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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').
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"

27839 results found.

  1. EP250304a: Pan-STARRS r and i-band imaging and photometry
  2. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  3. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  4. GRB 250313A: Fermi GBM Final Real-time Localization
  5. EP250304a: SVOM/VT optical observation
  6. EP250311a/GRB 250311A: EP-FXT follow-up observation
  7. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  8. EP250302a: Chandra X-ray Detection
  9. GRB 250312A: Swift-XRT refined Analysis
  10. GRB 250312A: Enhanced Swift-XRT position
  11. GRB 250312B: Fermi GBM Final Localization
  12. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  13. GRB 250226B: Fermi GBM Observation
  14. Swift GRB 250312A: Global MASTER-Net observations report
  15. GRB 250302A: Fermi GBM Observation
  16. GRB 250312A: Swift detection of a burst
  17. GRB 241213A: VIRT Optical Upper Limit
  18. GRB 241228A: VIRT Optical Upper Limit
  19. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  20. GRB 250223B: Fermi GBM Observation
  21. GRB 250311A: Swift-XRT observations
  22. GRB 250228A: Fermi GBM Observation
  23. GRB 250309B: 1.3m DFOT Optical observations
  24. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  25. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  26. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  27. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  28. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  29. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  30. GRB 250309B: PRIME near-infrared detection
  31. EP250304a: Chandra detection
  32. GRB 250225B: Swift-BAT refined analysis
  33. GRB 250311A: Tiled Swift observations
  34. EP250311a/GRB 250311A: EP-WXT detection
  35. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  36. GRB 250311B: SVOM detection of a burst
  37. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  38. IceCube-250309A: Upper limits from Fermi-GBM Observations
  39. Konus-Wind detection of GRB 250309B
  40. IPN triangulation of GRB 250308A (short)
  41. IPN triangulation of GRB 250309B
  42. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  43. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  44. GRB 250309B: Swift-XRT refined Analysis
  45. GRB 250309B / AT2025dws: Swift-UVOT detection
  46. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  47. IceCube-250309A: No candidates from the Zwicky Transient Facility
  48. Fermi-LAT gamma-ray observations of IceCube-250309A
  49. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  50. GRB 250309B: Fermi GBM Final Localization
  51. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  52. GRB 230509B: Tiled Swift observations
  53. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  54. EP250308a: GSP optical upper limit
  55. EP250308a: Einstein Probe detection of an X-ray transient
  56. GRB 250309A: Fermi GBM Final Real-time Localization
  57. GRB 250306A: EIRSAT-1 GMOD detection
  58. Konus-Wind detection of GRB 250306A
  59. GRB 250307A: Fermi GBM Final Real-time Localization
  60. GRB 250306A: Swift-BAT refined analysis
  61. GRB 250306A: NuSTAR detection of the prompt emission
  62. EP250304a: MeerKAT detection of a possible radio counterpart
  63. GRB 250305A: AstroSat CZTI detection
  64. GRB 250306A: AstroSat CZTI detection
  65. Swift GRB 250306A: Global MASTER-Net observations report
  66. GRB 250306A: Swift detection of a burst
  67. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  68. GRB 250305A: Fermi GBM Final Real-time Localization
  69. EP 250304A: Optical counterpart detection by LCO
  70. EP250302A: 1.3m DFOT optical afterglow detection
  71. Konus-Wind detection of GRB 250222A
  72. IPN triangulation of GRB 250222A
  73. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  74. EP250304a: Swift-XRT detection of a fading X-ray source
  75. EP250304a: TRT optical counterpart detection
  76. EP250304a: Einstein Probe detection of an X-ray transient
  77. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  78. EP250225a: the candidate optical counterpart is an AGN
  79. EP250302a: Swift/UVOT detection
  80. EP250302a: Swift-XRT observations of a fading X-ray source
  81. EP250302a: Einstein Probe detection of an X-ray transient
  82. EP250302a: Montarrenti Observatory optical detection
  83. EP250302a: FTW optical and NIR detection
  84. EP250302a: Nanshan/HMT optical counterpart detection
  85. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  86. GRB 250302A: Fermi GBM Final Real-time Localization
  87. GRB 250228A: Fermi GBM Final Localization
  88. EP250228a: Optical observations with Kinder and Swift/UVOT
  89. Konus-Wind detection of GRB 250226A
  90. GRB 250225B: EIRSAT-1 GMOD Detection
  91. GRB 250225B: VLT/HAWKI near-infrared observations
  92. EP250227a: Optical upper limits with Kinder observations
  93. EP250227a: Einstein Probe detected of a fast X-ray transient
  94. EP250228a: updates on the EP observations
  95. EP250225a: EP-FXT follow-up observation
  96. EP250228a: Swift/XRT localisation
  97. EP250228a: Einstein Probe detection of an X-ray transient
  98. GRB 250226A / EP250226a: LCO detection of the afterglow
  99. GRB 250226B: INTEGRAL SPI-ACS and PICsIT detection
  100. EP250226a/GRB 250226A: INTEGRAL SPI-ACS and PICsIT detection

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