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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"

27212 results found.

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

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