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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').
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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"

12169 results found.

  1. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  2. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  3. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  4. GRB 250806A: Gemini observations of host galaxy candidate
  5. GRB 250821A: Kilonova-Catcher optical upper limits
  6. EP250821a: Swift/XRT counterpart fading
  7. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  8. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  9. GRB 250821A: Swift-XRT refined Analysis
  10. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  11. EP250821a: Swift XRT and UVOT counterpart detection
  12. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  13. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  14. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  15. GRB 250821A: Swift detection of a burst
  16. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  17. EP250821a: Einstein Probe detection of an X-ray transient
  18. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  19. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  20. GRB 250818B: Liverpool Telescope optical detections
  21. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  22. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  23. GRB 250820A: Fermi GBM Final Real-time Localization
  24. Swift GRB 250818A: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  26. GRB 250818B: Swift-XRT afterglow detection
  27. GRB 250818B: SVOM detection of a short burst
  28. sb25081602: Swift-XRT observations
  29. SVOM/sb25081602: detection of a likely X-ray transient
  30. GRB 250815A: Fermi GBM Final Localization
  31. GRB 250814A: Further COLIBRÍ optical upper limit
  32. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  33. GRB 250814A: GRAWITA TNG NIR observations
  34. GRB 250812A: SVOM/VT optical continued observation
  35. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  36. GRB 250814A: P200/WIRC observations of the afterglow candidate
  37. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  38. GRB 250814A: Possible afterglow candidate from P200/WIRC
  39. Subject GRB 250813B: SVOM/MXT refined analysis
  40. GRB 250813A: AstroSat CZTI detection
  41. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  42. GRB 250813B: Swift-XRT afterglow detection
  43. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  44. GRB 250813B: Ondrejov D50 fast decay
  45. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  46. GRB 250812A: NTT spectroscopic redshift z = 2.57
  47. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  48. IceCube Alert 250813.14: Global MASTER-Net observations report
  49. GRB 250812A: Kilonova-Catcher optical afterglow detection
  50. EP250812a: Swift-XRT counterpart detection
  51. EP250812a: Einstein Probe detection of an X-ray transient
  52. GRB 250812A: Swift-XRT afterglow detection
  53. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  54. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  55. Corrected Swift-XRT Refined Analysis of GRB 250809A
  56. GRB 250808A: Swift-XRT candidate counterpart detection
  57. GRB 250808A: SVOM detection of a long burst
  58. Konus-Wind detection of GRB 250807A
  59. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  60. GRB 250807A: Swift-XRT refined Analysis
  61. GRB 250806A: SVOM/ECLAIRs refined analysis
  62. GRB 250807A: AstroSat CZTI detection of bright long burst
  63. GRB 250807B: Swift-XRT refined Analysis
  64. GRB 250806A: EP-FXT observation
  65. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  66. EP250806a: SVOM /VT optical candidate
  67. GRB 250806A: Swift-XRT counterpart detection
  68. EP250806a: Einstein Probe detection of an X-ray transient
  69. GRB 250806A: SVOM detection of a soft burst
  70. GRB 250805A: Swift-XRT refined Analysis
  71. GRB 250804C: AstroSat CZTI detection of a long burst
  72. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  73. GRB 250805A: Swift-XRT observations
  74. Swift GRB250805.26: Global MASTER-Net observations report
  75. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  76. The EP-WXT trigger 01709198251 is likely a flaring star
  77. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  78. The EP-WXT trigger 01709198202 is likely a flaring star
  79. EP250711a: CrAO and Assy optical observations
  80. EP250730a: Einstein Probe detection of an X-ray transient
  81. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  82. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  83. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  84. GRB 250725A: AstroSat CZTI detection
  85. Fermi trigger No 775387550: Global MASTER-Net observations report
  86. GRB 250727A: Swift-XRT observations
  87. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  88. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  89. The EP-WXT trigger 01709195487 is likely a flaring star
  90. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  91. GRB 250725A: Swift-XRT refined Analysis
  92. Konus-Wind detection of GRB 250725A
  93. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  94. GRB 250725A: Fermi-LAT detection
  95. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  96. GRB 250725A: Swift detection of a burst
  97. Fermi GRB 250725A: Global MASTER-Net observations report
  98. Swift GRB 250725A: Global MASTER-Net observations report
  99. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  100. SVOM J195836+32283/sb25072103: NIR observations with WINTER

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