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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"

43952 results found.

  1. EP250315a: Einstein Probe detection of an X-ray transient
  2. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  3. SVOM/MXT upper limit on GRB 250314A
  4. GRB 250314A: SVOM/VT upper limit
  5. GRB 250314A: NOT near-infrared candidate counterpart
  6. GRB 250313A: Fermi GBM Detection
  7. GRB 250313A: CALET Gamma-Ray Burst Monitor detection
  8. GRB 250312B: Fermi GBM Observation
  9. GRB 250313A: Swift-XRT observations
  10. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  11. Konus-Wind detection of GRB 250313A
  12. Konus-Wind detection of GRB 250308A
  13. GRB 250314A: SVOM detection of a burst
  14. EP250311a/GRB 250311A: Correction to EP-WXT detection time
  15. GRB 250313B: SVOM/GRM observation of a soft bright short burst
  16. GRB 250313A: SVOM/GRM observation of a bright long burst
  17. FRB 20250206A: Nondetection of Repeating Bursts from FRB 20250206A with FAST
  18. GRB 250313A: AstroSat CZTI detection of a bright long burst
  19. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  20. Fermi trigger No 763581136: Global MASTER-Net observations report
  21. GRB 250313A: Fermi-LAT detection
  22. GRB 250313A: Swift ToO observations
  23. EP250304a: Pan-STARRS r and i-band imaging and photometry
  24. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  25. EP trigger ID 01709061302: Lick/Kast spectroscopy with the 3 m Shane telescope
  26. Fermi GRB 250313A: Global MASTER-Net observations report
  27. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  28. GRB 250313A???: BALROG localization (Fermi Trigger / GRB 250313607)
  29. GRB 250313A: Fermi GBM Final Real-time Localization
  30. The EP-WXT trigger 01709132551 is not a real source
  31. EP250304a: SVOM/VT optical observation
  32. EP250311a/GRB 250311A: EP-FXT follow-up observation
  33. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  34. EP250302a: Chandra X-ray Detection
  35. GRB 250312A: Swift-XRT refined Analysis
  36. Fermi Gamma-ray Burst Monitor trigger 763509110/250312911 is not a GRB
  37. Fermi trigger No 763509110: Global MASTER-Net observations report
  38. Fermi GRB 250312B: Global MASTER-Net observations report
  39. GRB 250312A: Enhanced Swift-XRT position
  40. GRB 250312B: Fermi GBM Final Localization
  41. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  42. GRB 250226B: Fermi GBM Observation
  43. Swift GRB 250312A: Global MASTER-Net observations report
  44. GRB 250302A: Fermi GBM Observation
  45. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  46. GRB 250312A: Swift detection of a burst
  47. GRB 241213A: VIRT Optical Upper Limit
  48. GRB 241228A: VIRT Optical Upper Limit
  49. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  50. GRB 250223B: Fermi GBM Observation
  51. GRB 250311A: Swift-XRT observations
  52. GRB 250228A: Fermi GBM Observation
  53. GRB 250309B: 1.3m DFOT Optical observations
  54. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  55. EP250311a: Global MASTER-Net observations report
  56. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  57. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  58. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  59. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  60. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  61. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  62. GRB 250309B: PRIME near-infrared detection
  63. EP250304a: Chandra detection
  64. GRB 250225B: Swift-BAT refined analysis
  65. GRB 250311A/EP250311a: TRT optical upper limit
  66. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  67. GRB 250311A: Tiled Swift observations
  68. EP250311a/GRB 250311A: EP-WXT detection
  69. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  70. GRB 250311B: SVOM detection of a burst
  71. GRB 250309B: SVOM/VT optical observation
  72. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  73. The EP-WXT trigger 01709132425 is not a real source
  74. GRB 250309B / AT2025dws: further SAO RAS optical observations
  75. IceCube-250309A: Upper limits from Fermi-GBM Observations
  76. EP250308a: 1.6m Mephisto optical upper limits
  77. Konus-Wind detection of GRB 250309B
  78. IPN triangulation of GRB 250308A (short)
  79. IPN triangulation of GRB 250309B
  80. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  81. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  82. GRB 250309B: Swift-XRT refined Analysis
  83. GRB 250309B / IceCube-250309A: GECAM-B observations
  84. GRB 250309B / AT2025dws: OSIRIS+/GTC spectroscopy z=1.898
  85. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  86. GRB 250309B / AT2025dws: SAO RAS optical observations
  87. GRB 250309B / AT2025dws: Swift-UVOT detection
  88. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  89. GRB 250309B: Fermi GBM Observation
  90. Fermi GRB 250309B: Global MASTER-Net observations report
  91. Fermi GRB 250309A: Global MASTER-Net observations report
  92. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  93. IceCube-250309A: No candidates from the Zwicky Transient Facility
  94. Fermi-LAT gamma-ray observations of IceCube-250309A
  95. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  96. GRB 250309B: Fermi GBM Final Localization
  97. Correction to GCN 39633 - Swift is observing GRB 250309B/IceCube-250309A!
  98. GRB 230509B: Tiled Swift observations
  99. GRB 250308A: SVOM/GRM observation of a bright short burst
  100. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event

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