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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').
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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"

10363 results found.

  1. Fermi GRB 250407A: Global MASTER-Net observations report
  2. GRB 250407A: SRG/ART-XC afterglow detection
  3. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  4. Konus-Wind detection of GRB 250406B (short/hard)
  5. GRB 250406A: AstroSat CZTI detection
  6. Fermi trigger No 765663719: Global MASTER-Net observations report
  7. Fermi GRB 250406A: Global MASTER-Net observations report
  8. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  9. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  10. Konus-Wind detection of GRB 250404A / EP250404a
  11. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  12. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  13. GRB 250404B: AstroSat CZTI detection of a short burst
  14. GRB 250403A: AstroSat CZTI detection
  15. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  16. EP250404a: LCO optical counterpart detection
  17. Fermi GRB 250404A: Global MASTER-Net observations report
  18. EP250404a: Xinglong decaying optical counterpart
  19. EP250404a: Global MASTER-Net observations report
  20. EP250404a: AKO Optical Afterglow Detection
  21. EP250404a: LAST detection of optical counterpart
  22. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  23. EP250404a: Mephisto multi-band optical detection
  24. EP250321A: J band upper limit by SYSU 80cm telescope
  25. EP250404a: BOOTES-4/JGT optical afterglow detection
  26. EP250404a: Nanshan/HMT optical counterpart detection
  27. EP250404a: Einstein Probe detection of an X-ray transient
  28. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  29. GRB 250402A: EP-FXT afterglow detection
  30. GRB 250322A: 10 GHz VLA radio upper limits
  31. GRB 250403A: GOTO optical counterpart follow-up observations
  32. GRB 250403A : SVOM detection of a burst
  33. GRB 250402B: AstroSat CZTI detection of a short burst
  34. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  35. GRB 250331D: Fermi GBM observation
  36. GRB 250328A: AbAO AS-32 Optical Observations
  37. GRB 250322B: GRBAlpha detection
  38. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  39. Fermi GRB 250331D: Global MASTER-Net observations report
  40. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  41. Konus-Wind detection of GRB 250327B
  42. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  43. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  44. Fermi-LAT gamma-ray observations of IceCube-250330A
  45. GRB 250331A: MAXI/GSC detection
  46. Fermi GRB 250330B: Global MASTER-Net observations report
  47. IceCube Alert 250330.35: Global MASTER-Net observations report
  48. GRB 250329B: Swift-XRT afterglow detection
  49. Swift GRB250330.26: Global MASTER-Net observations report
  50. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  51. GRB 250329A: SVOM detection of a burst
  52. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  53. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  54. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  55. GRB 250327A: Swift-XRT refined Analysis
  56. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  57. Konus-Wind detection of GRB 250322A (short)
  58. IPN triangulation of GRB 250322B
  59. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  60. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  61. GRB 250322A: AstroSat CZTI detection of a short burst
  62. GRB 250322B: AstroSat CZTI detection of a bright long burst
  63. GRB 250322A: NOT optical upper limits
  64. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  65. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  66. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  67. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  68. GRB 250320B: Fermi GBM Observation
  69. GRB 250320B: Fermi-LAT detection
  70. GRB 250320B: AstroSat CZTI detection
  71. Swift GRB 250321A: Global MASTER-Net observations report
  72. Fermi GRB 250321A: Global MASTER-Net observations report
  73. EP250226a/GRB 250226A: KAIT optical observations
  74. GRB 250320B: Fermi GBM Final Real-time Localization
  75. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  76. GRB 250320A: Fermi GBM Final Real-time Localization
  77. Fermi GRB 250319B: Global MASTER-Net observations report
  78. GRB 250317C: AstroSat CZTI detection
  79. GRB 250316A: Swift-XRT afterglow detection
  80. Fermi GRB 250316A: Global MASTER-Net observations report
  81. GRB 250314A: EP-FXT afterglow detection
  82. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  83. GRB 250312B: GRBAlpha detection
  84. EP250315a: Einstein Probe detection of an X-ray transient
  85. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  86. GRB 250314A: NOT near-infrared candidate counterpart
  87. GRB 250313A: Fermi GBM Detection
  88. GRB 250312B: Fermi GBM Observation
  89. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  90. Konus-Wind detection of GRB 250313A
  91. Konus-Wind detection of GRB 250308A
  92. GRB 250314A: SVOM detection of a burst
  93. GRB 250313A: AstroSat CZTI detection of a bright long burst
  94. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  95. GRB 250313A: Fermi-LAT detection
  96. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  97. Fermi GRB 250313A: Global MASTER-Net observations report
  98. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  99. EP250302a: Chandra X-ray Detection
  100. GRB 250312A: Swift-XRT refined Analysis

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