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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. 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').
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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.

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subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

24663 results found.

  1. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  2. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  3. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  4. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  5. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  6. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  7. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  8. GRB 250309B: PRIME near-infrared detection
  9. GRB 250225B: Swift-BAT refined analysis
  10. GRB 250311A/EP250311a: TRT optical upper limit
  11. EP250311a/GRB 250311A: EP-WXT detection
  12. GRB 250311B: SVOM detection of a burst
  13. GRB 250311A/MAXI J1457-026: MAXI/GSC detection
  14. GRB 250309B / AT2025dws: further SAO RAS optical observations
  15. EP250308a: 1.6m Mephisto optical upper limits
  16. Konus-Wind detection of GRB 250309B
  17. IPN triangulation of GRB 250308A (short)
  18. IceCube-241224A: MASTER detection of PKS 1217+02 blazar flare with Zhirkov effect
  19. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  20. GRB 250309B: Swift-XRT refined Analysis
  21. GRB 250309B / IceCube-250309A: GECAM-B observations
  22. GRB 250309B / AT2025dws: SAO RAS optical observations
  23. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  24. GRB 250309B: Fermi GBM Observation
  25. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  26. IceCube-250309A: No candidates from the Zwicky Transient Facility
  27. Fermi-LAT gamma-ray observations of IceCube-250309A
  28. IceCube-250309A - IceCube observation of a high-energy neutrino candidate track-like event
  29. GRB 250309B: BALROG localization (Fermi Trigger 763198715 / GRB 250309318)
  30. EP250308a: GSP optical upper limit
  31. EP250308a: Einstein Probe detection of an X-ray transient
  32. EP250308a: NOT optical upper limit
  33. GRB 250306A: EIRSAT-1 GMOD detection
  34. GRB 250306A: Swift-BAT refined analysis
  35. GRB 250306A: NuSTAR detection of the prompt emission
  36. EP250304a: MeerKAT detection of a possible radio counterpart
  37. IceCube-241016A: MASTER flaring blazar 5BZU J073038.29-320820.2 with Zhirkov effect
  38. GRB 250305A: AstroSat CZTI detection
  39. EP250302a:Xinglong optical observations
  40. LIGO/Virgo/KAGRA S250207bg: Update-5 NED Galaxies in the Localization Volume
  41. LIGO/Virgo/KAGRA S250207bg: Updated Sky localization
  42. GRB250101A: Radio upper limits from VLA observations
  43. GRB 250305A: SVOM/GRM observation of a burst
  44. The EP-WXT trigger 01709132323 is likely a flaring star
  45. EP250304A: Upper limits from Fermi-GBM Observations
  46. Fermi-LAT Gamma-ray Observations of IceCube-250302A
  47. EP250302a: Optical Observations at CrAO and SAO RAS
  48. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  49. EP 250304A: Optical counterpart detection by LCO
  50. EP250302A: 1.3m DFOT optical afterglow detection
  51. IceCube-250302A: Upper limits from a search for additional neutrino events in IceCube
  52. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  53. EP250304a: REM NIR upper limits
  54. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  55. EP250302a: Mondy Continued Optical Observations
  56. EP250304a: Swift-XRT detection of a fading X-ray source
  57. EP250304a: TRT optical counterpart detection
  58. LIGO/Virgo/KAGRA S250304cb: Identification of a GW compact binary merger candidate
  59. EP250304a: Einstein Probe detection of an X-ray transient
  60. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  61. EP250302a: SAO RAS optical observations
  62. EP250302a : GIT optical follow-up
  63. EP250225a: the candidate optical counterpart is an AGN
  64. EP250302a: Kinder optical follow-up observations
  65. LIGO/Virgo/KAGRA S250302av: 2 counterpart neutrino candidate events from an IceCube neutrino search
  66. EP250302a: Swift/UVOT detection
  67. EP250302a: optical observation from the INAF Asiago Observatory
  68. EP250302a: REM NIR upper limits
  69. IceCube-241113A: MASTER flaring blazar 5BZB J1311+0853 with Zhirkov effect
  70. EP250302a: Mondy Observations and Optical Light Curve
  71. EP250302a: VLT/MUSE optical redshift z = 1.131
  72. EP250302A: VLT near-infrared observations
  73. EP250302A: VLT/X-shooter tentative redshift
  74. EP250302a: OHP/T193 optical and spectroscopic observations
  75. EP250302a: Swift-XRT observations of a fading X-ray source
  76. EP250302a: Einstein Probe detection of an X-ray transient
  77. EP250302a: SVOM/C-GFT optical observations
  78. GRB 250226A: GRANDMA Optical Observations
  79. EP250302a: Montarrenti Observatory optical detection
  80. EP250302a: Nanshan/HMT optical counterpart detection
  81. LIGO/Virgo/KAGRA S250206dm: early X-ray upper limits from Einstein Probe WXT and preliminary results of FXT observations
  82. GRB 250225B: VLT near-infrared afterglow confirmation
  83. EP250228a: Optical observations with Kinder and Swift/UVOT
  84. Konus-Wind detection of GRB 250226A
  85. GRB 250225B: EIRSAT-1 GMOD Detection
  86. GRB 250226A: KAO Optical Upper Limit
  87. GRB 250226A: AbAO AS-32 Optical Upper Limit
  88. EP250227a: Global MASTER-Net observations report
  89. EP250223A: Upper limits from Fermi-GBM Observations
  90. EP250227a: TRT optical upper limit
  91. GRB 250225B: VLT/HAWKI near-infrared observations
  92. EP250227a: Optical upper limits with Kinder observations
  93. EP250227a: NOT optical observations
  94. EP250227a: Einstein Probe detected of a fast X-ray transient
  95. EP250228a: updates on the EP observations
  96. GRB 250226A: Fermi GBM Observation
  97. EP250223a: J band upper limit by SYSU 80cm telescope
  98. EP250228a: Swift/XRT localisation
  99. EP250228a: Einstein Probe detection of an X-ray transient
  100. GRB 250226A / EP250226a: LCO detection of the afterglow

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