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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"

19662 results found.

  1. GRB 250725A: SVOM/VT optical candidate
  2. GRB 250725A: MASTER-OAFA optical detection of very fast afterglow
  3. GRB 250725A: Enhanced Swift-XRT position
  4. GRB 250725A: Swift detection of a burst
  5. Swift GRB 250725A: Global MASTER-Net OT detection
  6. Swift GRB 250725A: Global MASTER-Net observations report
  7. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  8. Swift-BAT trigger 1334535 is not a GRB
  9. GRB 250721A: Swift-XRT observations
  10. GRB 250717B: SVOM/GRM observation
  11. GRB 250721A: Tiled Swift observations
  12. GRB 250717B: COLIBRÍ optical upper limit
  13. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  14. GRB 250717B: Swift-XRT observations
  15. Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
  16. Swift Trigger 1334535: a possible GRB 250718A
  17. Swift GRB250718.01: Global MASTER-Net observations report
  18. GRB 250717B: Swift ToO observations
  19. GRB 270713A: Kitab and AbAO Optical Observations
  20. GRB 250717B: Fermi GBM Observation
  21. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  22. GRB 250716A: Swift-XRT afterglow detection
  23. GRB 250716A: Swift ToO observations
  24. GRB 250713A: SVOM/C-GFT upper limit
  25. GRB 250713A: Swift-XRT observations
  26. GRB 250706A: Swift-BAT refined analysis
  27. GRB 250702F: Swift-BAT refined analysis
  28. GRB 250628A: Swift-BAT refined analysis
  29. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  30. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  31. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  32. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  33. GRB 250706B/C: Fermi-LAT detection
  34. GRB 250706B: Swift/UVOT Detection
  35. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  36. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  37. GRB 250702F: GRANDMA observations
  38. GRB 250706A: Swift-XRT refined Analysis
  39. GRB 250706A: Swift/UVOT Upper Limits
  40. GRB 250706A: REM optical/NIR observations
  41. Swift GRB 250706A: Global MASTER-Net observations report
  42. GRB 250706A: JinShan optical upper limits
  43. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  44. GRB250706B: Swift-XRT counterpart detection
  45. GRB 250706A: GROWTH-India Telescope optical upper limit
  46. GRB 250706A: Swift detection of a burst
  47. GRB 250704B: Swift-XRT refined Analysis
  48. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  49. GRB 250704B: Swift/UVOT Upper Limits
  50. GRB 250704A: Swift/UVOT Detection
  51. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  52. GRB 250702F: Kilonova-Catcher optical afterglow detection
  53. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  54. GRB 250704A: SVOM/VT optical observation
  55. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  56. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  57. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  58. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  59. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  60. EP250704a / GRB250704B: Swift-XRT counterpart detection
  61. GRB 250704A: Swift-XRT afterglow detection
  62. GRB 250702B / EP2050702a: FTW optical and NIR observations
  63. Konus-Wind detection of GRB 250702F
  64. GRB 250702F: GROWTH-India Telescope optical observations
  65. EP250702a: WFST optical observations
  66. GRB 250702F: SVOM/VT optical observation
  67. GRB 250702F: Swift/UVOT Detection
  68. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  69. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  70. GRB 250702F: Swift-XRT refined Analysis
  71. GRB 250702F: Fermi GBM Observation
  72. GRB 250702F: Leavitt Observatory optical observations
  73. GRB 250702F: AKO Optical Afterglow Detection
  74. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  75. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  76. GRB 250702F: Skynet Optical Observations
  77. GRB 250424A: VIRT Optical Upper Limit
  78. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  79. GRB 250702F: TRT Optical Observation
  80. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  81. GRB 250702F: REM optical afterglow detection
  82. GRB 250702F: DDOTI Optical Observation
  83. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  84. GRB 250702F: COLIBRÍ Observations of the Afterglow
  85. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  86. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  87. GRB 250702F: Enhanced Swift-XRT position
  88. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  89. GRB 250702F: NOT observations of the optical afterglow
  90. GRB 250702F: MASTER optical afterglow observation
  91. GRB 250702F: GOTO optical counterpart detection
  92. GRB 250702F: Ondrejov D50 optical afterglow detection
  93. GRB 250702F: Swift detection of a burst with an optical counterpart
  94. Swift GRB 250702F: Global MASTER-Net observations report
  95. GRB 250628B: Swift-XRT observations
  96. GRB 250628B: SVOM/VT optical upper limit
  97. GRB 250628A: REM optical/NIR upper limits
  98. GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
  99. GRB 250628A: VLT/X-shooter upper limits
  100. GRB 250628A: Swift/UVOT Upper Limits

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