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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"

32536 results found.

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

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