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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"

12172 results found.

  1. GRB 250823A: Fermi GBM Final Real-time Localization
  2. Swift GRB250823.84: Global MASTER-Net observations report
  3. Konus-Wind detection of GRB 250821B
  4. LIGO/Virgo/KAGRA S250818k: HST nIR detection of AT 2025ulz
  5. LIGO/Virgo/KAGRA S250818k: J-GEM follow-up observation for AT2025ulz
  6. LIGO/Virgo/KAGRA S250818k: PRIME nIR observations of AT2025ulz
  7. GRB 250806A: Gemini observations of host galaxy candidate
  8. GRB 250821A: Kilonova-Catcher optical upper limits
  9. EP250821a: Swift/XRT counterpart fading
  10. LIGO/Virgo/KAGRA S250818k: Pan-STARRS coverage of the skymap and candidate counterparts
  11. LIGO/Virgo/KAGRA S250818k: Continued fading and reddening of AT2025ulz from Keck/LRIS imaging observations
  12. GRB 250821A: Swift-XRT refined Analysis
  13. LIGO/Virgo/KAGRA S250818k : Tautenburg observations, upper limits
  14. EP250821a: Swift XRT and UVOT counterpart detection
  15. LIGO/Virgo/KAGRA S250818k: GOTO counterpart search and upper limits
  16. EP250821a: Preliminary analysis of the EP-WXT and EP-FXT observations
  17. GRB 250814A: CMO SAI and SAO RAS izJ observations.
  18. GRB 250821A: Swift detection of a burst
  19. LIGO/Virgo/KAGRA S250818k: EP/FXT observation of AT 2025ulz
  20. EP250821a: Einstein Probe detection of an X-ray transient
  21. LIGO/Virgo/KAGRA S250818k: Multi-band Gemini GMOS Detections
  22. LIGO/Virgo/KAGRA S250818k: AstroSat CZTI non-detection and upper limits
  23. GRB 250818B: Liverpool Telescope optical detections
  24. LIGO/Virgo/KAGRA S250818k: Properties of the low-significance GW compact binary merger candidate potentially associated with AT 2025ulz
  25. Fermi Gamma-ray Burst Monitor trigger 777342746/250820022 is not a GRB
  26. GRB 250820A: Fermi GBM Final Real-time Localization
  27. Swift GRB 250818A: Global MASTER-Net observations report
  28. LIGO/Virgo/KAGRA S250818k: Coverage and upper limits from MAXI/GSC observations
  29. GRB 250818B: Swift-XRT afterglow detection
  30. GRB 250818B: SVOM detection of a short burst
  31. sb25081602: Swift-XRT observations
  32. SVOM/sb25081602: detection of a likely X-ray transient
  33. GRB 250815A: Fermi GBM Final Localization
  34. GRB 250814A: Further COLIBRÍ optical upper limit
  35. GRB 250814A: detection of the afterglow candidate with Liverpool Telescope
  36. GRB 250814A: GRAWITA TNG NIR observations
  37. GRB 250812A: SVOM/VT optical continued observation
  38. LIGO/Virgo/KAGRA S250813k: Swift XRT observations, 2 X-ray sources
  39. GRB 250814A: P200/WIRC observations of the afterglow candidate
  40. GRB 250814A: possible optical afterglow candidate at Spanish observatories
  41. GRB 250814A: Possible afterglow candidate from P200/WIRC
  42. Subject GRB 250813B: SVOM/MXT refined analysis
  43. GRB 250813A: AstroSat CZTI detection
  44. Fermi-LAT Gamma-ray Observations of IceCube-250813A
  45. GRB 250813B: Swift-XRT afterglow detection
  46. GRB 250814A: Swift detection of a burst coincident with a subthreshold GW trigger
  47. GRB 250813B: Ondrejov D50 fast decay
  48. LIGO/Virgo/KAGRA S250813k: NED Galaxies in the 4-Update Localization Volume
  49. GRB 250812A: NTT spectroscopic redshift z = 2.57
  50. EP250812a: refined analysis of the EP-WXT and EP-FXT observations
  51. IceCube Alert 250813.14: Global MASTER-Net observations report
  52. GRB 250812A: Kilonova-Catcher optical afterglow detection
  53. EP250812a: Swift-XRT counterpart detection
  54. EP250812a: Einstein Probe detection of an X-ray transient
  55. GRB 250812A: Swift-XRT afterglow detection
  56. Fermi-LAT Gamma-ray Observations of IceCube-250804A
  57. LIGO/Virgo/KAGRA S250810ck: Identification of a GW compact binary merger candidate
  58. Corrected Swift-XRT Refined Analysis of GRB 250809A
  59. GRB 250808A: Swift-XRT candidate counterpart detection
  60. GRB 250808A: SVOM detection of a long burst
  61. Konus-Wind detection of GRB 250807A
  62. IceCube-250804A: Upper limits from a search for additional neutrino events in IceCube
  63. GRB 250807A: Swift-XRT refined Analysis
  64. GRB 250806A: SVOM/ECLAIRs refined analysis
  65. GRB 250807A: AstroSat CZTI detection of bright long burst
  66. GRB 250807B: Swift-XRT refined Analysis
  67. GRB 250806A: EP-FXT observation
  68. EP250806a: refined analysis of the EP-WXT and EP-FXT observations
  69. EP250806a: SVOM /VT optical candidate
  70. GRB 250806A: Swift-XRT counterpart detection
  71. EP250806a: Einstein Probe detection of an X-ray transient
  72. GRB 250806A: SVOM detection of a soft burst
  73. GRB 250805A: Swift-XRT refined Analysis
  74. GRB 250804C: AstroSat CZTI detection of a long burst
  75. IceCube-250804A - IceCube observation of a high-energy neutrino candidate track-like event
  76. GRB 250805A: Swift-XRT observations
  77. Swift GRB250805.26: Global MASTER-Net observations report
  78. Fermi Gamma-ray Burst Monitor trigger 775945985/250803856 is not a GRB
  79. The EP-WXT trigger 01709198251 is likely a flaring star
  80. LIGO/Virgo/KAGRA S250802dn: Identification of a GW compact binary merger candidate
  81. The EP-WXT trigger 01709198202 is likely a flaring star
  82. EP250711a: CrAO and Assy optical observations
  83. EP250730a: Einstein Probe detection of an X-ray transient
  84. LIGO/Virgo/KAGRA S250726ak: Upper limits from Swift/BAT-GUANO
  85. LIGO/Virgo/KAGRA S250725l: Upper limits from Swift/BAT-GUANO
  86. LIGO/Virgo/KAGRA S250727dc: Upper limits from Swift/BAT-GUANO
  87. GRB 250725A: AstroSat CZTI detection
  88. Fermi trigger No 775387550: Global MASTER-Net observations report
  89. GRB 250727A: Swift-XRT observations
  90. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  91. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  92. The EP-WXT trigger 01709195487 is likely a flaring star
  93. Swift detection of the Soft Gamma Repeater PSR J1647-4552
  94. GRB 250725A: Swift-XRT refined Analysis
  95. Konus-Wind detection of GRB 250725A
  96. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  97. GRB 250725A: Fermi-LAT detection
  98. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  99. GRB 250725A: Swift detection of a burst
  100. Fermi GRB 250725A: Global MASTER-Net observations report

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