. EP250827a: Swift/UVOT Detection
  36. EP250828a: NOT optical counterpart confirmation
  37. EP250828a: SVOM/VT optical candidate
  38. EP250828a: Seimei/TriCCS optical counterpart detection
  39. GRB 250828B: Swift detection of a burst
  40. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  41. EP250828a: Optical upper limit with Kinder observations
  42. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  43. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  44. EP250827a: LCO observations show fading optical counterpart
  45. GRB 250828A: Fermi GBM Final Localization
  46. EP250828a: Einstein Probe detection of an X-ray transient
  47. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  48. GRID detection of GRB 250824A
  49. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  50. EP250827A: VLT/X-shooter redshift confirmation
  51. Fermi GRB 250827A: Global MASTER-Net observations report
  52. EP250827a: confirmation of optical rebrightening with LCO
  53. EP250827a: GOTO observation of the optical afterglow
  54. GRB 250826A: SVOM/GRM observation
  55. GRB 250827A: Fermi GBM Final Real-time Localization
  56. EP250827A: An optical rebrightening was detected by LCO.
  57. EP250827a: Swift-XRT counterpart detection
  58. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  59. The EP-WXT trigger 01709200800 is likely a flaring star
  60. EP250827a: TRT optical observations
  61. EP250827a: BOOTES-7 early optical dectection
  62. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  63. EP250827a: Gemini-South redshift z = 1.613
  64. EP250827a: Global MASTER-Net observations report
  65. EP250827a: Las Cumbres independent detection of the optical counterpart
  66. EP250827a: Gemini-South optical counterpart detection
  67. EP250827a: Einstein Probe detection of an X-ray transient
  68. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  69. Fermi GRB 250826A: Global MASTER-Net observations report
  70. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  71. EP250821a: Gemini GMOS Redshift Confirmation
  72. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  73. Fermi trigger No 777883624: Global MASTER-Net observations report
  74. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  75. GRB 250826A: Fermi GBM Final Real-time Localization
  76. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  77. Fermi GRB 250824B: Global MASTER-Net observations report
  78. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  79. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  80. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  81. GRB 250823A: Swift-BAT refined analysis
  82. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  83. GRB 250821B: AstroSat CZTI detection
  84. GRB 250819A: AstroSat CZTI detection
  85. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  86. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  87. GRB 250821B: Insight-HXMT detection
  88. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  89. GRB 250823A: Swift-XRT refined Analysis
  90. EP250821a: MeerKAT radio counterpart
  91. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  92. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  93. GRB 250824B: Fermi GBM Final Real-time Localization
  94. The EP-WXT trigger 01709200707 is likely a flaring star
  95. GRB 250823A: COLIBRÍ optical observations
  96. The EP-WXT trigger 01709200706 is likely a flaring star
  97. GRB 250823A: SVOM/VT optical observation
  98. GRB 250824A: Fermi GBM Final Real-time Localization
  99. GRB 250823A: Swift/UVOT Detection
  100. GRB 250823A: NOT optical observations

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