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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"

43012 results found.

  1. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  2. EP250831a: EP-FXT follow-up observation
  3. EP250831a: Swift-XRT observations
  4. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  5. IceCube Alert 250831.75: Global MASTER-Net observations report
  6. EP250831a: Global MASTER-Net observations report
  7. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  8. EP250831a: EP-WXT detection of a fast X-ray transient
  9. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  10. GRB 250831A: Swift-XRT counterpart detection
  11. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  12. GRB 250831A: SVOM/VT upper limit with VHF data
  13. GRB 250831A: SVOM detection of a soft burst
  14. GRB 250830B: Swift-XRT observations
  15. EP250830a: Global MASTER-Net observations report
  16. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  17. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  18. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  19. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  20. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  21. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  22. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  23. GRB 250830B: Swift ToO observations
  24. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  25. GRB 250830B: MAXI/GSC detection
  26. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  27. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  28. The EP-WXT trigger 01709200994 is likely a flaring star
  29. GRB 250828B: Swift-BAT refined analysis
  30. EP250821a: SOAR observations
  31. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  32. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  33. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  34. GRB 250808B: SVOM detection of a burst through offline search
  35. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  36. EP250828a: Optical counterpart detection with Kinder observations
  37. EP250828a: Liverpool Telescope upper limits
  38. Swift GRB 250828B: Global MASTER-Net observations report
  39. EP250828a: Global MASTER-Net observations report
  40. EP-WXT trigger 01709200800 : KAIT optical observations
  41. EP250828a: KAIT optical upper limit
  42. EP250827a: Swift/UVOT Detection
  43. EP250828a: NOT optical counterpart confirmation
  44. EP250828a: SVOM/VT optical candidate
  45. EP250828a: Seimei/TriCCS optical counterpart detection
  46. GRB 250828B: Swift detection of a burst
  47. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  48. EP250828a: Optical upper limit with Kinder observations
  49. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  50. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  51. EP250827a: LCO observations show fading optical counterpart
  52. GRB 250828A: Fermi GBM Final Localization
  53. EP250828a: Einstein Probe detection of an X-ray transient
  54. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  55. GRID detection of GRB 250824A
  56. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  57. EP250827A: VLT/X-shooter redshift confirmation
  58. Fermi GRB 250827A: Global MASTER-Net observations report
  59. EP250827a: confirmation of optical rebrightening with LCO
  60. EP250827a: GOTO observation of the optical afterglow
  61. GRB 250826A: SVOM/GRM observation
  62. GRB 250827A: Fermi GBM Final Real-time Localization
  63. EP250827A: An optical rebrightening was detected by LCO.
  64. EP250827a: Swift-XRT counterpart detection
  65. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  66. The EP-WXT trigger 01709200800 is likely a flaring star
  67. EP250827a: TRT optical observations
  68. EP250827a: BOOTES-7 early optical dectection
  69. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  70. EP250827a: Gemini-South redshift z = 1.613
  71. EP250827a: Global MASTER-Net observations report
  72. EP250827a: Las Cumbres independent detection of the optical counterpart
  73. EP250827a: Gemini-South optical counterpart detection
  74. EP250827a: Einstein Probe detection of an X-ray transient
  75. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  76. Fermi GRB 250826A: Global MASTER-Net observations report
  77. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  78. EP250821a: Gemini GMOS Redshift Confirmation
  79. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  80. Fermi trigger No 777883624: Global MASTER-Net observations report
  81. GRB 250826A: Fermi GBM Final Real-time Localization
  82. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  83. Fermi GRB 250824B: Global MASTER-Net observations report
  84. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  85. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  86. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  87. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  88. GRB 250821B: AstroSat CZTI detection
  89. GRB 250819A: AstroSat CZTI detection
  90. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  91. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  92. GRB 250821B: Insight-HXMT detection
  93. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  94. GRB 250823A: Swift-XRT refined Analysis
  95. EP250821a: MeerKAT radio counterpart
  96. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars
  97. LIGO/Virgo/KAGRA S250818k: Swift Observations of AT 2025ulz - Second Epoch
  98. GRB 250824B: Fermi GBM Final Real-time Localization
  99. The EP-WXT trigger 01709200707 is likely a flaring star
  100. GRB 250823A: COLIBRÍ optical observations

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