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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"

24635 results found.

  1. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  2. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  3. GRB 250117A: GECAM observation of a short burst
  4. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  5. GRB 250119B: BALROG localization (Fermi Trigger 758968026 / GRB 250119352)
  6. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  7. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  8. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  9. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  10. EP250108a / AT2025kg: GMG Optical Observations
  11. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  12. GRB 241217A / EP241217B: radio detection with the VLA
  13. GRB 250116A: Fermi GBM Observation of an Extremely Interesting Burst
  14. GRB 250114B: Swift-XRT afterglow detection
  15. EP250108a: MeerKAT radio upper limit
  16. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  17. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  18. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  19. IPN triangulation of GRB 250113A
  20. GRB 250114B: Liverpool Telescope optical upper limit
  21. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  22. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  23. GRB 250114B: Swift-XRT observations
  24. GRB 250114A: LCO optical counterpart detection.
  25. GRB 250114B: OHP/T193 optical upper limit
  26. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  27. GRB 250114A: Swift-XRT refined Analysis
  28. GRB 250114A: LCOGT optical afterglow i-band detection
  29. GRB 250114B : GIT optical upper limit
  30. EP250111a: SAO RAS optical upper limit
  31. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  32. GRB 250114B: a short GRB detected with INTEGRAL
  33. GRB 250114A: Enhanced Swift-XRT position
  34. GRB 250114A: REM detection of the optical and NIR counterpart
  35. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  36. Swift GRB250114A: Global MASTER-Net OT detection
  37. GRB 250114A: LCO optical observations
  38. GRB 250114A: TRT optical observations
  39. GRB 250114A: Swift detection of a burst with an optical counterpart
  40. GRB 250101A: Terskol Zeiss-2000 optical observations
  41. EP250108a / AT 2025kg: SAO RAS optical observations
  42. EP241021a: SMA radio observation
  43. GRB 250113A: SVOM/GRM observation of a long burst
  44. GRB 250107A: VZLUSAT-2 detection
  45. EP250109b: optical upper limits with the Liverpool Telescope
  46. GRB 250106A: Swift-XRT afterglow detection
  47. EP250111a: KAIT optical observations
  48. GRB 250109A / EP250109a: Mephisto optical upper limits
  49. EP250108a: Mephisto detection
  50. EP250111a: Mondy optical observation
  51. EP250108a / AT 2025kg: LCO optical observations
  52. EP250108a / AT 2025kg: Swift UVOT detections
  53. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  54. EP250111a: NOT likely optical counterpart
  55. GRB 250101B: Fermi GBM Observation
  56. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  57. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250108A: Swift/XRT afterglow fading
  59. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  60. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  61. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  62. EP-WXT trigger EP250108a:Xinglong optical follow-up observations
  63. GRB 250101A: CMO RC-500 optical observations
  64. GRB 250109A: Fermi GBM Observation
  65. EP250108a: NOT optical observations
  66. EP-WXT trigger EP250109a:Xinglong optical follow-up observations
  67. GRB 250109a: GMG Optical Upper Limit
  68. EP250109a: Swift/UVOT non-detection
  69. IPN triangulation of GRB 250107D (short/hard)
  70. EP250108a: Liverpool Telescope likely optical counterpart
  71. GRB 250108B: Swift-BAT refined analysis
  72. GRB 250108B: 1.3m DFOT upper limit
  73. GRB 250108B: REM optical/NIR upper limits
  74. GRB 250101A: Terskol K-800 optical observations
  75. EP250109a: Swift/XRT non-detection
  76. GRB 250108A: Swift/UVOT Upper Limits
  77. LIGO/Virgo/KAGRA S250109bi: Identification of a GW compact binary merger candidate
  78. GRB 250108A: NOT optical upper limit
  79. EP250108a: EP-WXT detection of an X-ray transient
  80. LIGO/Virgo/KAGRA S250109f: Identification of a GW compact binary merger candidate
  81. GRB 250108B: Swift-XRT refined Analysis
  82. GRB 250103A: 1.6m Mephisto optical observations
  83. GRB 250108A: Swift-XRT afterglow detection
  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 250103A: Swift-XRT afterglow detection
  88. GRB 250108B: Enhanced Swift-XRT position
  89. GRB 250108B: Swift detection of a burst
  90. GRB 250107A: Fermi GBM Observation
  91. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  92. GRB 250106A: SVOM/VT 2nd optical deep observation
  93. GRB 250101A: J band upper limit by SYSU 80cm telescope
  94. EPWXT01709129925: Xinglong optical observations
  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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