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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"

22212 results found.

  1. Integral GRB250114.55: Global MASTER-Net observations report
  2. GRB 250114A: LCOGT optical afterglow i-band detection
  3. GRB 250114B: Swift ToO observations
  4. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  5. GRB 250113A: INTEGRAL/SPI-ACS detection
  6. GRB 250114A: REM detection of the optical and NIR counterpart
  7. GRB 250114A: LCO optical observations
  8. GRB 250114A: TRT optical observations
  9. Swift GRB 250114A: Global MASTER-Net observations report
  10. GRB 250101A: Terskol Zeiss-2000 optical observations
  11. EP250108a / AT 2025kg: SAO RAS optical observations
  12. EP241021a: SMA radio observation
  13. EP250109b: optical upper limits with the Liverpool Telescope
  14. GRB 250106A: Swift-XRT afterglow detection
  15. Fermi trigger No 758442826: Global MASTER-Net observations report
  16. EP250111a: KAIT optical observations
  17. GRB 250109A / EP250109a: Mephisto optical upper limits
  18. EP250108a: Mephisto detection
  19. EP250111a: Mondy optical observation
  20. EP250108a / AT 2025kg: LCO optical observations
  21. EP250111a: Global MASTER-Net observations report
  22. EP250108a / AT 2025kg: Swift UVOT detections
  23. EP250108a: optical follow-up observations with the Liverpool Telescope
  24. EP250111a: NOT likely optical counterpart
  25. EP250111a: a new X-ray transient detected by Einstein Probe
  26. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  27. EP250108a: further NOT optical observations
  28. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  29. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  30. GRB 250108A: Swift/XRT afterglow fading
  31. Konus-Wind detection of GRB 250107C
  32. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  33. GRB 250101A: CMO RC-500 optical observations
  34. EP250108a: NOT optical observations
  35. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  36. EP250109a: Swift/UVOT non-detection
  37. EP250108a: Liverpool Telescope likely optical counterpart
  38. GRB 250108B: Gemini-North likely redshift z = 2.197
  39. GRB 250108B: 1.3m DFOT upper limit
  40. GRB 250108B: REM optical/NIR upper limits
  41. EP250109a: SVOM/VT optical candidate
  42. EP250109a: Global MASTER-Net observations report
  43. GRB 250101A: Terskol K-800 optical observations
  44. EP250109a: GOTO optical upper limits
  45. GRB 250108A: Swift/UVOT Upper Limits
  46. EP250108a: Global MASTER-Net observations report
  47. EP250109a: EP-WXT detection of an X-ray transient
  48. GRB 250108A: NOT optical upper limit
  49. EP250108a: EP-WXT detection of an X-ray transient
  50. Swift GRB 250108B: Global MASTER-Net observations report
  51. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  52. GRB 250103A: 1.6m Mephisto optical observations
  53. GRB 250108A: Swift-XRT afterglow detection
  54. GRB 250108A:SVOM/VT optical candidate
  55. GRB 250108B: Swift/UVOT Upper Limits
  56. GRB 250103A: Swift-XRT afterglow detection
  57. GRB 250108A: Swift ToO observations
  58. Fermi GRB 250107B: Global MASTER-Net observations report
  59. GRB 250107A: Swift ToO observations
  60. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  61. GRB 250106A: SVOM/VT 2nd optical deep observation
  62. GRB 250101A: J band upper limit by SYSU 80cm telescope
  63. EPWXT01709129925: Xinglong optical observations
  64. GRB 250106A: NOT optical observations
  65. GRB 250103B: REM optical/NIR upper limits
  66. GRB 250101A: REM optical/NIR counterpart detection
  67. GRB 250106A: Swift-XRT observations
  68. GRB 250106A: SVOM/VT optical candidate
  69. GRB 250106A: Swift ToO observations
  70. GRB 250106A: SVOM detection of a long burst
  71. Fermi trigger No 757753930: Global MASTER-Net observations report
  72. GRB 241229A: SVOM/VT optical upperlimit
  73. GRB 250103A: Bassano Bresciano Observatory upper limit
  74. GRB 250103A: Swift-XRT observations
  75. GRB 250101A: 1.3m DFOT optical afterglow detection
  76. GRB 241229A: 1.3m DFOT upper limit
  77. GRB 241228B: 1.3m DFOT Optical observations
  78. GRB 241228A: 1.3m DFOT upper limit
  79. GRB 250103A: NOT spectroscopic redshift
  80. GRB 250103B：SVOM/VT optical counterpart
  81. GRB 250103A: Montarrenti Observatory optical detection
  82. GRB 250101A: further LCOGT optical afterglow observations
  83. GRB 250103A: NOT optical observations
  84. Swift GRB 250103B: Global MASTER-Net observations report
  85. GRB 250103A: SVOM/VT optical counterpart confirmation
  86. GRB 250103A: Swift ToO observations
  87. GRB 250101a: Liverpool Telescope optical follow-up
  88. Fermi GRB 250102A: Global MASTER-Net observations report
  89. GRB 250103A: GOTO optical upper limit
  90. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  91. IceCube Alert 250102.58: Global MASTER-Net observations report
  92. EP241231b: optical upper limit with the Liverpool Telescope
  93. LIGO/Virgo/KAGRA S241230bd: Upper limits from Swift/BAT-GUANO
  94. GRB 250101A: further SAO RAS optical observations
  95. GRB 250101A: LCO optical counterpart detection
  96. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  97. GRB 250101A NUTTelA-TAO / BSTI Early Measurements
  98. GRB 250101A: Swift/UVOT Detection
  99. GRB 250101A: 1.6m Mephisto multi-band optical followup
  100. GRB 250101A: Montarrenti Observatory optical observations and rebrightening

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