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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"

27216 results found.

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

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