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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"

27226 results found.

  1. GRB 250114B : GIT optical upper limit
  2. GRB 250114A: REM detection of the optical and NIR counterpart
  3. Swift GRB250114A: Global MASTER-Net OT detection
  4. GRB 250114A: LCO optical observations
  5. GRB 250114A: TRT optical observations
  6. Swift GRB 250114A: Global MASTER-Net observations report
  7. GRB 250114A: Swift detection of a burst with an optical counterpart
  8. GRB 250101A: Terskol Zeiss-2000 optical observations
  9. EP241021a: SMA radio observation
  10. GRB 250113A: SVOM/GRM observation of a long burst
  11. EP250109b: optical upper limits with the Liverpool Telescope
  12. Fermi trigger No 758442826: Global MASTER-Net observations report
  13. EP250111a: KAIT optical observations
  14. GRB 250109A / EP250109a: Mephisto optical upper limits
  15. EP250108a: Mephisto detection
  16. EP250111a: Mondy optical observation
  17. EP250108a / AT 2025kg: LCO optical observations
  18. EP250111a: Global MASTER-Net observations report
  19. EP250111a: Swift/XRT detection and fading
  20. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  21. EP250108a: optical follow-up observations with the Liverpool Telescope
  22. EP250111a: NOT likely optical counterpart
  23. EP250111a: a new X-ray transient detected by Einstein Probe
  24. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  25. GRB 250101B: Fermi GBM Observation
  26. EP250108a: further NOT optical observations
  27. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  28. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  29. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  30. EP-WXT trigger EP250108a：Xinglong optical follow-up observations
  31. GRB 250101A: CMO RC-500 optical observations
  32. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  33. EP250108a: EP-FXT follow-up observation
  34. GRB 250109A: Fermi GBM Observation
  35. The EP-WXT trigger 01709130111 is likely a flaring star
  36. EP250108a: NOT optical observations
  37. EP-WXT trigger EP250109a：Xinglong optical follow-up observations
  38. GRB 250109a: GMG Optical Upper Limit
  39. Konus-Wind detection of GRB 250107D (short/hard)
  40. EP250108a: Liverpool Telescope likely optical counterpart
  41. GRB 250108B: Swift-BAT refined analysis
  42. GRB 250108B: 1.3m DFOT upper limit
  43. GRB 250108B: REM optical/NIR upper limits
  44. GRB 250109A /EP250109a: Fermi GBM Final Localization
  45. EP250109a: SVOM/VT optical candidate
  46. EP250109a: Global MASTER-Net observations report
  47. GRB 250107C: SVOM/GRM observation
  48. GRB 250101A: Terskol K-800 optical observations
  49. EP250109a: GOTO optical upper limits
  50. GRB 250108A: Swift/UVOT Upper Limits
  51. EP250108a: Global MASTER-Net observations report
  52. EP250109a: EP-WXT detection of an X-ray transient
  53. EP250108a: EP-WXT detection of an X-ray transient
  54. GRB 250108B: Swift-XRT refined Analysis
  55. Swift GRB 250108B: Global MASTER-Net observations report
  56. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  57. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  58. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  59. GRB 250103A: 1.6m Mephisto optical observations
  60. GRB 250108A:SVOM/VT optical candidate
  61. GRB 250108B: Swift/UVOT Upper Limits
  62. GRB 250108B: Swift detection of a burst
  63. GRB 250108A: SVOM detection of a soft long burst
  64. GRB 250107A: Fermi GBM Observation
  65. GRB 241228B: Fermi-LAT detection
  66. Fermi GRB 250107B: Global MASTER-Net observations report
  67. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  68. GRB 250107B: Fermi GBM Final Real-time Localization
  69. GRB 250106A: SVOM/VT 2nd optical deep observation
  70. GRB 250101A: J band upper limit by SYSU 80cm telescope
  71. GRB 250107A: Fermi GBM Final Real-time Localization
  72. EPWXT01709129925: Xinglong optical observations
  73. GRB 250106A: NOT optical observations
  74. GRB 250103B: REM optical/NIR upper limits
  75. GRB 250101A: REM optical/NIR counterpart detection
  76. GRB 250106A: SVOM/VT optical candidate
  77. The EP-WXT trigger 01709129925 is likely a flaring star
  78. GRB 250106A: SVOM detection of a long burst
  79. Fermi trigger No 757753930: Global MASTER-Net observations report
  80. GRB 241229A: SVOM/VT optical upperlimit
  81. GRB 250103B: Swift-XRT refined Analysis
  82. GRB 250103A: Bassano Bresciano Observatory upper limit
  83. GRB 250101A: 1.3m DFOT optical afterglow detection
  84. GRB 241229A: 1.3m DFOT upper limit
  85. GRB 241228B: 1.3m DFOT Optical observations
  86. GRB 241228A: 1.3m DFOT upper limit
  87. GRB 250103B：SVOM/VT optical counterpart
  88. GRB 250101A: further LCOGT optical afterglow observations
  89. GRB 250103A: Fermi GBM Observation
  90. GRB 250103B: LCOGT Optical Upper Limit
  91. Swift GRB 250103B: Global MASTER-Net observations report
  92. GRB 250103A: SVOM/VT optical counterpart confirmation
  93. EP250101a: Liverpool Telescope optical upper limit
  94. GRB 250101a: Liverpool Telescope optical follow-up
  95. GRB 250103B: SVOM detection of a long burst
  96. GRB 250103B: Swift detection of a burst
  97. GRB 250103A: Xinglong 2.16m Optical Candidate
  98. Fermi GRB 250102A: Global MASTER-Net observations report
  99. GRB 250101B: SVOM/GRM observation
  100. GRB 250103A: GOTO optical upper limit

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