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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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').
Advanced Search

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.

Advanced Search Examples (click to copy):

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

21953 results found.

  1. GRB 250128B: SAO RAS Zeiss-1000 and CrAO ZTSh optical upper limits
  2. GRB 250128B: VLA radio upper limit
  3. Ep250125A: 1.3m DFOT optical upper limit
  4. GRB 250129A: Skynet optical observations
  5. GRB 250129A: KAIT optical observations of the rebrightening around 5.1 hours
  6. GRB 250128B: Gemini-North optical extended source detection
  7. The EP-WXT trigger 01709131085: KAIT confirmation of the stellar flare
  8. GRB 250129A: Swift/UVOT Detection
  9. GRB 250128B: VLT/HAWKI near-infrared observations
  10. GRB 250127A: CrAO and Terskol optical upper limits
  11. GRB 250128B: VLT/FORS2 optical observations
  12. GRB 250129A: REM optical/NIR afterglow detection
  13. GRB 250129A: OHP/T193 optical and spectroscopy observations
  14. GRB 250129A: Early afterglow detection by LCO.
  15. GRB 250129A: LCO optical observations
  16. GRB 250129A: NOT optical observations and redshift confirmation
  17. GRB 250129A: GOTO optical observations show brightening afterglow
  18. GRB 250129A: VLT/X-shooter redshift of z = 2.151
  19. Swift GRB 250129A: Global MASTER-Net observations report
  20. Fermi GRB 250128B: Global MASTER-Net observations report
  21. GRB 250128B: GOTO optical upper limit
  22. Swift GRB 250128B: Global MASTER-Net observations report
  23. EP250125a: Upper limits from Swift/BAT-GUANO
  24. GRB 250128B: LCO optical observations
  25. GRB 250127A: Swift-XRT observations
  26. GRB 250127B: DDOTI Upper Limit on the Afterglow
  27. Fermi-LAT Gamma-ray Observations of IceCube-250102A
  28. Fermi GRB 250128A: Global MASTER-Net observations report
  29. Fermi GRB 250127B: Global MASTER-Net observations report
  30. Fermi-LAT Gamma-ray Observations of IceCube-250101A
  31. GRB 250127A: SVOM/VT upper limit
  32. GRB 250127A: Swift ToO observations
  33. GRB 250127A: LCO optical upper limit
  34. EP250125A: Non-detection from Fermi-GBM Observations
  35. EP250125a: Optical upper limit with Kinder observations
  36. EP250125a: REM optical counterpart detection
  37. EP250125a: Swift/XRT detection of a fading counterpart
  38. EP250125a: a new X-ray transient detected by Einstein Probe
  39. EP250125a: Gemini-South optical afterglow discovery and redshift z = 2.89
  40. GRB 250121A: Swift/BAT-GUANO localization skymap of a burst
  41. EP250108a: AbAO, CMO and Terskol optical upper limits
  42. GRB 250121A: INTEGRAL/SPI-ACS detection
  43. LIGO/Virgo S250119cv: Swift XRT observations, 5 X-ray sources
  44. GRB 250119C: Swift/BAT-GUANO localization skymap of a short burst
  45. GRB 250119B: Swift/BAT-GUANO localization skymap of a long burst
  46. Fermi-LAT Gamma-ray Observations of IceCube-241224A
  47. GRB 250118A: Swift/BAT-GUANO localization skymap of a short burst
  48. EP250108a/AT2025kg: 1.3m DFOT Optical observations
  49. ATCA detection of possible radio counterpart to GRB 250114A
  50. EP250108a / SN2025kg: Non-detection from ATCA radio follow-up observations
  51. GRB 250119B: INTEGRAL/SPI-ACS detection
  52. LIGO/Virgo/KAGRA S250119cv: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  53. EP 250108A: Late-time optical observation by LCO
  54. LIGO/Virgo/KAGRA S250119cv: Updated NED Galaxies in the Localization Volume
  55. LIGO/Virgo/KAGRA S250119cv: NED Galaxies in the Localization Volume
  56. GRB 250117A: Swift/BAT-GUANO localization skymap of a short burst
  57. EP250108a / SN2025kg: Gemini GMOS-S confirmation of an associated broad-lined SN Ic
  58. EP250108a/AT 2025kg: NOT spectroscopy in agreement with SN Ic-BL
  59. EP250108a / AT 2025kg: the kangaroo is hopping, evidence for optical rebrightening
  60. GRB 250117A: GECAM observation of a short burst
  61. EP250108a / AT2025kg: GMG Optical Observations
  62. EP250108a / AT2025kg: VLA radio upper limit
  63. GRB 241217A / EP241217B: radio detection with the VLA
  64. GRB 250116A: INTEGRAL/SPI-ACS and PICsIT detection
  65. GRB 250114B: Swift-XRT afterglow detection
  66. GRB 250114B: SVOM/VT upper limit
  67. EP250108a: MeerKAT radio upper limit
  68. LIGO/Virgo/KAGRA S250114ax: Updated NED Galaxies in the Localization Volume
  69. GRB 250101A: Calapai Observatory, Massa S. Giorgio (Messina), optical observations and rebrightening.
  70. GRB 250114B: Liverpool Telescope optical upper limit
  71. LIGO/Virgo/KAGRA S250114ax: GLADEnet Completeness: Potential Host Galaxies in the 90% Credible Volume
  72. GRB 250114B : MITSuME Akeno optical afterglow candidate detection
  73. GRB 250114B: Swift-XRT observations
  74. GRB 250114A: LCO optical counterpart detection.
  75. GRB 250114A: GRANDMA/TAROT optical afterglow detection
  76. Integral GRB250114.55: Global MASTER-Net observations report
  77. GRB 250114A: LCOGT optical afterglow i-band detection
  78. GRB 250114B: Swift ToO observations
  79. LIGO/Virgo/KAGRA S250114ax: NED Galaxies in the Localization Volume
  80. GRB 250113A: INTEGRAL/SPI-ACS detection
  81. GRB 250114A: REM detection of the optical and NIR counterpart
  82. GRB 250114A: LCO optical observations
  83. GRB 250114A: TRT optical observations
  84. Swift GRB 250114A: Global MASTER-Net observations report
  85. GRB 250101A: Terskol Zeiss-2000 optical observations
  86. EP250108a / AT 2025kg: SAO RAS optical observations
  87. EP241021a: SMA radio observation
  88. EP250109b: optical upper limits with the Liverpool Telescope
  89. GRB 250106A: Swift-XRT afterglow detection
  90. Fermi trigger No 758442826: Global MASTER-Net observations report
  91. EP250111a: KAIT optical observations
  92. GRB 250109A / EP250109a: Mephisto optical upper limits
  93. EP250108a: Mephisto detection
  94. EP250111a: Mondy optical observation
  95. EP250108a / AT 2025kg: LCO optical observations
  96. EP250111a: Global MASTER-Net observations report
  97. EP250108a / AT 2025kg: Swift UVOT detections
  98. EP250108a: optical follow-up observations with the Liverpool Telescope
  99. EP250111a: NOT likely optical counterpart
  100. EP250111a: a new X-ray transient detected by Einstein Probe

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