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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"

18513 results found.

  1. EP250321a: TRT optical counterpart detection
  2. EP250321a: Einstein Probe detection of an X-ray transient
  3. GRB 250321A: GOTO optical upper limits
  4. GRB 250314A: Keck/NIRC2 J-band upper limit
  5. EP250226a/GRB 250226A: KAIT optical observations
  6. GRB 250321A: Swift detection of a burst
  7. GRB 250309B: Proof-of-concept for Joint ZTF+EP Experiment
  8. GRB 250317B: Mondy AZT-33IK Continued Optical Observations
  9. LIGO/Virgo/KAGRA S250206dm: LIGHETR followup observations of AT2025azn
  10. GRB 250317B: SVOM/COLIBRI (F-GFT) follow-up observations
  11. GRB 250314A: ATCA radio upper limits
  12. GRB 250317C: SVOM/GRM observation of a long burst
  13. GRB 250317B: Leavitt Observatory optical upper limit
  14. GRB 250309B/AT2025dws: further ATCA observations
  15. GRB 250317B: Mondy AZT-33IK Optical Observations
  16. GRB 250317C: AstroSat CZTI detection
  17. GRB 250317B: NOT optical observations suggest an optical plateau phase
  18. GRB 250317B: OHP/T193 optical observations
  19. GRB250312A: Swift/UVOT Upper Limits
  20. GRB 250317B: REM optical/NIR observations
  21. GRB 250316A: Swift/UVOT Upper Limits
  22. GRB 250314A: REM optical/NIR upper limits
  23. GRB 250316A: AbAO AS-32 Optical Upper Limit
  24. EP 250317B: Fading optical counterpart detection by LCO
  25. GRB 250316A: Swift-XRT afterglow detection
  26. GRB 250317B: LCO detection of the fading optical afterglow
  27. GRB 250317B: SVOM/VT detection of an optical candidate from VHF data
  28. GRB 250317B: SVOM/F-GFT (COLIBRÍ) Detection of a Fading Optical Counterpart
  29. GRB 250317B: SVOM detection of a burst / correction to GRB name of GCN 39752
  30. GRB 250317B: SVOM detection of a burst
  31. GRB 250314A: SVOM/GRM analysis
  32. The EP-WXT trigger 01709132801 is likely a flaring star
  33. GRB 250314A: EP-FXT afterglow detection
  34. EP250315a: refined analysis of the EP-WXT and EP-FXT observations
  35. GRB 250314A: Swift/UVOT Upper Limits
  36. GRB 250314A: Swift XRT Detection
  37. EP250315a: optical counterpart candidate detected by Gemini North
  38. EP250315a: Einstein Probe detection of an X-ray transient
  39. GRB 250226A: Mondy AZT-33IK and Koshka Zeiss-1000 Optical Upper Limits
  40. SVOM/MXT upper limit on GRB 250314A
  41. GRB 250314A: SVOM/VT upper limit
  42. GRB 250314A: NOT near-infrared candidate counterpart
  43. GRB250314A: SVOM/VT lack of bright optical candidate from VHF data
  44. GRB 250314A: SVOM detection of a burst
  45. IceCube-250309A: MASTER detection of J140105.33-091631.6 blazar flare with Zhirkov effect
  46. EP250304a: Pan-STARRS r and i-band imaging and photometry
  47. GRB 250312B: Swift/BAT-GUANO localization skymap of a burst
  48. GRB 250309B: PRIME near-infrared upper limits in 2nd epoch
  49. EP250311a/GRB 250311A: EP-FXT follow-up observation
  50. ATCA detection of the radio counterpart of GRB 250309B-AT2025dws
  51. GRB 250312A: Enhanced Swift-XRT position
  52. GRB 250309B/AT2025dws: Daochen/RC-10 optical counterpart observation
  53. GRB 250312A: Swift detection of a burst
  54. GRB 241213A: VIRT Optical Upper Limit
  55. GRB 241228A: VIRT Optical Upper Limit
  56. GRB 250311A/EP250311a: Optical upper limits with Kinder observations
  57. GRB 250309B: 1.3m DFOT Optical observations
  58. GRB 250308A: Swift/BAT-GUANO localization skymap of a short burst
  59. GRB 250302A: Swift/BAT-GUANO localization skymap of a burst
  60. GRB 250228A: Swift/BAT-GUANO localization skymap of a likely short burst
  61. GRB 250226B: Swift/BAT-GUANO localization skymap of a likely long GRB
  62. GRB 250226A: Swift/BAT-GUANO localization skymap of a long GRB
  63. GRB 250223B: Swift/BAT-GUANO localization skymap of a short burst
  64. GRB 250309B: PRIME near-infrared detection
  65. GRB 250225B: Swift-BAT refined analysis
  66. GRB 250311A/EP250311a: TRT optical upper limit
  67. EP250311a/GRB 250311A: EP-WXT detection
  68. The EP-WXT trigger 01709132425 is not a real source
  69. GRB 250309B / AT2025dws: further SAO RAS optical observations
  70. EP250308a: 1.6m Mephisto optical upper limits
  71. IPN triangulation of GRB 250308A (short)
  72. GRB 250309B/AT2025dws : COLIBRÍ Detection of the Optical Counterpart
  73. GRB 250309B / AT2025dws: SAO RAS optical observations
  74. AT 2025dws, likely optical counterpart of GRB 250309B: LCO confirmation of fast fading
  75. GRB250309B: One candidate counterpart from the Zwicky Transient Facility
  76. IceCube-250309A: No candidates from the Zwicky Transient Facility
  77. IceCube Alert 250309.32: Global MASTER-Net observations report
  78. EP250308a: Global MASTER-Net observations report
  79. EP250308a: Einstein Probe detection of an X-ray transient
  80. EP250308a: NOT optical upper limit
  81. GRB 250309A: Fermi GBM Final Real-time Localization
  82. The EP-WXT trigger 01709132387 is likely a flaring star
  83. EP250304a: MeerKAT detection of a possible radio counterpart
  84. EP250302a:Xinglong optical observations
  85. GRB250101A: Radio upper limits from VLA observations
  86. GRB 250305A: SVOM/GRM observation of a burst
  87. The EP-WXT trigger 01709132323 is likely a flaring star
  88. EP250302a: Optical Observations at CrAO and SAO RAS
  89. GRB 250219A: SVOM/C-GFT optical upper limit at early phase
  90. EP 250304A: Optical counterpart detection by LCO
  91. EP250302A: 1.3m DFOT optical afterglow detection
  92. EP250304a: refined analysis of the EP-WXT and EP-FXT observations
  93. EP250304a: REM NIR upper limits
  94. EP250304a: Swift/UVOT detection of an optical counterpart with a rising light curve
  95. EP250302a: Mondy Continued Optical Observations
  96. EP250304a: TRT optical counterpart detection
  97. EP250304a: Einstein Probe detection of an X-ray transient
  98. LIGO/Virgo/KAGRA S250223dk and Swift/BAT-GUANO ID 762004910: Swift/UVOT Upper Limits
  99. EP250302a: SAO RAS optical observations
  100. EP250302a : GIT optical follow-up

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