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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"

32538 results found.

  1. Konus-Wind detection of GRB 250119B
  2. IPN triangulation of GRB 250119B
  3. Improved IPN triangulation of GRB 250107C
  4. GRB 250114A: Swift-BAT refined analysis
  5. GRB 250121A: INTEGRAL/SPI-ACS detection
  6. GRB 250121A: Fermi-LAT detection
  7. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  8. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  9. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  10. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  11. GRB 250119B: Fermi GBM Observation
  12. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  13. Konus-Wind detection of GRB 250117A
  14. IPN triangulation of GRB 250117A (short)
  15. ATCA detection of possible radio counterpart to GRB 250114A
  16. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  17. GRB 250119B: INTEGRAL/SPI-ACS detection
  18. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  19. EP 250108A: Late-time optical observation by LCO
  20. GRB 250117A: SVOM/GRM observation of a short burst
  21. LIGO/Virgo/KAGRA S250119cv: Updated Sky localization and EM Bright Classification
  22. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  23. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  24. LIGO/Virgo/KAGRA S250119cv: Identification of a GW compact binary merger candidate
  25. LIGO/Virgo/KAGRA S250119ag: Updated Sky localization
  26. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  27. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  28. GRB 250117A: GECAM observation of a short burst
  29. LIGO/Virgo/KAGRA S250118dp: Updated Sky localization
  30. LIGO/Virgo/KAGRA S250119ag: Identification of a GW compact binary merger candidate
  31. LIGO/Virgo/KAGRA S250118dp: Identification of a GW compact binary merger candidate
  32. LIGO/Virgo/KAGRA S250118t: Updated Sky localization
  33. LIGO/Virgo/KAGRA S250118az: Identification of a GW compact binary merger candidate
  34. EP250108a / AT2025kg: GMG Optical Observations
  35. LIGO/Virgo/KAGRA S250118t: Identification of a GW compact binary merger candidate
  36. EP250108a / AT2025kg: VLA radio upper limit
  37. Konus-Wind detection of GRB 250116A
  38. GRB 250116A: GECAM-B detection of a long burst
  39. GRB 241217A / EP241217B: radio detection with the VLA
  40. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  41. GRB 250116A: Fermi-LAT detection
  42. GRB 250114B: Swift-XRT afterglow detection
  43. GRB 250114B: SVOM/VT upper limit
  44. EP250108a: MeerKAT radio upper limit
  45. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  46. LIGO/Virgo/KAGRA S250114ax: Updated Sky localization
  47. Konus-Wind detection of GRB 250113A
  48. IPN triangulation of GRB 250113A
  49. GRB 250114B: Liverpool Telescope optical upper limit
  50. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  51. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  52. GRB 250114A: LCO optical counterpart detection.
  53. GRB 250114B: OHP/T193 optical upper limit
  54. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  55. GRB 250114A: LCOGT optical afterglow i-band detection
  56. GRB 250114B : GIT optical upper limit
  57. GRB 250114B: Swift ToO observations
  58. EP250111a: SAO RAS optical upper limit
  59. EP250108a: correction to GCN 38908
  60. GRB 250113A: INTEGRAL/SPI-ACS detection
  61. GRB 250114A: VLT/X-shooter spectroscopic redshift z = 4.732
  62. GRB 250114A: REM detection of the optical and NIR counterpart
  63. LIGO/Virgo/KAGRA S250114ax: Identification of a GW compact binary merger candidate
  64. GRB 250114A: LCO optical observations
  65. GRB 250114A: TRT optical observations
  66. Swift GRB 250114A: Global MASTER-Net observations report
  67. GRB 250101A: Terskol Zeiss-2000 optical observations
  68. EP250108a / AT 2025kg: SAO RAS optical observations
  69. EP241021a: SMA radio observation
  70. GRB 250107A: VZLUSAT-2 detection
  71. GRB 250109A / EP250109a: GRBAlpha detection
  72. GRB 250107D: GRBAlpha detection
  73. EP250111a: KAIT optical observations
  74. GRB 250109A / EP250109a: Mephisto optical upper limits
  75. EP250108a: Mephisto detection
  76. EP250111a: Mondy optical observation
  77. EP250108a / AT 2025kg: LCO optical observations
  78. EP250111a: Global MASTER-Net observations report
  79. EP250111a: Swift/XRT detection and fading
  80. EP250108a / AT 2025kg: Swift UVOT detections
  81. EP250108a / AT 2025kg (the "kangaroo”): VLT/X-shooter spectroscopic redshift z = 0.176 and LFBOT classification
  82. EP250108a: optical follow-up observations with the Liverpool Telescope
  83. EP250111a: NOT likely optical counterpart
  84. EP250109a/GRB 250109A:SVOM/VT optical counterpart
  85. GRB 250101B: Fermi GBM Observation
  86. EP250108a: further NOT optical observations
  87. GRB 250109A / EP250109a: Terskol (INASAN) and SAO RAS observations
  88. GRB 250109A / EP250109A: Swift/BAT-GUANO localization skymap of a burst
  89. GRB 250109A / EP250109a: Swift detection of the X-ray afterglow
  90. GRB 250108A: Swift/XRT afterglow fading
  91. GRB 250107D: CALET Gamma-Ray Burst Monitor detection
  92. GRB 250107C: CALET Gamma-Ray Burst Monitor detection
  93. Konus-Wind detection of GRB 250107C
  94. LIGO/Virgo/KAGRA S250109bi: Updated Sky localization
  95. LIGO/Virgo/KAGRA S250109f: Updated Sky localization
  96. LIGO/Virgo/KAGRA S250108eo: Updated Sky localization
  97. GRB 250101A: CMO RC-500 optical observations
  98. EP250109a / GRB 250109A: refined EP-WXT analysis and EP-FXT follow-up observation
  99. EP250108a: EP-FXT follow-up observation
  100. GRB 250109A: Fermi GBM Observation

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