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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"

43953 results found.

  1. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  2. IceCube Alert 250309.32: Global MASTER-Net observations report
  3. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  4. EP250308a: Global MASTER-Net observations report
  5. EP250308a: GSP optical upper limit
  6. EP250308a: FTW optical and NIR upper limits
  7. EP250308a: Einstein Probe detection of an X-ray transient
  8. EP250308a: NOT optical upper limit
  9. GRB 250309A: Fermi GBM Final Real-time Localization
  10. GRB 250306A: EIRSAT-1 GMOD detection
  11. The EP-WXT trigger 01709132387 is likely a flaring star
  12. Fermi GRB 250307A: Global MASTER-Net observations report
  13. Konus-Wind detection of GRB 250306A
  14. GRB 250307A: Fermi GBM Final Real-time Localization
  15. GRB 250306A: Swift-BAT refined analysis
  16. GRB 250306A: NuSTAR detection of the prompt emission
  17. EP250304a: MeerKAT detection of a possible radio counterpart
  18. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  19. GRB 250305A: AstroSat CZTI detection
  20. EP250302a:Xinglong optical observations
  21. GRB 250306A: AstroSat CZTI detection
  22. Fermi trigger No 762963055: Global MASTER-Net observations report
  23. Fermi Gamma-ray Burst Monitor trigger 762963055/250306591 is not a GRB
  24. Swift GRB 250306A: Global MASTER-Net observations report
  25. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  26. GRB 250306A: Swift detection of a burst
  27. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  28. GRB250101A: Radio upper limits from VLA observations
  29. LIGO/Virgo/KAGRA S250306ej: Retraction of GW compact binary merger candidate
  30. GRB 250305A: SVOM/GRM observation of a burst
  31. The EP-WXT trigger 01709132323 is likely a flaring star
  32. EP250304A: Upper limits from Fermi-GBM Observations
  33. Fermi GRB 250305A: Global MASTER-Net observations report
  34. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  35. GRB 250305A: Fermi GBM Final Real-time Localization
  36. EP250302a: Optical Observations at CrAO and SAO RAS
  37. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  38. EP 250304A: Optical counterpart detection by LCO
  39. EP250302A: 1.3m DFOT optical afterglow detection
  40. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  41. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  42. Konus-Wind detection of GRB 250222A
  43. EP250304a: REM NIR upper limits
  44. IPN triangulation of GRB 250222A
  45. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  46. EP250302a: Mondy Continued Optical Observations
  47. EP250304a: VLT/X-shooter redshift z = 0.200
  48. EP250304a: Swift-XRT detection of a fading X-ray source
  49. EP250304a: TRT optical counterpart detection
  50. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  51. EP250304a: Global MASTER-Net observations report
  52. EP250304a: Einstein Probe detection of an X-ray transient
  53. The EP-WXT trigger 01709132212 is not a real source
  54. EP250302a: SVOM/VT optical observation
  55. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  56. EP250302a: SAO RAS optical observations
  57. EP250302a : GIT optical follow-up
  58. EP250302a: VLT/X-shooter redshift confirmation
  59. EP250225a: the candidate optical counterpart is an AGN
  60. EP250302a: Kinder optical follow-up observations
  61. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  62. EP250302a: Swift/UVOT detection
  63. EP250302a: NUTTelA-TAO Early Measurments
  64. EP250302a: optical observation from the INAF Asiago Observatory
  65. EP250302a: REM NIR upper limits
  66. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  67. EP250302a: Mondy Observations and Optical Light Curve
  68. EP250302a: VLT/MUSE optical redshift z = 1.131
  69. INTEGRAL: end of scientific operations
  70. EP250302A: VLT near-infrared observations
  71. EP250302A: VLT/X-shooter tentative redshift
  72. EP250302a: OHP/T193 optical and spectroscopic observations
  73. EP250302a: Global MASTER-Net observations report
  74. EP250302a: Swift-XRT observations of a fading X-ray source
  75. EP250302a: Einstein Probe detection of an X-ray transient
  76. EP250302a: SVOM/C-GFT optical observations
  77. GRB 250226A: GRANDMA Optical Observations
  78. Fermi GRB 250302A: Global MASTER-Net observations report
  79. EP250302a: FTW optical and NIR detection
  80. EP250302a: Nanshan/HMT optical counterpart detection
  81. IceCube-250302A - IceCube observation of a high-energy neutrino candidate track-like event
  82. GRB 250302A: Fermi GBM Final Real-time Localization
  83. GRB 250228A: Fermi GBM Final Localization
  84. The EP-WXT trigger 01709132140 is likely a flaring star
  85. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  86. EP250228a: Optical observations with Kinder and Swift/UVOT
  87. Konus-Wind detection of GRB 250226A
  88. GRB 250225B: EIRSAT-1 GMOD Detection
  89. GRB 250226A: KAO Optical Upper Limit
  90. GRB 250226A: AbAO AS-32 Optical Upper Limit
  91. EP250227a: Global MASTER-Net observations report
  92. EP250223A: Upper limits from Fermi-GBM Observations
  93. EP250227a: TRT optical upper limit
  94. GRB 250225B: VLT/HAWKI near-infrared observations
  95. EP250227a: Optical upper limits with Kinder observations
  96. EP250227a: NOT optical observations
  97. EP250227a: Einstein Probe detected of a fast X-ray transient
  98. EP250228a: updates on the EP observations
  99. GRB 250226A: Fermi GBM Observation
  100. EP250225a: EP-FXT follow-up observation

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