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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"

37256 results found.

  1. GRB 250830C: AstroSat CZTI detection of a long burst
  2. LIGO/Virgo/KAGRA S250831cc: Coverage and upper limits from MAXI/GSC observations
  3. GRB 250831A (SVOM trigger sb25083102) is likely an outburst from star G 272-61
  4. GRB 250831A: Swift-XRT counterpart detection
  5. GRB 250831A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 250831A: SVOM/VT upper limit with VHF data
  7. GRB 250831A: SVOM detection of a soft burst
  8. GRB 250830B: Swift-XRT observations
  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. GRB 250830B: Swift ToO observations
  13. GRB 250830B: MAXI/GSC detection
  14. GRB 250830A / MAXI J0853+337: MAXI/GSC detection
  15. GRB 250828B: Swift-BAT refined analysis
  16. EP250827a: very early ATLAS detections, starting 43 sec after the EP trigger
  17. LIGO/Virgo/KAGRA S250725j: Observations with the NSF-DOE Vera C. Rubin Observatory
  18. LIGO/Virgo/KAGRA S250818k: MeerKAT detection of an increase in radio flux from AT2025ulz
  19. GRB 250808B: SVOM detection of a burst through offline search
  20. EP250828a: Optical counterpart detection with Kinder observations
  21. Swift GRB 250828B: Global MASTER-Net observations report
  22. EP-WXT trigger 01709200800 : KAIT optical observations
  23. EP250828a: KAIT optical upper limit
  24. GRB 250828B: Swift detection of a burst
  25. EP250828a: Optical upper limit with Kinder observations
  26. GRB 250828A: Fermi GBM Final Localization
  27. GRID detection of GRB 250824A
  28. Fermi GRB 250827A: Global MASTER-Net observations report
  29. EP250827a: GOTO observation of the optical afterglow
  30. GRB 250826A: SVOM/GRM observation
  31. GRB 250827A: Fermi GBM Final Real-time Localization
  32. EP250827A: An optical rebrightening was detected by LCO.
  33. EP250827a / GRB 250827A: MASTER-OAFA OT observation
  34. EP250827a: Gemini-South optical counterpart detection
  35. Fermi GRB 250826A: Global MASTER-Net observations report
  36. GRB 250806A: HiPERCAM/GTC limits on a possible supernova
  37. LIGO/Virgo/KAGRA S250818k: SAO RAS BTA z-band observations of AT2025ulz
  38. Fermi Gamma-ray Burst Monitor trigger 777883624/250826283 is not a GRB
  39. GRB 250826A: Fermi GBM Final Real-time Localization
  40. LIGO/Virgo/KAGRA S250818k: GTC/OSIRIS Confirmation of Rebrightening of AT2025ulz
  41. Fermi GRB 250824B: Global MASTER-Net observations report
  42. GRB 250823A: Swift-BAT refined analysis
  43. GRB 250821B: AstroSat CZTI detection
  44. GRB 250819A: AstroSat CZTI detection
  45. LIGO/Virgo/KAGRA S250818k: MASTER predicovery limits of the AT2025ulz/ZTF25abjmnps KN candidate
  46. GRB 250821B: Insight-HXMT detection
  47. GRB 250823A: Swift-XRT refined Analysis
  48. GRB 250824B: Fermi GBM Final Real-time Localization
  49. GRB 250823A: COLIBRÍ optical observations
  50. GRB 250823A: SVOM/VT optical observation
  51. GRB 250824A: Fermi GBM Final Real-time Localization
  52. GRB 250823A: Swift/UVOT Detection
  53. GRB 250823A: NOT optical observations
  54. LIGO/Virgo/KAGRA S250818k: COLIBRÍ confirmation of rebrightening of AT2025ulz
  55. GRB 250823A: Fermi GBM Observation
  56. GRB 250818B: MeerKAT Detection
  57. GRB 250823A: Enhanced Swift-XRT position
  58. GRB 250823A: LCOGT Optical Detection
  59. GRB 250823A: BOOTES6/DPRT early optical detection
  60. GRB 250823A: Liverpool Telescope optical detection
  61. GRB 250823A: Swift detection of a burst
  62. GRB 250823A: Fermi GBM Final Real-time Localization
  63. Konus-Wind detection of GRB 250821B
  64. LIGO/Virgo/KAGRA S250818k: JinShan optical observations of AT2025ulz
  65. GRB 250806A: Gemini observations of host galaxy candidate
  66. IPN triangulation of GRB 250821B (long/bright)
  67. GRB 250821A: Kilonova-Catcher optical upper limits
  68. EP250821a: Swift/XRT counterpart fading
  69. GRB 250812A: SVOM/ECLAIRs refined analysis
  70. GRB 250821A: Swift-BAT refined analysis
  71. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  72. EP250821a: Swift/UVOT further observations.
  73. GRB 250821A: VLT/FORS2 Optical Observation
  74. GRB 250821A: GECAM-B detection
  75. GRB 250821B: SVOM/GRM observation
  76. EP250821a: SVOM/VT optical observation
  77. Fermi GRB 250821B: Global MASTER-Net observations report
  78. GRB 250821A: NOT z-band upper limit
  79. GRB 250821C: Fermi GBM Final Real-time Localization
  80. GRB 250821A: KAIT optical upper limit
  81. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  82. GRB 250821A: Swift-XRT refined Analysis
  83. Swift GRB 250821A: Global MASTER-Net observations report
  84. GRB 250821B: Fermi GBM Detection
  85. GRB 250821B: BALROG localization (Fermi Trigger / GRB 250821672)
  86. GRB 250821B: Fermi GBM Final Localization of a Bright Burst
  87. GRB 250821A: Enhanced Swift-XRT position
  88. GRB 250821A: Swift/UVOT Upper Limits
  89. GRB 250821A: LCOGT Optical Upper Limits
  90. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  91. GRB 250821A: Prompt enhanced Swift-XRT position
  92. GRB 250821A: Swift detection of a burst
  93. GRB 250819A: SVOM/GRM observation of a possible “long” duration type I burst
  94. GRB 250819A: Insight-HXMT detection
  95. GRB 250818B: 10 GHz VLA detection
  96. GRB 250814A: Swift/UVOT Upper Limits
  97. GRB 250813B: Swift/UVOT Upper Limit
  98. IPN triangulation of GRB 250816A (short)
  99. IPN triangulation of GRB 250814C (short)
  100. IPN triangulation of GRB 250804B (short)

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