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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.

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

32717 results found.

  1. GRB 250327B: GOTO optical counterpart detection
  2. GRB 250327B: SVOM/VT optically bright counterpart
  3. GRB 250327B: SAO RAS optical candidate
  4. FRB 20250316A: Gemini Imaging and Spectroscopy of the Sub-arcsecond Localization Region of FRB 20250316A
  5. GRB 250327A: J-band observations with WINTER
  6. GRB 250327A: SVOM/VT optical candidate
  7. FRB 20250316A: Pan-STARRS r and i-band imaging and photometry
  8. GRB 250327A: Fermi GBM observation
  9. Fermi GRB 250327A: Global MASTER-Net observations report
  10. Swift GRB 250327A: Global MASTER-Net observations report
  11. GRB 250327A: DDOTI Optical Observations
  12. GRB 250327A: COLIBRÍ optical upper limit
  13. GRB 250327A: Swift detection of a burst
  14. LIGO/Virgo/KAGRA S250326y: Updated Sky localization
  15. Konus-Wind detection of GRB 250322A (short)
  16. IPN triangulation of GRB 250322B
  17. LIGO/Virgo/KAGRA S250326y: Identification of a GW compact binary merger candidate
  18. EP250321a: Mondy AZT-33IK Continued Optical Observations
  19. GRB 250322A: third epoch of NOT optical observations
  20. GRB 250322A: Swift-BAT refined analysis
  21. GRB 250321B: ISON-Kitab RC-36 Optical Upper Limit
  22. FRB 250316A: NOT optical upper limit for the X ray source EP J120944.2+585060
  23. GRB 250322A: further NOT optical observations
  24. EP-WXT trigger 01709133021: Optical upper limit through Kinder observations
  25. GRB 250322A: Swift/UVOT Upper Limits
  26. GRB 250322A: VLT/X-shooter redshift confirmation of the putative host galaxy
  27. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  28. GRB 250322B: NuSTAR detection of the prompt emission and regular dips during the burst
  29. EP250321a: TNOT Observation of Optical Counterpart
  30. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  31. GRB 250322A: Gemini-North redshift of candidate host galaxy
  32. EP250304a: VLT/MUSE spectroscopic observation of its associated supernova SN 2025fhm
  33. GRB 250322A: AstroSat CZTI detection of a short burst
  34. GRB250322A: STEP/T80S optical limits
  35. GRB 250322A: Gemini-South optical observations
  36. GRB 250322A: VLT optical observations
  37. GRB 250322A: VLT near-infrared observations
  38. FRB 250316A: DDOTI Continued Optical Observations
  39. GRB 250322A: NOT optical upper limits
  40. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  41. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  42. GRB 250322A: MASTER optical observation
  43. EP250321a: Liverpool Telescope optical follow-up
  44. EP250321a: Mondy AZT-33IK Optical Observations
  45. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  46. EP250321a: KAIT optical observations
  47. EP250321A: COLIBRÍ Continuing Optical Observations
  48. GRB 250225B: GECAM-A detection
  49. GRB 250312A: GECAM-A detection
  50. GRB 250321B: Swift ToO observations
  51. EP250321a: WFST optical observations
  52. GRB 250320B: NuSTAR detection of the prompt emission from two broad bursts and preliminary analysis
  53. GRB 250320A: NuSTAR Detection of the Prompt Emission and Preliminary Results
  54. GRB 250320B: Fermi GBM Observation
  55. EP250321a: Xinglong 216 decaying optical observations
  56. GRB 250321A: Swift-BAT refined analysis
  57. GRB 250320B: Fermi-LAT detection
  58. EP250321a: SVOM/VT optical observation
  59. EP 250321A: Optical counterpart detection by LCO.
  60. EP250321a: Kinder optical follow-up observations
  61. GRB 250321A: Swift/UVOT Upper Limits
  62. GRB 250320B: SVOM/GRM observation of a long burst
  63. EP250321a: LCO optical counterpart detection
  64. EP250321a: Swift-XRT detection of an X-ray source
  65. EP250321A: COLIBRÍ Optical Observations
  66. EP250321a: VLT/X-shooter redshift z = 4.368
  67. GRB 250320B: AstroSat CZTI detection
  68. EP250321a: REM optical/NIR afterglow detection
  69. Fermi GRB 250320B: Global MASTER-Net observations report
  70. EP250321a: TRT optical counterpart detection
  71. EP250321a: Global MASTER-Net observations report
  72. Swift GRB 250321A: Global MASTER-Net observations report
  73. Fermi GRB 250321A: Global MASTER-Net observations report
  74. GRB 250321A: GOTO optical upper limits
  75. GRB 250321A: Swift-XRT localisation
  76. GRB 250314A: Keck/NIRC2 J-band upper limit
  77. EP250226a/GRB 250226A: KAIT optical observations
  78. GRB 250321A: Fermi GBM Observation
  79. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  80. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  81. Fermi GRB 250319B: Global MASTER-Net observations report
  82. GRB 250313A: GRBAlpha detection
  83. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  84. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  85. LIGO/Virgo/KAGRA S250319bu: Updated Sky localization
  86. GRB 250314A: ATCA radio upper limits
  87. EP250302a: VLA observations
  88. GRB 250317B: OHP/T193 continued follow-up
  89. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  90. GRB 250317C: SVOM/GRM observation of a long burst
  91. GRB 250317B: Leavitt Observatory optical upper limit
  92. GRB 250309B/AT2025dws: further ATCA observations
  93. GRB 250317B: Mondy AZT-33IK Optical Observations
  94. GRB 250317C: AstroSat CZTI detection
  95. GRB 250317B: NOT optical observations suggest an optical plateau phase
  96. GRB 250317B: GTC/OSIRIS+ spectroscopic redshift z=3.44
  97. GRB 250317B: OHP/T193 optical observations
  98. GRB250312A: Swift/UVOT Upper Limits
  99. GRB 250317B: REM optical/NIR observations
  100. GRB 250317B: Swift-XRT observations

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