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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"

41974 results found.

  1. GRB 250901A: EP-FXT follow-up observation
  2. GRB 250901A: NOT optical observations
  3. GRB 250902A: Fermi GBM Final Real-time Localization
  4. IceCube-Cascade 250828A: Upper limits from a search for additional neutrino events in IceCube
  5. GRB 250901A: SVOM/VT optical afterglow with VHF data
  6. GRB 250901A: Swift-XRT afterglow detection
  7. EP250901a: Swift-XRT observations
  8. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  9. GRB 250901A: LCO optical upper limit
  10. EP250827b: Swift observations of AT 2025wkm
  11. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  12. EP250827b: Gemini Spectroscopy of AT 2025wkm
  13. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  14. EP250831a: NOT optical observations and tentative afterglow candidate
  15. EP250827b: FTW Observations of AT 2025wkm
  16. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  17. GRB 250901A: SVOM detection of a burst
  18. GRB 250831B: SVOM/GRM observation
  19. GRB 250830C: Insight-HXMT detection
  20. EP250901a: Mephisto optical upper limits
  21. GRB 250830C: GECAM-B detection
  22. EP250901a: Global MASTER-Net observations report
  23. GRB 250830C: AstroSat CZTI detection of a long burst
  24. EP250901a: Einstein Probe detection of an X-ray transient
  25. EP250831a: EP-FXT follow-up observation
  26. EP250831a: Swift-XRT observations
  27. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  28. IceCube Alert 250831.75: Global MASTER-Net observations report
  29. EP250831a: Global MASTER-Net observations report
  30. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  31. EP250831a: EP-WXT detection of a fast X-ray transient
  32. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  33. GRB 250831A: Swift-XRT counterpart detection
  34. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  35. GRB 250831A: SVOM/VT upper limit with VHF data
  36. GRB 250831A: SVOM detection of a soft burst
  37. GRB 250830B: Swift-XRT observations
  38. EP250830a: Global MASTER-Net observations report
  39. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  40. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  41. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  42. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  43. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  44. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  45. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  46. GRB 250830B: Swift ToO observations
  47. GRB 250830B: MAXI/GSC detection
  48. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  49. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  50. The EP-WXT trigger 01709200994 is likely a flaring star
  51. GRB 250828B: Swift-BAT refined analysis
  52. EP250821a: SOAR observations
  53. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  54. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  55. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  56. GRB 250808B: SVOM detection of a burst through offline search
  57. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  58. EP250828a: Optical counterpart detection with Kinder observations
  59. EP250828a: Liverpool Telescope upper limits
  60. Swift GRB 250828B: Global MASTER-Net observations report
  61. EP250828a: Global MASTER-Net observations report
  62. EP-WXT trigger 01709200800 : KAIT optical observations
  63. EP250827a: Swift/UVOT Detection
  64. EP250828a: NOT optical counterpart confirmation
  65. EP250828a: SVOM/VT optical candidate
  66. GRB 250828B: Swift detection of a burst
  67. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  68. EP250828a: Optical upper limit with Kinder observations
  69. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  70. EP250827a: LCO observations show fading optical counterpart
  71. GRB 250828A: Fermi GBM Final Localization
  72. EP250828a: Einstein Probe detection of an X-ray transient
  73. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  74. GRID detection of GRB 250824A
  75. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  76. EP250827A: VLT/X-shooter redshift confirmation
  77. Fermi GRB 250827A: Global MASTER-Net observations report
  78. EP250827a: confirmation of optical rebrightening with LCO
  79. EP250827a: GOTO observation of the optical afterglow
  80. GRB 250826A: SVOM/GRM observation
  81. GRB 250827A: Fermi GBM Final Real-time Localization
  82. EP250827A: An optical rebrightening was detected by LCO.
  83. EP250827a: Swift-XRT counterpart detection
  84. The EP-WXT trigger 01709200800 is likely a flaring star
  85. EP250827a: TRT optical observations
  86. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  87. EP250827a: Gemini-South redshift z = 1.613
  88. EP250827a: Global MASTER-Net observations report
  89. EP250827a: Las Cumbres independent detection of the optical counterpart
  90. EP250827a: Gemini-South optical counterpart detection
  91. EP250827a: Einstein Probe detection of an X-ray transient
  92. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  93. Fermi GRB 250826A: Global MASTER-Net observations report
  94. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  95. EP250821a: Gemini GMOS Redshift Confirmation
  96. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  97. Fermi trigger No 777883624: Global MASTER-Net observations report
  98. GRB 250826A: Fermi GBM Final Real-time Localization
  99. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  100. Fermi GRB 250824B: Global MASTER-Net observations report

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