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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

32489 results found.

  1. GRB 250114B: Liverpool Telescope optical upper limit
  2. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  3. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  4. GRB 250114A: LCO optical counterpart detection.
  5. GRB 250114B: OHP/T193 optical upper limit
  6. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  7. GRB 250114A: LCOGT optical afterglow i-band detection
  8. GRB 250114B : GIT optical upper limit
  9. GRB 250114B: Swift ToO observations
  10. EP250111a: SAO RAS optical upper limit
  11. EP250108a: correction to GCN 38908
  12. GRB 250113A: INTEGRAL/SPI-ACS detection
  13. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  14. GRB 250114A: REM detection of the optical and NIR counterpart
  15. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  16. GRB 250114A: LCO optical observations
  17. GRB 250114A: TRT optical observations
  18. Swift GRB 250114A: Global MASTER-Net observations report
  19. GRB 250101A: Terskol Zeiss-2000 optical observations
  20. EP250108a / AT 2025kg: SAO RAS optical observations
  21. EP241021a: SMA radio observation
  22. GRB 250107A: VZLUSAT-2 detection
  23. GRB 250109A / EP250109a: GRBAlpha detection
  24. GRB 250107D: GRBAlpha detection
  25. EP250111a: KAIT optical observations
  26. GRB 250109A / EP250109a: Mephisto optical upper limits
  27. EP250108a: Mephisto detection
  28. EP250111a: Mondy optical observation
  29. EP250108a / AT 2025kg: LCO optical observations
  30. EP250111a: Global MASTER-Net observations report
  31. EP250111a: Swift/XRT detection and fading
  32. EP250108a / AT 2025kg: Swift UVOT detections
  33. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  34. EP250108a: optical follow-up observations with the Liverpool Telescope
  35. EP250111a: NOT likely optical counterpart
  36. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  37. GRB 250101B: Fermi GBM Observation
  38. EP250108a: further NOT optical observations
  39. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  40. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  41. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  42. GRB 250108A: Swift/XRT afterglow fading
  43. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  44. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  45. Konus-Wind detection of GRB 250107C
  46. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  47. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  48. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  49. GRB 250101A: CMO RC-500 optical observations
  50. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  51. EP250108a: EP-FXT follow-up observation
  52. GRB 250109A: Fermi GBM Observation
  53. EP250108a: NOT optical observations
  54. GRB 250109a: GMG Optical Upper Limit
  55. EP250109a: Swift/UVOT non-detection
  56. Konus-Wind detection of GRB 250107D (short/hard)
  57. IPN triangulation of GRB 250107D (short/hard)
  58. IPN triangulation of GRB 250107C
  59. EP250108a: Liverpool Telescope likely optical counterpart
  60. GRB 250108B: Gemini-North likely redshift z = 2.197
  61. GRB 250108B: Swift-BAT refined analysis
  62. GRB 250108B: 1.3m DFOT upper limit
  63. GRB 250108B: REM optical/NIR upper limits
  64. GRB 250109A /EP250109a: Fermi GBM Final Localization
  65. EP250109a: SVOM/VT optical candidate
  66. EP250109a: Global MASTER-Net observations report
  67. GRB 250101A: Terskol K-800 optical observations
  68. EP250109a: GOTO optical upper limits
  69. EP250109a: Swift/XRT non-detection
  70. GRB 250108A: Swift/UVOT Upper Limits
  71. EP250108a: Global MASTER-Net observations report
  72. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  73. GRB 250108A: NOT optical upper limit
  74. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  75. Swift GRB 250108B: Global MASTER-Net observations report
  76. Fermi Gamma-ray Burst Monitor trigger 758061038/250108855 is not a GRB
  77. GRB 250108B: Gemini-North Candidate Optical Afterglow Detection
  78. GRB 250103A: 1.6m Mephisto optical observations
  79. GRB 250108A:SVOM/VT optical candidate
  80. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  81. GRB 250108B: Swift/UVOT Upper Limits
  82. GRB 250108A: Swift ToO observations
  83. GRB 250107A: Fermi GBM Observation
  84. GRB 241228B: Fermi-LAT detection
  85. Fermi GRB 250107B: Global MASTER-Net observations report
  86. GRB 250107A: Swift ToO observations
  87. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  88. GRB 250106A: SVOM/VT 2nd optical deep observation
  89. GRB 250101A: J band upper limit by SYSU 80cm telescope
  90. GRB 250106A: NOT optical observations
  91. LIGO/Virgo/KAGRA S250104v: Updated Sky localization
  92. GRB 250103B: REM optical/NIR upper limits
  93. GRB 250101A: REM optical/NIR counterpart detection
  94. GRB 250106A: Swift-XRT observations
  95. GRB 250106A: SVOM/VT optical candidate
  96. GRB 250106A: Swift ToO observations
  97. GRB 241229A: SVOM/VT optical upperlimit
  98. GRB 250103B: LCO/1m optical afterglow candidate detection
  99. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  100. GRB 250103A: Swift-XRT observations

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