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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.

Advanced Search Examples (click to copy):

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

11762 results found.

  1. GRB 250407A: SRG/ART-XC afterglow detection
  2. LIGO/Virgo/KAGRA S250331o: Upper limits from Swift/BAT-GUANO
  3. Konus-Wind detection of GRB 250406B (short/hard)
  4. GRB 250406A: AstroSat CZTI detection
  5. Fermi trigger No 765663719: Global MASTER-Net observations report
  6. Fermi GRB 250406A: Global MASTER-Net observations report
  7. EP250404a / GRB 250404A: Montarrenti Observatory optical observations
  8. EP250404a / GRB 250404A: J band observations by SYSU 80cm telescope
  9. Konus-Wind detection of GRB 250404A / EP250404a
  10. EP250404a: refined analysis of the EP-WXT and EP-FXT observations
  11. GRB 250404A / EP250404a: Leavitt Observatory optical counterpart detection
  12. GRB 250404B: AstroSat CZTI detection of a short burst
  13. GRB 250403A: AstroSat CZTI detection
  14. EP250404a: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
  15. EP250404a: LCO optical counterpart detection
  16. Fermi GRB 250404A: Global MASTER-Net observations report
  17. EP250404a: Xinglong decaying optical counterpart
  18. EP250404a: Global MASTER-Net observations report
  19. EP250404a: AKO Optical Afterglow Detection
  20. EP250404a: LAST detection of optical counterpart
  21. GRB 250402A: Swift/BAT-GUANO localization skymap of a burst
  22. EP250404a: Mephisto multi-band optical detection
  23. EP250321A: J band upper limit by SYSU 80cm telescope
  24. EP250404a: BOOTES-4/JGT optical afterglow detection
  25. EP250404a: Nanshan/HMT optical counterpart detection
  26. EP250404a: Einstein Probe detection of an X-ray transient
  27. IceCube-250330A: MASTER detection of PKS 2032+107 blazar flare with Zhirkov effect
  28. GRB 250402A: EP-FXT afterglow detection
  29. GRB 250322A: 10 GHz VLA radio upper limits
  30. GRB 250403A: GOTO optical counterpart follow-up observations
  31. GRB 250403A : SVOM detection of a burst
  32. GRB 250402B: AstroSat CZTI detection of a short burst
  33. GRB 250331C: Calapai Observatory, Massa S. Giorgio (Messina), upper limit
  34. GRB 250331D: Fermi GBM observation
  35. GRB 250328A: AbAO AS-32 Optical Observations
  36. GRB 250322B: GRBAlpha detection
  37. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 2)
  38. Fermi GRB 250331D: Global MASTER-Net observations report
  39. GRB 250329A: AbAO, Mondy and SAO RAS optical upper limits
  40. Konus-Wind detection of GRB 250327B
  41. LIGO/Virgo/KAGRA S250331o: NED Galaxies in the 3-Initial Localization Volume
  42. LIGO/Virgo/KAGRA S250328ae: Swift XRT observations, 34 possible X-ray sources
  43. Fermi-LAT gamma-ray observations of IceCube-250330A
  44. GRB 250331A: MAXI/GSC detection
  45. Fermi GRB 250330B: Global MASTER-Net observations report
  46. IceCube Alert 250330.35: Global MASTER-Net observations report
  47. GRB 250329B: Swift-XRT afterglow detection
  48. Swift GRB250330.26: Global MASTER-Net observations report
  49. LIGO/Virgo/KAGRA S250328ae: DECam DESGW Candidates (Epoch 1)
  50. GRB 250329A: SVOM detection of a burst
  51. LIGO/Virgo/KAGRA S250328ae: NED Galaxies in the 4-Update Localization Volume
  52. EP250302a: SPI-ACS/INTEGRAL Upper Limit
  53. GRB 250327B: Swift-XRT detection of the X-ray afterglow
  54. GRB 250327A: Swift-XRT refined Analysis
  55. FRB 20250316A: The sub-arcsecond localization of FRB 20250316A using CHIME/FRB Outriggers coincides with reported X-ray counterparts
  56. Konus-Wind detection of GRB 250322A (short)
  57. IPN triangulation of GRB 250322B
  58. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  59. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  60. GRB 250322A: AstroSat CZTI detection of a short burst
  61. GRB 250322B: AstroSat CZTI detection of a bright long burst
  62. GRB 250322A: NOT optical upper limits
  63. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  64. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  65. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  66. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  67. GRB 250320B: Fermi GBM Observation
  68. GRB 250320B: Fermi-LAT detection
  69. GRB 250320B: AstroSat CZTI detection
  70. Swift GRB 250321A: Global MASTER-Net observations report
  71. Fermi GRB 250321A: Global MASTER-Net observations report
  72. EP250226a/GRB 250226A: KAIT optical observations
  73. GRB 250320B: Fermi GBM Final Real-time Localization
  74. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  75. GRB 250320A: Fermi GBM Final Real-time Localization
  76. Fermi GRB 250319B: Global MASTER-Net observations report
  77. GRB 250317C: AstroSat CZTI detection
  78. GRB 250316A: Swift-XRT afterglow detection
  79. Fermi GRB 250316A: Global MASTER-Net observations report
  80. GRB 250314A: EP-FXT afterglow detection
  81. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  82. GRB 250312B: GRBAlpha detection
  83. EP250315a: Einstein Probe detection of an X-ray transient
  84. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  85. GRB 250314A: NOT near-infrared candidate counterpart
  86. GRB 250313A: Fermi GBM Detection
  87. GRB 250312B: Fermi GBM Observation
  88. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  89. Konus-Wind detection of GRB 250313A
  90. Konus-Wind detection of GRB 250308A
  91. GRB 250314A: SVOM detection of a burst
  92. GRB 250313A: AstroSat CZTI detection of a bright long burst
  93. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  94. GRB 250313A: Fermi-LAT detection
  95. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  96. Fermi GRB 250313A: Global MASTER-Net observations report
  97. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  98. EP250302a: Chandra X-ray Detection
  99. GRB 250312A: Swift-XRT refined Analysis
  100. Fermi trigger No 763509110: Global MASTER-Net observations report

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