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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"

20391 results found.

  1. EP250324A: COLIBRÍ/DDRAGO Optical Observations
  2. FRB 250316A: COLIBRÍ/DDRAGO Optical follow up of the X ray source EP J120944.2+585060
  3. GRB 250321B: Swift-XRT observations
  4. EP250321a: TNOT Observation of Optical Counterpart
  5. FRB 250316A: DDOTI Continued Optical Observations (Third Epoch)
  6. GRB 250322A: VLT optical observations
  7. GRB 250322A: VLT near-infrared observations
  8. FRB 250316A: DDOTI Continued Optical Observations
  9. GRB 250322A: NOT optical upper limits
  10. GRB 250322A: Enhanced Swift-XRT position
  11. GRB 250321B: SVOM/COLIBRÍ (F-GFT) follow-up observations
  12. FRB 20250316A: Kinder optical upper limits of the Einstein Probe candidate X-ray source EP J120944.2+585060
  13. EP250321a: Liverpool Telescope optical follow-up
  14. EP250321a: Mondy AZT-33IK Optical Observations
  15. GRB 250322A: Swift detection of a short burst
  16. FRB 20250316A: detection of a candidate associated X-ray source EP J120944.2+585060 by Einstein Probe
  17. EP250321a: refined analysis of the EP-WXT and EP-FXT observations
  18. EP250321a: KAIT optical observations
  19. EP250321A: COLIBRÍ Continuing Optical Observations
  20. EP250321a: WFST optical observations
  21. EP250321a: Xinglong 216 decaying optical observations
  22. GRB 250321A: Swift-XRT refined Analysis
  23. EP 250321A: Optical counterpart detection by LCO.
  24. EP250321a: Kinder optical follow-up observations
  25. GRB 250321A: Swift/UVOT Upper Limits
  26. GRB 250320B: SVOM/GRM observation of a long burst
  27. EP250321a: LCO optical counterpart detection
  28. EP250321A: COLIBRÍ Optical Observations
  29. GRB 250320B: AstroSat CZTI detection
  30. EP250321a: REM optical/NIR afterglow detection
  31. EP250321a: TRT optical counterpart detection
  32. EP250321a: Einstein Probe detection of an X-ray transient
  33. GRB 250321A: GOTO optical upper limits
  34. GRB 250314A: Keck/NIRC2 J-band upper limit
  35. EP250226a/GRB 250226A: KAIT optical observations
  36. GRB 250321A: Swift detection of a burst
  37. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  38. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  39. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  40. EP250302a: VLA observations
  41. LIGO/Virgo/KAGRA S250319bu: Identification of a GW compact binary merger candidate
  42. GRB 250317C: SVOM/GRM observation of a long burst
  43. GRB 250317B: Leavitt Observatory optical upper limit
  44. GRB 250317B: Mondy AZT-33IK Optical Observations
  45. GRB 250317B: NOT optical observations suggest an optical plateau phase
  46. GRB 250317B: OHP/T193 optical observations
  47. GRB250312A: Swift/UVOT Upper Limits
  48. GRB 250317B: REM optical/NIR observations
  49. GRB 250316A: Swift/UVOT Upper Limits
  50. GRB 250314A: REM optical/NIR upper limits
  51. GRB 250316A: AbAO AS-32 Optical Upper Limit
  52. EP 250317B: Fading optical counterpart detection by LCO
  53. GRB 250316A: Swift-XRT afterglow detection
  54. GRB 250317B: LCO detection of the fading optical afterglow
  55. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  56. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  57. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  58. GRB 250317B: SVOM detection of a burst
  59. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  60. GRB 250314A: Swift/UVOT Upper Limits
  61. GRB 250314A: Swift XRT Detection
  62. EP250315a: optical counterpart candidate detected by Gemini North
  63. GRB 250314A: VLT/X-shooter dropout, redshift z ~ 7.3
  64. EP250315a: Einstein Probe detection of an X-ray transient
  65. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  66. SVOM/MXT upper limit on GRB 250314A
  67. GRB 250314A: SVOM/VT upper limit
  68. GRB 250314A: NOT near-infrared candidate counterpart
  69. GRB 250313A: Fermi GBM Detection
  70. GRB 250313A: Swift-XRT observations
  71. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  72. Konus-Wind detection of GRB 250313A
  73. GRB 250314A: SVOM detection of a burst
  74. EP250304a: Pan-STARRS r and i-band imaging and photometry
  75. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  76. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  77. GRB 250312A: Enhanced Swift-XRT position
  78. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  79. GRB 250312A: Swift detection of a burst
  80. GRB 241213A: VIRT Optical Upper Limit
  81. GRB 241228A: VIRT Optical Upper Limit
  82. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  83. GRB 250311A: Swift-XRT observations
  84. GRB 250309B: 1.3m DFOT Optical observations
  85. IceCube-250309A: Upper limits from a search for additional neutrino events in IceCube
  86. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  87. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  88. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  89. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  90. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  91. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  92. GRB 250309B: PRIME near-infrared detection
  93. GRB 250225B: Swift-BAT refined analysis
  94. GRB 250311A/EP250311a: TRT optical upper limit
  95. IceCube-250309A: MITSuME Akeno and Seimei/TriCCS optical observations
  96. EP250311a/GRB 250311A: EP-WXT detection
  97. GRB 250309B / AT2025dws: further SAO RAS optical observations
  98. EP250308a: 1.6m Mephisto optical upper limits
  99. IPN triangulation of GRB 250308A (short)
  100. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart

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