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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.

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

32715 results found.

  1. SVOM/sb25021804: COLIBRÍ/DDRAGO Confirmation of Variability
  2. SVOM/sb25021804: QSO variability in Liverpool Telescope observations
  3. GRB 250217C: COLIBRÍ/DDRAGO Upper Limits on the Optical Counterpart
  4. GRB 250217C: DDOTI Upper Limits on the Optical Afterglow
  5. GRB 250217C: SVOM/GRM observation
  6. GRB 250217C: Tiled Swift observations
  7. GRB 250217C: Fermi GBM Observation
  8. GRB 250215A / EP250215A: Encouraging Follow-up Observations of a BdHN I with a Rest-Frame Duration 2.3 s at z=4.61
  9. IPN triangulation of GRB 250217C (short)
  10. Transient SVOM/sb25021804: COLIBRÍ/DDRAGO Optical Upper Limits on the Optical Counterpart
  11. LIGO/Virgo/KAGRA S250206dm: AZT-33IK Target Optical Observations
  12. GRB 250216A: AstroSat CZTI detection
  13. GRB 250217C: AstroSat CZTI detection of a short burst
  14. Fermi GRB 250217C: Global MASTER-Net observations report
  15. LIGO/Virgo/KAGRA S250206dm: observation in AbAO, optical transient near NED/GLADE+ galaxy WISEA J021210.14+514821.7
  16. Fermi GRB 250217A: Global MASTER-Net observations report
  17. GRANDMA/OPD observations of GRB250215A
  18. Fermi GRB 250216A: Global MASTER-Net observations report
  19. GRB 250215A / EP250215a: LCO detection of the afterglow
  20. EP250212a: FTW optical and NIR upper limits
  21. GRB 250215A: Swift/UVOT Upper Limits
  22. GRB 250215A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  23. EP250215a / GRB 250215A : GTC redshift z = 4.61
  24. GRB 250215A: Fermi GBM Observation
  25. EP250215a / GRB 250215A : NOT optical observations
  26. GRB 250215A/EP250215a: 1.6m Mephisto optical observation report
  27. GRB 250215A / EP250215a: Gemini-South optical observation of a likely rebrightening
  28. LIGO/Virgo/KAGRA S250206dm: MASTER LC AT2025bbo
  29. GRB 250213A: COLIBRÍ/DDRAGO Optical Upper Limits on the Afterglow
  30. GRB 250215A: Swift-XRT refined Analysis
  31. GRB 250215A: SVOM/GRM observation
  32. EP250215a / GRB 250215A: AstroSat CZTI detection
  33. GRB 250215A / EP250215a: SVOM/VT optical candidate comfirmation
  34. EP250215a: Global MASTER-Net observations report
  35. EP250215A/GRB 250215A: INTEGRAL SPI-ACS detection
  36. EP250215a / GRB 250215A (potentially): NOT likely optical counterpart
  37. EP250215a: EP-WXT detection and FXT follow-up observation of an X-ray transient
  38. Fermi GRB 250215A: Global MASTER-Net observations report
  39. GRB 250213A：SVOM/VT optical candidate
  40. EP250207b: Xinglong optical upper limit
  41. Fermi GRB 250214A: Global MASTER-Net observations report
  42. GRB 250213A: Swift ToO observations
  43. EP250212a: Xinglong optical upper limit
  44. LIGO/Virgo/KAGRA S250206dm: DECam GW-MMADS candidates
  45. EP250212a: Global MASTER-Net observations report
  46. GRB 250205A: VIRT Optical Upper Limit
  47. GRB 250205A: Leavitt Observatory optical upper limit
  48. GRB 250210A: GRBAlpha detection
  49. EP250207B: Chandra localization of the X-ray counterpart
  50. LIGO/Virgo/KAGRA S250206dm: FTW observations of counterpart candidates AT2025bbo and AT2025bcx, and of NED galaxies
  51. EP250207b: VLA radio upper limits
