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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"

41968 results found.

  1. EP250901a: Swift-XRT observations
  2. LIGO/Virgo/KAGRA S250830bp: DECam GW-MMADS candidates
  3. GRB 250901A: LCO optical upper limit
  4. EP250827b: Swift observations of AT 2025wkm
  5. LIGO/Virgo/KAGRA S250830bp: DECam DESGW Epoch 1 Candidates
  6. EP250827b: Gemini Spectroscopy of AT 2025wkm
  7. LIGO/Virgo/KAGRA S250901cb: Identification of a GW compact binary merger candidate
  8. EP250831a: NOT optical observations and tentative afterglow candidate
  9. EP250827b: FTW Observations of AT 2025wkm
  10. EP250827b: Contemporaneous detection of EP X-ray flare EP250827b and ZTF transient ZTF25abmpngy/AT2025wkm
  11. GRB 250901A: SVOM detection of a burst
  12. GRB 250831B: SVOM/GRM observation
  13. GRB 250830C: Insight-HXMT detection
  14. EP250901a: Mephisto optical upper limits
  15. GRB 250830C: GECAM-B detection
  16. EP250901a: Global MASTER-Net observations report
  17. GRB 250830C: AstroSat CZTI detection of a long burst
  18. EP250901a: Einstein Probe detection of an X-ray transient
  19. EP250831a: EP-FXT follow-up observation
  20. EP250831a: Swift-XRT observations
  21. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  22. IceCube Alert 250831.75: Global MASTER-Net observations report
  23. EP250831a: Global MASTER-Net observations report
  24. IceCube-250831A - IceCube observation of a high-energy neutrino candidate track-like event
  25. EP250831a: EP-WXT detection of a fast X-ray transient
  26. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  27. GRB 250831A: Swift-XRT counterpart detection
  28. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  29. GRB 250831A: SVOM/VT upper limit with VHF data
  30. GRB 250831A: SVOM detection of a soft burst
  31. GRB 250830B: Swift-XRT observations
  32. EP250830a: Global MASTER-Net observations report
  33. EP250830a/GRB 250830B: Einstein Probe detection of an X-ray transient and Swift/XRT follow-up
  34. LIGO/Virgo/KAGRA S250830bp: Coverage and upper limits from MAXI/GSC observations
  35. LIGO/Virgo/KAGRA S250830bp GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  36. LIGO/Virgo/KAGRA S250830bp: NED Galaxies in the 4-Update Localization Volume
  37. LIGO/Virgo/KAGRA S250830bp: Updated Sky localization, EM Bright Classification, and Source Classification
  38. LIGO/Virgo/KAGRA S250830bp: Identification of a GW compact binary merger candidate
  39. EP-WXT trigger 01709200994: Liverpool Telescope upper limits
  40. GRB 250830B: Swift ToO observations
  41. GRB 250830B: MAXI/GSC detection
  42. LIGO/Virgo/KAGRA S250830m: Identification of a GW compact binary merger candidate
  43. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  44. The EP-WXT trigger 01709200994 is likely a flaring star
  45. GRB 250828B: Swift-BAT refined analysis
  46. EP250821a: SOAR observations
  47. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  48. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  49. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  50. GRB 250808B: SVOM detection of a burst through offline search
  51. EP250828a: refined analysis of the EP-WXT and EP-FXT observations
  52. EP250828a: Optical counterpart detection with Kinder observations
  53. EP250828a: Liverpool Telescope upper limits
  54. Swift GRB 250828B: Global MASTER-Net observations report
  55. EP250828a: Global MASTER-Net observations report
  56. EP-WXT trigger 01709200800 : KAIT optical observations
  57. EP250827a: Swift/UVOT Detection
  58. EP250828a: NOT optical counterpart confirmation
  59. EP250828a: SVOM/VT optical candidate
  60. GRB 250828B: Swift detection of a burst
  61. EP250827a: STEP/T80S Confirmation of fading optical counterpart
  62. EP250828a: Optical upper limit with Kinder observations
  63. LIGO/Virgo/KAGRA S250818k: uGMRT 1.3 GHz observations of AT2025ulz
  64. EP250827a: LCO observations show fading optical counterpart
  65. GRB 250828A: Fermi GBM Final Localization
  66. EP250828a: Einstein Probe detection of an X-ray transient
  67. EP250827a: Preliminary analysis of the EP-WXT and EP-FXT observations
  68. GRID detection of GRB 250824A
  69. LIGO/Virgo/KAGRA S250827fo: Identification of a GW compact binary merger candidate
  70. EP250827A: VLT/X-shooter redshift confirmation
  71. Fermi GRB 250827A: Global MASTER-Net observations report
  72. EP250827a: confirmation of optical rebrightening with LCO
  73. EP250827a: GOTO observation of the optical afterglow
  74. GRB 250826A: SVOM/GRM observation
  75. GRB 250827A: Fermi GBM Final Real-time Localization
  76. EP250827A: An optical rebrightening was detected by LCO.
  77. EP250827a: Swift-XRT counterpart detection
  78. The EP-WXT trigger 01709200800 is likely a flaring star
  79. EP250827a: TRT optical observations
  80. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  81. EP250827a: Gemini-South redshift z = 1.613
  82. EP250827a: Global MASTER-Net observations report
  83. EP250827a: Las Cumbres independent detection of the optical counterpart
  84. EP250827a: Gemini-South optical counterpart detection
  85. EP250827a: Einstein Probe detection of an X-ray transient
  86. LIGO/Virgo/KAGRA S250827l: Identification of a GW compact binary merger candidate
  87. Fermi GRB 250826A: Global MASTER-Net observations report
  88. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  89. EP250821a: Gemini GMOS Redshift Confirmation
  90. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  91. Fermi trigger No 777883624: Global MASTER-Net observations report
  92. GRB 250826A: Fermi GBM Final Real-time Localization
  93. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  94. Fermi GRB 250824B: Global MASTER-Net observations report
  95. LIGO/Virgo/KAGRA S250818k: VLA upper limits on AT2025ulz
  96. LIGO/Virgo/KAGRA S250818k: nature of the AT2025ulz/ZTF25abjmnnps OT
  97. LIGO/Virgo/KAGRA S250818k: Pan-STARRS imaging confirms re-brightening of SN2025ulz
  98. GRB 250823A: Swift-BAT refined analysis
  99. LIGO/Virgo/KAGRA S250818k: Continued Keck I LRIS spectroscopy of ZTF25abjmnps (AT2025ulz)
  100. GRB 250821B: AstroSat CZTI detection

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