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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"

26057 results found.

  1. Swift GRB250718.01: Global MASTER-Net observations report
  2. GRB 250717B: Swift ToO observations
  3. GRB 270713A: Kitab and AbAO Optical Observations
  4. GRB 250717B: Fermi GBM Observation
  5. GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
  6. GRB 250716A: Swift-XRT afterglow detection
  7. GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
  8. GRB 250716A: Swift ToO observations
  9. GRB 250713A: SVOM/VT optical upper limit
  10. GRB 250713A: SVOM/C-GFT upper limit
  11. GRB 250713A: Swift-XRT observations
  12. GRB 250706A: Swift-BAT refined analysis
  13. GRB 250702F: Swift-BAT refined analysis
  14. GRB 250628A: Swift-BAT refined analysis
  15. GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
  16. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  17. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  18. GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
  19. GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
  20. GRB 250704B / EP250704a: VLA radio detection
  21. GRB 250706B: SVOM observations interpreted as the afterglow of GRB 250706C
  22. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  23. GRB 250706B/C: VLT/X-shooter redshift z = 0.942
  24. GRB 250706B/C: Fermi-LAT detection
  25. GRB 250706B: Swift/UVOT Detection
  26. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  27. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 250702F: GRANDMA observations
  29. GRB 250706A: Swift-XRT refined Analysis
  30. GRB 250706B: refined SVOM/MXT data analysis
  31. GRB 250706A: Swift/UVOT Upper Limits
  32. GRB 250706B: REM optical observations
  33. GRB 250706A: REM optical/NIR observations
  34. Swift GRB 250706A: Global MASTER-Net observations report
  35. GRB 250706A: JinShan optical upper limits
  36. GRB 250706A: SAO RAS optical observations
  37. EP250704A: NOWT Detection
  38. GRB 250706A: SVOM/C-GFT upper limit in eary phase
  39. GRB250706B: Swift-XRT counterpart detection
  40. GRB 250706B: iTelescope optical observations
  41. EP250704a / GRB 250704B: end of optical plateau phase and rapid fading of the counterpart
  42. GRB 250706B: SVOM/VT optical observation
  43. GRB 250706B: TRT bright optical counterpart detection
  44. GRB 250706A: GROWTH-India Telescope optical upper limit
  45. GRB 250706A: Swift detection of a burst
  46. GRB 250704B: Swift-XRT refined Analysis
  47. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  48. GRB 250704B: Swift/UVOT Upper Limits
  49. GRB 250704A: Swift/UVOT Detection
  50. GRB 250702F: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  51. EP250704a / GRB 250704B: NOT observations of the optical afterglow
  52. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  53. GRB 250702F: Kilonova-Catcher optical afterglow detection
  54. GRB250702F: afterglow detected by joint EP-ZTF shadowing program
  55. EP250704a / GRB 250704B: JinShan optical observations
  56. GRB 250704A: SVOM/VT optical observation
  57. EP250704a / GRB 250704B : GROWTH-India Telescope optical observations
  58. GRBs 250702B,D,E / EP250702a: fast fading, extremely red counterpart
  59. EP250704a / GRB 250704B: SVOM/VT optical blue counterpart
  60. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  61. GRB 250704A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 1.091
  62. GRBs 250702B/C/D/E / EP250702a: Swift/UVOT Upper Limits
  63. EP250704a / GRB250704B: Swift-XRT counterpart detection
  64. GRB 250704A: Swift-XRT afterglow detection
  65. GRB 250702B / EP2050702a: FTW optical and NIR observations
  66. Konus-Wind detection of GRB 250702F
  67. EP250704a / GRB 250704B - REM observations
  68. GRB 250702F: GROWTH-India Telescope optical observations
  69. EP250704a / GRB 250704B: VLT/FORS2 optical afterglow detection
  70. GRB 250704A: REM retraction of optical afterglow detection and updated limit
  71. EP250702a: WFST optical observations
  72. GRB 250702F: optical photometry from Konkoly
  73. GRB 250704A: REM detection of the optical afterglow
  74. GRB 250702F: SVOM/VT optical observation
  75. GRB 250702F: Swift/UVOT Detection
  76. Fermi GBM Analysis of GRB 250702B (formerly B,D,E); dissociation of C burst
  77. GRBs 250702B,C,D,E / EP250702a: 2.2m CAHA optical upper limit
  78. GRB 250702F: Swift-XRT refined Analysis
  79. GRB 250702F: Fermi GBM Observation
  80. GRB 250702F: Leavitt Observatory optical observations
  81. GRB 250702F: AKO Optical Afterglow Detection
  82. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  83. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  84. GRB 250702F: Skynet Optical Observations
  85. GRB 250424A: VIRT Optical Upper Limit
  86. GRBs 250702B/C/D/E / EP250702a: Swift XRT localization
  87. GRB 250702F: TRT Optical Observation
  88. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  89. GRB 250702F: REM optical afterglow detection
  90. GRB 250702F: DDOTI Optical Observation
  91. GRB 250702B,C,D,E / EP 250702a: MAXI/GSC detection
  92. GRB 250702F: COLIBRÍ Observations of the Afterglow
  93. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  94. GRB 250702D, C, E: Swift/BAT-GUANO localization skymap of a burst or galactic transient
  95. GRB 250702F: Enhanced Swift-XRT position
  96. GRB 250702F: GTC/OSIRIS+ spectroscopic redshift z = 1.520
  97. GRB 250702F: NOT observations of the optical afterglow
  98. GRB 250702F: MASTER optical afterglow observation
  99. GRB 250702F: GOTO optical counterpart detection
  100. GRB 250702F: Ondrejov D50 optical afterglow detection

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