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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"

43016 results found.

  1. GRB 250830C: GECAM-B detection
  2. EP250901a: Global MASTER-Net observations report
  3. GRB 250830C: AstroSat CZTI detection of a long burst
  4. EP250901a: Einstein Probe detection of an X-ray transient
  5. LIGO/Virgo/KAGRA S250830m: Updated Sky localization
  6. EP250831a: EP-FXT follow-up observation
  7. EP250831a: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  9. IceCube Alert 250831.75: Global MASTER-Net observations report
  10. EP250831a: Global MASTER-Net observations report
  11. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  12. EP250831a: EP-WXT detection of a fast X-ray transient
  13. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  14. GRB 250831A: Swift-XRT counterpart detection
  15. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  16. GRB 250831A: SVOM/VT upper limit with VHF data
  17. GRB 250831A: SVOM detection of a soft burst
  18. GRB 250830B: Swift-XRT observations
  19. EP250830a: Global MASTER-Net observations report
  20. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  21. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  22. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  23. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  24. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  25. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  26. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  27. GRB 250830B: Swift ToO observations
  28. EP-WXT trigger 01709200994: confirmation of a stellar flare by BOOTES-6
  29. GRB 250830B: MAXI/GSC detection
  30. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  31. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  32. The EP-WXT trigger 01709200994 is likely a flaring star
  33. GRB 250828B: Swift-BAT refined analysis
  34. EP250821a: SOAR observations
  35. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  36. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  37. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  38. GRB 250808B: SVOM detection of a burst through offline search
  39. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  40. EP250828a: Optical counterpart detection with Kinder observations
  41. EP250828a: Liverpool Telescope upper limits
  42. Swift GRB 250828B: Global MASTER-Net observations report
  43. EP250828a: Global MASTER-Net observations report
  44. EP-WXT trigger 01709200800 : KAIT optical observations
  45. EP250828a: KAIT optical upper limit
  46. EP250827a: Swift/UVOT Detection
  47. EP250828a: NOT optical counterpart confirmation
  48. EP250828a: SVOM/VT optical candidate
  49. EP250828a: Seimei/TriCCS optical counterpart detection
  50. GRB 250828B: Swift detection of a burst
  51. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  52. EP250828a: Optical upper limit with Kinder observations
  53. LIGO/Virgo/KAGRA S250827fo: Updated Sky localization
  54. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  55. EP250827a: LCO observations show fading optical counterpart
  56. GRB 250828A: Fermi GBM Final Localization
  57. EP250828a: Einstein Probe detection of an X-ray transient
  58. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  59. GRID detection of GRB 250824A
  60. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  61. EP250827A: VLT/X-shooter redshift confirmation
  62. Fermi GRB 250827A: Global MASTER-Net observations report
  63. EP250827a: confirmation of optical rebrightening with LCO
  64. EP250827a: GOTO observation of the optical afterglow
  65. GRB 250826A: SVOM/GRM observation
  66. GRB 250827A: Fermi GBM Final Real-time Localization
  67. EP250827A: An optical rebrightening was detected by LCO.
  68. EP250827a: Swift-XRT counterpart detection
  69. LIGO/Virgo/KAGRA S250827l: Updated Sky localization
  70. The EP-WXT trigger 01709200800 is likely a flaring star
  71. EP250827a: TRT optical observations
  72. EP250827a: BOOTES-7 early optical dectection
  73. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  74. EP250827a: Gemini-South redshift z = 1.613
  75. EP250827a: Global MASTER-Net observations report
  76. EP250827a: Las Cumbres independent detection of the optical counterpart
  77. EP250827a: Gemini-South optical counterpart detection
  78. EP250827a: Einstein Probe detection of an X-ray transient
  79. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  80. Fermi GRB 250826A: Global MASTER-Net observations report
  81. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  82. EP250821a: Gemini GMOS Redshift Confirmation
  83. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  84. Fermi trigger No 777883624: Global MASTER-Net observations report
  85. GRB 250826A: Fermi GBM Final Real-time Localization
  86. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  87. Fermi GRB 250824B: Global MASTER-Net observations report
  88. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  89. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  90. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  91. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  92. GRB 250821B: AstroSat CZTI detection
  93. GRB 250819A: AstroSat CZTI detection
  94. LIGO/Virgo/KAGRA S250818k: FTW Observations Show Continued Reddening of AT 2025ulz
  95. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  96. GRB 250821B: Insight-HXMT detection
  97. LIGO/Virgo/KAGRA S250818k: ENGRAVE observations of SN 2025ulz as a type II supernova
  98. GRB 250823A: Swift-XRT refined Analysis
  99. EP250821a: MeerKAT radio counterpart
  100. EP triggers 01709200706 and 01709200707: GOTO confirmation of flaring stars

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