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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').
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"

11757 results found.

  1. Fermi trigger No 775387550: Global MASTER-Net observations report
  2. GRB 250727A: Swift-XRT observations
  3. LIGO/Virgo/KAGRA S250727dc: Identification of a GW compact binary merger candidate
  4. LIGO/Virgo/KAGRA S250727cl: Identification of a GW compact binary merger candidate
  5. The EP-WXT trigger 01709195487 is likely a flaring star
  6. GRB 250725A: Swift-XRT refined Analysis
  7. Konus-Wind detection of GRB 250725A
  8. LIGO/Virgo/KAGRA S250725j: NED Galaxies in the 3-Initial Localization Volume
  9. GRB 250725A: Fermi-LAT detection
  10. LIGO/Virgo/KAGRA S250725l: Identification of a GW compact binary merger candidate
  11. GRB 250725A: Swift detection of a burst
  12. Fermi GRB 250725A: Global MASTER-Net observations report
  13. Swift GRB 250725A: Global MASTER-Net observations report
  14. SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
  15. SVOM J195836+32283/sb25072103: NIR observations with WINTER
  16. GRB 250717B: SVOM/GRM observation
  17. The SVOM alert sb25072103 is not due to a GRB, but to a new galactic transient SVOM J195836+32283.
  18. GRB 250721A: MAXI/GSC detection
  19. GRB 250720B: Fermi GBM Final Localization Correction
  20. GRB 250720A: Fermi GBM Final Localization
  21. Fermi trigger No 774730635: Global MASTER-Net observations report
  22. Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
  23. LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
  24. GRB 270713A: Kitab and AbAO Optical Observations
  25. Konus-Wind detection of GRB 250716A
  26. GRB 250716A: Swift-XRT afterglow detection
  27. Fermi GRB 250716A: Global MASTER-Net observations report
  28. GRB 250713A: SVOM/C-GFT upper limit
  29. GRB 250713A: Swift-XRT observations
  30. EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
  31. Fermi GRB 250711A: Global MASTER-Net observations report
  32. EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
  33. LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
  34. GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
  35. LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
  36. LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
  37. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
  38. GRB 250704B / EP250704a: VLA radio detection
  39. GRB 250706B/C: Konus-Wind analysis of the prompt emission
  40. GRB 250704B / EP250704a: Mondy and AbAO optical observations
  41. Fermi-LAT Gamma-ray Observations of IceCube-250706A
  42. GRB 250706B/C: Fermi-LAT detection
  43. IceCube-250706A: Global MASTER-Net observations report
  44. EP250702a/ GRB 250702B: NuSTAR X-ray Observations
  45. GRB 250706C: Konus-Wind detection of a very bright GRB ~1200 s before GRB 250706B
  46. GRB 250704A: Swift/BAT-GUANO localization skymap of a burst
  47. GRB 250706B: refined SVOM/MXT data analysis
  48. GRB 250706A: SAO RAS optical observations
  49. GRB250706B: Swift-XRT counterpart detection
  50. GRB 250706B: iTelescope optical observations
  51. GRB 250706B: SVOM detection of a long burst
  52. GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
  53. EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
  54. Konus-Wind detection of GRB 250703A
  55. EP250704a/GRB 250704B: GSP observations of the optical counterpart
  56. Konus-Wind detection of short/hard GRB 250704B/ EP250704a
  57. EP250704a/GRB 250704B VLT/HAWK-I NIR afterglow detection
  58. LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 3-Initial Localization Volume
  59. EP250704a: refined analysis of the EP-WXT and FXT follow-up observations
  60. EP250704a / GRB250704B: Swift-XRT counterpart detection
  61. GRB 250704A: Swift-XRT afterglow detection
  62. Konus-Wind detection of GRB 250702F
  63. EP250704a: COLIBRÍ optical counterpart candidate
  64. EP250704a: Einstein Probe detection of an X-ray transient
  65. LIGO/Virgo/KAGRA S250704ab: Coverage and upper limits from MAXI/GSC observations
  66. GRB 250704A: SVOM detection of a burst
  67. Fermi GRB 250703A: Global MASTER-Net observations report
  68. GRB 250702F: Swift-XRT refined Analysis
  69. GRBs 250702B,C,D,E / EP250702a: VLT/HAWK-I NIR candidate
  70. GRBs 250702B,C,D,E / EP250702a: SVOM/GRM observation
  71. GRBs 250702B,C,D,E / EP250702a: Konus-Wind detection of a hard X-ray transient activity
  72. EP250702a: Global MASTER-Net observations report
  73. EP250702a : an X-ray transient detected by Einstein Probe likely associated with GRB 250702B,C,D,E
  74. Fermi GRB 250702C: Global MASTER-Net observations report
  75. Konus-Wind detection of GRB 250627A
  76. LIGO/Virgo/KAGRA S250701bp: Identification of a GW compact binary merger candidate
  77. GRB 250628B: Swift-XRT observations
  78. GRB 250628A: REM optical/NIR upper limits
  79. GRB 250628B: SVOM detection of a long burst
  80. GRB 250628A: Swift-XRT refined Analysis
  81. Fermi GRB 250626A: Global MASTER-Net observations report
  82. GRB 250628A: Swift detection of a burst
  83. GRB 250625A: Leavitt Observatory afterglow detection
  84. GRB 250625A: ABObservatory afterglow detection
  85. GRB 250625A: OHP/T193 optical detection
  86. GRB 250625A: Fermi-LAT detection
  87. GRB 250625A: Swift-XRT refined Analysis
  88. Swift GRB 250625A: Global MASTER-Net observations report
  89. GRB 250620B: Fermi GBM Observation
  90. GRB 250625A: SAO RAS possible optical afterglow
  91. Fermi GRB 250625A: Global MASTER-Net observations report
  92. GRB 250625A: Swift detection of a burst
  93. GRB 250620A: AstroSat CZTI detection
  94. The EP-WXT trigger 01709179396 is likely a flaring star CSTAR 38580
  95. GRB 241018A: Maidanak optical observations
  96. GRB 250620C: AstroSat CZTI detection
  97. sb25061207/GRB 250612D - SVOM/ECLAIRs refined analysis
  98. Fermi GRB 250623A: Global MASTER-Net observations report
  99. Fermi trigger No 772190032: Global MASTER-Net observations report
  100. Konus-Wind detection of GRB 250620C

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