  52. EP250212a: Liverpool Telescope optical upper limits
  53. EP250212a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  54. GRB250101A: Radio upper limits from GMRT observations
  55. EP250207B: GTC z-band Observations
  56. Fermi GRB 250212A: Global MASTER-Net observations report
  57. LIGO/Virgo/KAGRA S250206dm: NEWFIRM NIR Follow-up of AT2025ber
  58. GRB 250205A: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  59. EP250207b: NOT optical counterpart candidate
  60. GRB 250211A: SVOM trigger sb25021103 is not a GRB
  61. LIGO/Virgo/KAGRA S250206dm: GECKO Continued Observaiton with 7DT
  62. GRB 250211A: Swift ToO observations
  63. LIGO/Virgo/KAGRA S250206dm: AT 2025bbo observations with WFST
  64. LIGO/Virgo/KAGRA S250211be: Updated Sky localization
  65. GRB 250207A: Fermi GBM Observation
  66. GRB 250206A: Fermi GBM Observation
  67. GRB 250205A / EP250205A: radio detection with the VLA
  68. IceCube-250207A: One candidate from the Zwicky Transient Facility
  69. EP250207b: Tentative z-band brightening source
  70. LIGO/Virgo/KAGRA S250206dm: continued in SOAR galaxy targeted observations and identification of one possible transient
  71. LIGO/Virgo/KAGRA S250206dm: Kinder confirmation of a possible artefact in AT 2025bbo
  72. Konus-Wind detection of GRB 250207A
  73. Konus-Wind detection of GRB 250206A
  74. GRB 250210A: SVOM/GRM observation of a long burst
  75. EP250207b: Liverpool Telescope possible optical counterpart
  76. EP250207b: Global MASTER-Net observations report
  77. Gemini-South spectroscopic redshift of EP250207b host galaxy candidate (z=0.082)
  78. LIGO/Virgo/KAGRA S250211be: Identification of a GW compact binary merger candidate
  79. LIGO/Virgo/KAGRA S250211aa: Updated Sky localization and EM Bright Classification
  80. LIGO/Virgo/KAGRA S250211aa: Identification of a GW compact binary merger candidate
  81. GRB 250207A: Skynet optical afterglow observations
  82. LIGO/VIRGO/KAGRA S250206dm: AT 2025bbo spectroscopic observations with NIRES on Keck II
  83. LIGO/Virgo/KAGRA S250206dm: Gemini-North spectroscopic observation of AT2025bbo and its host galaxy
  84. GRB 241128A: VIRT Optical Upper Limit
  85. EP250207b: Gemini GMOS-N z-band observations
  86. EP250207A: Upper limits from Fermi-GBM Observations
  87. GRB 250210A: INTEGRAL SPI-ACS detection
  88. GRB 250210A: AstroSat CZTI detection
  89. LIGO/Virgo/KAGRA S250206dm: MASTER detection AT2025bbo
  90. GRB 250209A: MAXI/GSC detection (possible detection of an X-ray flare from 1RXS J145110.3+310648)
  91. Fermi GRB 250210A: Global MASTER-Net observations report
  92. LIGO/Virgo/KAGRA S250206dm: Upper limits from GECAM Observations
  93. IceCube-250207A: Upper limits from a search for additional neutrino events in IceCube
  94. LIGO/Virgo/KAGRA S250206dm: COLIBRÍ/DDRAGO Observations of AT2025bbo and Galaxies in the Localization Volume
  95. LIGO/Virgo/KAGRA S250206dm: Observations from WINTER
  96. GRB 250204B: GRBAlpha detection
  97. GRB 250204A: GRBAlpha detection
  98. LIGO/Virgo/KAGRA S250206dm & FRB 20250206A: MASTER observations and possible mother galaxy
  99. LIGO/Virgo/KAGRA S250206dm: Optical observations of candidate AT 2025bbo with Kinder
  100. Fermi-LAT Gamma-ray Observations of IceCube-250207A

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