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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"

45442 results found.

  1. Fermi GRB 250327A: Global MASTER-Net observations report
  2. Swift GRB 250327A: Global MASTER-Net observations report
  3. GRB 250327A: DDOTI Optical Observations
  4. GRB 250327A: COLIBRÍ optical upper limit
  5. GRB 250327A: Swift detection of a burst
  6. GRB 250327A: Fermi GBM Final Real-time Localization
  7. Fermi trigger No 764700395: Global MASTER-Net observations report
  8. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  9. Konus-Wind detection of GRB 250322A (short)
  10. IPN triangulation of GRB 250322B
  11. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  12. EP250321a: Mondy AZT-33IK Continued Optical Observations
  13. Swift follow-up observations of FRB250316A and EP J120944.2+585060
  14. GRB 250322A: third epoch of NOT optical observations
  15. GRB 250322A: Swift-BAT refined analysis
  16. The EP-WXT trigger 01709133021 (designated as EP250324a) is not a real source
  17. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  18. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  19. GRB 250322A: further NOT optical observations
  20. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  21. GRB 250322A: Swift/UVOT Upper Limits
  22. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  23. GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
  24. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  25. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  26. GRB 250321B: Swift-XRT observations
  27. GRB 250322A: Swift-XRT refined Analysis
  28. EP250321a: TNOT Observation of Optical Counterpart
  29. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  30. GRB 250322A: Gemini-North redshift of candidate host galaxy
  31. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  32. SVOM/sb25032302: SVOM detection of a long X-ray transient
  33. GRB 250322A: AstroSat CZTI detection of a short burst
  34. GRB 250322B: AstroSat CZTI detection of a bright long burst
  35. GRB250322A: STEP/T80S optical limits
  36. GRB 250322A: Gemini-South optical observations
  37. GRB 250322A: VLT optical observations
  38. GRB 250322A: VLT near-infrared observations
  39. FRB 250316A: DDOTI Continued Optical Observations
  40. GRB 250322A: NOT optical upper limits
  41. GRB 250322A: Enhanced Swift-XRT position
  42. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  43. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  44. GRB 250322A: MASTER optical observation
  45. EP250321a: Liverpool Telescope optical follow-up
  46. EP250321a: Mondy AZT-33IK Optical Observations
  47. GRB 250322A: Swift detection of a short burst
  48. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  49. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  50. EP250321a: KAIT optical observations
  51. EP250321A: COLIBRÍ Continuing Optical Observations
  52. GRB 250225B: GECAM-A detection
  53. GRB 250312A: GECAM-A detection
  54. GRB 250321B: Swift ToO observations
  55. EP250321a: WFST optical observations
  56. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  57. GRB 250321C: Fermi GBM Final Real-time Localization
  58. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  59. GRB 250320B: Fermi GBM Observation
  60. EP250321a: Xinglong 216 decaying optical observations
  61. GRB 250321A: Swift-BAT refined analysis
  62. GRB 250321A: Swift-XRT refined Analysis
  63. GRB 250320B: Fermi-LAT detection
  64. GRB 250321B: SVOM detection of a sub-threshold transient event
  65. EP250321a: SVOM/VT optical observation
  66. EP 250321A: Optical counterpart detection by LCO.
  67. EP250321a: Kinder optical follow-up observations
  68. GRB 250321A: Swift/UVOT Upper Limits
  69. GRB 250320B: SVOM/GRM observation of a long burst
  70. EP250321a: LCO optical counterpart detection
  71. EP250321a: Swift-XRT detection of an X-ray source
  72. EP250321A: COLIBRÍ Optical Observations
  73. EP250321a: VLT/X-shooter redshift z = 4.368
  74. GRB 250320B: AstroSat CZTI detection
  75. EP250321a: REM optical/NIR afterglow detection
  76. Fermi GRB 250320B: Global MASTER-Net observations report
  77. EP250321a: BOOTES-5/JGT optical afterglow detection
  78. EP250321a: TRT optical counterpart detection
  79. EP250321a: Global MASTER-Net observations report
  80. Swift GRB 250321A: Global MASTER-Net observations report
  81. Fermi GRB 250321A: Global MASTER-Net observations report
  82. EP250321a: Einstein Probe detection of an X-ray transient
  83. GRB 250321A: GOTO optical upper limits
  84. GRB 250321A: Swift-XRT localisation
  85. GRB 250314A: Keck/NIRC2 J-band upper limit
  86. EP250226a/GRB 250226A: KAIT optical observations
  87. GRB 250321A: Fermi GBM Observation
  88. GRB 250321A: Swift detection of a burst
  89. GRB 250321A: Fermi GBM Final Real-time Localization
  90. GRB 250320B: Fermi GBM Final Real-time Localization
  91. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  92. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  93. GRB 250320A: Fermi GBM Final Real-time Localization
  94. Fermi GRB 250319B: Global MASTER-Net observations report
  95. FRB 20250316A: Upper limits for gamma-ray transient from Insight-HXMT/HE observations
  96. GRB 250313A: GRBAlpha detection
  97. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  98. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  99. GRB 250319B: Fermi GBM Final Localization
  100. GRB 250319A: Fermi GBM Final Localization

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