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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"

27215 results found.

  1. LIGO/Virgo/KAGRA S250304cb: Upper limits from Swift/BAT-GUANO
  2. GRB 250226B: Fermi GBM Observation
  3. Swift GRB 250312A: Global MASTER-Net observations report
  4. GRB 250302A: Fermi GBM Observation
  5. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  6. GRB 250312A: Swift detection of a burst
  7. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  8. GRB 250223B: Fermi GBM Observation
  9. GRB 250311A: Swift-XRT observations
  10. GRB 250228A: Fermi GBM Observation
  11. GRB 250309B: 1.3m DFOT Optical observations
  12. EP250311a: Global MASTER-Net observations report
  13. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  14. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  15. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  16. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  17. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  18. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  19. GRB 250309B: PRIME near-infrared detection
  20. GRB 250225B: Swift-BAT refined analysis
  21. GRB 250311A/EP250311a: TRT optical upper limit
  22. EP250311a/GRB 250311A: EP-WXT detection
  23. GRB 250308A: CALET Gamma-Ray Burst Monitor detection
  24. GRB 250311B: SVOM detection of a burst
  25. GRB 250309B: SVOM/VT optical observation
  26. The EP-WXT trigger 01709132425 is not a real source
  27. EP250308a: 1.6m Mephisto optical upper limits
  28. IPN triangulation of GRB 250309B
  29. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  30. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  31. GRB 250309B: Swift-XRT refined Analysis
  32. GRB 250309B / IceCube-250309A: GECAM-B observations
  33. Liverpool Telecope observations of AT 2025dws / GRB 250309B
  34. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  35. GRB 250309B: Fermi GBM Observation
  36. Fermi GRB 250309B: Global MASTER-Net observations report
  37. Fermi GRB 250309A: Global MASTER-Net observations report
  38. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  39. Fermi-LAT gamma-ray observations of IceCube-250309A
  40. GRB 250308A: SVOM/GRM detection of QPO in the tail emission
  41. GRB 250309B: Fermi GBM Final Localization
  42. GRB 250308A: SVOM/GRM observation of a bright short burst
  43. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  44. IceCube Alert 250309.32: Global MASTER-Net observations report
  45. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  46. EP250308a: Global MASTER-Net observations report
  47. EP250308a: GSP optical upper limit
  48. EP250308a: FTW optical and NIR upper limits
  49. EP250308a: Einstein Probe detection of an X-ray transient
  50. EP250308a: NOT optical upper limit
  51. GRB 250309A: Fermi GBM Final Real-time Localization
  52. The EP-WXT trigger 01709132387 is likely a flaring star
  53. Fermi GRB 250307A: Global MASTER-Net observations report
  54. GRB 250307A: Fermi GBM Final Real-time Localization
  55. GRB 250306A: Swift-BAT refined analysis
  56. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  57. EP250302a:Xinglong optical observations
  58. Fermi trigger No 762963055: Global MASTER-Net observations report
  59. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  60. Swift GRB 250306A: Global MASTER-Net observations report
  61. GRB 250306A: Swift detection of a burst
  62. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  63. GRB 250305A: SVOM/GRM observation of a burst
  64. The EP-WXT trigger 01709132323 is likely a flaring star
  65. EP250304A: Upper limits from Fermi-GBM Observations
  66. Fermi GRB 250305A: Global MASTER-Net observations report
  67. GRB 250305A: Fermi GBM Final Real-time Localization
  68. EP250302a: Optical Observations at CrAO and SAO RAS
  69. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  70. EP 250304A: Optical counterpart detection by LCO
  71. EP250302A: 1.3m DFOT optical afterglow detection
  72. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  73. EP250304a: REM NIR upper limits
  74. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  75. EP250302a: Mondy Continued Optical Observations
  76. EP250304a: VLT/X-shooter redshift z = 0.200
  77. EP250304a: Swift-XRT detection of a fading X-ray source
  78. EP250304a: TRT optical counterpart detection
  79. EP250304a: Global MASTER-Net observations report
  80. EP250304a: Einstein Probe detection of an X-ray transient
  81. The EP-WXT trigger 01709132212 is not a real source
  82. EP250302a: SVOM/VT optical observation
  83. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  84. EP250302a : GIT optical follow-up
  85. EP250225a: the candidate optical counterpart is an AGN
  86. EP250302a: Kinder optical follow-up observations
  87. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  88. EP250302a: Swift/UVOT detection
  89. EP250302a: NUTTelA-TAO Early Measurments
  90. EP250302a: optical observation from the INAF Asiago Observatory
  91. EP250302a: REM NIR upper limits
  92. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  93. EP250302a: Mondy Observations and Optical Light Curve
  94. EP250302a: VLT/MUSE optical redshift z = 1.131
  95. EP250302a: OHP/T193 optical and spectroscopic observations
  96. EP250302a: Global MASTER-Net observations report
  97. EP250302a: Xinglong F60B optical observation
  98. EP250302a: Swift-XRT observations of a fading X-ray source
  99. EP250302a: Einstein Probe detection of an X-ray transient
  100. EP250302a: SVOM/C-GFT optical observations

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