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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"

32494 results found.

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

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