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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"

43118 results found.

  1. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  2. GRB 250114A: REM detection of the optical and NIR counterpart
  3. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  4. Swift GRB250114A: Global MASTER-Net OT detection
  5. GRB 250114A: LCO optical observations
  6. GRB 250114A: TRT optical observations
  7. Swift GRB 250114A: Global MASTER-Net observations report
  8. GRB 250114A: Swift detection of a burst with an optical counterpart
  9. EP250108a / AT 2025kg: SAO RAS optical observations
  10. EP241021a: SMA radio observation
  11. GRB 250113A: SVOM/GRM observation of a long burst
  12. GRB 250107A: VZLUSAT-2 detection
  13. EP250109b: optical upper limits with the Liverpool Telescope
  14. GRB 250109A / EP250109a: GRBAlpha detection
  15. GRB 250107D: GRBAlpha detection
  16. GRB 250106A: Swift-XRT afterglow detection
  17. Fermi trigger No 758442826: Global MASTER-Net observations report
  18. EP250111a: KAIT optical observations
  19. GRB 250109A / EP250109a: Mephisto optical upper limits
  20. EP250108a: Mephisto detection
  21. EP250108a / AT 2025kg: LCO optical observations
  22. EP250111a: Global MASTER-Net observations report
  23. EP250111a: Swift/XRT detection and fading
  24. EP250108a / AT 2025kg: Swift UVOT detections
  25. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  26. EP250108a: optical follow-up observations with the Liverpool Telescope
  27. EP250111a: NOT likely optical counterpart
  28. EP250111a: a new X-ray transient detected by Einstein Probe
  29. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  30. GRB 250101B: Fermi GBM Observation
  31. EP250108a: further NOT optical observations
  32. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  33. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  34. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  35. GRB 250108A: Swift/XRT afterglow fading
  36. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  37. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  38. Konus-Wind detection of GRB 250107C
  39. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  40. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  41. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  42. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  43. EP250108a: EP-FXT follow-up observation
  44. GRB 250109A: Fermi GBM Observation
  45. The EP-WXT trigger 01709130111 is likely a flaring star
  46. EP250108a: NOT optical observations
  47. GRB 250109a: GMG Optical Upper Limit
  48. EP250109a: Swift/UVOT non-detection
  49. Konus-Wind detection of GRB 250107D (short/hard)
  50. IPN triangulation of GRB 250107D (short/hard)
  51. IPN triangulation of GRB 250107C
  52. EP250108a: Liverpool Telescope likely optical counterpart
  53. GRB 250108B: Gemini-North likely redshift z = 2.197
  54. GRB 250108B: 1.3m DFOT upper limit
  55. GRB 250108B: REM optical/NIR upper limits
  56. GRB 250109A /EP250109a: Fermi GBM Final Localization
  57. EP250109a: SVOM/VT optical candidate
  58. EP250109a: Global MASTER-Net observations report
  59. GRB 250107C: SVOM/GRM observation
  60. GRB 250101A: Terskol K-800 optical observations
  61. EP250109a: GOTO optical upper limits
  62. EP250109a: Swift/XRT non-detection
  63. GRB 250108A: Swift/UVOT Upper Limits
  64. EP250108a: Global MASTER-Net observations report
  65. EP250109a: EP-WXT detection of an X-ray transient
  66. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  67. GRB 250108A: NOT optical upper limit
  68. EP250108a: EP-WXT detection of an X-ray transient
  69. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  70. GRB 250108B: Swift-XRT refined Analysis
  71. Swift GRB 250108B: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S250108ha: Retraction of GW compact binary merger candidate
  73. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  74. GRB 250103A: 1.6m Mephisto optical observations
  75. GRB 250108A: Swift-XRT afterglow detection
  76. GRB 250108A:SVOM/VT optical candidate
  77. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  78. GRB 250108B: Swift/UVOT Upper Limits
  79. GRB 250103A: Swift-XRT afterglow detection
  80. GRB 250108B: Enhanced Swift-XRT position
  81. GRB 250108B: Swift detection of a burst
  82. GRB 250108A: Swift ToO observations
  83. GRB 250108A: SVOM detection of a soft long burst
  84. GRB 250107A: Fermi GBM Observation
  85. GRB 241228B: Fermi-LAT detection
  86. Fermi GRB 250107B: Global MASTER-Net observations report
  87. GRB 250107A: Swift ToO observations
  88. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  89. GRB 250107B: Fermi GBM Final Real-time Localization
  90. GRB 250106A: SVOM/VT 2nd optical deep observation
  91. GRB 250107A: Fermi GBM Final Real-time Localization
  92. EPWXT01709129925: Xinglong optical observations
  93. GRB 250106A: NOT optical observations
  94. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  95. GRB 250103B: REM optical/NIR upper limits
  96. GRB 250101A: REM optical/NIR counterpart detection
  97. GRB 250106A: Swift-XRT observations
  98. GRB 250106A: SVOM/VT optical candidate
  99. GRB 250106A: Swift ToO observations
  100. The EP-WXT trigger 01709129925 is likely a flaring star

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