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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.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

21526 results found.

  1. LIGO/Virgo/KAGRA S250727dc: DECam GW-MMADS upper limits of AT 2025smm
  2. LIGO/Virgo/KAGRA S250727dc: PRIME J-band upper limits of AT 2025smm
  3. GRB 250728A: Swift-XRT observations
  4. GRB 250728A: COLIBRÍ optical upper limit
  5. GRB 250728A: Fermi GBM Observation
  6. LIGO/Virgo/KAGRA S250727dc: Swift-UVOT detection of a new source, AT 2025smm
  7. GRB 250728A: Swift ToO observations
  8. GRB 250728A: Swift/BAT-GUANO arcminute localization of a short burst
  9. GRB 250727A: EP-FXT counterpart detection
  10. GRB250727A: SVOM/VT optical upper limit
  11. GRB 250727A: Swift-XRT observations
  12. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  13. GRB 250725A: Swift-XRT refined Analysis
  14. GRB 250725A: Fermi GBM Observation
  15. GRB 250725A: Swift-BAT refined analysis
  16. Konus-Wind detection of GRB 250725A
  17. GRB 250725A: SVOM/GRM observation
  18. GRB 250725A: Global MASTER-Net: First Optical Synchronous Observatios of Short GRB.
  19. GRB 250725A: Swift/UVOT Upper Limits
  20. GRB 250725A: Fermi-LAT detection
  21. GRB 250725A: BOOTES-7 early optical detection
  22. GRB 250725A: SVOM/VT optical candidate
  23. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  24. GRB 250725A: Enhanced Swift-XRT position
  25. GRB 250725A: Swift detection of a burst
  26. Swift GRB 250725A: Global MASTER-Net OT detection
  27. Swift GRB 250725A: Global MASTER-Net observations report
  28. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  29. Swift-BAT trigger 1334535 is not a GRB
  30. GRB 250721A: Swift-XRT observations
  31. GRB 250717B: SVOM/GRM observation
  32. GRB 250721A: Tiled Swift observations
  33. GRB 250717B: COLIBRÍ optical upper limit
  34. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  35. GRB 250717B: Swift-XRT observations
  36. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  37. Swift Trigger 1334535: a possible GRB 250718A
  38. Swift GRB250718.01: Global MASTER-Net observations report
  39. GRB 250717B: Swift ToO observations
  40. GRB 270713A: Kitab and AbAO Optical Observations
  41. GRB 250717B: Fermi GBM Observation
  42. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  43. GRB 250716A: Swift-XRT afterglow detection
  44. GRB 250716A: Swift ToO observations
  45. GRB 250713A: SVOM/VT optical upper limit
  46. GRB 250713A: SVOM/C-GFT upper limit
  47. GRB 250713A: Swift-XRT observations
  48. GRB 250706A: Swift-BAT refined analysis
  49. GRB 250702F: Swift-BAT refined analysis
  50. GRB 250628A: Swift-BAT refined analysis
  51. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  52. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  53. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  54. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  55. GRB 250706B/C: Fermi-LAT detection
  56. GRB 250706B: Swift/UVOT Detection
  57. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  58. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  59. GRB 250702F: GRANDMA observations
  60. GRB 250706A: Swift-XRT refined Analysis
  61. GRB 250706A: Swift/UVOT Upper Limits
  62. GRB 250706A: REM optical/NIR observations
  63. Swift GRB 250706A: Global MASTER-Net observations report
  64. GRB 250706A: JinShan optical upper limits
  65. GRB 250706A: SAO RAS optical observations
  66. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  67. GRB250706B: Swift-XRT counterpart detection
  68. GRB 250706A: GROWTH-India Telescope optical upper limit
  69. GRB 250706A: Swift detection of a burst
  70. GRB 250704B: Swift-XRT refined Analysis
  71. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  72. GRB 250704B: Swift/UVOT Upper Limits
  73. GRB 250704A: Swift/UVOT Detection
  74. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  75. GRB 250702F: Kilonova-Catcher optical afterglow detection
  76. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  77. GRB 250704A: SVOM/VT optical observation
  78. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  79. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  80. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  81. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  82. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  83. EP250704a / GRB250704B: Swift-XRT counterpart detection
  84. GRB 250704A: Swift-XRT afterglow detection
  85. GRB 250702B / EP2050702a: FTW optical and NIR observations
  86. Konus-Wind detection of GRB 250702F
  87. GRB 250702F: GROWTH-India Telescope optical observations
  88. EP250702a: WFST optical observations
  89. GRB 250702F: SVOM/VT optical observation
  90. GRB 250702F: Swift/UVOT Detection
  91. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  92. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  93. GRB 250702F: Swift-XRT refined Analysis
  94. GRB 250702F: Fermi GBM Observation
  95. GRB 250702F: Leavitt Observatory optical observations
  96. GRB 250702F: AKO Optical Afterglow Detection
  97. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  98. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  99. GRB 250702F: Skynet Optical Observations
  100. GRB 250424A: VIRT Optical Upper Limit

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